feel

package module
v1.0.6 Latest Latest
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 Go to latest Published: Mar 8, 2026 License: MIT Imports: 15 Imported by: 1

README

feel

An interpreter for the FEEL - Friendly Enough Expression Language, written in Go(lang). FEEL is broadly used in DMN and BPMN to provide rule engine and script support. The feel module can be imported into other Go projects or used as command line executable.

Credits

This library is based on work of @superisaac/FEEL.go and many thanks and credits go to him.

Build

  • run make build to build feel interpreter bin/feel
  • run make test to run testing

Use in golang applications

import (
  feel "github.com/pbinitiative/feel"
)

res, err := feel.EvalString("5 + 7")

Examples, with using the CLI tool


% bin/feel -c '"hello " + "world"'
"hello world"

% bin/feel -c '(function(a, b) a + b)(5, 8)'
13

# dump AST tree instead of evaluating the script
% bin/feel -c 'bind("a", 5); if a > 3 then "larger" else "smaller"' -ast
(explist (call bind ["a", 5]) (if (> a 3) "larger"  "smaller"))

% bin/feel -c 'some x in [3, 4, 8, 9] satisfies x % 2 = 0'
4

% bin/feel -c 'every x in [3, 4, 8, 9] satisfies x % 2 = 0'
[
  4,
  8
]

Documentation

Index

Constants

View Source 
const (
	TokenEOF               = "eof"
	TokenSpace             = "space"
	TokenCommentSingleLine = "comment/singleline"
	TokenCommentMultiline  = "comment/multiline"

	TokenName = "name"
	//TokenFuncall  = "funcall"
	TokenTemporal = "temporal"
	TokenString   = "string"

	TokenKeyword = "keyword"
	TokenNumber  = "number"
)
View Source 
const (
	Prec = 34 * 8
)

Variables

View Source 
var (
	ErrParseNumber = errors.New("fail to parse number")
)
View Source 
var ErrParseTemporal = errors.New("fail to parse temporal value")
View Source 
var Zero = N(0)

Functions

func CompareValues 

func CompareValues(leftVal, rightVal any) int

func EvalString 

func EvalString(input string) (any, error)

func EvalStringWithScope 

func EvalStringWithScope(input string, scope Scope) (any, error)

func ParseTemporalValue 

func ParseTemporalValue(temporalStr string) (interface{}, error)

Types

type ArgSizeError 

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

func (ArgSizeError) Error 

func (self ArgSizeError) Error() string

type ArgTypeError 

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

func (ArgTypeError) Error 

func (self ArgTypeError) Error() string

type ArrayNode 

type ArrayNode struct {
	Elements []Node
	// contains filtered or unexported fields
}

func (ArrayNode) Eval 

func (arrNode ArrayNode) Eval(intp *Interpreter) (any, error)

func (ArrayNode) Repr 

func (arrNode ArrayNode) Repr() string

func (ArrayNode) TextRange 

func (arrNode ArrayNode) TextRange() TextRange

type Binop 

type Binop struct {
	Op    string
	Left  Node
	Right Node
	// contains filtered or unexported fields
}

Binop binary operator

func (Binop) Eval 

func (binop Binop) Eval(intp *Interpreter) (any, error)

func (Binop) Repr 

func (binop Binop) Repr() string

func (Binop) TextRange 

func (binop Binop) TextRange() TextRange

type BoolNode 

type BoolNode struct {
	Value bool
	// contains filtered or unexported fields
}

func (BoolNode) Eval 

func (boolNode BoolNode) Eval(intp *Interpreter) (any, error)

Eval Evaluate bool node

func (BoolNode) Repr 

func (boolNode BoolNode) Repr() string

func (BoolNode) TextRange 

func (boolNode BoolNode) TextRange() TextRange

type DotOp 

type DotOp struct {
	Left Node
	Attr string
	// contains filtered or unexported fields
}

DotOp function call

func (DotOp) Eval 

func (dotop DotOp) Eval(intp *Interpreter) (any, error)

func (DotOp) Repr 

func (dotop DotOp) Repr() string

func (DotOp) TextRange 

func (dotop DotOp) TextRange() TextRange

type EvalError 

type EvalError struct {
	Code    int
	Short   string
	Message string
}

func NewErrBadInput added in v0.1.5 

func NewErrBadInput(row int, column int, inputText string) *EvalError

func NewErrBadOp 

func NewErrBadOp(leftType, op, rightType string) *EvalError

func NewErrIndex 

func NewErrIndex(msg string) *EvalError

func NewErrKeyNotFound 

func NewErrKeyNotFound(keyName string) *EvalError

func NewErrKeywordArgument 

func NewErrKeywordArgument(argName string) *EvalError

NewErrKeywordArgument argument errors

func NewErrTooFewArguments 

func NewErrTooFewArguments(required []string) *EvalError

func NewErrTooManyArguments 

func NewErrTooManyArguments() *EvalError

func NewErrTypeMismatch 

func NewErrTypeMismatch(expectType string) *EvalError

func NewEvalError 

func NewEvalError(code int, short string, msgs ...string) *EvalError

func (EvalError) Error 

func (evalError EvalError) Error() string

type EveryExpr 

type EveryExpr struct {
	Varname    string
	ListExpr   Node
	FilterExpr Node
	// contains filtered or unexported fields
}

EveryExpr Every expression

func (EveryExpr) Eval 

func (ee EveryExpr) Eval(intp *Interpreter) (any, error)

func (EveryExpr) Repr 

func (ee EveryExpr) Repr() string

func (EveryExpr) TextRange 

func (ee EveryExpr) TextRange() TextRange

type ExprList 

type ExprList struct {
	Elements []Node
	// contains filtered or unexported fields
}

ExprList Expression List

func (ExprList) Eval 

func (exprList ExprList) Eval(intp *Interpreter) (any, error)

func (ExprList) Repr 

func (exprList ExprList) Repr() string

func (ExprList) TextRange 

func (exprList ExprList) TextRange() TextRange

type FEELDate 

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

func ParseDate 

func ParseDate(timeStr string) (*FEELDate, error)

func (FEELDate) Date 

func (d FEELDate) Date() time.Time

func (FEELDate) GetAttr 

func (d FEELDate) GetAttr(name string) (interface{}, bool)

func (FEELDate) MarshalJSON 

func (d FEELDate) MarshalJSON() ([]byte, error)

func (FEELDate) String 

func (d FEELDate) String() string

type FEELDatetime 

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

func MustParseDatetime 

func MustParseDatetime(temporalStr string) *FEELDatetime

func ParseDatetime 

func ParseDatetime(temporalStr string) (*FEELDatetime, error)

func (*FEELDatetime) Add 

func (dt *FEELDatetime) Add(dur *FEELDuration) *FEELDatetime

func (FEELDatetime) Compare 

func (dt FEELDatetime) Compare(other FEELDatetime) int

func (FEELDatetime) Date 

func (dt FEELDatetime) Date() time.Time

func (FEELDatetime) Equal 

func (dt FEELDatetime) Equal(other FEELDatetime) bool

func (FEELDatetime) GetAttr 

func (dt FEELDatetime) GetAttr(name string) (interface{}, bool)

func (FEELDatetime) MarshalJSON 

func (dt FEELDatetime) MarshalJSON() ([]byte, error)

func (FEELDatetime) String 

func (dt FEELDatetime) String() string

func (*FEELDatetime) Sub 

func (dt *FEELDatetime) Sub(v HasTime) *FEELDuration

func (FEELDatetime) Time 

func (dt FEELDatetime) Time() time.Time

type FEELDuration 

type FEELDuration struct {
	Neg     bool
	Years   int
	Months  int
	Days    int
	Hours   int
	Minutes int
	Seconds int
}

func NewFEELDuration 

func NewFEELDuration(dur time.Duration) *FEELDuration

func ParseDuration 

func ParseDuration(temporalStr string) (*FEELDuration, error)

func (FEELDuration) Duration 

func (duration FEELDuration) Duration() time.Duration

func (FEELDuration) GetAttr 

func (duration FEELDuration) GetAttr(name string) (interface{}, bool)

func (FEELDuration) MarshalJSON 

func (duration FEELDuration) MarshalJSON() ([]byte, error)

func (FEELDuration) Negative 

func (duration FEELDuration) Negative() *FEELDuration

func (FEELDuration) String 

func (duration FEELDuration) String() string

type FEELTime 

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

func ParseTime 

func ParseTime(temporalStr string) (*FEELTime, error)

func (FEELTime) GetAttr 

func (t FEELTime) GetAttr(name string) (interface{}, bool)

func (FEELTime) MarshalJSON 

func (t FEELTime) MarshalJSON() ([]byte, error)

func (FEELTime) String 

func (t FEELTime) String() string

func (FEELTime) Time 

func (t FEELTime) Time() time.Time

type ForExpr 

type ForExpr struct {
	Varname    string
	ListExpr   Node
	ReturnExpr Node
	// contains filtered or unexported fields
}

ForExpr FOR expression

func (ForExpr) Eval 

func (fe ForExpr) Eval(intp *Interpreter) (any, error)

func (ForExpr) Repr 

func (fe ForExpr) Repr() string

func (ForExpr) TextRange 

func (fe ForExpr) TextRange() TextRange

type FunCall 

type FunCall struct {
	FunRef Node
	Args   []funcallArg
	// contains filtered or unexported fields
}

func (FunCall) Eval 

func (fc FunCall) Eval(intp *Interpreter) (any, error)

func (FunCall) EvalFunDef 

func (fc FunCall) EvalFunDef(intp *Interpreter, funDef *FunDef) (any, error)

func (FunCall) EvalMacro 

func (fc FunCall) EvalMacro(intp *Interpreter, macro *Macro) (any, error)

func (FunCall) EvalNativeFun 

func (fc FunCall) EvalNativeFun(intp *Interpreter, funDef *NativeFun) (any, error)

func (FunCall) Repr 

func (fc FunCall) Repr() string

func (FunCall) TextRange 

func (fc FunCall) TextRange() TextRange

type FunDef 

type FunDef struct {
	Args []string
	Body Node
	// contains filtered or unexported fields
}

FunDef function definition

func (FunDef) Eval 

func (fd FunDef) Eval(intp *Interpreter) (any, error)

func (FunDef) EvalCall 

func (fd FunDef) EvalCall(intp *Interpreter, args []any) (any, error)

func (FunDef) Repr 

func (fd FunDef) Repr() string

func (FunDef) TextRange 

func (fd FunDef) TextRange() TextRange

type HasAttrs 

type HasAttrs interface {
	GetAttr(name string) (interface{}, bool)
}

type HasDate 

type HasDate interface {
	Date() time.Time
}

type HasTime 

type HasTime interface {
	Time() time.Time
}

type IfExpr 

type IfExpr struct {
	Cond       Node
	ThenBranch Node
	ElseBranch Node
	// contains filtered or unexported fields
}

func (IfExpr) Eval 

func (ifExpr IfExpr) Eval(intp *Interpreter) (any, error)

func (IfExpr) Repr 

func (ifExpr IfExpr) Repr() string

func (IfExpr) TextRange 

func (ifExpr IfExpr) TextRange() TextRange

type Interpreter 

type Interpreter struct {
	ScopeStack []Scope
}

func NewIntepreter 

func NewIntepreter() *Interpreter

func (*Interpreter) Bind 

func (i *Interpreter) Bind(name string, value any)

Bind the value to the name of current scope

func (Interpreter) Len 

func (i Interpreter) Len() int

func (*Interpreter) Pop 

func (i *Interpreter) Pop() Scope

func (*Interpreter) Push 

func (i *Interpreter) Push(scp Scope)

func (*Interpreter) PushEmpty 

func (i *Interpreter) PushEmpty()

func (Interpreter) Resolve 

func (i Interpreter) Resolve(name string) (any, bool)

Resolve a name from the top of scopestack to bottom

func (Interpreter) Set 

func (i Interpreter) Set(name string, value any) bool

Set the name and set to new value

func (Interpreter) String 

func (i Interpreter) String() string

type Macro 

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

func NewMacro 

func NewMacro(fn MacroDef) *Macro

func (*Macro) Help 

func (self *Macro) Help(help string) *Macro

func (*Macro) Optional 

func (self *Macro) Optional(argNames ...string) *Macro

func (*Macro) Required 

func (self *Macro) Required(argNames ...string) *Macro

func (*Macro) Vararg 

func (self *Macro) Vararg(argName string) *Macro

type MacroDef 

type MacroDef func(intp *Interpreter, args map[string]Node, varArgs []Node) (interface{}, error)

type MapNode 

type MapNode struct {
	Values []mapItem
	// contains filtered or unexported fields
}

func (MapNode) Eval 

func (mapNode MapNode) Eval(intp *Interpreter) (any, error)

func (MapNode) Repr 

func (mapNode MapNode) Repr() string

func (MapNode) TextRange 

func (mapNode MapNode) TextRange() TextRange

type MultiTests 

type MultiTests struct {
	Elements []Node
	// contains filtered or unexported fields
}

func (MultiTests) Eval 

func (mt MultiTests) Eval(intp *Interpreter) (any, error)

func (MultiTests) Repr 

func (mt MultiTests) Repr() string

func (MultiTests) TextRange 

func (mt MultiTests) TextRange() TextRange

type NativeFun 

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

func NewNativeFunc 

func NewNativeFunc(fn NativeFunDef) *NativeFun

func (NativeFun) ArgNameAt 

func (nativeFun NativeFun) ArgNameAt(at int) (string, bool)

func (*NativeFun) Call 

func (nativeFun *NativeFun) Call(intp *Interpreter, args map[string]interface{}) (interface{}, error)

func (*NativeFun) Help 

func (nativeFun *NativeFun) Help(help string) *NativeFun

func (*NativeFun) Optional 

func (nativeFun *NativeFun) Optional(argNames ...string) *NativeFun

func (*NativeFun) Required 

func (nativeFun *NativeFun) Required(argNames ...string) *NativeFun

func (*NativeFun) Vararg 

func (nativeFun *NativeFun) Vararg(argName string) *NativeFun

type NativeFunDef 

type NativeFunDef func(args map[string]interface{}) (interface{}, error)

NativeFunDef native function

type Node 

type Node interface {
	Repr() string
	Eval(*Interpreter) (interface{}, error)
	TextRange() TextRange
}

func ParseString 

func ParseString(input string) (Node, error)

type NullNode 

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

func (NullNode) Eval 

func (nullNode NullNode) Eval(intp *Interpreter) (any, error)

func (NullNode) Repr 

func (nullNode NullNode) Repr() string

func (NullNode) TextRange 

func (nullNode NullNode) TextRange() TextRange

type NullValue 

type NullValue struct {
}

func (NullValue) Equal 

func (self NullValue) Equal(other NullValue) bool

func (NullValue) MarshalJSON 

func (self NullValue) MarshalJSON() ([]byte, error)

type Number 

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

func N 

func N(v interface{}) *Number

func NewNumber 

func NewNumber(strn string) *Number

func NewNumberFromFloat 

func NewNumberFromFloat(input float64) *Number

func NewNumberFromInt64 

func NewNumberFromInt64(input int64) *Number

func ParseNumberWithErr 

func ParseNumberWithErr(v interface{}) (*Number, error)

func (*Number) Add 

func (n *Number) Add(other *Number) *Number

func (*Number) Cmp 

func (n *Number) Cmp(other *Number) int

func (Number) Compare 

func (n Number) Compare(other Number) int

func (Number) Equal 

func (n Number) Equal(other Number) bool

func (Number) Float64 

func (n Number) Float64() float64

func (*Number) FloatDiv 

func (n *Number) FloatDiv(other *Number) *Number

func (Number) Int 

func (n Number) Int() int

func (Number) Int64 

func (n Number) Int64() int64

func (*Number) IntDiv 

func (n *Number) IntDiv(other *Number) *Number

func (*Number) IntMod 

func (n *Number) IntMod(other *Number) *Number

func (Number) MarshalJSON 

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

func (*Number) Mul 

func (n *Number) Mul(other *Number) *Number

func (Number) String 

func (n Number) String() string

func (*Number) Sub 

func (n *Number) Sub(other *Number) *Number

type NumberNode 

type NumberNode struct {
	Value string
	// contains filtered or unexported fields
}

func (NumberNode) Eval 

func (numberNode NumberNode) Eval(intp *Interpreter) (any, error)

Eval Evaluate Number node

func (NumberNode) Repr 

func (numberNode NumberNode) Repr() string

func (NumberNode) TextRange 

func (numberNode NumberNode) TextRange() TextRange

type Parser 

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

func NewParser 

func NewParser(scanner *Scanner) *Parser

func (Parser) CurrentToken 

func (p Parser) CurrentToken() ScannerToken

func (*Parser) Parse 

func (p *Parser) Parse() (Node, error)

func (Parser) Unexpected 

func (p Parser) Unexpected(expects ...string) *UnexpectedToken

type Prelude 

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

func GetPrelude 

func GetPrelude() *Prelude

func (*Prelude) Bind 

func (self *Prelude) Bind(name string, value interface{}) *Prelude

func (*Prelude) Load 

func (self *Prelude) Load()

func (*Prelude) Resolve 

func (self *Prelude) Resolve(name string) (interface{}, bool)

type RangeNode 

type RangeNode struct {
	StartOpen bool
	Start     Node

	EndOpen bool
	End     Node
	// contains filtered or unexported fields
}

func (RangeNode) Eval 

func (rangeNode RangeNode) Eval(intp *Interpreter) (any, error)

func (RangeNode) Repr 

func (rangeNode RangeNode) Repr() string

func (RangeNode) TextRange 

func (rangeNode RangeNode) TextRange() TextRange

type RangeValue 

type RangeValue struct {
	StartOpen bool
	Start     any

	EndOpen bool
	End     any
}

func (RangeValue) AfterPoint 

func (rv RangeValue) AfterPoint(p any) (bool, error)

func (RangeValue) AfterRange 

func (rv RangeValue) AfterRange(other RangeValue) (bool, error)

func (RangeValue) BeforePoint 

func (rv RangeValue) BeforePoint(p any) (bool, error)

func (RangeValue) BeforeRange 

func (rv RangeValue) BeforeRange(other RangeValue) (bool, error)

func (RangeValue) Contains 

func (rv RangeValue) Contains(p any) bool

func (RangeValue) Includes 

func (rv RangeValue) Includes(other RangeValue) (bool, error)

func (RangeValue) Position 

func (rv RangeValue) Position(p any) (int, error)

type ScanPosition 

type ScanPosition struct {
	Row    int
	Column int
}

type Scanner 

type Scanner struct {
	Pos   ScanPosition
	Eaten int
	// contains filtered or unexported fields
}

func NewScanner 

func NewScanner(input string) *Scanner

func (Scanner) Current 

func (scanner Scanner) Current() ScannerToken

func (*Scanner) Next 

func (scanner *Scanner) Next() error

func (*Scanner) Tokens 

func (scanner *Scanner) Tokens() ([]ScannerToken, error)

Tokens Find all tokens

type ScannerToken 

type ScannerToken struct {
	Kind  string
	Value string
	Pos   ScanPosition
}

func (ScannerToken) Expect 

func (token ScannerToken) Expect(tokenKinds ...string) bool

func (ScannerToken) ExpectKeywords 

func (token ScannerToken) ExpectKeywords(words ...string) bool

func (ScannerToken) IsOp 

func (token ScannerToken) IsOp() bool

type Scope 

type Scope map[string]interface{}

type SomeExpr 

type SomeExpr struct {
	Varname    string
	ListExpr   Node
	FilterExpr Node
	// contains filtered or unexported fields
}

SomeExpr some expression

func (SomeExpr) Eval 

func (sexpr SomeExpr) Eval(intp *Interpreter) (any, error)

func (SomeExpr) Repr 

func (sexpr SomeExpr) Repr() string

func (SomeExpr) TextRange 

func (sexpr SomeExpr) TextRange() TextRange

type StringNode 

type StringNode struct {
	Value string
	// contains filtered or unexported fields
}

func (StringNode) Content 

func (stringNode StringNode) Content() string

func (StringNode) Eval 

func (stringNode StringNode) Eval(intp *Interpreter) (any, error)

func (StringNode) Repr 

func (stringNode StringNode) Repr() string

func (StringNode) TextRange 

func (stringNode StringNode) TextRange() TextRange

type TemporalNode 

type TemporalNode struct {
	Value string
	// contains filtered or unexported fields
}

func (TemporalNode) Content 

func (tempNode TemporalNode) Content() string

func (TemporalNode) Eval 

func (tempNode TemporalNode) Eval(intp *Interpreter) (any, error)

func (TemporalNode) Repr 

func (tempNode TemporalNode) Repr() string

func (TemporalNode) TextRange 

func (tempNode TemporalNode) TextRange() TextRange

type TextRange 

type TextRange struct {
	Start ScanPosition
	End   ScanPosition
}

type UnexpectedToken 

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

func NewUnexpectedToken 

func NewUnexpectedToken(token ScannerToken, callers []string, expects []string) *UnexpectedToken

func (UnexpectedToken) Error 

func (self UnexpectedToken) Error() string

type Var 

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

Var variable

func (Var) Eval 

func (v Var) Eval(intp *Interpreter) (any, error)

func (Var) Repr 

func (v Var) Repr() string

func (Var) TextRange 

func (v Var) TextRange() TextRange

Source Files

View all Source files

Directories

Path Synopsis
cmd
testcase-extractor command
testcase-extractor/fs
testcase-extractor/model/dmn
testcase-extractor/model/tck
testcase-extractor/model/tcktestconfig
testcase-extractor/model/testconfig

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