asn1go

README

asn1go

Rationale

Built-in Go libraries for asn1 support are either reflection-based (crypto/asn1) or very low-level (golang.org/x/crypto/cryptobyte). Idea is to provide Protobuf-like experience for working with ASN1 in Golang.

Note: currently provided code generator implementation creates definitions to be used with crypto/asn1, so all its limitations (no real CHOICE support) apply for this project as well.

Architecture

1. Custom Lexer consumes from bufio.Reader and called by Parser
2. Parser is built using goyacc based on BNF provided in X.680 standard. As the result, Parser produces ASN1 module AST.
3. AST is used by Code Generator to produce declarations, serialization, and deserialization code.

Supported features

Feature categories

Feature	Parsing	Codegen
Exports	Syntax only	No
Imports	Yes	No
Type assignments	Yes	Yes
Value assignments	Yes	Partial [^f1]
XML	No
Objects	No
Parameterization	No

[^f1]: Only literal values are supported, referenced values are not implemented.

Types

Type	Parsing	Codegen
BIT STRING	Yes	Yes; named bits not translated
BOOLEAN	Yes	Yes
CHARACTER STRING	Yes	Yes
CHOICE	Yes	Yes; common demoninator type is used
Embedded PDV	No
External	No
ENUMERATED	Yes [^t4]	Yes; alternative values not translated
Instance Of	No
INTEGER	Yes	Yes
NULL	Yes
Object Class	No
Object Identifier	Yes
OCTET STRING	Yes	Yes
REAL	Yes	Yes
Relative OID	No
SEQUENCE	Yes [^t1]	Yes
SEQUENCE OF	Yes	Yes
SET	Yes [^t1]	Yes
SET OF	Yes	Yes
ANY	Yes [^t2]	Yes
Tagged types	Yes	Yes [^t3]
Constrained types	Partial	Partial; generates wrapped type

[^t1]: With ASN.1 syntax limitations: two component type lists, exceptions and extension addition groups are not supported, extensions are not exposed in generated Go code. [^t2]: Not defined in the latest ASN.1 standard. [^t3]: Used by encoding/asn1 only in SEQUENCE and SET fields. CHOICE with tagged alternatives is represented as RawValue. [^t4]: With ASN.1 syntax limitations: explicit extensibility and non-literal values are not supported.

Values

Value	Parsing	Codegen
BOOLEAN	Yes	Yes
INTEGER	Yes	Yes
OID	Yes	No
Real	Yes	Yes
Referenced	No
Object class fields	No
BIT STRING	No
Other	No

Roadmap

1. Lexer

• identifiers
• numbers
• keywords
• symbols
• strings, bit strings, hex strings
• XML

1. Parser

• module definition BNF
• parse Kerberos (rfc4120)
• yield AST from parser
• parse SNMPv1 (rfc1157, rfc1155); no codegen, depends on CHOICE
• parse LDAP (rfc4511, partially - required minor modifications); no codegen, depends on CHOICE
• parse X.509 (rfc 5280) - depends on ANY
• SNMPv2 (rfc3411–3418)

1. Code Generator

• declaration generator
• crypto/asn1 compatible generation mode
• verify serialization on Kerberos
• DER serialization generator
• DER deserialization generator

1. Supported ASN features

• SET type
• ANY type (1988 standard) - mapped to interface{}
• CHOICE type - mapped to interface{}, or asn1.RawValue if selections are tagged
• Extensions in SEQUENCE, SET, CHOICE
• Add more as found

Adding features

Real-world ASN.1 descriptions from RFC documents are used to gauge completeness of the implementation. Standard itself is pretty huge, so features are added as needed.

Typically, this requires:

1. Modifying asn1.y to uncomment unsupported branches of syntax notation, and add missing declarations. Refer to goyacc documentation for .y syntax notation.
2. Extending ast.go with necessary fields and types.
3. Modifying codegen.go to produce corresponding Go declarations. Note that not all ASN declarations can be mapped to crypto/asn1.

For example, refer to CHOICE implementation.

Documentation

Index

• Constants
• Variables
• func MarshalToFile(val interface{}, path string, mode os.FileMode) error
• type AnyType
• type Assignment
• type AssignmentList
  • func (l AssignmentList) Get(name string) Assignment
  • func (l AssignmentList) GetType(name string) *TypeAssignment
  • func (l AssignmentList) GetValue(name string) *ValueAssignment
• type BitStringType
• type Boolean
  • func (Boolean) Type() Type
• type BooleanType
• type CharacterStringType
• type ChoiceExtension
• type ChoiceType
• type CodeGenerator
  • func NewCodeGenerator(params GenParams) CodeGenerator
• type ComponentType
• type ComponentTypeList
• type ComponentTypeLists
• type ComponentsOfComponentType
• type Constraint
  • func SingleElementConstraint(elem Elements) Constraint
• type ConstraintSpec
• type ConstraintedType
• type DefinedValue
  • func (DefinedValue) Type() Type
• type DefinitiveIdentifier
• type DefinitiveObjIdComponent
• type ElementSetSpec
• type Elements
• type EnumeratedType
• type EnumerationItem
• type Exclusions
• type ExtensionAddition
• type ExtensionAdditions
• type GenParams
• type GenType
• type GeneralConstraint
• type GlobalModuleReference
• type IdentifiedIntegerValue
  • func (x IdentifiedIntegerValue) Type() Type
• type Identifier
  • func (id Identifier) Name() string
• type InnerTypeConstraint
• type IntegerRepr
• type IntegerType
• type IntersectionElements
• type Intersections
• type ModuleBody
• type ModuleDefinition
  • func ParseFile(name string) (*ModuleDefinition, error)
  • func ParseStream(reader io.Reader) (*ModuleDefinition, error)
  • func ParseString(str string) (*ModuleDefinition, error)
• type ModuleIdentifier
• type ModuleReference
• type MyLexer
  • func (lex *MyLexer) Error(e string)
  • func (lex *MyLexer) Lex(lval *yySymType) int
• type NamedBit
• type NamedComponentType
• type NamedNumber
• type NamedNumberValue
• type NamedType
• type NullType
• type Number
  • func (x Number) IntValue() int
  • func (Number) Type() Type
  • func (x Number) UnaryMinus() Number
• type ObjectIdElement
• type ObjectIdentifierType
• type ObjectIdentifierValue
  • func (ObjectIdentifierValue) Type() Type
• type OctetStringType
• type RangeEndpoint
  • func (e RangeEndpoint) IsUnspecified() bool
• type Real
  • func (x Real) Type() Type
  • func (x Real) UnaryMinus() Real
• type RealType
• type Reference
• type RestrictedStringType
• type SequenceOfType
• type SequenceType
• type SetOfType
• type SetType
• type SingleValue
• type SizeConstraint
• type SubtypeConstraint
• type Symbol
• type SymbolsFromModule
• type Tag
• type TaggedType
• type Type
• type TypeAssignment
  • func (v TypeAssignment) Reference() Reference
• type TypeConstraint
• type TypeReference
  • func (r TypeReference) Name() string
• type Unions
• type Value
• type ValueAssignment
  • func (v ValueAssignment) Reference() Reference
• type ValueRange
• type ValueReference
  • func (r ValueReference) Name() string

Constants

const (
	TAGS_EXPLICIT = iota
	TAGS_IMPLICIT
	TAGS_AUTOMATIC
)

Consts for ModuleDefinition.TagDefault.

const (
	CLASS_CONTEXT_SPECIFIC = iota // when not specified
	CLASS_UNIVERSAL
	CLASS_APPLICATION
	CLASS_PRIVATE
)

Tag class constants.

const (
	GeneralizedTimeName = "GeneralizedTime"
	UTCTimeName         = "UTCTime"
)

Names for useful types.

const ABSENT = 57389

const ABSTRACT_SYNTAX = 57393

const ALL = 57397

const ANY = 57469

const APOSTROPHE = 57382

const APPLICATION = 57401

const ASSIGNMENT = 57357

const AT = 57385

const AUTOMATIC = 57405

const BEGIN = 57409

const BIT = 57413

const BMPString = 57417

const BOOLEAN = 57421

const BSTRING = 57351

const BY = 57425

const CARET = 57388

const CHARACTER = 57429

const CHOICE = 57433

const CLASS = 57437

const CLOSE_CURLY = 57369

const CLOSE_ROUND = 57375

const CLOSE_SQUARE = 57377

const COLON = 57379

const COMMA = 57372

const COMPONENT = 57441

const COMPONENTS = 57445

const CONSTRAINED = 57449

const CONTAINING = 57453

const CSTRING = 57355

const DEFAULT = 57457

const DEFINED = 57470

const DEFINITIONS = 57461

const DOT = 57373

const ELLIPSIS = 57359

const EMBEDDED = 57465

const ENCODED = 57390

const END = 57394

const ENUMERATED = 57398

const EQUALS = 57380

const EXCEPT = 57402

const EXCLAMATION = 57387

const EXPLICIT = 57406

const EXPONENT = 57367

const EXPORTS = 57410

const EXTENSIBILITY = 57414

const EXTERNAL = 57418

const FALSE = 57422

const FROM = 57426

const GREATER = 57371

const GeneralString = 57434

const GeneralizedTime = 57430

const GraphicString = 57438

const HSTRING = 57353

const IA5String = 57442

const IDENTIFIER = 57446

const IMPLICIT = 57450

const IMPLIED = 57454

const IMPORTS = 57458

const INCLUDES = 57462

const INSTANCE = 57466

const INTEGER = 57391

const INTERSECTION = 57395

const ISO646String = 57399

const LEFT_VERSION_BRACKETS = 57360

const LESS = 57370

const MAX = 57403

const MIN = 57407

const MINUS = 57378

const MINUS_INFINITY = 57411

const NEWLINE = 57347

const NULL = 57415

const NUMBER = 57350

const NumericString = 57419

const OBJECT = 57423

const OCTET = 57431

const OF = 57435

const OPEN_CURLY = 57368

const OPEN_ROUND = 57374

const OPEN_SQUARE = 57376

const OPTIONAL = 57439

const ObjectDescriptor = 57427

const PATTERN = 57443

const PDV = 57447

const PIPE = 57386

const PLUS_INFINITY = 57451

const PRESENT = 57455

const PRIVATE = 57463

const PrintableString = 57459

const QUOTATION_MARK = 57381

const RANGE_SEPARATOR = 57358

const REAL = 57467

const RELATIVE_OID = 57392

const RIGHT_VERSION_BRACKETS = 57361

const SEMICOLON = 57384

const SEQUENCE = 57396

const SET = 57400

const SIZE = 57404

const SPACE = 57383

const STRING = 57408

const SYNTAX = 57412

const T61String = 57416

const TAGS = 57420

const TRUE = 57428

const TYPEORMODULEREFERENCE = 57348

const TYPE_IDENTIFIER = 57432

const TeletexString = 57424

const UNION = 57436

const UNIQUE = 57440

const UNIVERSAL = 57444

const UTCTime = 57452

const UTF8String = 57456

const UniversalString = 57448

const VALUEIDENTIFIER = 57349

const VideotexString = 57460

const VisibleString = 57464

const WHITESPACE = 57346

const WITH = 57468

const XMLASN1TYPENAME = 57366

const XMLBSTRING = 57352

const XMLCSTRING = 57356

const XMLHSTRING = 57354

const XML_BOOLEAN_FALSE = 57365

const XML_BOOLEAN_TRUE = 57364

const XML_END_TAG_START = 57362

const XML_SINGLE_START_END = 57363

Variables

var (
	RESERVED_WORDS map[string]int = map[string]int{
		"ABSENT":           ABSENT,
		"ENCODED":          ENCODED,
		"INTEGER":          INTEGER,
		"RELATIVE-OID":     RELATIVE_OID,
		"ABSTRACT-SYNTAX":  ABSTRACT_SYNTAX,
		"END":              END,
		"INTERSECTION":     INTERSECTION,
		"SEQUENCE":         SEQUENCE,
		"ALL":              ALL,
		"ENUMERATED":       ENUMERATED,
		"ISO646String":     ISO646String,
		"SET":              SET,
		"APPLICATION":      APPLICATION,
		"EXCEPT":           EXCEPT,
		"MAX":              MAX,
		"SIZE":             SIZE,
		"AUTOMATIC":        AUTOMATIC,
		"EXPLICIT":         EXPLICIT,
		"MIN":              MIN,
		"STRING":           STRING,
		"BEGIN":            BEGIN,
		"EXPORTS":          EXPORTS,
		"MINUS-INFINITY":   MINUS_INFINITY,
		"SYNTAX":           SYNTAX,
		"BIT":              BIT,
		"EXTENSIBILITY":    EXTENSIBILITY,
		"NULL":             NULL,
		"T61String":        T61String,
		"BMPString":        BMPString,
		"EXTERNAL":         EXTERNAL,
		"NumericString":    NumericString,
		"TAGS":             TAGS,
		"BOOLEAN":          BOOLEAN,
		"FALSE":            FALSE,
		"OBJECT":           OBJECT,
		"TeletexString":    TeletexString,
		"BY":               BY,
		"FROM":             FROM,
		"ObjectDescriptor": ObjectDescriptor,
		"TRUE":             TRUE,
		"CHARACTER":        CHARACTER,
		"GeneralizedTime":  GeneralizedTime,
		"OCTET":            OCTET,
		"TYPE-IDENTIFIER":  TYPE_IDENTIFIER,
		"CHOICE":           CHOICE,
		"GeneralString":    GeneralString,
		"OF":               OF,
		"UNION":            UNION,
		"CLASS":            CLASS,
		"GraphicString":    GraphicString,
		"OPTIONAL":         OPTIONAL,
		"UNIQUE":           UNIQUE,
		"COMPONENT":        COMPONENT,
		"IA5String":        IA5String,
		"PATTERN":          PATTERN,
		"UNIVERSAL":        UNIVERSAL,
		"COMPONENTS":       COMPONENTS,
		"IDENTIFIER":       IDENTIFIER,
		"PDV":              PDV,
		"UniversalString":  UniversalString,
		"CONSTRAINED":      CONSTRAINED,
		"IMPLICIT":         IMPLICIT,
		"PLUS-INFINITY":    PLUS_INFINITY,
		"UTCTime":          UTCTime,
		"CONTAINING":       CONTAINING,
		"IMPLIED":          IMPLIED,
		"PRESENT":          PRESENT,
		"UTF8String":       UTF8String,
		"DEFAULT":          DEFAULT,
		"IMPORTS":          IMPORTS,
		"PrintableString":  PrintableString,
		"VideotexString":   VideotexString,
		"DEFINITIONS":      DEFINITIONS,
		"INCLUDES":         INCLUDES,
		"PRIVATE":          PRIVATE,
		"VisibleString":    VisibleString,
		"EMBEDDED":         EMBEDDED,
		"INSTANCE":         INSTANCE,
		"REAL":             REAL,
		"WITH":             WITH,
		"ANY":              ANY,
		"DEFINED":          DEFINED,
	}
)

var (
	// USEFUL_TYPES are defined in X.680, section 41.
	// These are built-in types that behave like type assignments that are always in scope.
	// TODO: clarify why UTCTimeName is missing here.
	USEFUL_TYPES map[string]Type = map[string]Type{
		GeneralizedTimeName: TaggedType{
			Tag:  Tag{Class: CLASS_UNIVERSAL, ClassNumber: Number(24)},
			Type: RestrictedStringType{VisibleString}},
	}
)

Functions

func MarshalToFile

func MarshalToFile(val interface{}, path string, mode os.FileMode) error

Types

type AnyType

type AnyType struct {
	// Identifier is set if IDENTIFIED BY is provided.
	Identifier Identifier
}

AnyType is an ast representation of ANY type. It is NOT defined in X.680, but added for compatibility with older ASN definitions, e.g. X.509. See X.208, section 27.

type Assignment

type Assignment interface {
	Reference() Reference
}

Assignment is interface for Assignment nodes. Only TypeAssignment and ValueAssignment are supported. Other assignment types (value sets, xml values, objects) are not implemented.

type AssignmentList

type AssignmentList []Assignment

AssignmentList holds assignments in module body.

func (AssignmentList) Get

func (l AssignmentList) Get(name string) Assignment

Get finds Assignment by defined reference name, or returns nil if not found.

func (AssignmentList) GetType

func (l AssignmentList) GetType(name string) *TypeAssignment

GetType returns TypeAssignment by name, or nil if not found.

func (AssignmentList) GetValue

func (l AssignmentList) GetValue(name string) *ValueAssignment

GetValue returns ValueAssignment by name, or nil if not found.

type BitStringType

type BitStringType struct {
	NamedBits []NamedBit
}

BitStringType is an ast representation of BIT STRING type.

type Boolean

type Boolean bool

Boolean is a bool value. It is named BooleanValue in BNF. See X.680, section 17.3.

func (Boolean) Type

func (Boolean) Type() Type

Type implements Value.

type BooleanType

type BooleanType struct{}

BooleanType is an ast representation of BOOLEAN type.

type CharacterStringType

type CharacterStringType struct{}

CharacterStringType is an ast representation of CHARACTER STRING type. It is defined as UnrestrictedCharacterStringType in BNF.

type ChoiceExtension

type ChoiceExtension interface {
	// contains filtered or unexported methods
}

ChoiceExtension is a type for choice extensions. Only NamedType is implemented, ExtensionAdditionAlternativesGroup is not supported.

type ChoiceType

type ChoiceType struct {
	AlternativeTypeList []NamedType
	ExtensionTypes      []ChoiceExtension
}

ChoiceType is an ast representation of CHOICE type. It is partially implemented, exceptions are ignored.

type CodeGenerator

type CodeGenerator interface {
	Generate(module ModuleDefinition, writer io.Writer) error
}

CodeGenerator is an interface for code generation from ASN.1 modules.

func NewCodeGenerator

func NewCodeGenerator(params GenParams) CodeGenerator

NewCodeGenerator creates a new code generator from provided params.

type ComponentType

type ComponentType interface {
	ExtensionAddition
	// contains filtered or unexported methods
}

ComponentType is a component type of SEQUENCE or SET. It can be used in ExtensionAddition context, so types implementing it must implement both.

type ComponentTypeList

type ComponentTypeList []ComponentType

ComponentTypeList is a list of ComponentType.

type ComponentTypeLists

type ComponentTypeLists struct {
	Components         ComponentTypeList
	ExtensionAdditions ExtensionAdditions
	TrailingComponents ComponentTypeList
}

ComponentTypeLists is not used in AST directly but is used in parser for intermediate representation.

type ComponentsOfComponentType

type ComponentsOfComponentType struct {
	Type Type
}

ComponentsOfComponentType is content of COMPONENTS OF clause.

type Constraint

type Constraint struct {
	ConstraintSpec ConstraintSpec
}

Constraint is a constraint applied to a type.

func SingleElementConstraint

func SingleElementConstraint(elem Elements) Constraint

SingleElementConstraint is a Constraint of single intersection elements.

type ConstraintSpec

type ConstraintSpec interface {
	// contains filtered or unexported methods
}

ConstraintSpec can be SubtypeConstraint or GeneralConstraint. GeneralConstraint is not implemented.

type ConstraintedType

type ConstraintedType struct {
	Type       Type
	Constraint Constraint
}

ConstraintedType is a type with constraints applied. General constraints are not implemented in parser, and exception spec is not preserved in AST.

type DefinedValue

type DefinedValue struct {
	// ModuleName, if non-empty, specifies module where value was defined.
	ModuleName ModuleReference
	// ValueName is name of the value.
	// It should always be provided.
	ValueName ValueReference
}

DefinedValue represents value reference.

func (DefinedValue) Type

func (DefinedValue) Type() Type

Type implements Value.

type DefinitiveIdentifier

type DefinitiveIdentifier []DefinitiveObjIdComponent

DefinitiveIdentifier is fully qualified name of the module.

type DefinitiveObjIdComponent

type DefinitiveObjIdComponent struct {
	Name string
	Id   int
}

DefinitiveObjIdComponent is part of DefinitiveIdentifier.

type ElementSetSpec

type ElementSetSpec interface {
	Elements
	// contains filtered or unexported methods
}

ElementSetSpec is element of the SubtypeConstraint.

type Elements

type Elements interface {
	// contains filtered or unexported methods
}

Elements is one of subtype elements (values, type constraints, etc).

type EnumeratedType

type EnumeratedType struct {
	// Alternatives of the enumeration.
	RootEnumeration       []EnumerationItem
	AdditionalEnumeration []EnumerationItem
}

EnumeratedType is an ast representation of ENUMERATED type. TODO: implement enumerations properly.

type EnumerationItem

type EnumerationItem interface {
	// contains filtered or unexported methods
}

EnumerationItem is interface for items. It can be NamedNumber of Identifier.

type Exclusions

type Exclusions struct {
	Elements Elements
}

Exclusions are Elements excluded from IntersectionElements.

type ExtensionAddition

type ExtensionAddition interface {
	// contains filtered or unexported methods
}

ExtensionAddition is a single element of extension addition.

type ExtensionAdditions

type ExtensionAdditions []ExtensionAddition

ExtensionAdditions is a list of extension additions in SET or SEQUENCE.

type GenParams

type GenParams struct {
	// Package is go package name.
	// If not specified, ASN.1 module name will be used to derive go module name.
	Package string
	// Type is a type of code generation to run.
	// TODO: deprecate in favor of separate New methods.
	Type GenType
	// IntegerRepr controls how INTEGER type is expressed in generated go code.
	IntegerRepr IntegerRepr
}

GenParams is code generator configuration.

type GenType

type GenType int

GenType is code generator type.

const (
	// GEN_DECLARATIONS is code generator that is
	GEN_DECLARATIONS GenType = iota
)

type GeneralConstraint

type GeneralConstraint struct{}

GeneralConstraint is not implemented. It is defined by X.682. TODO: implement or remove.

type GlobalModuleReference

type GlobalModuleReference struct {
	Reference          string
	AssignedIdentifier Value
}

GlobalModuleReference fully qualifies module from which symbols are imported.

type IdentifiedIntegerValue

type IdentifiedIntegerValue struct {
	Name string
	// contains filtered or unexported fields
}

IdentifiedIntegerValue is named value defined for the type. TODO: use of these in assignments is not implemented.

func (IdentifiedIntegerValue) Type

func (x IdentifiedIntegerValue) Type() Type

Type implements Value.

type Identifier

type Identifier string

Identifier is a non-referential identifier. This is a lexical construct, named `identifier` in the doc. See X.680, section 11.3.

func (Identifier) Name

func (id Identifier) Name() string

Name returns name of the reference.

type InnerTypeConstraint

type InnerTypeConstraint struct{}

InnerTypeConstraint is WITH COMPONENT constraint. Contents are not represented in parsed AST and are ignored.

type IntegerRepr

type IntegerRepr string

IntegerRepr is enum controlling how INTEGER is represented.

const (
	IntegerReprInt64  IntegerRepr = "int64"
	IntegerReprBigInt IntegerRepr = "big.Int"
)

IntegerRepr modes supported.

type IntegerType

type IntegerType struct {
	NamedNumberList []NamedNumber
}

IntegerType is an ast representation of INTEGER type.

type IntersectionElements

type IntersectionElements struct {
	Elements   Elements
	Exclusions Exclusions
}

IntersectionElements is part of Intersections.

type Intersections

type Intersections []IntersectionElements

Intersections is a part of SubtypeConstraint.

type ModuleBody

type ModuleBody struct {
	AssignmentList AssignmentList
	Imports        []SymbolsFromModule
}

ModuleBody holds module body. TODO: implement Exports.

type ModuleDefinition

type ModuleDefinition struct {
	ModuleIdentifier ModuleIdentifier
	// TagDefault is default tagging behavior, one of TAGS_ constants.
	TagDefault           int
	ExtensibilityImplied bool
	ModuleBody           ModuleBody
}

ModuleDefinition represents ASN.1 ModuleName. This and all other AST types are named according to their BNF in X.680 document, if not specified otherwise. See: X.680, section 12.

func ParseFile

func ParseFile(name string) (*ModuleDefinition, error)

ParseFile parses ASN.1 definition file into ASN.1 AST.

func ParseStream

func ParseStream(reader io.Reader) (*ModuleDefinition, error)

ParseStream reads text of ASN.1 definitions from provided reader and parses it into ASN.1 AST.

func ParseString

func ParseString(str string) (*ModuleDefinition, error)

ParseString parses string containing ASN.1 definitions into ASN.1 AST.

type ModuleIdentifier

type ModuleIdentifier struct {
	Reference            string
	DefinitiveIdentifier DefinitiveIdentifier
}

ModuleIdentifier is root of ASN.1 module.

type ModuleReference

type ModuleReference string

ModuleReference refers to a module. This is lexical construct, named `modulereference` in the doc. See X.680, section 11.5.

type MyLexer

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

MyLexer is an ASN.1 lexer that is producing lexems for the generated goyacc parser.

func (*MyLexer) Error

func (lex *MyLexer) Error(e string)

Error implements yyLexer, and is used by the parser to communicate errors.

func (*MyLexer) Lex

func (lex *MyLexer) Lex(lval *yySymType) int

Lex implements yyLexer. It is reading runes from the bufReader, stores some state in lval if needed, and returns token type. If syntax error was detected, it saves it in err, and returns -1, which is understood by goyacc as end of input.

type NamedBit

type NamedBit struct {
	Name Identifier
	// Index is index of the bit.
	// Will have Number or DefinedValue type.
	Index Value
}

NamedBit is a named bit in BIT STRING.

type NamedComponentType

type NamedComponentType struct {
	NamedType  NamedType
	IsOptional bool
	Default    *Value
}

NamedComponentType is an entry in a SEQUENCE definition.

type NamedNumber

type NamedNumber struct {
	Name  Identifier
	Value NamedNumberValue
}

NamedNumber is number with name. It is mainly used as Enumerated and Integer definitions.

type NamedNumberValue

type NamedNumberValue interface {
	// contains filtered or unexported methods
}

NamedNumberValue signifies that value can be a value of named number.

type NamedType

type NamedType struct {
	Identifier Identifier
	Type       Type
}

NamedType is a identifier-type tuple. It's used as element in SequenceType, SetType, ChoiceType and some other types.

type NullType

type NullType struct{}

NullType is an ast representation of NULL type.

type Number

type Number int

Number is an integer value. This is a lexical construct, named `number` in the doc. See X.680, section 11.8.

func (Number) IntValue

func (x Number) IntValue() int

IntValue returns value of the number.

func (Number) Type

func (Number) Type() Type

Type implements Value.

func (Number) UnaryMinus

func (x Number) UnaryMinus() Number

UnaryMinus returns negated Number.

type ObjectIdElement

type ObjectIdElement struct {
	// Name is non-empty in name-and-number form.
	Name string
	// ID is set in Number or NameAndNumber form, if number is specified as number literal.
	ID int
	// Reference is set in NameAndNumber form, when number is provided as DefinedValue.
	// NameForm is always parsed as Reference.
	Reference *DefinedValue
}

ObjectIdElement is object id element in name, number or name and number form.

type ObjectIdentifierType

type ObjectIdentifierType struct{}

ObjectIdentifierType is an ast representation of OBJECT IDENTIFIER type.

type ObjectIdentifierValue

type ObjectIdentifierValue []ObjectIdElement

ObjectIdentifierValue is a value of OBJECT IDENTIFIER type.

func (ObjectIdentifierValue) Type

func (ObjectIdentifierValue) Type() Type

Type implements Value.

type OctetStringType

type OctetStringType struct{}

OctetStringType is an ast representation of OCTET STRING type.

type RangeEndpoint

type RangeEndpoint struct {
	Value  Value
	IsOpen bool // X<..<X
}

RangeEndpoint is left or right side of the ValueRange.

func (RangeEndpoint) IsUnspecified

func (e RangeEndpoint) IsUnspecified() bool

IsUnspecified corresponds to MIN or MAX of the range.

type Real

type Real float64

Real is a floating point value. This is a lexical construct, named `realnumber` in the doc. See X.680, section 11.9.

func (Real) Type

func (x Real) Type() Type

Type implements Value.

func (Real) UnaryMinus

func (x Real) UnaryMinus() Real

UnaryMinus returns negated value.

type RealType

type RealType struct{}

RealType is an ast representation of REAL type.

type Reference

type Reference interface {
	Name() string
}

Reference is an interface for a reference. There are different reference types depending on a referent.

type RestrictedStringType

type RestrictedStringType struct {
	// LexType is a lexem value for restricted string (e.g. IA5String).
	LexType int
}

RestrictedStringType is a type for strings with restricted character set. It is defined as RestrictedCharacterStringType in BNF. See X.680, section 36.1.

type SequenceOfType

type SequenceOfType struct {
	Type Type
}

SequenceOfType is an ast representation of SEQUENCE OF type.

type SequenceType

type SequenceType struct {
	Components         ComponentTypeList
	ExtensionAdditions ExtensionAdditions
}

SequenceType is an ast representation of SEQUENCE type. TODO: Exceptions are not supported.

type SetOfType

type SetOfType struct {
	Type Type
}

SetOfType is an ast representation of SET OF type.

type SetType

type SetType struct {
	Components         ComponentTypeList
	ExtensionAdditions ExtensionAdditions
}

SetType is an ast representation of SEQUENCE type. TODO: Extensions are not supported.

type SingleValue

type SingleValue struct {
	Value
}

SingleValue is included or excluded value.

type SizeConstraint

type SizeConstraint struct {
	Constraint Constraint
}

SizeConstraint is a SIZE constraint expressed by another Constraint.

type SubtypeConstraint

type SubtypeConstraint []ElementSetSpec

SubtypeConstraint describes list of element sets that can be used in constainted type

type Symbol

type Symbol interface {
	// contains filtered or unexported methods
}

Symbol is exported or imported symbol. Only References are supported, ParameterizedReference is not implemented.

type SymbolsFromModule

type SymbolsFromModule struct {
	SymbolList []Symbol
	Module     GlobalModuleReference
}

SymbolsFromModule holds imports from particular module.

type Tag

type Tag struct {
	// Class is a tag class, one of CLASS_ constants.
	// E.g. UNIVERSAL, APPLICATION.
	Class int
	// ClassNumber is a tag value.
	// Will hold DefinedValue or Number.
	ClassNumber Value
}

Tag is a tag value.

type TaggedType

type TaggedType struct {
	// Tag assigned to a type.
	Tag Tag
	// Type that is being tagged.
	Type Type
	// TagType is one of TAGS_ constants.
	// E.g. IMPLICIT, EXPLICIT.
	TagType int
	// HasTagType is set to true if TagType was explicitly specified in module syntax.
	// Otherwise, TagType would hold module default.
	HasTagType bool // true if explicitly set
}

TaggedType is a tagged type.

type Type

type Type interface {
	// contains filtered or unexported methods
}

Type is a builtin, referenced or constrained type.

type TypeAssignment

type TypeAssignment struct {
	TypeReference TypeReference
	Type          Type
}

TypeAssignment defines TypeReference of specified Type.

func (TypeAssignment) Reference

func (v TypeAssignment) Reference() Reference

Reference implements Assignment.

type TypeConstraint

type TypeConstraint struct {
	Type Type
}

TypeConstraint is a type constraint.

type TypeReference

type TypeReference string

TypeReference refers to a type defined in same module or imported from different module. This is lexical construct, named `typereference` in the doc. See X.680, section 11.2.

func (TypeReference) Name

func (r TypeReference) Name() string

Name implements Reference.

type Unions

type Unions []Intersections

Unions is ElementSetSpec and Elements

type Value

type Value interface {
	Type() Type
}

Value is interface for values.

type ValueAssignment

type ValueAssignment struct {
	ValueReference ValueReference
	Type           Type
	Value          Value
}

ValueAssignment defines ValueReference of Type with given Value.

func (ValueAssignment) Reference

func (v ValueAssignment) Reference() Reference

Reference implements Assignment.

type ValueRange

type ValueRange struct {
	LowerEndpoint RangeEndpoint
	UpperEndpoint RangeEndpoint
}

ValueRange is included or excluded range.

type ValueReference

type ValueReference string

ValueReference refers to a value defined in same module or imported from different module. This is lexical construct, named `valuereference` in the doc. See X.680, section 11.2.

func (ValueReference) Name

func (r ValueReference) Name() string

Name implements Reference.