ast

package
v0.9.2 Latest Latest
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 Go to latest Published: Sep 24, 2018 License: Apache-2.0 Imports: 22 Imported by: 0

Documentation

Overview

Package ast declares Rego syntax tree types and also includes a parser and compiler for preparing policies for execution in the policy engine.

Rego policies are defined using a relatively small set of types: modules, package and import declarations, rules, expressions, and terms. At their core, policies consist of rules that are defined by one or more expressions over documents available to the policy engine. The expressions are defined by intrinsic values (terms) such as strings, objects, variables, etc.

Rego policies are typically defined in text files and then parsed and compiled by the policy engine at runtime. The parsing stage takes the text or string representation of the policy and converts it into an abstract syntax tree (AST) that consists of the types mentioned above. The AST is organized as follows: 

Module
 |
 +--- Package (Reference)
 |
 +--- Imports
 |     |
 |     +--- Import (Term)
 |
 +--- Rules
       |
       +--- Rule
             |
             +--- Head
             |     |
             |     +--- Name (Variable)
             |     |
             |     +--- Key (Term)
             |     |
             |     +--- Value (Term)
             |
             +--- Body
                   |
                   +--- Expression (Term | Terms)

At query time, the policy engine expects policies to have been compiled. The compilation stage takes one or more modules and compiles them into a format that the policy engine supports.

Index

Examples

Constants

View Source 
const (
	// ParseErr indicates an unclassified parse error occurred.
	ParseErr = "rego_parse_error"

	// CompileErr indicates an unclassified compile error occurred.
	CompileErr = "rego_compile_error"

	// TypeErr indicates a type error was caught.
	TypeErr = "rego_type_error"

	// UnsafeVarErr indicates an unsafe variable was found during compilation.
	UnsafeVarErr = "rego_unsafe_var_error"

	// RecursionErr indicates recursion was found during compilation.
	RecursionErr = "rego_recursion_error"
)
View Source 
const (
	// CompleteDoc represents a document that is completely defined by the rule.
	CompleteDoc = iota

	// PartialSetDoc represents a set document that is partially defined by the rule.
	PartialSetDoc = iota

	// PartialObjectDoc represents an object document that is partially defined by the rule.
	PartialObjectDoc = iota
)
View Source 
const CompileErrorLimitDefault = 10

CompileErrorLimitDefault is the default number errors a compiler will allow before exiting.

Variables

View Source 
var Abs = &Builtin{
	Name: "abs",
	Decl: types.NewFunction(
		types.Args(types.N),
		types.N,
	),
}

Abs returns the number without its sign.

View Source 
var All = &Builtin{
	Name: "all",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.A),
				types.NewArray(nil, types.A),
			),
		),
		types.B,
	),
}

All takes a list and returns true if all of the items are true. A collection of length 0 returns true.

View Source 
var And = &Builtin{
	Name:  "and",
	Infix: "&",
	Decl: types.NewFunction(
		types.Args(
			types.NewSet(types.A),
			types.NewSet(types.A),
		),
		types.NewSet(types.A),
	),
}

And performs an intersection operation on sets.

View Source 
var Any = &Builtin{
	Name: "any",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.A),
				types.NewArray(nil, types.A),
			),
		),
		types.B,
	),
}

Any takes a collection and returns true if any of the items is true. A collection of length 0 returns false.

View Source 
var ArrayConcat = &Builtin{
	Name: "array.concat",
	Decl: types.NewFunction(
		types.Args(
			types.NewArray(nil, types.A),
			types.NewArray(nil, types.A),
		),
		types.NewArray(nil, types.A),
	),
}

ArrayConcat returns the result of concatenating two arrays together.

View Source 
var Assign = &Builtin{
	Name:  "assign",
	Infix: ":=",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

Assign represents the assignment (":=") operator.

View Source 
var Base64Decode = &Builtin{
	Name: "base64.decode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

Base64Decode deserializes the base64 encoded input string.

View Source 
var Base64Encode = &Builtin{
	Name: "base64.encode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

Base64Encode serializes the input string into base64 encoding.

View Source 
var Base64UrlDecode = &Builtin{
	Name: "base64url.decode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

Base64UrlDecode deserializes the base64url encoded input string.

View Source 
var Base64UrlEncode = &Builtin{
	Name: "base64url.encode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

Base64UrlEncode serializes the input string into base64url encoding.

View Source 
var BuiltinMap map[string]*Builtin

BuiltinMap provides a convenient mapping of built-in names to built-in definitions.

View Source 
var Builtins []*Builtin

Builtins is the registry of built-in functions supported by OPA. Call RegisterBuiltin to add a new built-in.

View Source 
var CastArray = &Builtin{
	Name: "cast_array",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.NewArray(nil, types.A),
	),
}

CastArray checks the underlying type of the input. If it is array or set, an array containing the values is returned. If it is not an array, an error is thrown.

View Source 
var CastBoolean = &Builtin{
	Name: "cast_boolean",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.B,
	),
}

CastBoolean returns input if it is a boolean; if not returns error.

View Source 
var CastNull = &Builtin{
	Name: "cast_null",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.NewNull(),
	),
}

CastNull returns null if input is null; if not returns error.

View Source 
var CastObject = &Builtin{
	Name: "cast_object",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.NewObject(nil, types.NewDynamicProperty(types.A, types.A)),
	),
}

CastObject returns the given object if it is null; throws an error otherwise

View Source 
var CastSet = &Builtin{
	Name: "cast_set",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.NewSet(types.A),
	),
}

CastSet checks the underlying type of the input. If it is a set, the set is returned. If it is an array, the array is returned in set form (all duplicates removed) If neither, an error is thrown

View Source 
var CastString = &Builtin{
	Name: "cast_string",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.S,
	),
}

CastString returns input if it is a string; if not returns error. For formatting variables, see sprintf

View Source 
var Clock = &Builtin{
	Name: "time.clock",
	Decl: types.NewFunction(
		types.Args(types.N),
		types.NewArray([]types.Type{types.N, types.N, types.N}, nil),
	),
}

Clock returns the [hour, minute, second] of the day for the nanoseconds since epoch.

View Source 
var Concat = &Builtin{
	Name: "concat",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.NewAny(
				types.NewSet(types.S),
				types.NewArray(nil, types.S),
			),
		),
		types.S,
	),
}

Concat joins an array of strings with an input string.

View Source 
var Contains = &Builtin{
	Name: "contains",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

Contains returns true if the search string is included in the base string

View Source 
var Count = &Builtin{
	Name: "count",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.A),
				types.NewArray(nil, types.A),
				types.NewObject(nil, types.NewDynamicProperty(types.A, types.A)),
				types.S,
			),
		),
		types.N,
	),
}

Count takes a collection or string and counts the number of elements in it.

View Source 
var CryptoX509ParseCertificates = &Builtin{
	Name: "crypto.x509.parse_certificates",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.NewArray(nil, types.NewObject(nil, types.NewDynamicProperty(types.S, types.A))),
	),
}

CryptoX509ParseCertificates returns one or more certificates from the given base64 encoded string containing DER encoded certificates that have been concatenated.

View Source 
var Date = &Builtin{
	Name: "time.date",
	Decl: types.NewFunction(
		types.Args(types.N),
		types.NewArray([]types.Type{types.N, types.N, types.N}, nil),
	),
}

Date returns the [year, month, day] for the nanoseconds since epoch.

View Source 
var DefaultBuiltins = [...]*Builtin{

	Equality,

	Assign,

	GreaterThan,
	GreaterThanEq,
	LessThan,
	LessThanEq,
	NotEqual,
	Equal,

	Plus,
	Minus,
	Multiply,
	Divide,
	Round,
	Abs,
	Rem,

	And,
	Or,

	Count,
	Sum,
	Product,
	Max,
	Min,
	Any,
	All,

	ArrayConcat,

	ToNumber,
	CastObject,
	CastNull,
	CastBoolean,
	CastString,
	CastSet,
	CastArray,

	RegexMatch,
	RegexSplit,
	GlobsMatch,
	RegexTemplateMatch,

	SetDiff,
	Intersection,
	Union,

	Concat,
	FormatInt,
	IndexOf,
	Substring,
	Lower,
	Upper,
	Contains,
	StartsWith,
	EndsWith,
	Split,
	Replace,
	Trim,
	Sprintf,

	JSONMarshal,
	JSONUnmarshal,
	Base64Encode,
	Base64Decode,
	Base64UrlEncode,
	Base64UrlDecode,
	URLQueryDecode,
	URLQueryEncode,
	URLQueryEncodeObject,
	YAMLMarshal,
	YAMLUnmarshal,

	JWTDecode,
	JWTVerifyRS256,
	JWTVerifyPS256,
	JWTVerifyES256,
	JWTVerifyHS256,

	NowNanos,
	ParseNanos,
	ParseRFC3339Nanos,
	ParseDurationNanos,
	Date,
	Clock,
	Weekday,

	CryptoX509ParseCertificates,

	WalkBuiltin,

	Sort,

	IsNumber,
	IsString,
	IsBoolean,
	IsArray,
	IsSet,
	IsObject,
	IsNull,
	TypeNameBuiltin,

	HTTPSend,

	RegoParseModule,

	Trace,

	NetCIDROverlap,
}

DefaultBuiltins is the registry of built-in functions supported in OPA by default. When adding a new built-in function to OPA, update this list.

View Source 
var DefaultRootDocument = VarTerm("data")

DefaultRootDocument is the default root document.

All package directives inside source files are implicitly prefixed with the DefaultRootDocument value.

View Source 
var DefaultRootRef = Ref{DefaultRootDocument}

DefaultRootRef is a reference to the root of the default document.

All refs to data in the policy engine's storage layer are prefixed with this ref.

View Source 
var Divide = &Builtin{
	Name:  "div",
	Infix: "/",
	Decl: types.NewFunction(
		types.Args(types.N, types.N),
		types.N,
	),
}

Divide divides the first number by the second number.

View Source 
var EndsWith = &Builtin{
	Name: "endswith",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

EndsWith returns true if the search string begins with the base string

View Source 
var Equal = &Builtin{
	Name:  "equal",
	Infix: "==",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

Equal represents the "==" comparison operator.

View Source 
var Equality = &Builtin{
	Name:  "eq",
	Infix: "=",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

Equality represents the "=" operator.

View Source 
var FormatInt = &Builtin{
	Name: "format_int",
	Decl: types.NewFunction(
		types.Args(
			types.N,
			types.N,
		),
		types.S,
	),
}

FormatInt returns the string representation of the number in the given base after converting it to an integer value.

View Source 
var GlobsMatch = &Builtin{
	Name: "regex.globs_match",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

GlobsMatch takes two strings regexp-style strings and evaluates to true if their intersection matches a non-empty set of non-empty strings. Examples:

  • "a.a." and ".b.b" -> true.
  • "[a-z]*" and [0-9]+" -> not true.
View Source 
var GreaterThan = &Builtin{
	Name:  "gt",
	Infix: ">",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

GreaterThan represents the ">" comparison operator.

View Source 
var GreaterThanEq = &Builtin{
	Name:  "gte",
	Infix: ">=",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

GreaterThanEq represents the ">=" comparison operator.

View Source 
var HTTPSend = &Builtin{
	Name: "http.send",
	Decl: types.NewFunction(
		types.Args(
			types.NewObject(nil, types.NewDynamicProperty(types.S, types.A)),
		),
		types.NewObject(nil, types.NewDynamicProperty(types.A, types.A)),
	),
}

HTTPSend returns a HTTP response to the given HTTP request.

View Source 
var IgnoreDuringPartialEval = []*Builtin{
	NowNanos,
	HTTPSend,
}

IgnoreDuringPartialEval is a set of built-in functions that should not be evaluated during partial evaluation. These functions are not partially evaluated because they are not pure.

View Source 
var IndexOf = &Builtin{
	Name: "indexof",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.N,
	),
}

IndexOf returns the index of a substring contained inside a string

View Source 
var InputRootDocument = VarTerm("input")

InputRootDocument names the document containing query arguments.

View Source 
var InputRootRef = Ref{InputRootDocument}

InputRootRef is a reference to the root of the input document.

All refs to query arguments are prefixed with this ref.

View Source 
var Intersection = &Builtin{
	Name: "intersection",
	Decl: types.NewFunction(
		types.Args(
			types.NewSet(types.NewSet(types.A)),
		),
		types.NewSet(types.A),
	),
}

Intersection returns the intersection of the given input sets

View Source 
var IsArray = &Builtin{
	Name: "is_array",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsArray returns true if the input value is an array.

View Source 
var IsBoolean = &Builtin{
	Name: "is_boolean",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsBoolean returns true if the input value is a boolean.

View Source 
var IsNull = &Builtin{
	Name: "is_null",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsNull returns true if the input value is null.

View Source 
var IsNumber = &Builtin{
	Name: "is_number",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsNumber returns true if the input value is a number

View Source 
var IsObject = &Builtin{
	Name: "is_object",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsObject returns true if the input value is an object.

View Source 
var IsSet = &Builtin{
	Name: "is_set",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsSet returns true if the input value is a set.

View Source 
var IsString = &Builtin{
	Name: "is_string",
	Decl: types.NewFunction(
		types.Args(
			types.A,
		),
		types.B,
	),
}

IsString returns true if the input value is a string.

View Source 
var JSONMarshal = &Builtin{
	Name: "json.marshal",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.S,
	),
}

JSONMarshal serializes the input term.

View Source 
var JSONUnmarshal = &Builtin{
	Name: "json.unmarshal",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.A,
	),
}

JSONUnmarshal deserializes the input string.

View Source 
var JWTDecode = &Builtin{
	Name: "io.jwt.decode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.NewArray([]types.Type{
			types.NewObject(nil, types.NewDynamicProperty(types.A, types.A)),
			types.NewObject(nil, types.NewDynamicProperty(types.A, types.A)),
			types.S,
		}, nil),
	),
}

JWTDecode decodes a JSON Web Token and outputs it as an Object.

View Source 
var JWTVerifyES256 = &Builtin{
	Name: "io.jwt.verify_es256",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

JWTVerifyES256 verifies if a ES256 JWT signature is valid or not.

View Source 
var JWTVerifyHS256 = &Builtin{
	Name: "io.jwt.verify_hs256",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

JWTVerifyHS256 verifies if a HS256 (secret) JWT signature is valid or not.

View Source 
var JWTVerifyPS256 = &Builtin{
	Name: "io.jwt.verify_ps256",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

JWTVerifyPS256 verifies if a PS256 JWT signature is valid or not.

View Source 
var JWTVerifyRS256 = &Builtin{
	Name: "io.jwt.verify_rs256",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

JWTVerifyRS256 verifies if a RS256 JWT signature is valid or not.

View Source 
var Keywords = [...]string{
	"not",
	"package",
	"import",
	"as",
	"default",
	"else",
	"with",
	"null",
	"true",
	"false",
}

Keywords contains strings that map to language keywords.

View Source 
var LessThan = &Builtin{
	Name:  "lt",
	Infix: "<",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

LessThan represents the "<" comparison operator.

View Source 
var LessThanEq = &Builtin{
	Name:  "lte",
	Infix: "<=",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

LessThanEq represents the "<=" comparison operator.

View Source 
var Lower = &Builtin{
	Name: "lower",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

Lower returns the input string but with all characters in lower-case

View Source 
var Max = &Builtin{
	Name: "max",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.A),
				types.NewArray(nil, types.A),
			),
		),
		types.A,
	),
}

Max returns the maximum value in a collection.

View Source 
var Min = &Builtin{
	Name: "min",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.A),
				types.NewArray(nil, types.A),
			),
		),
		types.A,
	),
}

Min returns the minimum value in a collection.

View Source 
var Minus = &Builtin{
	Name:  "minus",
	Infix: "-",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(types.N, types.NewSet(types.A)),
			types.NewAny(types.N, types.NewSet(types.A)),
		),
		types.NewAny(types.N, types.NewSet(types.A)),
	),
}

Minus subtracts the second number from the first number or computes the diff between two sets.

View Source 
var Multiply = &Builtin{
	Name:  "mul",
	Infix: "*",
	Decl: types.NewFunction(
		types.Args(types.N, types.N),
		types.N,
	),
}

Multiply multiplies two numbers together.

View Source 
var NetCIDROverlap = &Builtin{
	Name: "net.cidr_overlap",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

NetCIDROverlap checks if an ip overlaps with cidr and returns true or false

View Source 
var NotEqual = &Builtin{
	Name:  "neq",
	Infix: "!=",
	Decl: types.NewFunction(
		types.Args(types.A, types.A),
		types.B,
	),
}

NotEqual represents the "!=" comparison operator.

View Source 
var NowNanos = &Builtin{
	Name: "time.now_ns",
	Decl: types.NewFunction(
		nil,
		types.N,
	),
}

NowNanos returns the current time since epoch in nanoseconds.

View Source 
var Or = &Builtin{
	Name:  "or",
	Infix: "|",
	Decl: types.NewFunction(
		types.Args(
			types.NewSet(types.A),
			types.NewSet(types.A),
		),
		types.NewSet(types.A),
	),
}

Or performs a union operation on sets.

View Source 
var ParseDurationNanos = &Builtin{
	Name: "time.parse_duration_ns",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.N,
	),
}

ParseDurationNanos returns the duration in nanoseconds represented by a duration string. Duration string is similar to the Go time.ParseDuration string

View Source 
var ParseNanos = &Builtin{
	Name: "time.parse_ns",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.N,
	),
}

ParseNanos returns the time in nanoseconds parsed from the string in the given format.

View Source 
var ParseRFC3339Nanos = &Builtin{
	Name: "time.parse_rfc3339_ns",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.N,
	),
}

ParseRFC3339Nanos returns the time in nanoseconds parsed from the string in RFC3339 format.

View Source 
var Plus = &Builtin{
	Name:  "plus",
	Infix: "+",
	Decl: types.NewFunction(
		types.Args(types.N, types.N),
		types.N,
	),
}

Plus adds two numbers together.

View Source 
var Product = &Builtin{
	Name: "product",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.N),
				types.NewArray(nil, types.N),
			),
		),
		types.N,
	),
}

Product takes an array or set of numbers and multiplies them.

View Source 
var RegexMatch = &Builtin{
	Name: "re_match",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

RegexMatch takes two strings and evaluates to true if the string in the second position matches the pattern in the first position.

View Source 
var RegexSplit = &Builtin{
	Name: "regex.split",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.NewArray(nil, types.S),
	),
}

RegexSplit splits the input string by the occurences of the given pattern.

View Source 
var RegexTemplateMatch = &Builtin{
	Name: "regex.template_match",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
			types.S,
			types.S,
		),
		types.B,
	),
}

RegexTemplateMatch takes two strings and evaluates to true if the string in the second position matches the pattern in the first position.

View Source 
var RegoParseModule = &Builtin{
	Name: "rego.parse_module",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.NewObject(nil, types.NewDynamicProperty(types.S, types.A)),
	),
}

RegoParseModule parses the input Rego file and returns a JSON representation of the AST.

View Source 
var Rem = &Builtin{
	Name:  "rem",
	Infix: "%",
	Decl: types.NewFunction(
		types.Args(types.N, types.N),
		types.N,
	),
}

Rem returns the remainder for x%y for y != 0.

View Source 
var Replace = &Builtin{
	Name: "replace",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
			types.S,
		),
		types.S,
	),
}

Replace returns the given string with all instances of the second argument replaced by the third.

View Source 
var ReservedVars = NewVarSet(
	DefaultRootDocument.Value.(Var),
	InputRootDocument.Value.(Var),
)

ReservedVars is the set of names that refer to implicitly ground vars.

View Source 
var RootDocumentNames = NewSet(
	DefaultRootDocument,
	InputRootDocument,
)

RootDocumentNames contains the names of top-level documents that can be referred to in modules and queries.

View Source 
var RootDocumentRefs = NewSet(
	NewTerm(DefaultRootRef),
	NewTerm(InputRootRef),
)

RootDocumentRefs contains the prefixes of top-level documents that all non-local references start with.

View Source 
var Round = &Builtin{
	Name: "round",
	Decl: types.NewFunction(
		types.Args(types.N),
		types.N,
	),
}

Round rounds the number up to the nearest integer.

View Source 
var SetDiff = &Builtin{
	Name: "set_diff",
	Decl: types.NewFunction(
		types.Args(
			types.NewSet(types.A),
			types.NewSet(types.A),
		),
		types.NewSet(types.A),
	),
}

SetDiff has been replaced by the minus built-in.

View Source 
var Sort = &Builtin{
	Name: "sort",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewArray(nil, types.A),
				types.NewSet(types.A),
			),
		),
		types.NewArray(nil, types.A),
	),
}

Sort returns a sorted array.

View Source 
var Split = &Builtin{
	Name: "split",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.NewArray(nil, types.S),
	),
}

Split returns an array containing elements of the input string split on a delimiter.

View Source 
var Sprintf = &Builtin{
	Name: "sprintf",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.NewArray(nil, types.A),
		),
		types.S,
	),
}

Sprintf returns the given string, formatted.

View Source 
var StartsWith = &Builtin{
	Name: "startswith",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.B,
	),
}

StartsWith returns true if the search string begins with the base string

View Source 
var Substring = &Builtin{
	Name: "substring",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.N,
			types.N,
		),
		types.S,
	),
}

Substring returns the portion of a string for a given start index and a length. 

If the length is less than zero, then substring returns the remainder of the string.
View Source 
var Sum = &Builtin{
	Name: "sum",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.NewSet(types.N),
				types.NewArray(nil, types.N),
			),
		),
		types.N,
	),
}

Sum takes an array or set of numbers and sums them.

View Source 
var SystemDocumentKey = String("system")

SystemDocumentKey is the name of the top-level key that identifies the system document.

View Source 
var ToNumber = &Builtin{
	Name: "to_number",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.N,
				types.S,
				types.B,
				types.NewNull(),
			),
		),
		types.N,
	),
}

ToNumber takes a string, bool, or number value and converts it to a number. Strings are converted to numbers using strconv.Atoi. Boolean false is converted to 0 and boolean true is converted to 1.

View Source 
var Trace = &Builtin{
	Name: "trace",
	Decl: types.NewFunction(
		types.Args(
			types.S,
		),
		types.B,
	),
}

Trace prints a note that is included in the query explanation.

View Source 
var Trim = &Builtin{
	Name: "trim",
	Decl: types.NewFunction(
		types.Args(
			types.S,
			types.S,
		),
		types.S,
	),
}

Trim returns the given string will all leading or trailing instances of the second argument removed.

View Source 
var TypeNameBuiltin = &Builtin{
	Name: "type_name",
	Decl: types.NewFunction(
		types.Args(
			types.NewAny(
				types.A,
			),
		),
		types.S,
	),
}

TypeNameBuiltin returns the type of the input.

View Source 
var URLQueryDecode = &Builtin{
	Name: "urlquery.decode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

URLQueryDecode decodes a URL encoded input string.

View Source 
var URLQueryEncode = &Builtin{
	Name: "urlquery.encode",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

URLQueryEncode encodes the input string into a URL encoded string.

View Source 
var URLQueryEncodeObject = &Builtin{
	Name: "urlquery.encode_object",
	Decl: types.NewFunction(
		types.Args(
			types.NewObject(
				nil,
				types.NewDynamicProperty(
					types.S,
					types.NewAny(
						types.S,
						types.NewArray(nil, types.S),
						types.NewSet(types.S))))),
		types.S,
	),
}

URLQueryEncodeObject encodes the given JSON into a URL encoded query string.

View Source 
var Union = &Builtin{
	Name: "union",
	Decl: types.NewFunction(
		types.Args(
			types.NewSet(types.NewSet(types.A)),
		),
		types.NewSet(types.A),
	),
}

Union returns the union of the given input sets

View Source 
var Upper = &Builtin{
	Name: "upper",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.S,
	),
}

Upper returns the input string but with all characters in upper-case

View Source 
var WalkBuiltin = &Builtin{
	Name:     "walk",
	Relation: true,
	Decl: types.NewFunction(
		types.Args(types.A),
		types.NewArray(
			[]types.Type{
				types.NewArray(nil, types.A),
				types.A,
			},
			nil,
		),
	),
}

WalkBuiltin generates [path, value] tuples for all nested documents (recursively).

View Source 
var Weekday = &Builtin{
	Name: "time.weekday",
	Decl: types.NewFunction(
		types.Args(types.N),
		types.S,
	),
}

Weekday returns the day of the week (Monday, Tuesday, ...) for the nanoseconds since epoch.

View Source 
var Wildcard = &Term{Value: Var("_")}

Wildcard represents the wildcard variable as defined in the language.

View Source 
var WildcardPrefix = "$"

WildcardPrefix is the special character that all wildcard variables are prefixed with when the statement they are contained in is parsed.

View Source 
var YAMLMarshal = &Builtin{
	Name: "yaml.marshal",
	Decl: types.NewFunction(
		types.Args(types.A),
		types.S,
	),
}

YAMLMarshal serializes the input term.

View Source 
var YAMLUnmarshal = &Builtin{
	Name: "yaml.unmarshal",
	Decl: types.NewFunction(
		types.Args(types.S),
		types.A,
	),
}

YAMLUnmarshal deserializes the input string.

Functions

func Compare added in v0.2.0 

func Compare(a, b interface{}) int

Compare returns an integer indicating whether two AST values are less than, equal to, or greater than each other.

If a is less than b, the return value is negative. If a is greater than b, the return value is positive. If a is equal to b, the return value is zero.

Different types are never equal to each other. For comparison purposes, types are sorted as follows:

nil < Null < Boolean < Number < String < Var < Ref < Array < Object < Set < ArrayComprehension < Expr < Body < Rule < Import < Package < Module.

Arrays and Refs are equal iff both a and b have the same length and all corresponding elements are equal. If one element is not equal, the return value is the same as for the first differing element. If all elements are equal but a and b have different lengths, the shorter is considered less than the other.

Objects are considered equal iff both a and b have the same sorted (key, value) pairs and are of the same length. Other comparisons are consistent but not defined.

Sets are considered equal iff the symmetric difference of a and b is empty. Other comparisons are consistent but not defined.

func ContainsComprehensions added in v0.5.8 

func ContainsComprehensions(v interface{}) bool

ContainsComprehensions returns true if the Value v contains comprehensions.

func ContainsRefs added in v0.5.8 

func ContainsRefs(v interface{}) bool

ContainsRefs returns true if the Value v contains refs.

func IsComprehension added in v0.5.11 

func IsComprehension(x Value) bool

IsComprehension returns true if the supplied value is a comprehension.

func IsConstant added in v0.4.9 

func IsConstant(v Value) bool

IsConstant returns true if the AST value is constant.

func IsError added in v0.4.0 

func IsError(code string, err error) bool

IsError returns true if err is an AST error with code.

func IsKeyword added in v0.2.2 

func IsKeyword(s string) bool

IsKeyword returns true if s is a language keyword.

func IsScalar added in v0.2.0 

func IsScalar(v Value) bool

IsScalar returns true if the AST value is a scalar.

func IsUnknownValueErr added in v0.9.0 

func IsUnknownValueErr(err error) bool

IsUnknownValueErr returns true if the err is an UnknownValueErr.

func IsValidImportPath added in v0.3.0 

func IsValidImportPath(v Value) (err error)

IsValidImportPath returns an error indicating if the import path is invalid. If the import path is invalid, err is nil.

func JSON added in v0.4.9 

func JSON(v Value) (interface{}, error)

JSON returns the JSON representation of v. The value must not contain any refs or terms that require evaluation (e.g., vars, comprehensions, etc.)

func Parse 

func Parse(filename string, b []byte, opts ...Option) (interface{}, error)

Parse parses the data from b using filename as information in the error messages.

func ParseFile 

func ParseFile(filename string, opts ...Option) (i interface{}, err error)

ParseFile parses the file identified by filename.

func ParseReader 

func ParseReader(filename string, r io.Reader, opts ...Option) (interface{}, error)

ParseReader parses the data from r using filename as information in the error messages.

func ParseStatements 

func ParseStatements(filename, input string) ([]Statement, []*Comment, error)

ParseStatements returns a slice of parsed statements. This is the default return value from the parser.

func Pretty added in v0.7.0 

func Pretty(w io.Writer, x interface{})

Pretty writes a pretty representation of the AST rooted at x to w.

This is function is intended for debug purposes when inspecting ASTs.

func RegisterBuiltin 

func RegisterBuiltin(b *Builtin)

RegisterBuiltin adds a new built-in function to the registry.

func Transform added in v0.2.0 

func Transform(t Transformer, x interface{}) (interface{}, error)

Transform iterates the AST and calls the Transform function on the Transformer t for x before recursing.

func TransformComprehensions added in v0.5.8 

func TransformComprehensions(x interface{}, f func(interface{}) (Value, error)) (interface{}, error)

TransformComprehensions calls the functio nf on all comprehensions under x.

func TransformRefs added in v0.2.0 

func TransformRefs(x interface{}, f func(Ref) (Value, error)) (interface{}, error)

TransformRefs calls the function f on all references under x.

func TransformVars added in v0.7.0 

func TransformVars(x interface{}, f func(Var) (Value, error)) (interface{}, error)

TransformVars calls the function f on all vars under x.

func TypeName added in v0.3.0 

func TypeName(x interface{}) string

TypeName returns a human readable name for the AST element type.

func ValueToInterface added in v0.4.9 

func ValueToInterface(v Value, resolver Resolver) (interface{}, error)

ValueToInterface returns the Go representation of an AST value. The AST value should not contain any values that require evaluation (e.g., vars, comprehensions, etc.)

func Walk 

func Walk(v Visitor, x interface{})

Walk iterates the AST by calling the Visit function on the Visitor v for x before recursing.

func WalkBeforeAndAfter added in v0.7.0 

func WalkBeforeAndAfter(v BeforeAndAfterVisitor, x interface{})

WalkBeforeAndAfter iterates the AST by calling the Visit function on the Visitor v for x before recursing.

func WalkBodies added in v0.2.0 

func WalkBodies(x interface{}, f func(Body) bool)

WalkBodies calls the function f on all bodies under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkClosures 

func WalkClosures(x interface{}, f func(interface{}) bool)

WalkClosures calls the function f on all closures under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkExprs added in v0.4.9 

func WalkExprs(x interface{}, f func(*Expr) bool)

WalkExprs calls the function f on all expressions under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkNodes added in v0.9.2 

func WalkNodes(x interface{}, f func(Node) bool)

WalkNodes calls the function f on all nodes under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkRefs 

func WalkRefs(x interface{}, f func(Ref) bool)

WalkRefs calls the function f on all references under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkRules added in v0.4.10 

func WalkRules(x interface{}, f func(*Rule) bool)

WalkRules calls the function f on all rules under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkTerms added in v0.7.0 

func WalkTerms(x interface{}, f func(*Term) bool)

WalkTerms calls the function f on all terms under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkVars added in v0.2.1 

func WalkVars(x interface{}, f func(Var) bool)

WalkVars calls the function f on all vars under x. If the function f returns true, AST nodes under the last node will not be visited.

func WalkWiths added in v0.4.1 

func WalkWiths(x interface{}, f func(*With) bool)

WalkWiths calls the function f on all with modifiers under x. If the function f returns true, AST nodes under the last node will not be visited.

Types

type ArgErrDetail added in v0.4.9 

type ArgErrDetail struct {
	Have []types.Type `json:"have"`
	Want []types.Type `json:"want"`
}

ArgErrDetail represents a generic argument error.

func (*ArgErrDetail) Lines added in v0.4.9 

func (d *ArgErrDetail) Lines() []string

Lines returns the string representation of the detail.

type Args added in v0.5.0 

type Args []*Term

Args represents zero or more arguments to a rule.

func (Args) Copy added in v0.5.0 

func (a Args) Copy() Args

Copy returns a deep copy of a.

func (Args) Loc added in v0.9.2 

func (a Args) Loc() *Location

Loc returns the Location of a.

func (Args) SetLoc added in v0.9.2 

func (a Args) SetLoc(loc *Location)

SetLoc sets the location on a.

func (Args) String added in v0.5.0 

func (a Args) String() string

func (Args) Vars added in v0.5.9 

func (a Args) Vars() VarSet

Vars returns a set of vars that appear in a.

type Array 

type Array []*Term

Array represents an array as defined by the language. Arrays are similar to the same types as defined by JSON with the exception that they can contain Vars and References.

func (Array) Compare added in v0.5.0 

func (arr Array) Compare(other Value) int

Compare compares arr to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Array) Copy added in v0.2.2 

func (arr Array) Copy() Array

Copy returns a deep copy of arr.

func (Array) Equal 

func (arr Array) Equal(other Value) bool

Equal returns true if arr is equal to other.

func (Array) Find added in v0.4.5 

func (arr Array) Find(path Ref) (Value, error)

Find returns the value at the index or an out-of-range error.

func (Array) Get added in v0.4.9 

func (arr Array) Get(pos *Term) *Term

Get returns the element at pos or nil if not possible.

func (Array) Hash 

func (arr Array) Hash() int

Hash returns the hash code for the Value.

func (Array) IsGround 

func (arr Array) IsGround() bool

IsGround returns true if all of the Array elements are ground.

func (Array) MarshalJSON added in v0.3.0 

func (arr Array) MarshalJSON() ([]byte, error)

MarshalJSON returns JSON encoded bytes representing arr.

func (Array) Sorted added in v0.6.0 

func (arr Array) Sorted() Array

Sorted returns a new Array that contains the sorted elements of arr.

func (Array) String 

func (arr Array) String() string

type ArrayComprehension 

type ArrayComprehension struct {
	Term *Term `json:"term"`
	Body Body  `json:"body"`
}

ArrayComprehension represents an array comprehension as defined in the language.

func (*ArrayComprehension) Compare added in v0.5.0 

func (ac *ArrayComprehension) Compare(other Value) int

Compare compares ac to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (*ArrayComprehension) Copy added in v0.2.2 

func (ac *ArrayComprehension) Copy() *ArrayComprehension

Copy returns a deep copy of ac.

func (*ArrayComprehension) Equal 

func (ac *ArrayComprehension) Equal(other Value) bool

Equal returns true if ac is equal to other.

func (*ArrayComprehension) Find added in v0.4.5 

func (ac *ArrayComprehension) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (*ArrayComprehension) Hash 

func (ac *ArrayComprehension) Hash() int

Hash returns the hash code of the Value.

func (*ArrayComprehension) IsGround 

func (ac *ArrayComprehension) IsGround() bool

IsGround returns true if the Term and Body are ground.

func (*ArrayComprehension) String 

func (ac *ArrayComprehension) String() string

type BeforeAndAfterVisitor added in v0.7.0 

type BeforeAndAfterVisitor interface {
	Visitor
	Before(x interface{})
	After(x interface{})
}

BeforeAndAfterVisitor wraps Visitor to provie hooks for being called before and after the AST has been visited.

type Body 

type Body []*Expr

Body represents one or more expressions contained inside a rule or user function.

func MustParseBody 

func MustParseBody(input string) Body

MustParseBody returns a parsed body. If an error occurs during parsing, panic.

func NewBody added in v0.2.0 

func NewBody(exprs ...*Expr) Body

NewBody returns a new Body containing the given expressions. The indices of the immediate expressions will be reset.

func ParseBody 

func ParseBody(input string) (Body, error)

ParseBody returns exactly one body. If multiple bodies are parsed, an error is returned.

func (*Body) Append added in v0.4.1 

func (body *Body) Append(expr *Expr)

Append adds the expr to the body and updates the expr's index accordingly.

func (Body) Compare added in v0.2.0 

func (body Body) Compare(other Body) int

Compare returns an integer indicating whether body is less than, equal to, or greater than other.

If body is a subset of other, it is considered less than (and vice versa).

func (Body) Contains 

func (body Body) Contains(x *Expr) bool

Contains returns true if this body contains the given expression.

func (Body) Copy added in v0.2.2 

func (body Body) Copy() Body

Copy returns a deep copy of body.

func (Body) Equal 

func (body Body) Equal(other Body) bool

Equal returns true if this Body is equal to the other Body.

func (Body) Hash 

func (body Body) Hash() int

Hash returns the hash code for the Body.

func (Body) IsGround 

func (body Body) IsGround() bool

IsGround returns true if all of the expressions in the Body are ground.

func (Body) Loc 

func (body Body) Loc() *Location

Loc returns the location of the Body in the definition.

func (Body) MarshalJSON added in v0.9.0 

func (body Body) MarshalJSON() ([]byte, error)

MarshalJSON returns JSON encoded bytes representing body.

func (Body) Set added in v0.6.0 

func (body Body) Set(expr *Expr, pos int)

Set sets the expr in the body at the specified position and updates the expr's index accordingly.

func (Body) SetLoc added in v0.9.2 

func (body Body) SetLoc(loc *Location)

SetLoc sets the location on body.

func (Body) String 

func (body Body) String() string

func (Body) Vars 

func (body Body) Vars(params VarVisitorParams) VarSet

Vars returns a VarSet containing variables in body. The params can be set to control which vars are included.

type Boolean 

type Boolean bool

Boolean represents a boolean value defined by JSON.

func (Boolean) Compare added in v0.5.0 

func (bol Boolean) Compare(other Value) int

Compare compares bol to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Boolean) Equal 

func (bol Boolean) Equal(other Value) bool

Equal returns true if the other Value is a Boolean and is equal.

func (Boolean) Find added in v0.4.5 

func (bol Boolean) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (Boolean) Hash 

func (bol Boolean) Hash() int

Hash returns the hash code for the Value.

func (Boolean) IsGround 

func (bol Boolean) IsGround() bool

IsGround always returns true.

func (Boolean) String 

func (bol Boolean) String() string

type Builtin 

type Builtin struct {
	Name     string          // Unique name of built-in function, e.g., <name>(arg1,arg2,...,argN)
	Infix    string          // Unique name of infix operator. Default should be unset.
	Decl     *types.Function // Built-in function type declaration.
	Relation bool            // Indicates if the built-in acts as a relation.
}

Builtin represents a built-in function supported by OPA. Every built-in function is uniquely identified by a name.

func (*Builtin) Call added in v0.7.0 

func (b *Builtin) Call(operands ...*Term) *Term

Call creates a new term for the built-in with the given operands.

func (*Builtin) Expr 

func (b *Builtin) Expr(operands ...*Term) *Expr

Expr creates a new expression for the built-in with the given operands.

func (*Builtin) IsTargetPos 

func (b *Builtin) IsTargetPos(i int) bool

IsTargetPos returns true if a variable in the i-th position will be bound by evaluating the call expression.

func (*Builtin) Ref added in v0.5.9 

func (b *Builtin) Ref() Ref

Ref returns a Ref that refers to the built-in function.

type Call added in v0.7.0 

type Call []*Term

Call represents as function call in the language.

func (Call) Compare added in v0.7.0 

func (c Call) Compare(other Value) int

Compare compares c to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Call) Copy added in v0.7.0 

func (c Call) Copy() Call

Copy returns a deep copy of c.

func (Call) Find added in v0.7.0 

func (c Call) Find(Ref) (Value, error)

Find returns the current value or a not found error.

func (Call) Hash added in v0.7.0 

func (c Call) Hash() int

Hash returns the hash code for the Value.

func (Call) IsGround added in v0.7.0 

func (c Call) IsGround() bool

IsGround returns true if the Value is ground.

func (Call) MakeExpr added in v0.7.0 

func (c Call) MakeExpr(output *Term) *Expr

MakeExpr returns an ew Expr from this call.

func (Call) String added in v0.7.0 

func (c Call) String() string

type Cloner added in v0.6.0 

type Cloner interface {
	Clone() interface{}
}

Cloner is implemented by any value that has a Clone method, which returns a copy of the value. This is mainly used for types which are not passed by value (e.g map, slice, chan) or structs that contain such types.

This is used in conjunction with the global state feature to create proper copies of the state to allow the parser to properly restore the state in the case of backtracking.

type Comment added in v0.4.0 

type Comment struct {
	Text     []byte
	Location *Location
}

Comment contains the raw text from the comment in the definition.

func NewComment added in v0.4.0 

func NewComment(text []byte) *Comment

NewComment returns a new Comment object.

func (*Comment) Loc added in v0.4.0 

func (c *Comment) Loc() *Location

Loc returns the location of the comment in the definition.

func (*Comment) SetLoc added in v0.9.2 

func (c *Comment) SetLoc(loc *Location)

SetLoc sets the location on c.

func (*Comment) String added in v0.4.0 

func (c *Comment) String() string

type Compiler 

type Compiler struct {

	// Errors contains errors that occurred during the compilation process.
	// If there are one or more errors, the compilation process is considered
	// "failed".
	Errors Errors

	// Modules contains the compiled modules. The compiled modules are the
	// output of the compilation process. If the compilation process failed,
	// there is no guarantee about the state of the modules.
	Modules map[string]*Module

	// ModuleTree organizes the modules into a tree where each node is keyed by
	// an element in the module's package path. E.g., given modules containing
	// the following package directives: "a", "a.b", "a.c", and "a.b", the
	// resulting module tree would be:
	//
	//  root
	//    |
	//    +--- data (no modules)
	//           |
	//           +--- a (1 module)
	//                |
	//                +--- b (2 modules)
	//                |
	//                +--- c (1 module)
	//
	ModuleTree *ModuleTreeNode

	// RuleTree organizes rules into a tree where each node is keyed by an
	// element in the rule's path. The rule path is the concatenation of the
	// containing package and the stringified rule name. E.g., given the
	// following module:
	//
	//  package ex
	//  p[1] { true }
	//  p[2] { true }
	//  q = true
	//
	//  root
	//    |
	//    +--- data (no rules)
	//           |
	//           +--- ex (no rules)
	//                |
	//                +--- p (2 rules)
	//                |
	//                +--- q (1 rule)
	RuleTree *TreeNode

	// Graph contains dependencies between rules. An edge (u,v) is added to the
	// graph if rule 'u' refers to the virtual document defined by 'v'.
	Graph *Graph

	// TypeEnv holds type information for values inferred by the compiler.
	TypeEnv *TypeEnv
	// contains filtered or unexported fields
}

Compiler contains the state of a compilation process.

func NewCompiler 

func NewCompiler() *Compiler

NewCompiler returns a new empty compiler.

func (*Compiler) Compile 

func (c *Compiler) Compile(modules map[string]*Module)

Compile runs the compilation process on the input modules. The compiled version of the modules and associated data structures are stored on the compiler. If the compilation process fails for any reason, the compiler will contain a slice of errors.

Example 
package main

import (
	"fmt"

	"github.com/open-policy-agent/opa/ast"
)

func main() {

	// Define an input module that will be compiled.
	exampleModule := `package opa.example

import data.foo
import input.bar

p[x] { foo[x]; not bar[x]; x >= min_x }
min_x = 100 { true }`

	// Parse the input module to obtain the AST representation.
	mod, err := ast.ParseModule("my_module", exampleModule)
	if err != nil {
		fmt.Println("Parse error:", err)
	}

	// Create a new compiler instance and compile the module.
	c := ast.NewCompiler()

	mods := map[string]*ast.Module{
		"my_module": mod,
	}

	if c.Compile(mods); c.Failed() {
		fmt.Println("Compile error:", c.Errors)
	}

	fmt.Println("Expr 1:", c.Modules["my_module"].Rules[0].Body[0])
	fmt.Println("Expr 2:", c.Modules["my_module"].Rules[0].Body[1])
	fmt.Println("Expr 3:", c.Modules["my_module"].Rules[0].Body[2])
	fmt.Println("Expr 4:", c.Modules["my_module"].Rules[0].Body[3])

}

Output:


Expr 1: data.foo[x]
Expr 2: not input.bar[x]
Expr 3: __local0__ = data.opa.example.min_x
Expr 4: gte(x, __local0__)

func (*Compiler) Failed 

func (c *Compiler) Failed() bool

Failed returns true if a compilation error has been encountered.

func (*Compiler) GetArity added in v0.7.0 

func (c *Compiler) GetArity(ref Ref) int

GetArity returns the number of args a function referred to by ref takes. If ref refers to built-in function, the built-in declaration is consulted, otherwise, the ref is used to perform a ruleset lookup.

func (*Compiler) GetRules added in v0.4.0 

func (c *Compiler) GetRules(ref Ref) (rules []*Rule)

GetRules returns a slice of rules that are referred to by ref.

E.g., given the following module: 

package a.b.c

p[x] = y { q[x] = y; ... } # rule1
q[x] = y { ... }           # rule2

The following calls yield the rules on the right. 

GetRules("data.a.b.c.p")	=> [rule1]
GetRules("data.a.b.c.p.x")	=> [rule1]
GetRules("data.a.b.c.q")	=> [rule2]
GetRules("data.a.b.c")		=> [rule1, rule2]
GetRules("data.a.b.d")		=> nil

func (*Compiler) GetRulesExact added in v0.2.0 

func (c *Compiler) GetRulesExact(ref Ref) (rules []*Rule)

GetRulesExact returns a slice of rules referred to by the reference.

E.g., given the following module: 

	package a.b.c

	p[k] = v { ... }    # rule1
 p[k1] = v1 { ... }  # rule2

The following calls yield the rules on the right. 

GetRulesExact("data.a.b.c.p")   => [rule1, rule2]
GetRulesExact("data.a.b.c.p.x") => nil
GetRulesExact("data.a.b.c")     => nil

func (*Compiler) GetRulesForVirtualDocument added in v0.2.0 

func (c *Compiler) GetRulesForVirtualDocument(ref Ref) (rules []*Rule)

GetRulesForVirtualDocument returns a slice of rules that produce the virtual document referred to by the reference.

E.g., given the following module: 

	package a.b.c

	p[k] = v { ... }    # rule1
 p[k1] = v1 { ... }  # rule2

The following calls yield the rules on the right. 

GetRulesForVirtualDocument("data.a.b.c.p")   => [rule1, rule2]
GetRulesForVirtualDocument("data.a.b.c.p.x") => [rule1, rule2]
GetRulesForVirtualDocument("data.a.b.c")     => nil

func (*Compiler) GetRulesWithPrefix added in v0.2.0 

func (c *Compiler) GetRulesWithPrefix(ref Ref) (rules []*Rule)

GetRulesWithPrefix returns a slice of rules that share the prefix ref.

E.g., given the following module: 

package a.b.c

p[x] = y { ... }  # rule1
p[k] = v { ... }  # rule2
q { ... }         # rule3

The following calls yield the rules on the right. 

GetRulesWithPrefix("data.a.b.c.p")   => [rule1, rule2]
GetRulesWithPrefix("data.a.b.c.p.a") => nil
GetRulesWithPrefix("data.a.b.c")     => [rule1, rule2, rule3]

func (*Compiler) QueryCompiler added in v0.2.2 

func (c *Compiler) QueryCompiler() QueryCompiler

QueryCompiler returns a new QueryCompiler object.

func (*Compiler) RuleIndex added in v0.4.9 

func (c *Compiler) RuleIndex(path Ref) RuleIndex

RuleIndex returns a RuleIndex built for the rule set referred to by path. The path must refer to the rule set exactly, i.e., given a rule set at path data.a.b.c.p, refs data.a.b.c.p.x and data.a.b.c would not return a RuleIndex built for the rule.

func (*Compiler) SetErrorLimit added in v0.5.3 

func (c *Compiler) SetErrorLimit(limit int) *Compiler

SetErrorLimit sets the number of errors the compiler can encounter before it quits. Zero or a negative number indicates no limit.

func (*Compiler) WithModuleLoader added in v0.3.0 

func (c *Compiler) WithModuleLoader(f ModuleLoader) *Compiler

WithModuleLoader sets f as the ModuleLoader on the compiler.

The compiler will invoke the ModuleLoader after resolving all references in the current set of input modules. The ModuleLoader can return a new collection of parsed modules that are to be included in the compilation process. This process will repeat until the ModuleLoader returns an empty collection or an error. If an error is returned, compilation will stop immediately.

type DocKind 

type DocKind int

DocKind represents the collection of document types that can be produced by rules.

type Error added in v0.2.0 

type Error struct {
	Code     string       `json:"code"`
	Message  string       `json:"message"`
	Location *Location    `json:"location,omitempty"`
	Details  ErrorDetails `json:"details,omitempty"`
}

Error represents a single error caught during parsing, compiling, etc.

func NewError added in v0.2.0 

func NewError(code string, loc *Location, f string, a ...interface{}) *Error

NewError returns a new Error object.

func (*Error) Error added in v0.2.0 

func (e *Error) Error() string

type ErrorDetails added in v0.4.9 

type ErrorDetails interface {
	Lines() []string
}

ErrorDetails defines the interface for detailed error messages.

type Errors added in v0.2.0 

type Errors []*Error

Errors represents a series of errors encountered during parsing, compiling, etc.

func (Errors) Error added in v0.2.0 

func (e Errors) Error() string

type Expr 

type Expr struct {
	Location  *Location   `json:"-"`
	Generated bool        `json:"generated,omitempty"`
	Index     int         `json:"index"`
	Negated   bool        `json:"negated,omitempty"`
	Terms     interface{} `json:"terms"`
	With      []*With     `json:"with,omitempty"`
}

Expr represents a single expression contained inside the body of a rule.

func MustParseExpr added in v0.2.0 

func MustParseExpr(input string) *Expr

MustParseExpr returns a parsed expression. If an error occurs during parsing, panic.

func NewBuiltinExpr 

func NewBuiltinExpr(terms ...*Term) *Expr

NewBuiltinExpr creates a new Expr object with the supplied terms. The builtin operator must be the first term.

func NewExpr added in v0.2.1 

func NewExpr(terms interface{}) *Expr

NewExpr returns a new Expr object.

func ParseExpr added in v0.2.0 

func ParseExpr(input string) (*Expr, error)

ParseExpr returns exactly one expression. If multiple expressions are parsed, an error is returned.

func (*Expr) Compare added in v0.2.0 

func (expr *Expr) Compare(other *Expr) int

Compare returns an integer indicating whether expr is less than, equal to, or greater than other.

Expressions are compared as follows:

1. Preceding expression (by Index) is always less than the other expression. 2. Non-negated expressions are always less than than negated expressions. 3. Single term expressions are always less than built-in expressions.

Otherwise, the expression terms are compared normally. If both expressions have the same terms, the modifiers are compared.

func (*Expr) Complement 

func (expr *Expr) Complement() *Expr

Complement returns a copy of this expression with the negation flag flipped.

func (*Expr) Copy added in v0.2.2 

func (expr *Expr) Copy() *Expr

Copy returns a deep copy of expr.

func (*Expr) Equal 

func (expr *Expr) Equal(other *Expr) bool

Equal returns true if this Expr equals the other Expr.

func (*Expr) Hash 

func (expr *Expr) Hash() int

Hash returns the hash code of the Expr.

func (*Expr) IncludeWith added in v0.4.1 

func (expr *Expr) IncludeWith(target *Term, value *Term) *Expr

IncludeWith returns a copy of expr with the with modifier appended.

func (*Expr) IsAssignment added in v0.7.0 

func (expr *Expr) IsAssignment() bool

IsAssignment returns true if this an assignment expression.

func (*Expr) IsCall added in v0.5.9 

func (expr *Expr) IsCall() bool

IsCall returns true if this expression calls a function.

func (*Expr) IsEquality 

func (expr *Expr) IsEquality() bool

IsEquality returns true if this is an equality expression.

func (*Expr) IsGround 

func (expr *Expr) IsGround() bool

IsGround returns true if all of the expression terms are ground.

func (*Expr) Loc added in v0.9.2 

func (expr *Expr) Loc() *Location

Loc returns the Location of expr.

func (*Expr) NoWith added in v0.4.1 

func (expr *Expr) NoWith() *Expr

NoWith returns a copy of expr where the with modifier has been removed.

func (*Expr) Operand added in v0.4.9 

func (expr *Expr) Operand(pos int) *Term

Operand returns the term at the zero-based pos. If the expr does not include at least pos+1 terms, this function returns nil.

func (*Expr) Operands added in v0.4.9 

func (expr *Expr) Operands() []*Term

Operands returns the built-in function operands.

func (*Expr) Operator added in v0.5.9 

func (expr *Expr) Operator() Ref

Operator returns the name of the function or built-in this expression refers to. If this expression is not a function call, returns nil.

func (*Expr) SetLoc added in v0.9.2 

func (expr *Expr) SetLoc(loc *Location)

SetLoc sets the location on expr.

func (*Expr) SetLocation added in v0.5.6 

func (expr *Expr) SetLocation(loc *Location) *Expr

SetLocation sets the expr's location and returns the expr itself.

func (*Expr) SetOperator added in v0.7.0 

func (expr *Expr) SetOperator(term *Term) *Expr

SetOperator sets the expr's operator and returns the expr itself. If expr is not a call expr, this function will panic.

func (*Expr) String 

func (expr *Expr) String() string

func (*Expr) UnmarshalJSON 

func (expr *Expr) UnmarshalJSON(bs []byte) error

UnmarshalJSON parses the byte array and stores the result in expr.

func (*Expr) Vars 

func (expr *Expr) Vars(params VarVisitorParams) VarSet

Vars returns a VarSet containing variables in expr. The params can be set to control which vars are included.

type GenericTransformer added in v0.2.0 

type GenericTransformer struct {
	// contains filtered or unexported fields
}

GenericTransformer implements the Transformer interface to provide a utility to transform AST nodes using a closure.

func NewGenericTransformer added in v0.5.11 

func NewGenericTransformer(f func(x interface{}) (interface{}, error)) *GenericTransformer

NewGenericTransformer returns a new GenericTransformer that will transform AST nodes using the function f.

func (*GenericTransformer) Transform added in v0.2.0 

func (t *GenericTransformer) Transform(x interface{}) (interface{}, error)

Transform calls the function f on the GenericTransformer.

type GenericVisitor 

type GenericVisitor struct {
	// contains filtered or unexported fields
}

GenericVisitor implements the Visitor interface to provide a utility to walk over AST nodes using a closure. If the closure returns true, the visitor will not walk over AST nodes under x.

func NewGenericVisitor added in v0.4.1 

func NewGenericVisitor(f func(x interface{}) bool) *GenericVisitor

NewGenericVisitor returns a new GenericVisitor that will invoke the function f on AST nodes.

func (*GenericVisitor) Visit 

func (vis *GenericVisitor) Visit(x interface{}) Visitor

Visit calls the function f on the GenericVisitor.

type Graph added in v0.5.0 

type Graph struct {
	// contains filtered or unexported fields
}

Graph represents the graph of dependencies between rules.

func NewGraph added in v0.5.0 

func NewGraph(modules map[string]*Module, list func(Ref) []*Rule) *Graph

NewGraph returns a new Graph based on modules. The list function must return the rules referred to directly by the ref.

func (*Graph) Dependencies added in v0.5.0 

func (g *Graph) Dependencies(x util.T) map[util.T]struct{}

Dependencies returns the set of rules that x depends on.

func (*Graph) Sort added in v0.5.0 

func (g *Graph) Sort() (sorted []util.T, ok bool)

Sort returns a slice of rules sorted by dependencies. If a cycle is found, ok is set to false. 

type Head struct {
	Location *Location `json:"-"`
	Name     Var       `json:"name"`
	Args     Args      `json:"args,omitempty"`
	Key      *Term     `json:"key,omitempty"`
	Value    *Term     `json:"value,omitempty"`
}

Head represents the head of a rule.

func NewHead added in v0.4.1 

func NewHead(name Var, args ...*Term) *Head

NewHead returns a new Head object. If args are provided, the first will be used for the key and the second will be used for the value.

func (*Head) Compare added in v0.4.1 

func (head *Head) Compare(other *Head) int

Compare returns an integer indicating whether head is less than, equal to, or greater than other.

func (*Head) Copy added in v0.4.1 

func (head *Head) Copy() *Head

Copy returns a deep copy of head.

func (*Head) DocKind added in v0.4.1 

func (head *Head) DocKind() DocKind

DocKind returns the type of document produced by this rule.

func (*Head) Equal added in v0.4.1 

func (head *Head) Equal(other *Head) bool

Equal returns true if this head equals other.

func (*Head) Loc added in v0.9.2 

func (head *Head) Loc() *Location

Loc returns the Location of head.

func (*Head) SetLoc added in v0.9.2 

func (head *Head) SetLoc(loc *Location)

SetLoc sets the location on head.

func (*Head) String added in v0.2.0 

func (head *Head) String() string

func (*Head) Vars added in v0.4.1 

func (head *Head) Vars() VarSet

Vars returns a set of vars found in the head.

type Import 

type Import struct {
	Location *Location `json:"-"`
	Path     *Term     `json:"path"`
	Alias    Var       `json:"alias,omitempty"`
}

Import represents a dependency on a document outside of the policy namespace. Imports are optional.

func MustParseImports added in v0.2.2 

func MustParseImports(input string) []*Import

MustParseImports returns a slice of imports. If an error occurs during parsing, panic.

func ParseImports added in v0.2.2 

func ParseImports(input string) ([]*Import, error)

ParseImports returns a slice of Import objects.

func (*Import) Compare added in v0.2.0 

func (imp *Import) Compare(other *Import) int

Compare returns an integer indicating whether imp is less than, equal to, or greater than other.

func (*Import) Copy added in v0.2.2 

func (imp *Import) Copy() *Import

Copy returns a deep copy of imp.

func (*Import) Equal 

func (imp *Import) Equal(other *Import) bool

Equal returns true if imp is equal to other.

func (*Import) Loc 

func (imp *Import) Loc() *Location

Loc returns the location of the Import in the definition.

func (*Import) Name added in v0.2.2 

func (imp *Import) Name() Var

Name returns the variable that is used to refer to the imported virtual document. This is the alias if defined otherwise the last element in the path.

func (*Import) SetLoc added in v0.9.2 

func (imp *Import) SetLoc(loc *Location)

SetLoc sets the location on imp.

func (*Import) String 

func (imp *Import) String() string

type IndexResult added in v0.4.10 

type IndexResult struct {
	Kind    DocKind
	Rules   []*Rule
	Else    map[*Rule][]*Rule
	Default *Rule
}

IndexResult contains the result of an index lookup.

func NewIndexResult added in v0.4.10 

func NewIndexResult(kind DocKind) *IndexResult

NewIndexResult returns a new IndexResult object.

func (*IndexResult) Empty added in v0.4.10 

func (ir *IndexResult) Empty() bool

Empty returns true if there are no rules to evaluate.

type Location 

type Location struct {
	Text []byte `json:"-"`    // The original text fragment from the source.
	File string `json:"file"` // The name of the source file (which may be empty).
	Row  int    `json:"row"`  // The line in the source.
	Col  int    `json:"col"`  // The column in the row.
}

Location records a position in source code

func NewLocation 

func NewLocation(text []byte, file string, row int, col int) *Location

NewLocation returns a new Location object.

func (*Location) Compare added in v0.8.0 

func (loc *Location) Compare(other *Location) int

Compare returns -1, 0, or 1 to indicate if this loc is less than, equal to, or greater than the other. Comparison is performed on the file, row, and column of the Location (but not on the text.)

func (*Location) Equal added in v0.5.0 

func (loc *Location) Equal(other *Location) bool

Equal checks if two locations are equal to each other.

func (*Location) Errorf 

func (loc *Location) Errorf(f string, a ...interface{}) error

Errorf returns a new error value with a message formatted to include the location info (e.g., line, column, filename, etc.)

func (*Location) Format added in v0.2.0 

func (loc *Location) Format(f string, a ...interface{}) string

Format returns a formatted string prefixed with the location information.

func (*Location) String added in v0.2.2 

func (loc *Location) String() string

func (*Location) Wrapf 

func (loc *Location) Wrapf(err error, f string, a ...interface{}) error

Wrapf returns a new error value that wraps an existing error with a message formatted to include the location info (e.g., line, column, filename, etc.)

type Module 

type Module struct {
	Package  *Package   `json:"package"`
	Imports  []*Import  `json:"imports,omitempty"`
	Rules    []*Rule    `json:"rules,omitempty"`
	Comments []*Comment `json:"comments,omitempty"`
}

Module represents a collection of policies (defined by rules) within a namespace (defined by the package) and optional dependencies on external documents (defined by imports).

func MustParseModule 

func MustParseModule(input string) *Module

MustParseModule returns a parsed module. If an error occurs during parsing, panic.

func ParseModule 

func ParseModule(filename, input string) (*Module, error)

ParseModule returns a parsed Module object. For details on Module objects and their fields, see policy.go. Empty input will return nil, nil.

func (*Module) Compare added in v0.2.0 

func (mod *Module) Compare(other *Module) int

Compare returns an integer indicating whether mod is less than, equal to, or greater than other.

func (*Module) Copy added in v0.2.2 

func (mod *Module) Copy() *Module

Copy returns a deep copy of mod.

func (*Module) Equal 

func (mod *Module) Equal(other *Module) bool

Equal returns true if mod equals other.

func (*Module) RuleSet added in v0.4.9 

func (mod *Module) RuleSet(name Var) RuleSet

RuleSet returns a RuleSet containing named rules in the mod.

func (*Module) String added in v0.2.0 

func (mod *Module) String() string

type ModuleLoader added in v0.3.0 

type ModuleLoader func(resolved map[string]*Module) (parsed map[string]*Module, err error)

ModuleLoader defines the interface that callers can implement to enable lazy loading of modules during compilation.

type ModuleTreeNode 

type ModuleTreeNode struct {
	Key      Value
	Modules  []*Module
	Children map[Value]*ModuleTreeNode
	Hide     bool
}

ModuleTreeNode represents a node in the module tree. The module tree is keyed by the package path.

func NewModuleTree 

func NewModuleTree(mods map[string]*Module) *ModuleTreeNode

NewModuleTree returns a new ModuleTreeNode that represents the root of the module tree populated with the given modules.

func (*ModuleTreeNode) DepthFirst added in v0.2.2 

func (n *ModuleTreeNode) DepthFirst(f func(node *ModuleTreeNode) bool)

DepthFirst performs a depth-first traversal of the module tree rooted at n. If f returns true, traversal will not continue to the children of n.

func (*ModuleTreeNode) Size 

func (n *ModuleTreeNode) Size() int

Size returns the number of modules in the tree.

type Node added in v0.9.2 

type Node interface {
	fmt.Stringer
	Loc() *Location
	SetLoc(*Location)
}

Node represents a node in an AST. Nodes may be statements in a policy module or elements of an ad-hoc query, expression, etc.

type Null 

type Null struct{}

Null represents the null value defined by JSON.

func (Null) Compare added in v0.5.0 

func (null Null) Compare(other Value) int

Compare compares null to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Null) Equal 

func (null Null) Equal(other Value) bool

Equal returns true if the other term Value is also Null.

func (Null) Find added in v0.4.5 

func (null Null) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (Null) Hash 

func (null Null) Hash() int

Hash returns the hash code for the Value.

func (Null) IsGround 

func (null Null) IsGround() bool

IsGround always returns true.

func (Null) String 

func (null Null) String() string

type Number 

type Number json.Number

Number represents a numeric value as defined by JSON.

func (Number) Compare added in v0.5.0 

func (num Number) Compare(other Value) int

Compare compares num to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Number) Equal 

func (num Number) Equal(other Value) bool

Equal returns true if the other Value is a Number and is equal.

func (Number) Find added in v0.4.5 

func (num Number) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (Number) Float64 added in v0.8.2 

func (num Number) Float64() (float64, bool)

Float64 returns the float64 representation of num if possible.

func (Number) Hash 

func (num Number) Hash() int

Hash returns the hash code for the Value.

func (Number) Int added in v0.3.0 

func (num Number) Int() (int, bool)

Int returns the int representation of num if possible.

func (Number) IsGround 

func (num Number) IsGround() bool

IsGround always returns true.

func (Number) MarshalJSON added in v0.3.0 

func (num Number) MarshalJSON() ([]byte, error)

MarshalJSON returns JSON encoded bytes representing num.

func (Number) String 

func (num Number) String() string

type Object 

type Object interface {
	Value
	Len() int
	Get(*Term) *Term
	Copy() Object
	Insert(*Term, *Term)
	Iter(func(*Term, *Term) error) error
	Until(func(*Term, *Term) bool) bool
	Foreach(func(*Term, *Term))
	Map(func(*Term, *Term) (*Term, *Term, error)) (Object, error)
	Diff(other Object) Object
	Intersect(other Object) [][3]*Term
	Merge(other Object) (Object, bool)
	Keys() []*Term
}

Object represents an object as defined by the language.

func NewObject added in v0.6.0 

func NewObject(t ...[2]*Term) Object

NewObject creates a new Object with t.

type ObjectComprehension added in v0.5.2 

type ObjectComprehension struct {
	Key   *Term `json:"key"`
	Value *Term `json:"value"`
	Body  Body  `json:"body"`
}

ObjectComprehension represents an object comprehension as defined in the language.

func (*ObjectComprehension) Compare added in v0.5.2 

func (oc *ObjectComprehension) Compare(other Value) int

Compare compares oc to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (*ObjectComprehension) Copy added in v0.5.2 

func (oc *ObjectComprehension) Copy() *ObjectComprehension

Copy returns a deep copy of oc.

func (*ObjectComprehension) Equal added in v0.5.2 

func (oc *ObjectComprehension) Equal(other Value) bool

Equal returns true if oc is equal to other.

func (*ObjectComprehension) Find added in v0.5.2 

func (oc *ObjectComprehension) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (*ObjectComprehension) Hash added in v0.5.2 

func (oc *ObjectComprehension) Hash() int

Hash returns the hash code of the Value.

func (*ObjectComprehension) IsGround added in v0.5.2 

func (oc *ObjectComprehension) IsGround() bool

IsGround returns true if the Key, Value and Body are ground.

func (*ObjectComprehension) String added in v0.5.2 

func (oc *ObjectComprehension) String() string

type Option 

type Option func(*parser) Option

Option is a function that can set an option on the parser. It returns the previous setting as an Option.

func AllowInvalidUTF8 added in v0.6.0 

func AllowInvalidUTF8(b bool) Option

AllowInvalidUTF8 creates an Option to allow invalid UTF-8 bytes. Every invalid UTF-8 byte is treated as a utf8.RuneError (U+FFFD) by character class matchers and is matched by the any matcher. The returned matched value, c.text and c.offset are NOT affected.

The default is false.

func CommentsOption added in v0.5.0 

func CommentsOption() Option

CommentsOption returns a parser option to initialize the comments store within the parser.

func Debug 

func Debug(b bool) Option

Debug creates an Option to set the debug flag to b. When set to true, debugging information is printed to stdout while parsing.

The default is false.

func Entrypoint added in v0.6.0 

func Entrypoint(ruleName string) Option

Entrypoint creates an Option to set the rule name to use as entrypoint. The rule name must have been specified in the -alternate-entrypoints if generating the parser with the -optimize-grammar flag, otherwise it may have been optimized out. Passing an empty string sets the entrypoint to the first rule in the grammar.

The default is to start parsing at the first rule in the grammar.

func GlobalStore added in v0.5.0 

func GlobalStore(key string, value interface{}) Option

GlobalStore creates an Option to set a key to a certain value in the globalStore.

func InitState added in v0.6.0 

func InitState(key string, value interface{}) Option

InitState creates an Option to set a key to a certain value in the global "state" store.

func MaxExpressions added in v0.6.0 

func MaxExpressions(maxExprCnt uint64) Option

MaxExpressions creates an Option to stop parsing after the provided number of expressions have been parsed, if the value is 0 then the parser will parse for as many steps as needed (possibly an infinite number).

The default for maxExprCnt is 0.

func Memoize 

func Memoize(b bool) Option

Memoize creates an Option to set the memoize flag to b. When set to true, the parser will cache all results so each expression is evaluated only once. This guarantees linear parsing time even for pathological cases, at the expense of more memory and slower times for typical cases.

The default is false.

func Recover 

func Recover(b bool) Option

Recover creates an Option to set the recover flag to b. When set to true, this causes the parser to recover from panics and convert it to an error. Setting it to false can be useful while debugging to access the full stack trace.

The default is true.

func Statistics added in v0.6.0 

func Statistics(stats *Stats, choiceNoMatch string) Option

Statistics adds a user provided Stats struct to the parser to allow the user to process the results after the parsing has finished. Also the key for the "no match" counter is set.

Example usage: 

input := "input"
stats := Stats{}
_, err := Parse("input-file", []byte(input), Statistics(&stats, "no match"))
if err != nil {
    log.Panicln(err)
}
b, err := json.MarshalIndent(stats.ChoiceAltCnt, "", "  ")
if err != nil {
    log.Panicln(err)
}
fmt.Println(string(b))

type Package 

type Package struct {
	Location *Location `json:"-"`
	Path     Ref       `json:"path"`
}

Package represents the namespace of the documents produced by rules inside the module.

func MustParsePackage added in v0.2.2 

func MustParsePackage(input string) *Package

MustParsePackage returns a Package. If an error occurs during parsing, panic.

func ParsePackage added in v0.2.2 

func ParsePackage(input string) (*Package, error)

ParsePackage returns exactly one Package. If multiple statements are parsed, an error is returned.

func (*Package) Compare added in v0.2.0 

func (pkg *Package) Compare(other *Package) int

Compare returns an integer indicating whether pkg is less than, equal to, or greater than other.

func (*Package) Copy added in v0.2.2 

func (pkg *Package) Copy() *Package

Copy returns a deep copy of pkg.

func (*Package) Equal 

func (pkg *Package) Equal(other *Package) bool

Equal returns true if pkg is equal to other.

func (*Package) Loc 

func (pkg *Package) Loc() *Location

Loc returns the location of the Package in the definition.

func (*Package) SetLoc added in v0.9.2 

func (pkg *Package) SetLoc(loc *Location)

SetLoc sets the location on pkg.

func (*Package) String 

func (pkg *Package) String() string

type QueryCompiler added in v0.2.2 

type QueryCompiler interface {

	// Compile should be called to compile ad-hoc queries. The return value is
	// the compiled version of the query.
	Compile(q Body) (Body, error)

	// TypeEnv returns the type environment built after running type checking
	// on the query.
	TypeEnv() *TypeEnv

	// WithContext sets the QueryContext on the QueryCompiler. Subsequent calls
	// to Compile will take the QueryContext into account.
	WithContext(qctx *QueryContext) QueryCompiler

	// WithStageAfter registers a stage to run during query compilation after
	// the named stage.
	WithStageAfter(after string, stage QueryCompilerStage) QueryCompiler

	// RewrittenVars maps generated vars in the compiled query to vars from the
	// parsed query. For example, given the query "input := 1" the rewritten
	// query would be "__local0__ = 1". The mapping would then be {__local0__: input}.
	RewrittenVars() map[Var]Var
}

QueryCompiler defines the interface for compiling ad-hoc queries.

type QueryCompilerStage added in v0.7.0 

type QueryCompilerStage func(QueryCompiler, Body) (Body, error)

QueryCompilerStage defines the interface for stages in the query compiler.

type QueryContext added in v0.2.2 

type QueryContext struct {
	Package *Package
	Imports []*Import
	Input   Value
}

QueryContext contains contextual information for running an ad-hoc query.

Ad-hoc queries can be run in the context of a package and imports may be included to provide concise access to data.

func NewQueryContext added in v0.2.2 

func NewQueryContext() *QueryContext

NewQueryContext returns a new QueryContext object.

func (*QueryContext) Copy added in v0.2.2 

func (qc *QueryContext) Copy() *QueryContext

Copy returns a deep copy of qc.

func (*QueryContext) InputDefined added in v0.4.1 

func (qc *QueryContext) InputDefined() bool

InputDefined returns true if the input document is defined in qc.

func (*QueryContext) WithImports added in v0.4.0 

func (qc *QueryContext) WithImports(imports []*Import) *QueryContext

WithImports sets the imports on qc.

func (*QueryContext) WithInput added in v0.4.0 

func (qc *QueryContext) WithInput(input Value) *QueryContext

WithInput sets the input on qc.

func (*QueryContext) WithPackage added in v0.4.0 

func (qc *QueryContext) WithPackage(pkg *Package) *QueryContext

WithPackage sets the pkg on qc.

type QueryIterator 

type QueryIterator func(map[Var]Value, Value) error

QueryIterator defines the interface for querying AST documents with references.

type Ref 

type Ref []*Term

Ref represents a reference as defined by the language.

func EmptyRef 

func EmptyRef() Ref

EmptyRef returns a new, empty reference.

func MustParseRef 

func MustParseRef(input string) Ref

MustParseRef returns a parsed reference. If an error occurs during parsing, panic.

func ParseRef 

func ParseRef(input string) (Ref, error)

ParseRef returns exactly one reference.

func (Ref) Append added in v0.2.0 

func (ref Ref) Append(term *Term) Ref

Append returns a copy of ref with the term appended to the end.

func (Ref) Compare added in v0.5.0 

func (ref Ref) Compare(other Value) int

Compare compares ref to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Ref) Concat added in v0.9.0 

func (ref Ref) Concat(terms []*Term) Ref

Concat returns a ref with the terms appended.

func (Ref) ConstantPrefix added in v0.5.3 

func (ref Ref) ConstantPrefix() Ref

ConstantPrefix returns the constant portion of the ref starting from the head.

func (Ref) Copy added in v0.2.2 

func (ref Ref) Copy() Ref

Copy returns a deep copy of ref.

func (Ref) Dynamic added in v0.4.9 

func (ref Ref) Dynamic() int

Dynamic returns the offset of the first non-constant operand of ref.

func (Ref) Equal 

func (ref Ref) Equal(other Value) bool

Equal returns true if ref is equal to other.

func (Ref) Extend added in v0.3.0 

func (ref Ref) Extend(other Ref) Ref

Extend returns a copy of ref with the terms from other appended. The head of other will be converted to a string.

func (Ref) Find added in v0.4.5 

func (ref Ref) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (Ref) GroundPrefix added in v0.2.0 

func (ref Ref) GroundPrefix() Ref

GroundPrefix returns the ground portion of the ref starting from the head. By definition, the head of the reference is always ground.

func (Ref) HasPrefix added in v0.2.0 

func (ref Ref) HasPrefix(other Ref) bool

HasPrefix returns true if the other ref is a prefix of this ref.

func (Ref) Hash 

func (ref Ref) Hash() int

Hash returns the hash code for the Value.

func (Ref) Insert added in v0.6.0 

func (ref Ref) Insert(x *Term, pos int) Ref

Insert returns a copy of the ref with x inserted at pos. If pos < len(ref), existing elements are shifted to the right. If pos > len(ref)+1 this function panics.

func (Ref) IsGround 

func (ref Ref) IsGround() bool

IsGround returns true if all of the parts of the Ref are ground.

func (Ref) IsNested 

func (ref Ref) IsNested() bool

IsNested returns true if this ref contains other Refs.

func (Ref) OutputVars 

func (ref Ref) OutputVars() VarSet

OutputVars returns a VarSet containing variables that would be bound by evaluating 

this expression in isolation.

func (Ref) String 

func (ref Ref) String() string

type RefErrInvalidDetail added in v0.5.2 

type RefErrInvalidDetail struct {
	Ref   Ref        `json:"ref"`            // invalid ref
	Pos   int        `json:"pos"`            // invalid element
	Have  types.Type `json:"have,omitempty"` // type of invalid element (for var/ref elements)
	Want  types.Type `json:"want"`           // allowed type (for non-object values)
	OneOf []Value    `json:"oneOf"`          // allowed values (e.g., for object keys)
}

RefErrInvalidDetail describes an undefined reference error where the referenced value does not support the reference operand (e.g., missing object key, invalid key type, etc.)

func (*RefErrInvalidDetail) Lines added in v0.5.2 

func (r *RefErrInvalidDetail) Lines() []string

Lines returns the string representation of the detail.

type RefErrUnsupportedDetail added in v0.5.2 

type RefErrUnsupportedDetail struct {
	Ref  Ref        `json:"ref"`  // invalid ref
	Pos  int        `json:"pos"`  // invalid element
	Have types.Type `json:"have"` // referenced type
}

RefErrUnsupportedDetail describes an undefined reference error where the referenced value does not support dereferencing (e.g., scalars).

func (*RefErrUnsupportedDetail) Lines added in v0.5.2 

func (r *RefErrUnsupportedDetail) Lines() []string

Lines returns the string representation of the detail.

type Resolver added in v0.4.9 

type Resolver interface {
	Resolve(ref Ref) (value interface{}, err error)
}

Resolver defines the interface for resolving references to native Go values.

type Rule 

type Rule struct {
	Location *Location `json:"-"`
	Default  bool      `json:"default,omitempty"`
	Head     *Head     `json:"head"`
	Body     Body      `json:"body"`
	Else     *Rule     `json:"else,omitempty"`

	// Module is a pointer to the module containing this rule. If the rule
	// was NOT created while parsing/constructing a module, this should be
	// left unset. The pointer is not included in any standard operations
	// on the rule (e.g., printing, comparison, visiting, etc.)
	Module *Module `json:"-"`
}

Rule represents a rule as defined in the language. Rules define the content of documents that represent policy decisions.

func MustParseRule 

func MustParseRule(input string) *Rule

MustParseRule returns a parsed rule. If an error occurs during parsing, panic.

func ParseCompleteDocRuleFromEqExpr added in v0.5.6 

func ParseCompleteDocRuleFromEqExpr(module *Module, lhs, rhs *Term) (*Rule, error)

ParseCompleteDocRuleFromEqExpr returns a rule if the expression can be interpreted as a complete document definition.

func ParsePartialObjectDocRuleFromEqExpr added in v0.5.6 

func ParsePartialObjectDocRuleFromEqExpr(module *Module, lhs, rhs *Term) (*Rule, error)

ParsePartialObjectDocRuleFromEqExpr returns a rule if the expression can be interpreted as a partial object document definition.

func ParsePartialSetDocRuleFromTerm added in v0.5.6 

func ParsePartialSetDocRuleFromTerm(module *Module, term *Term) (*Rule, error)

ParsePartialSetDocRuleFromTerm returns a rule if the term can be interpreted as a partial set document definition.

func ParseRule 

func ParseRule(input string) (*Rule, error)

ParseRule returns exactly one rule. If multiple rules are parsed, an error is returned.

func ParseRuleFromBody added in v0.3.0 

func ParseRuleFromBody(module *Module, body Body) (*Rule, error)

ParseRuleFromBody returns a rule if the body can be interpreted as a rule definition. Otherwise, an error is returned.

func ParseRuleFromCallEqExpr added in v0.7.0 

func ParseRuleFromCallEqExpr(module *Module, lhs, rhs *Term) (*Rule, error)

ParseRuleFromCallEqExpr returns a rule if the term can be interpreted as a function definition (e.g., f(x) = y => f(x) = y { true }).

func ParseRuleFromCallExpr added in v0.5.9 

func ParseRuleFromCallExpr(module *Module, terms []*Term) (*Rule, error)

ParseRuleFromCallExpr returns a rule if the terms can be interpreted as a function returning true or some value (e.g., f(x) => f(x) = true { true }).

func ParseRuleFromExpr added in v0.5.6 

func ParseRuleFromExpr(module *Module, expr *Expr) (*Rule, error)

ParseRuleFromExpr returns a rule if the expression can be interpreted as a rule definition.

func (*Rule) Compare added in v0.2.0 

func (rule *Rule) Compare(other *Rule) int

Compare returns an integer indicating whether rule is less than, equal to, or greater than other.

func (*Rule) Copy added in v0.2.2 

func (rule *Rule) Copy() *Rule

Copy returns a deep copy of rule.

func (*Rule) Equal 

func (rule *Rule) Equal(other *Rule) bool

Equal returns true if rule is equal to other.

func (*Rule) Loc 

func (rule *Rule) Loc() *Location

Loc returns the location of the Rule in the definition.

func (*Rule) Path added in v0.2.0 

func (rule *Rule) Path() Ref

Path returns a ref referring to the document produced by this rule. If rule is not contained in a module, this function panics.

func (*Rule) SetLoc added in v0.9.2 

func (rule *Rule) SetLoc(loc *Location)

SetLoc sets the location on rule.

func (*Rule) String 

func (rule *Rule) String() string

type RuleIndex added in v0.4.9 

type RuleIndex interface {

	// Build tries to construct an index for the given rules. If the index was
	// constructed, ok is true, otherwise false.
	Build(rules []*Rule) (ok bool)

	// Lookup searches the index for rules that will match the provided
	// resolver. If the resolver returns an error, it is returned via err.
	Lookup(resolver ValueResolver) (result *IndexResult, err error)
}

RuleIndex defines the interface for rule indices.

type RuleSet added in v0.4.9 

type RuleSet []*Rule

RuleSet represents a collection of rules that produce a virtual document.

func NewRuleSet added in v0.4.9 

func NewRuleSet(rules ...*Rule) RuleSet

NewRuleSet returns a new RuleSet containing the given rules.

func (*RuleSet) Add added in v0.4.9 

func (rs *RuleSet) Add(rule *Rule)

Add inserts the rule into rs.

func (RuleSet) Contains added in v0.4.9 

func (rs RuleSet) Contains(rule *Rule) bool

Contains returns true if rs contains rule.

func (RuleSet) Diff added in v0.4.9 

func (rs RuleSet) Diff(other RuleSet) RuleSet

Diff returns a new RuleSet containing rules in rs that are not in other.

func (RuleSet) Equal added in v0.4.9 

func (rs RuleSet) Equal(other RuleSet) bool

Equal returns true if rs equals other.

func (RuleSet) Merge added in v0.4.9 

func (rs RuleSet) Merge(other RuleSet) RuleSet

Merge returns a ruleset containing the union of rules from rs an other.

func (RuleSet) String added in v0.4.9 

func (rs RuleSet) String() string

type Set added in v0.2.0 

type Set interface {
	Value
	Len() int
	Copy() Set
	Diff(Set) Set
	Intersect(Set) Set
	Union(Set) Set
	Add(*Term)
	Iter(func(*Term) error) error
	Until(func(*Term) bool) bool
	Foreach(func(*Term))
	Contains(*Term) bool
	Map(func(*Term) (*Term, error)) (Set, error)
	Reduce(*Term, func(*Term, *Term) (*Term, error)) (*Term, error)
	Sorted() Array
}

Set represents a set as defined by the language.

func NewSet added in v0.6.0 

func NewSet(t ...*Term) Set

NewSet returns a new Set containing t.

type SetComprehension added in v0.5.2 

type SetComprehension struct {
	Term *Term `json:"term"`
	Body Body  `json:"body"`
}

SetComprehension represents a set comprehension as defined in the language.

func (*SetComprehension) Compare added in v0.5.2 

func (sc *SetComprehension) Compare(other Value) int

Compare compares sc to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (*SetComprehension) Copy added in v0.5.2 

func (sc *SetComprehension) Copy() *SetComprehension

Copy returns a deep copy of sc.

func (*SetComprehension) Equal added in v0.5.2 

func (sc *SetComprehension) Equal(other Value) bool

Equal returns true if sc is equal to other.

func (*SetComprehension) Find added in v0.5.2 

func (sc *SetComprehension) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (*SetComprehension) Hash added in v0.5.2 

func (sc *SetComprehension) Hash() int

Hash returns the hash code of the Value.

func (*SetComprehension) IsGround added in v0.5.2 

func (sc *SetComprehension) IsGround() bool

IsGround returns true if the Term and Body are ground.

func (*SetComprehension) String added in v0.5.2 

func (sc *SetComprehension) String() string

type Statement 

type Statement interface {
	Node
}

Statement represents a single statement in a policy module.

func MustParseStatement 

func MustParseStatement(input string) Statement

MustParseStatement returns exactly one statement. If an error occurs during parsing, panic.

func MustParseStatements 

func MustParseStatements(input string) []Statement

MustParseStatements returns a slice of parsed statements. If an error occurs during parsing, panic.

func ParseStatement 

func ParseStatement(input string) (Statement, error)

ParseStatement returns exactly one statement. A statement might be a term, expression, rule, etc. Regardless, this function expects *exactly* one statement. If multiple statements are parsed, an error is returned.

type Stats added in v0.6.0 

type Stats struct {
	// ExprCnt counts the number of expressions processed during parsing
	// This value is compared to the maximum number of expressions allowed
	// (set by the MaxExpressions option).
	ExprCnt uint64

	// ChoiceAltCnt is used to count for each ordered choice expression,
	// which alternative is used how may times.
	// These numbers allow to optimize the order of the ordered choice expression
	// to increase the performance of the parser
	//
	// The outer key of ChoiceAltCnt is composed of the name of the rule as well
	// as the line and the column of the ordered choice.
	// The inner key of ChoiceAltCnt is the number (one-based) of the matching alternative.
	// For each alternative the number of matches are counted. If an ordered choice does not
	// match, a special counter is incremented. The name of this counter is set with
	// the parser option Statistics.
	// For an alternative to be included in ChoiceAltCnt, it has to match at least once.
	ChoiceAltCnt map[string]map[string]int
}

Stats stores some statistics, gathered during parsing

type String 

type String string

String represents a string value as defined by JSON.

func (String) Compare added in v0.5.0 

func (str String) Compare(other Value) int

Compare compares str to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (String) Equal 

func (str String) Equal(other Value) bool

Equal returns true if the other Value is a String and is equal.

func (String) Find added in v0.4.5 

func (str String) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (String) Hash 

func (str String) Hash() int

Hash returns the hash code for the Value.

func (String) IsGround 

func (str String) IsGround() bool

IsGround always returns true.

func (String) String 

func (str String) String() string

type Term 

type Term struct {
	Value    Value     `json:"value"` // the value of the Term as represented in Go
	Location *Location `json:"-"`     // the location of the Term in the source
}

Term is an argument to a function.

func ArrayComprehensionTerm 

func ArrayComprehensionTerm(term *Term, body Body) *Term

ArrayComprehensionTerm creates a new Term with an ArrayComprehension value.

func ArrayTerm 

func ArrayTerm(a ...*Term) *Term

ArrayTerm creates a new Term with an Array value.

func BooleanTerm 

func BooleanTerm(b bool) *Term

BooleanTerm creates a new Term with a Boolean value.

func CallTerm added in v0.7.0 

func CallTerm(terms ...*Term) *Term

CallTerm returns a new Term with a Call value defined by terms. The first term is the operator and the rest are operands.

func FloatNumberTerm added in v0.3.0 

func FloatNumberTerm(f float64) *Term

FloatNumberTerm creates a new Term with a floating point Number value.

func IntNumberTerm added in v0.3.0 

func IntNumberTerm(i int) *Term

IntNumberTerm creates a new Term with an integer Number value.

func Item 

func Item(key, value *Term) [2]*Term

Item is a helper for constructing an tuple containing two Terms representing a key/value pair in an Object.

func MustParseTerm 

func MustParseTerm(input string) *Term

MustParseTerm returns a parsed term. If an error occurs during parsing, panic.

func NewTerm added in v0.2.1 

func NewTerm(v Value) *Term

NewTerm returns a new Term object.

func NullTerm 

func NullTerm() *Term

NullTerm creates a new Term with a Null value.

func NumberTerm 

func NumberTerm(n json.Number) *Term

NumberTerm creates a new Term with a Number value.

func ObjectComprehensionTerm added in v0.5.2 

func ObjectComprehensionTerm(key, value *Term, body Body) *Term

ObjectComprehensionTerm creates a new Term with an ObjectComprehension value.

func ObjectTerm 

func ObjectTerm(o ...[2]*Term) *Term

ObjectTerm creates a new Term with an Object value.

func ParseTerm 

func ParseTerm(input string) (*Term, error)

ParseTerm returns exactly one term. If multiple terms are parsed, an error is returned.

func RefTerm 

func RefTerm(r ...*Term) *Term

RefTerm creates a new Term with a Ref value.

func SetComprehensionTerm added in v0.5.2 

func SetComprehensionTerm(term *Term, body Body) *Term

SetComprehensionTerm creates a new Term with an SetComprehension value.

func SetTerm added in v0.2.0 

func SetTerm(t ...*Term) *Term

SetTerm returns a new Term representing a set containing terms t.

func StringTerm 

func StringTerm(s string) *Term

StringTerm creates a new Term with a String value.

func VarTerm 

func VarTerm(v string) *Term

VarTerm creates a new Term with a Variable value.

func (*Term) Copy added in v0.2.2 

func (term *Term) Copy() *Term

Copy returns a deep copy of term.

func (*Term) Equal 

func (term *Term) Equal(other *Term) bool

Equal returns true if this term equals the other term. Equality is defined for each kind of term.

func (*Term) Get added in v0.7.0 

func (term *Term) Get(name *Term) *Term

Get returns a value referred to by name from the term.

func (*Term) Hash 

func (term *Term) Hash() int

Hash returns the hash code of the Term's value.

func (*Term) IsGround 

func (term *Term) IsGround() bool

IsGround returns true if this terms' Value is ground.

func (*Term) Loc added in v0.9.2 

func (term *Term) Loc() *Location

Loc returns the Location of term.

func (*Term) MarshalJSON 

func (term *Term) MarshalJSON() ([]byte, error)

MarshalJSON returns the JSON encoding of the term.

Specialized marshalling logic is required to include a type hint for Value.

func (*Term) SetLoc added in v0.9.2 

func (term *Term) SetLoc(loc *Location)

SetLoc sets the location on term.

func (*Term) SetLocation added in v0.5.0 

func (term *Term) SetLocation(loc *Location) *Term

SetLocation updates the term's Location and returns the term itself.

func (*Term) String 

func (term *Term) String() string

func (*Term) UnmarshalJSON 

func (term *Term) UnmarshalJSON(bs []byte) error

UnmarshalJSON parses the byte array and stores the result in term. Specialized unmarshalling is required to handle Value.

func (*Term) Vars 

func (term *Term) Vars() VarSet

Vars returns a VarSet with variables contained in this term.

type Transformer added in v0.2.0 

type Transformer interface {
	Transform(v interface{}) (interface{}, error)
}

Transformer defines the interface for transforming AST elements. If the transformer returns nil and does not indicate an error, the AST element will be set to nil and no transformations will be applied to children of the element.

type TreeNode added in v0.5.0 

type TreeNode struct {
	Key      Value
	Values   []util.T
	Children map[Value]*TreeNode
	Hide     bool
}

TreeNode represents a node in the rule tree. The rule tree is keyed by rule path.

func NewRuleTree added in v0.2.0 

func NewRuleTree(mtree *ModuleTreeNode) *TreeNode

NewRuleTree returns a new TreeNode that represents the root of the rule tree populated with the given rules.

func (*TreeNode) Child added in v0.5.0 

func (n *TreeNode) Child(k Value) *TreeNode

Child returns n's child with key k.

func (*TreeNode) DepthFirst added in v0.5.0 

func (n *TreeNode) DepthFirst(f func(node *TreeNode) bool)

DepthFirst performs a depth-first traversal of the rule tree rooted at n. If f returns true, traversal will not continue to the children of n.

func (*TreeNode) Size added in v0.5.0 

func (n *TreeNode) Size() int

Size returns the number of rules in the tree.

type TypeEnv added in v0.4.9 

type TypeEnv struct {
	// contains filtered or unexported fields
}

TypeEnv contains type info for static analysis such as type checking.

func NewTypeEnv added in v0.4.9 

func NewTypeEnv() *TypeEnv

NewTypeEnv returns an empty TypeEnv.

func (*TypeEnv) Get added in v0.4.9 

func (env *TypeEnv) Get(x interface{}) types.Type

Get returns the type of x.

type UnificationErrDetail added in v0.4.9 

type UnificationErrDetail struct {
	Left  types.Type `json:"a"`
	Right types.Type `json:"b"`
}

UnificationErrDetail describes a type mismatch error when two values are unified (e.g., x = [1,2,y]).

func (*UnificationErrDetail) Lines added in v0.4.9 

func (a *UnificationErrDetail) Lines() []string

Lines returns the string representation of the detail.

type UnknownValueErr added in v0.9.0 

type UnknownValueErr struct{}

UnknownValueErr indicates a ValueResolver was unable to resolve a reference because the reference refers to an unknown value.

func (UnknownValueErr) Error added in v0.9.0 

func (UnknownValueErr) Error() string

type Value 

type Value interface {
	Compare(other Value) int      // Compare returns <0, 0, or >0 if this Value is less than, equal to, or greater than other, respectively.
	Find(path Ref) (Value, error) // Find returns value referred to by path or an error if path is not found.
	Hash() int                    // Returns hash code of the value.
	IsGround() bool               // IsGround returns true if this value is not a variable or contains no variables.
	String() string               // String returns a human readable string representation of the value.
}

Value declares the common interface for all Term values. Every kind of Term value in the language is represented as a type that implements this interface:

- Null, Boolean, Number, String - Object, Array, Set - Variables, References - Array, Set, and Object Comprehensions - Calls

func InterfaceToValue 

func InterfaceToValue(x interface{}) (Value, error)

InterfaceToValue converts a native Go value x to a Value.

func MustInterfaceToValue added in v0.4.5 

func MustInterfaceToValue(x interface{}) Value

MustInterfaceToValue converts a native Go value x to a Value. If the conversion fails, this function will panic. This function is mostly for test purposes.

type ValueMap added in v0.2.0 

type ValueMap struct {
	// contains filtered or unexported fields
}

ValueMap represents a key/value map between AST term values. Any type of term can be used as a key in the map.

func NewValueMap added in v0.2.0 

func NewValueMap() *ValueMap

NewValueMap returns a new ValueMap.

func (*ValueMap) Copy added in v0.2.0 

func (vs *ValueMap) Copy() *ValueMap

Copy returns a shallow copy of the ValueMap.

func (*ValueMap) Delete added in v0.2.0 

func (vs *ValueMap) Delete(k Value)

Delete removes a key k from the map.

func (*ValueMap) Equal added in v0.2.0 

func (vs *ValueMap) Equal(other *ValueMap) bool

Equal returns true if this ValueMap equals the other.

func (*ValueMap) Get added in v0.2.0 

func (vs *ValueMap) Get(k Value) Value

Get returns the value in the map for k.

func (*ValueMap) Hash added in v0.2.0 

func (vs *ValueMap) Hash() int

Hash returns a hash code for this ValueMap.

func (*ValueMap) Iter added in v0.2.0 

func (vs *ValueMap) Iter(iter func(Value, Value) bool) bool

Iter calls the iter function for each key/value pair in the map. If the iter function returns true, iteration stops.

func (*ValueMap) Len added in v0.2.0 

func (vs *ValueMap) Len() int

Len returns the number of elements in the map.

func (*ValueMap) Put added in v0.2.0 

func (vs *ValueMap) Put(k, v Value)

Put inserts a key k into the map with value v.

func (*ValueMap) String added in v0.2.0 

func (vs *ValueMap) String() string

type ValueResolver added in v0.4.9 

type ValueResolver interface {
	Resolve(ref Ref) (value Value, err error)
}

ValueResolver defines the interface for resolving references to AST values.

type Var 

type Var string

Var represents a variable as defined by the language.

func (Var) Compare added in v0.5.0 

func (v Var) Compare(other Value) int

Compare compares v to other, return <0, 0, or >0 if it is less than, equal to, or greater than other.

func (Var) Equal 

func (v Var) Equal(other Value) bool

Equal returns true if the other Value is a Variable and has the same value (name).

func (Var) Find added in v0.4.5 

func (v Var) Find(path Ref) (Value, error)

Find returns the current value or a not found error.

func (Var) Hash 

func (v Var) Hash() int

Hash returns the hash code for the Value.

func (Var) IsGenerated added in v0.5.11 

func (v Var) IsGenerated() bool

IsGenerated returns true if this variable was generated during compilation.

func (Var) IsGround 

func (v Var) IsGround() bool

IsGround always returns false.

func (Var) IsWildcard added in v0.2.0 

func (v Var) IsWildcard() bool

IsWildcard returns true if this is a wildcard variable.

func (Var) String 

func (v Var) String() string

type VarSet 

type VarSet map[Var]struct{}

VarSet represents a set of variables.

func NewVarSet 

func NewVarSet(vs ...Var) VarSet

NewVarSet returns a new VarSet containing the specified variables.

func Unify 

func Unify(safe VarSet, a *Term, b *Term) VarSet

Unify returns a set of variables that will be unified when the equality expression defined by terms a and b is evaluated. The unifier assumes that variables in the VarSet safe are already unified.

func (VarSet) Add 

func (s VarSet) Add(v Var)

Add updates the set to include the variable "v".

func (VarSet) Contains 

func (s VarSet) Contains(v Var) bool

Contains returns true if the set contains the variable "v".

func (VarSet) Copy 

func (s VarSet) Copy() VarSet

Copy returns a shallow copy of the VarSet.

func (VarSet) Diff 

func (s VarSet) Diff(vs VarSet) VarSet

Diff returns a VarSet containing variables in s that are not in vs.

func (VarSet) Equal added in v0.2.1 

func (s VarSet) Equal(vs VarSet) bool

Equal returns true if s contains exactly the same elements as vs.

func (VarSet) Intersect 

func (s VarSet) Intersect(vs VarSet) VarSet

Intersect returns a VarSet containing variables in s that are in vs.

func (VarSet) String 

func (s VarSet) String() string

func (VarSet) Update 

func (s VarSet) Update(vs VarSet)

Update merges the other VarSet into this VarSet.

type VarVisitor added in v0.3.0 

type VarVisitor struct {
	// contains filtered or unexported fields
}

VarVisitor walks AST nodes under a given node and collects all encountered variables. The collected variables can be controlled by specifying VarVisitorParams when creating the visitor.

func NewVarVisitor added in v0.3.0 

func NewVarVisitor() *VarVisitor

NewVarVisitor returns a new VarVisitor object.

func (*VarVisitor) Vars added in v0.3.0 

func (vis *VarVisitor) Vars() VarSet

Vars returns a VarSet that contains collected vars.

func (*VarVisitor) Visit added in v0.3.0 

func (vis *VarVisitor) Visit(v interface{}) Visitor

Visit is called to walk the AST node v.

func (*VarVisitor) WithParams added in v0.3.0 

func (vis *VarVisitor) WithParams(params VarVisitorParams) *VarVisitor

WithParams sets the parameters in params on vis.

type VarVisitorParams added in v0.3.0 

type VarVisitorParams struct {
	SkipRefHead     bool
	SkipRefCallHead bool
	SkipObjectKeys  bool
	SkipClosures    bool
	SkipWithTarget  bool
	SkipSets        bool
}

VarVisitorParams contains settings for a VarVisitor.

type Visitor 

type Visitor interface {
	Visit(v interface{}) (w Visitor)
}

Visitor defines the interface for iterating AST elements. The Visit function can return a Visitor w which will be used to visit the children of the AST element v. If the Visit function returns nil, the children will not be visited.

type With added in v0.4.1 

type With struct {
	Location *Location `json:"-"`
	Target   *Term     `json:"target"`
	Value    *Term     `json:"value"`
}

With represents a modifier on an expression.

func (*With) Compare added in v0.4.1 

func (w *With) Compare(other *With) int

Compare returns an integer indicating whether w is less than, equal to, or greater than other.

func (*With) Copy added in v0.4.1 

func (w *With) Copy() *With

Copy returns a deep copy of w.

func (*With) Equal added in v0.4.1 

func (w *With) Equal(other *With) bool

Equal returns true if this With is equals the other With.

func (With) Hash added in v0.4.1 

func (w With) Hash() int

Hash returns the hash code of the With.

func (*With) Loc added in v0.9.2 

func (w *With) Loc() *Location

Loc returns the Location of w.

func (*With) SetLoc added in v0.9.2 

func (w *With) SetLoc(loc *Location)

SetLoc sets the location on w.

func (*With) SetLocation added in v0.7.0 

func (w *With) SetLocation(loc *Location) *With

SetLocation sets the location on w.

func (*With) String added in v0.4.1 

func (w *With) String() string

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