gep

gep

Gep (General Expression Parser) is tiny library used to evaluate expression to javascript function

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15

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0

Maintenance

Last Commit

4yrs ago

Contributors

2

Package

Dependencies

0

Size (min+gzip)

1.7KB

License

MIT

Type Definitions

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Readme

⚠️ Deprecated! It was renamed JEP

General Expression Parser

Build Status npm version js-standard-style

安装

npm install --save gep

bower install --save gep

使用

快速上手

try: CodePen JSFiddle

const gep = new Gep()

const fun = gep.make('a + 2 === 3')
const result = fun({a: 1})

console.log(result)
// true

使用参数

try: CodePen JSFiddle

const gep = new Gep({params: ['$', 'SQUARE_METER']})

const scope = {
  radius: 3,
  square (n) {
    return n * n
  },
  fixed (numObj, num) {
    return numObj.toFixed(num)
  },
}
const SQUARE_METER = 'm²'

const source = 'fixed((Math.PI + square(radius)), 2) + SQUARE_METER'
const result = gep.make(source)(scope, SQUARE_METER)

console.log(result)
// 12.14m²

API

参数

const gep = new Gep({
  cache: 1000,
  scope: '$',
  params: ['$', 'other_param'],
})

cache: Number 类型,gep 内部使用 LRU 缓存解析过的表达式,cache 表示最大缓存数,默认 1000

scope: String 类型,已解析的表达式或函数中,用于表示 scope 的变量名,默认 '$'

const gep = new Gep()
const parsed = gep.parse('a + b')
console.log(parsed)
// $.a+$.b

params: Array 类型,该数组中每一项都为 String 类型,执行函数时需要依次传入对应的参数。 第一个必须为 scope 对应的变量名。其余变量名,在表达式中可以直接被访问。

const gep = new Gep({
  params: ['$', 'other'],
})
const scope = {a: 1}
const other = {a: 2}
const result = gep.make('a + other.a')(scope, other)
console.log(result)
// 3

方法

parse: 参数为 String 类型的待编译的表达式,返回编译好的 String 类型表达式

const gep = new Gep()
const source = 'a + b'
const expression = gep.parse(source)
console.log(expression)
// $.a+$.b

build: 参数为 String 类型的已编译表达式,返回编译好的 Function (成功) 或 undefined (失败)

const gep = new Gep()
const source = 'a + b'
const expression = gep.parse(source) // $.a+$.b
const fun = gep.build(expression) // 返回函数,类似 function($){return $.a+$.b}
const result = fun({a: 1, b: 2})
console.log(result)
// 3

buildToString: 和 build 类似,参数为 String 类型的已编译表达式,返回的是函数字符串

const gep = new Gep()
const expression = gep.parse('a + b') // $.a+$.b
const funString = gep.buildToString(expression)
console.log(funString)
// function($){return $.a+$.b}

make: 和 build 类似,参数为 String 类型的待编译表达式,返回编译好的 Function (成功) 或 undefined (失败)

const gep = new Gep()
const source = 'a + b'
const fun = gep.make(source) // 返回函数,类似 function($){return $.a+$.b}
const result = fun({a: 1, b: 2})
console.log(result)
// 3

makeToString: 和 make 类似,参数为 String 类型的待编译表达式,返回的是函数字符串

const gep = new Gep()
const funString = gep.makeToString('a + b')
console.log(funString)
// function($){return $.a+$.b}

License

MIT

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