goexpr

README

Goexpr

Goexpr provides support for evaluating expressions with parameters, arimethetic, logical, and string operations.

• basic expression: 1 > 0
• parameterized expression: x > 0
• nested parameterized expression: a.b > 0
• arithmetic expression: (x * y / 100) >= 50
• string expression: real == "expected"
• float64 expression: (part / total) * 100

Installation

When used with Go modules, use the following import path:

go get github.com/leonests/goexpr

Quickstart

Example 1: Simple Usage Without Parameters

import "github.com/leonests/goexpr"

expr, err := goexpr.NewExpr("1 > 0")
result, err := expr.Eval(nil)
// result is true.

Example 2: Simple Usage With Parameters

import "github.com/leonests/goexpr"

expr, err := goexpr.NewExpr(`(x * y / 100) >= 50`)
param := map[string]interface{}{ "x": 100, "y": 50}
result, err := expr.Eval(parametes)
// result is true.

Advanced

Bracket Accessor

Dot Accessor

Method

Documentation

Index

• type Expr
  • func NewExpr(expr string) (res *Expr, err error)
  • func (expr *Expr) Eval(params map[string]interface{}) (interface{}, error)
• type ExprFunc
• type LexerToken
• type TokenType
  • func (op TokenType) Priority() opPriority
  • func (t TokenType) String() string

Types

type Expr

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

func NewExpr

func NewExpr(expr string) (res *Expr, err error)

func (*Expr) Eval

func (expr *Expr) Eval(params map[string]interface{}) (interface{}, error)

type ExprFunc

type ExprFunc func(args ...interface{}) (interface{}, error)

ExprFunc represents a function that can be called within an expression

type LexerToken

type LexerToken struct {
	Type  TokenType
	Value interface{}
}

type TokenType

type TokenType int //enum

const (
	ILLEGAL TokenType = iota

	// literal operators
	CHAR     // 'a', '爱', ...
	STRING   // "abc"
	NUMBER   // 123, 123.456 treated as float64
	BOOL     // true, false
	VARIABLE // a1, b_2, c
	SELECTOR // a.b.c,
	ACCESSOR // .a.b

	// prefix operators
	NOT // !
	NEG // -

	// normal operators
	ADD // +
	SUB // -
	MUL // *
	QUO // /
	REM // %

	AND // &
	OR  // |
	XOR // ^
	SHL // <<
	SHR // >>

	// ternary operators
	TERNARY_IF
	TERNARY_ELSE

	// logical operators
	LAND // &&
	LOR  // ||

	// comparer operators
	EQ  // ==
	NEQ // !=
	LT  // <
	GT  // >
	LEQ // <=
	GEQ // >=

	// clause operators
	LPAREN // (
	RPAREN // )

	LBRACKET // [
	RBRACKET // ]

	FUNC // represent function

	LITERAL // represent all literal operators
	CLAUSE  // represent all clause operators
	EOF
)

func (TokenType) Priority

func (op TokenType) Priority() opPriority

func (TokenType) String

func (t TokenType) String() string