traits

Documentation

Overview

Package traits defines interfaces that a type may implement to participate in operator overloads and function dispatch.

Index

• Constants
• type Adder
• type Comparer
• type Container
• type Divider
• type FieldTester
• type Indexer
• type Iterable
• type Iterator
• type Lister
• type Mapper
• type Matcher
• type Modder
• type Multiplier
• type MutableLister
• type Negater
• type Receiver
• type Sizer
• type Subtractor
• type Zeroer

Constants

const (
	// AdderType types provide a '+' operator overload.
	AdderType = 1 << iota

	// ComparerType types support ordering comparisons '<', '<=', '>', '>='.
	ComparerType

	// ContainerType types support 'in' operations.
	ContainerType

	// DividerType types support '/' operations.
	DividerType

	// FieldTesterType types support the detection of field value presence.
	FieldTesterType

	// IndexerType types support index access with dynamic values.
	IndexerType

	// IterableType types can be iterated over in comprehensions.
	IterableType

	// IteratorType types support iterator semantics.
	IteratorType

	// MatcherType types support pattern matching via 'matches' method.
	MatcherType

	// ModderType types support modulus operations '%'
	ModderType

	// MultiplierType types support '*' operations.
	MultiplierType

	// NegatorType types support either negation via '!' or '-'
	NegatorType

	// ReceiverType types support dynamic dispatch to instance methods.
	ReceiverType

	// SizerType types support the size() method.
	SizerType

	// SubtractorType type support '-' operations.
	SubtractorType
)

Types

type Adder

type Adder interface {
	// Add returns a combination of the current value and other value.
	//
	// If the other value is an unsupported type, an error is returned.
	Add(other ref.Val) ref.Val
}

Adder interface to support '+' operator overloads.

type Comparer

type Comparer interface {
	// Compare this value to the input other value, returning an Int:
	//
	//    this < other  -> Int(-1)
	//    this == other ->  Int(0)
	//    this > other  ->  Int(1)
	//
	// If the comparison cannot be made or is not supported, an error should
	// be returned.
	Compare(other ref.Val) ref.Val
}

Comparer interface for ordering comparisons between values in order to support '<', '<=', '>=', '>' overloads.

type Container

type Container interface {
	// Contains returns true if the value exists within the object.
	Contains(value ref.Val) ref.Val
}

Container interface which permits containment tests such as 'a in b'.

type Divider

type Divider interface {
	// Divide returns the result of dividing the current value by the input
	// denominator.
	//
	// A denominator value of zero results in an error.
	Divide(denominator ref.Val) ref.Val
}

Divider interface to support '/' operator overloads.

type FieldTester

type FieldTester interface {
	// IsSet returns true if the field is defined and set to a non-default
	// value. The method will return false if defined and not set, and an error
	// if the field is not defined.
	IsSet(field ref.Val) ref.Val
}

FieldTester indicates if a defined field on an object type is set to a non-default value.

For use with the `has()` macro.

type Indexer

type Indexer interface {
	// Get the value at the specified index or error.
	Get(index ref.Val) ref.Val
}

Indexer permits random access of elements by index 'a[b()]'.

type Iterable

type Iterable interface {
	// Iterator returns a new iterator view of the struct.
	Iterator() Iterator
}

Iterable aggregate types permit traversal over their elements.

type Iterator

type Iterator interface {
	ref.Val

	// HasNext returns true if there are unvisited elements in the Iterator.
	HasNext() ref.Val

	// Next returns the next element.
	Next() ref.Val
}

Iterator permits safe traversal over the contents of an aggregate type.

type Lister

type Lister interface {
	ref.Val
	Adder
	Container
	Indexer
	Iterable
	Sizer
}

Lister interface which aggregates the traits of a list.

type Mapper

type Mapper interface {
	ref.Val
	Container
	Indexer
	Iterable
	Sizer

	// Find returns a value, if one exists, for the input key.
	//
	// If the key is not found the function returns (nil, false).
	// If the input key is not valid for the map, or is Err or Unknown the function returns
	// (Unknown|Err, false).
	Find(key ref.Val) (ref.Val, bool)
}

Mapper interface which aggregates the traits of a maps.

type Matcher

type Matcher interface {
	// Match returns true if the pattern matches the current value.
	Match(pattern ref.Val) ref.Val
}

Matcher interface for supporting 'matches()' overloads.

type Modder

type Modder interface {
	// Modulo returns the result of taking the modulus of the current value
	// by the denominator.
	//
	// A denominator value of zero results in an error.
	Modulo(denominator ref.Val) ref.Val
}

Modder interface to support '%' operator overloads.

type Multiplier

type Multiplier interface {
	// Multiply returns the result of multiplying the current and input value.
	Multiply(other ref.Val) ref.Val
}

Multiplier interface to support '*' operator overloads.

type MutableLister

type MutableLister interface {
	Lister
	ToImmutableList() Lister
}

MutableLister interface which emits an immutable result after an intermediate computation.

type Negater

type Negater interface {
	// Negate returns the complement of the current value.
	Negate() ref.Val
}

Negater interface to support unary '-' and '!' operator overloads.

type Receiver

type Receiver interface {
	// Receive accepts a function name, overload id, and arguments and returns
	// a value.
	Receive(function string, overload string, args []ref.Val) ref.Val
}

Receiver interface for routing instance method calls within a value.

type Sizer

type Sizer interface {
	// Size returns the number of elements or length of the value.
	Size() ref.Val
}

Sizer interface for supporting 'size()' overloads.

type Subtractor

type Subtractor interface {
	// Subtract returns the result of subtracting the input from the current
	// value.
	Subtract(subtrahend ref.Val) ref.Val
}

Subtractor interface to support binary '-' operator overloads.

type Zeroer

type Zeroer interface {
	// IsZeroValue indicates whether the object is the zero value for the type.
	IsZeroValue() bool
}

Zeroer interface for testing whether a CEL value is a zero value for its type.