vue.js 源代码学习笔记 ----- helpers.js

/* @flow */

import { parseFilters } from ‘./parser/filter-parser‘

export function baseWarn (msg: string) {
  console.error(`[Vue parser]: ${msg}`)
}

export function pluckModuleFunction (
  modules: ?Array<Object>,
  key: string
): Array<Function> {
  return modules
    ? modules.map(m => m[key]).filter(_ => _)
    : []
}

export function addProp (el: ASTElement, name: string, value: string) {
  (el.props || (el.props = [])).push({ name, value })
}

export function addAttr (el: ASTElement, name: string, value: string) {
  (el.attrs || (el.attrs = [])).push({ name, value })
}

export function addDirective (
  el: ASTElement,
  name: string,
  rawName: string,
  value: string,
  arg: ?string,
  modifiers: ?ASTModifiers
) {
  (el.directives || (el.directives = [])).push({ name, rawName, value, arg, modifiers })
}

export function addHandler (
  el: ASTElement,
  name: string,
  value: string,
  modifiers: ?ASTModifiers,
  important: ?boolean
) {
  // check capture modifier
  if (modifiers && modifiers.capture) {
    delete modifiers.capture
    name = ‘!‘ + name // mark the event as captured
  }
  let events
  if (modifiers && modifiers.native) {
    delete modifiers.native
    events = el.nativeEvents || (el.nativeEvents = {})
  } else {
    events = el.events || (el.events = {})
  }
  const newHandler = { value, modifiers }
  const handlers = events[name]
  /* istanbul ignore if */
  if (Array.isArray(handlers)) {
    important ? handlers.unshift(newHandler) : handlers.push(newHandler)
  } else if (handlers) {
    events[name] = important ? [newHandler, handlers] : [handlers, newHandler]
  } else {
    events[name] = newHandler
  }
}

export function getBindingAttr (
  el: ASTElement,
  name: string,
  getStatic?: boolean
): ?string {
  const dynamicValue =
    getAndRemoveAttr(el, ‘:‘ + name) ||
    getAndRemoveAttr(el, ‘v-bind:‘ + name)
  if (dynamicValue != null) {
    return parseFilters(dynamicValue)
  } else if (getStatic !== false) {
    const staticValue = getAndRemoveAttr(el, name)
    if (staticValue != null) {
      return JSON.stringify(staticValue)
    }
  }
}

export function getAndRemoveAttr (el: ASTElement, name: string): ?string {
  let val
  if ((val = el.attrsMap[name]) != null) {
    const list = el.attrsList
    for (let i = 0, l = list.length; i < l; i++) {
      if (list[i].name === name) {
        list.splice(i, 1)
        break
      }
    }
  }
  return val
}

let len, str, chr, index, expressionPos, expressionEndPos

/**
 * parse directive model to do the array update transform. a[idx] = val => $$a.splice($$idx, 1, val)
 *
 * for loop possible cases:
 *
 * - test
 * - test[idx]
 * - test[test1[idx]]
 * - test["a"][idx]
 * - xxx.test[a[a].test1[idx]]
 * - test.xxx.a["asa"][test1[idx]]
 *
 */

export function parseModel (val: string): Object {
  str = val
  len = str.length
  index = expressionPos = expressionEndPos = 0

  if (val.indexOf(‘[‘) < 0 || val.lastIndexOf(‘]‘) < len - 1) {
    return {
      exp: val,
      idx: null
    }
  }

  while (!eof()) {
    chr = next()
    /* istanbul ignore if */
    if (isStringStart(chr)) {
      parseString(chr)
    } else if (chr === 0x5B) {
      parseBracket(chr)
    }
  }

  return {
    exp: val.substring(0, expressionPos),
    idx: val.substring(expressionPos + 1, expressionEndPos)
  }
}

function next (): number {
  return str.charCodeAt(++index)
}

function eof (): boolean {
  return index >= len
}

function isStringStart (chr: number): boolean {
  return chr === 0x22 || chr === 0x27
}

function parseBracket (chr: number): void {
  let inBracket = 1
  expressionPos = index
  while (!eof()) {
    chr = next()
    if (isStringStart(chr)) {
      parseString(chr)
      continue
    }
    if (chr === 0x5B) inBracket++
    if (chr === 0x5D) inBracket--
    if (inBracket === 0) {
      expressionEndPos = index
      break
    }
  }
}

function parseString (chr: number): void {
  const stringQuote = chr
  while (!eof()) {
    chr = next()
    if (chr === stringQuote) {
      break
    }
  }
}