eval

package
v0.0.0-...-551a65d Latest Latest
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 Go to latest Published: Jun 11, 2021 License: Apache-2.0 Imports: 10 Imported by: 0

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var Cache = NewCache(cache.NoExpiration, 0)

Cache declares a default cache for expression evaluation with no key experation

View Source 
var (

	// ErrEmptyExpression is returned for empty string used as expression input
	ErrEmptyExpression = errors.New("invalid empty expression")
)

Functions

This section is empty.

Types

type Array 

type Array struct {
	Pos lexer.Position

	Values []Value `parser:"\"[\" @@ { \",\" @@ } \"]\""`
	Ident  *string `parser:"| @Ident"`
}

Array provides support for array syntax and may contain any valid Values (mixed allowed)

func (*Array) Evaluate 

func (a *Array) Evaluate(instance Instance) (interface{}, error)

Evaluate implements Evaluatable interface

type ArrayComparison 

type ArrayComparison struct {
	Pos lexer.Position

	Op *string `parser:"( @( \"in\" | \"not\" \"in\" )"`
	// TODO: likely doesn't work with rhs expression
	Array *Array `parser:"@@ )"`
}

ArrayComparison represents syntax for array comparison

type Call 

type Call struct {
	Pos lexer.Position

	Name string        `parser:"@Ident"`
	Args []*Expression `parser:"\"(\" [ @@ { \",\" @@ } ] \")\""`
}

Call implements function call syntax

func (*Call) Evaluate 

func (c *Call) Evaluate(instance Instance) (interface{}, error)

Evaluate implements Evaluatable interface

type Comparison 

type Comparison struct {
	Pos lexer.Position

	Term             *Term             `parser:"@@"`
	ScalarComparison *ScalarComparison `parser:"[ @@"`
	ArrayComparison  *ArrayComparison  `parser:"| @@ ]"`
}

Comparison represents syntax for comparison operations

func (*Comparison) Evaluate 

func (c *Comparison) Evaluate(instance Instance) (interface{}, error)

Evaluate implements Evaluatable interface

type Evaluatable 

type Evaluatable interface {
	Evaluate(instance Instance) (interface{}, error)
}

Evaluatable abstracts part of an expression that can be evaluated for an instance

type Expression 

type Expression struct {
	Pos lexer.Position

	Comparison *Comparison `parser:"@@"`
	Op         *string     `parser:"[ @( \"|\" \"|\" | \"&\" \"&\" )"`
	Next       *Expression `parser:"  @@ ]"`
}

Expression represents basic expression syntax that can be evaluated for an Instance

func ParseExpression 

func ParseExpression(s string) (*Expression, error)

ParseExpression parses Expression from a string

func (*Expression) BoolEvaluate added in v0.9.0 

func (e *Expression) BoolEvaluate(instance Instance) (bool, error)

BoolEvaluate evaluates an expression for an instance as a boolean value

func (*Expression) Evaluate 

func (e *Expression) Evaluate(instance Instance) (interface{}, error)

Evaluate evaluates an expression for an instance

type ExpressionCache added in v0.9.0 

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

ExpressionCache implements cached parsing for expressions

func NewCache added in v0.9.0 

func NewCache(defaultExpiration, cleanupInterval time.Duration) *ExpressionCache

NewCache returns a new instance of evalCache

func (*ExpressionCache) ParseExpression added in v0.9.0 

func (c *ExpressionCache) ParseExpression(s string) (*Expression, error)

ParseExpression parses Expression from a string

func (*ExpressionCache) ParseIterable added in v0.9.0 

func (c *ExpressionCache) ParseIterable(s string) (*IterableExpression, error)

ParseIterable parses IterableExpression from a string

func (*ExpressionCache) ParsePath added in v0.9.0 

func (c *ExpressionCache) ParsePath(s string) (*PathExpression, error)

ParsePath parses PathExpression from a string

type Function 

type Function func(instance Instance, args ...interface{}) (interface{}, error)

Function describes a function callable for an instance

type FunctionMap 

type FunctionMap map[string]Function

FunctionMap describes a map of functions

type Instance 

type Instance interface {
	Var(name string) (interface{}, bool)
	Vars() VarMap
	Function(name string) (Function, bool)
	Functions() FunctionMap
}

Instance for evaluation

func NewInstance added in v0.9.0 

func NewInstance(vars VarMap, functions FunctionMap) Instance

NewInstance instantiates a new evaluation instance

type InstanceResult 

type InstanceResult struct {
	Instance Instance
	Passed   bool
}

InstanceResult captures an Instance along with the passed or failed status for the result

type IterableComparison 

type IterableComparison struct {
	Pos lexer.Position

	Fn               *string           `parser:"@( \"count\" | \"all\" | \"none\" )"`
	Expression       *Expression       `parser:"\"(\" @@ \")\""`
	ScalarComparison *ScalarComparison `parser:"[ @@ ]"`
}

IterableComparison allows evaluating a builtin pseudo-funciion for an iterable expression

type IterableExpression 

type IterableExpression struct {
	Pos lexer.Position

	IterableComparison *IterableComparison `parser:"@@"`
	Expression         *Expression         `parser:"| @@"`
}

IterableExpression represents an iterable expration that can be evaluated for an Iterator

func ParseIterable 

func ParseIterable(s string) (*IterableExpression, error)

ParseIterable parses IterableExpression from a string

func (*IterableExpression) Evaluate 

func (e *IterableExpression) Evaluate(instance Instance) (bool, error)

Evaluate evaluates an iterable expression for a single instance

func (*IterableExpression) EvaluateIterator 

func (e *IterableExpression) EvaluateIterator(it Iterator, global Instance) ([]*InstanceResult, error)

EvaluateIterator evaluates an iterable expression for an iterator

type Iterator 

type Iterator interface {
	Next() (Instance, error)
	Done() bool
}

Iterator abstracts iteration over a set of instances for expression evaluation

type PathExpression 

type PathExpression struct {
	Pos lexer.Position

	Path       *string     `parser:"@UnixSystemPath"`
	Expression *Expression `parser:"| @@"`
}

PathExpression represents an expression evaluating to a file path or file glob

func ParsePath 

func ParsePath(s string) (*PathExpression, error)

ParsePath parses PathExpression from a string

func (*PathExpression) Evaluate 

func (e *PathExpression) Evaluate(instance Instance) (interface{}, error)

Evaluate evaluates a path expression for an instance

type ScalarComparison 

type ScalarComparison struct {
	Pos lexer.Position

	Op   *string     `parser:"@( \">\" \"=\" | \"<\" \"=\" | \">\" | \"<\" | \"!\" \"=\" | \"=\" \"=\" | \"=\" \"~\" | \"!\" \"~\" )"`
	Next *Comparison `parser:"  @@"`
}

ScalarComparison represents syntax for scalar comparison

type Term 

type Term struct {
	Pos lexer.Position

	Unary *Unary  `parser:"@@"`
	Op    *string `parser:"[ @( \"&\" | \"|\" | \"^\" | \"+\" )"`
	Next  *Term   `parser:"  @@ ]"`
}

Term is an abstract term allowing optional binary bit operation syntax

func (*Term) Evaluate 

func (t *Term) Evaluate(instance Instance) (interface{}, error)

Evaluate implements Evaluatable interface

type Unary 

type Unary struct {
	Pos lexer.Position

	Op    *string `parser:"( @( \"!\" | \"-\" | \"^\" )"`
	Unary *Unary  `parser:"  @@ )"`
	Value *Value  `parser:"| @@"`
}

Unary is a unary bit operation syntax

func (*Unary) Evaluate 

func (u *Unary) Evaluate(instance Instance) (interface{}, error)

Evaluate implements Evaluatable interface

type Value 

type Value struct {
	Pos lexer.Position

	Hex           *string     `parser:"  @Hex"`
	Octal         *string     `parser:"| @Octal"`
	Decimal       *int64      `parser:"| @Decimal"`
	String        *string     `parser:"| @String"`
	Call          *Call       `parser:"| @@"`
	Variable      *string     `parser:"| @Ident"`
	Subexpression *Expression `parser:"| \"(\" @@ \")\""`
}

Value provides support for various value types in expression including integers in various form, strings, function calls, variables and subexpressions

func (*Value) Evaluate 

func (v *Value) Evaluate(instance Instance) (interface{}, error)

Evaluate implements Evaluatable interface

type VarMap 

type VarMap map[string]interface{}

VarMap describes a map of variables

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