feel

package module
v0.1.3 Latest Latest
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 Go to latest Published: Mar 15, 2025 License: MIT Imports: 16 Imported by: 0

README

FEEL.go

The interpreter of the FEEL language(Friendly Enough Expression Language) in go, FEEL is broadly used in DMN and BPMN to provide rule engine and script support, the FEEL.go module can be imported into other go projects or used as command line executable as FEEL interpreter.

Build

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

Examples


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

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

% bin/feel -c 'if a > 3 then "larger" else "smaller"' -vars '{a: 5}'
"larger"

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

for more examples please refer to testing

Use in golang codes

import (
  feel "github.com/superisaac/FEEL.go"
)

res, err := feel.EvalString(input)

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 Null = &NullValue{}
View Source 
var Zero = N(0)

Functions

func CompareValues added in v0.1.0 

func CompareValues(leftVal, rightVal any) int

func EvalString 

func EvalString(input string, varsList ...string) (any, error)

func EvalStringWithScope 

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

func ParseTemporalValue added in v0.1.0 

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

Types

type ArgSizeError 

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

ArgSizeError

func (ArgSizeError) Error 

func (err ArgSizeError) Error() string

type ArgTypeError 

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

arg type error

func (ArgTypeError) Error 

func (err ArgTypeError) Error() string

type ArrayNode 

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

array

func (ArrayNode) Eval 

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

func (ArrayNode) Repr 

func (node ArrayNode) Repr() string

func (ArrayNode) TextRange added in v0.1.0 

func (node ArrayNode) TextRange() TextRange

type Binop 

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

binary operator

func (Binop) Eval 

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

func (Binop) Repr 

func (op Binop) Repr() string

func (Binop) TextRange added in v0.1.0 

func (op Binop) TextRange() TextRange

type BoolNode 

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

bool

func (BoolNode) Eval 

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

Evaluate bool node

func (BoolNode) Repr 

func (node BoolNode) Repr() string

func (BoolNode) TextRange added in v0.1.0 

func (node BoolNode) TextRange() TextRange

type DotOp 

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

function call

func (DotOp) Eval 

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

func (DotOp) Repr 

func (op DotOp) Repr() string

func (DotOp) TextRange added in v0.1.0 

func (op DotOp) TextRange() TextRange

type EmptyNode added in v0.1.3 

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

Empty node

func (EmptyNode) Eval added in v0.1.3 

func (node EmptyNode) Eval(intp *Interpreter) (any, error)

func (EmptyNode) Repr added in v0.1.3 

func (node EmptyNode) Repr() string

func (EmptyNode) TextRange added in v0.1.3 

func (node EmptyNode) TextRange() TextRange

type EvalError 

type EvalError struct {
	Code    int
	Short   string
	Message string
}

func NewErrBadOp added in v0.1.0 

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

func NewErrIndex added in v0.1.0 

func NewErrIndex(msg string) *EvalError

func NewErrKeyNotFound added in v0.1.0 

func NewErrKeyNotFound(keyName string) *EvalError

func NewErrKeywordArgument added in v0.1.0 

func NewErrKeywordArgument(argName string) *EvalError

argument errors

func NewErrTooFewArguments added in v0.1.0 

func NewErrTooFewArguments(required []string) *EvalError

func NewErrTooManyArguments added in v0.1.0 

func NewErrTooManyArguments() *EvalError

func NewErrTypeMismatch added in v0.1.0 

func NewErrTypeMismatch(expectType string) *EvalError

func NewErrValue added in v0.1.0 

func NewErrValue(msg string) *EvalError

func NewEvalError 

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

func (EvalError) Error 

func (err EvalError) Error() string

type EveryExpr 

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

Every expression

func (EveryExpr) Eval 

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

func (EveryExpr) Repr 

func (node EveryExpr) Repr() string

func (EveryExpr) TextRange added in v0.1.0 

func (node EveryExpr) TextRange() TextRange

type FEELDate added in v0.1.0 

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

Date

func ParseDate added in v0.1.0 

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

func (FEELDate) Date added in v0.1.0 

func (date FEELDate) Date() time.Time

func (FEELDate) GetAttr added in v0.1.0 

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

func (FEELDate) MarshalJSON added in v0.1.0 

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

func (FEELDate) String added in v0.1.0 

func (date FEELDate) String() string

type FEELDatetime added in v0.1.0 

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

Date and Time

func MustParseDatetime added in v0.1.0 

func MustParseDatetime(temporalStr string) *FEELDatetime

func ParseDatetime added in v0.1.0 

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

func (*FEELDatetime) Add added in v0.1.0 

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

func (FEELDatetime) Compare added in v0.1.0 

func (sdt FEELDatetime) Compare(other FEELDatetime) int

func (FEELDatetime) Date added in v0.1.0 

func (sdt FEELDatetime) Date() time.Time

func (FEELDatetime) Equal added in v0.1.0 

func (sdt FEELDatetime) Equal(other FEELDatetime) bool

func (FEELDatetime) GetAttr added in v0.1.0 

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

func (FEELDatetime) MarshalJSON added in v0.1.0 

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

func (FEELDatetime) String added in v0.1.0 

func (sdt FEELDatetime) String() string

func (*FEELDatetime) Sub added in v0.1.0 

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

func (FEELDatetime) Time added in v0.1.0 

func (sdt FEELDatetime) Time() time.Time

type FEELDuration added in v0.1.0 

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

func NewFEELDuration added in v0.1.0 

func NewFEELDuration(dur time.Duration) *FEELDuration

func ParseDuration added in v0.1.0 

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

func (FEELDuration) Duration added in v0.1.0 

func (dur FEELDuration) Duration() time.Duration

func (FEELDuration) GetAttr added in v0.1.0 

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

func (FEELDuration) MarshalJSON added in v0.1.0 

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

func (*FEELDuration) Negative added in v0.1.0 

func (dur *FEELDuration) Negative() *FEELDuration

func (FEELDuration) String added in v0.1.0 

func (dur FEELDuration) String() string

type FEELTime added in v0.1.0 

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

time

func ParseTime added in v0.1.0 

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

func (FEELTime) GetAttr added in v0.1.0 

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

func (FEELTime) MarshalJSON added in v0.1.0 

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

func (FEELTime) String added in v0.1.0 

func (st FEELTime) String() string

func (FEELTime) Time added in v0.1.0 

func (st FEELTime) Time() time.Time

type ForExpr 

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

For expression

func (ForExpr) Eval 

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

func (ForExpr) Repr 

func (node ForExpr) Repr() string

func (ForExpr) TextRange added in v0.1.0 

func (node ForExpr) TextRange() TextRange

type FunCall 

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

func (FunCall) Eval 

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

func (FunCall) EvalFunDef 

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

func (FunCall) EvalMacro added in v0.1.0 

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

func (FunCall) EvalNativeFun 

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

func (FunCall) Repr 

func (fc FunCall) Repr() string

func (FunCall) TextRange added in v0.1.0 

func (fc FunCall) TextRange() TextRange

type FunDef 

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

function definition

func (FunDef) Eval 

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

func (FunDef) EvalCall added in v0.1.0 

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

func (FunDef) Repr 

func (fdef FunDef) Repr() string

func (FunDef) TextRange added in v0.1.0 

func (fdef FunDef) TextRange() TextRange

type HasAttrs added in v0.1.0 

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

type HasDate added in v0.1.0 

type HasDate interface {
	Date() time.Time
}

type HasTime added in v0.1.0 

type HasTime interface {
	Time() time.Time
}

type IfExpr 

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

if expression

func (IfExpr) Eval 

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

func (IfExpr) Repr 

func (node IfExpr) Repr() string

func (IfExpr) TextRange added in v0.1.0 

func (node IfExpr) TextRange() TextRange

type Interpreter 

type Interpreter struct {
	ScopeStack []Scope
}

func NewIntepreter 

func NewIntepreter() *Interpreter

intepreter

func (*Interpreter) Bind 

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

bind the value to the name of current scope

func (Interpreter) Len 

func (intp Interpreter) Len() int

func (*Interpreter) Pop 

func (intp *Interpreter) Pop() Scope

func (*Interpreter) Push 

func (intp *Interpreter) Push(scp Scope)

func (*Interpreter) PushEmpty 

func (intp *Interpreter) PushEmpty()

func (Interpreter) Resolve 

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

resolve a name from the top of scopestack to bottom

func (Interpreter) Set added in v0.1.0 

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

resolve the name and set to new value

func (Interpreter) String 

func (intp Interpreter) String() string

type Macro added in v0.1.0 

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

func NewMacro added in v0.1.0 

func NewMacro(fn MacroDef) *Macro

func (*Macro) Help added in v0.1.0 

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

func (*Macro) Optional added in v0.1.0 

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

func (*Macro) Required added in v0.1.0 

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

func (*Macro) Vararg added in v0.1.0 

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

type MacroDef added in v0.1.0 

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

macro

type MapNode 

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

func (MapNode) Eval 

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

func (MapNode) Repr 

func (node MapNode) Repr() string

func (MapNode) TextRange added in v0.1.0 

func (node MapNode) TextRange() TextRange

type MultiTests 

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

MultiTests

func (MultiTests) Eval 

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

func (MultiTests) Repr 

func (node MultiTests) Repr() string

func (MultiTests) TextRange added in v0.1.0 

func (node MultiTests) TextRange() TextRange

type NativeFun 

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

func NewNativeFunc 

func NewNativeFunc(fn NativeFunDef) *NativeFun

func (NativeFun) ArgNameAt added in v0.1.0 

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

func (*NativeFun) Call 

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

func (*NativeFun) Help added in v0.1.0 

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

func (*NativeFun) Optional added in v0.1.0 

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

func (*NativeFun) Required added in v0.1.0 

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

func (*NativeFun) Vararg added in v0.1.0 

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

type NativeFunDef 

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

native function

type Node added in v0.1.0 

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

func ParseString 

func ParseString(input string) (Node, error)

type NullNode 

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

null

func (NullNode) Eval 

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

func (NullNode) Repr 

func (node NullNode) Repr() string

func (NullNode) TextRange added in v0.1.0 

func (node NullNode) TextRange() TextRange

type NullValue 

type NullValue struct {
}

func (NullValue) Equal 

func (v NullValue) Equal(other NullValue) bool

func (NullValue) MarshalJSON added in v0.1.0 

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

type Number 

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

func N added in v0.1.0 

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 added in v0.1.0 

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

func (*Number) Add 

func (number *Number) Add(other *Number) *Number

func (*Number) Cmp 

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

func (Number) Compare 

func (number Number) Compare(other Number) int

func (Number) Equal 

func (number Number) Equal(other Number) bool

func (Number) Float64 added in v0.1.0 

func (number Number) Float64() float64

func (*Number) FloatDiv added in v0.1.0 

func (number *Number) FloatDiv(other *Number) *Number

func (Number) Int added in v0.1.0 

func (number Number) Int() int

func (Number) Int64 

func (number Number) Int64() int64

func (*Number) IntDiv 

func (number *Number) IntDiv(other *Number) *Number

func (*Number) IntMod 

func (number *Number) IntMod(other *Number) *Number

func (Number) MarshalJSON 

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

func (*Number) Mul 

func (number *Number) Mul(other *Number) *Number

func (Number) String 

func (number Number) String() string

func (*Number) Sub 

func (number *Number) Sub(other *Number) *Number

type NumberNode 

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

number

func (NumberNode) Eval 

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

Evaluate Number node

func (NumberNode) Repr 

func (node NumberNode) Repr() string

func (NumberNode) TextRange added in v0.1.0 

func (node 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
}

Prelude

func GetPrelude 

func GetPrelude() *Prelude

func (*Prelude) Bind 

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

func (*Prelude) Load 

func (prelude *Prelude) Load()

func (*Prelude) Resolve 

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

type RangeNode 

type RangeNode struct {
	StartOpen bool
	Start     Node

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

range

func (RangeNode) Eval 

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

func (RangeNode) Repr 

func (node RangeNode) Repr() string

func (RangeNode) TextRange added in v0.1.0 

func (node RangeNode) TextRange() TextRange

type RangeValue 

type RangeValue struct {
	StartOpen bool
	Start     any

	EndOpen bool
	End     any
}

func (RangeValue) AfterPoint added in v0.1.0 

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

func (RangeValue) AfterRange added in v0.1.0 

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

func (RangeValue) BeforePoint added in v0.1.0 

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

func (RangeValue) BeforeRange added in v0.1.0 

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

func (RangeValue) Contains 

func (rv RangeValue) Contains(p any) bool

func (RangeValue) Includes added in v0.1.0 

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

func (RangeValue) Position added in v0.1.0 

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)

* * 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]any

type SomeExpr 

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

Some expression

func (SomeExpr) Eval 

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

func (SomeExpr) Repr 

func (node SomeExpr) Repr() string

func (SomeExpr) TextRange added in v0.1.0 

func (node SomeExpr) TextRange() TextRange

type StringNode 

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

string

func (StringNode) Content 

func (node StringNode) Content() string

func (StringNode) Eval 

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

func (StringNode) Repr 

func (node StringNode) Repr() string

func (StringNode) TextRange added in v0.1.0 

func (node StringNode) TextRange() TextRange

type TemporalNode added in v0.1.0 

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

temporal

func (TemporalNode) Content added in v0.1.0 

func (node TemporalNode) Content() string

func (TemporalNode) Eval added in v0.1.0 

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

func (TemporalNode) Repr added in v0.1.0 

func (node TemporalNode) Repr() string

func (TemporalNode) TextRange added in v0.1.0 

func (node TemporalNode) TextRange() TextRange

type TextRange added in v0.1.0 

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 (err UnexpectedToken) Error() string

type Var 

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

variable

func (Var) Eval 

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

func (Var) Repr 

func (v Var) Repr() string

func (Var) TextRange added in v0.1.0 

func (v Var) TextRange() TextRange

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