lodash源码学习(7)

//now.js

var root = require(‘./_root‘);//运行环境，node环境下为global,浏览器环境为window

/**
 * 
 *
 * @returns {number} 得到一个时间戳.
 * @example
 *
 * _.defer(function(stamp) {
 *   console.log(_.now() - stamp);
 * }, _.now());
 * // => Logs the number of milliseconds it took for the deferred invocation.
 */
var now = function() {
  return root.Date.now();//直接调用Date对象的now方法
};

module.exports = now;

//after.js

var toInteger = require(‘./toInteger‘);//转化为整型

/** Error message constants. */
var FUNC_ERROR_TEXT = ‘Expected a function‘;

/**
 * 
 *
 * @param {number} n 在调用func之前需要执行的次数.
 * @param {Function} func 受限制的方法.
 * @returns {Function} 返回新的受限制的方法.
 * @example
 *
 * var saves = [‘profile‘, ‘settings‘];
 *
 * var done = _.after(saves.length, function() {
 *   console.log(‘done saving!‘);
 * });
 *
 * _.forEach(saves, function(type) {
 *   asyncSave({ ‘type‘: type, ‘complete‘: done });
 * });
 * // => Logs ‘done saving!‘ after the two async saves have completed.
 */
function after(n, func) {
  if (typeof func != ‘function‘) {//如果不是函数，抛出TypeError
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  n = toInteger(n);//闭包中保存的n值
  return function() {
    if (--n < 1) {//每次执行n-1,如果比1小，调用func方法
      return func.apply(this, arguments);
    }
  };
}

module.exports = after;

//ary.js

var createWrap = require(‘./_createWrap‘);//包装函数

var WRAP_ARY_FLAG = 128; //ary的位掩嘛

/**
 * 
 *
 * @static
 * @memberOf _
 * @since 3.0.0
 * @category Function
 * @param {Function} func 需要包装的函数.
 * @param {number} [n=func.length] 参数个数.
 * @param- {Object} [guard] 是否能作为遍历参数被_.map这样的方法调用.
 * @returns {Function} 返回新的包装之后的函数.
 * @example
 *
 * _.map([‘6‘, ‘8‘, ‘10‘], _.ary(parseInt, 1));
 * // => [6, 8, 10]
 */
function ary(func, n, guard) {
  n = guard ? undefined : n;
  n = (func && n == null) ? func.length : n;//如果没传n,默认参数数量func的参数个数
  return createWrap(func, WRAP_ARY_FLAG, undefined, undefined, undefined, undefined, n);//调用createWrap方法，并将结果返回
}

module.exports = ary;

//_createWrap.js

var baseSetData = require(‘./_baseSetData‘),
    createBind = require(‘./_createBind‘),
    createCurry = require(‘./_createCurry‘),
    createHybrid = require(‘./_createHybrid‘),//创建混合方法
    createPartial = require(‘./_createPartial‘),
    getData = require(‘./_getData‘),
    mergeData = require(‘./_mergeData‘),
    setData = require(‘./_setData‘),
    setWrapToString = require(‘./_setWrapToString‘),
    toInteger = require(‘./toInteger‘);

var FUNC_ERROR_TEXT = ‘Expected a function‘;

//各种方法的位掩码标识
var WRAP_BIND_FLAG = 1,
    WRAP_BIND_KEY_FLAG = 2,
    WRAP_CURRY_FLAG = 8,
    WRAP_CURRY_RIGHT_FLAG = 16,
    WRAP_PARTIAL_FLAG = 32,
    WRAP_PARTIAL_RIGHT_FLAG = 64;

var nativeMax = Math.max;//原生最大值方法

/**
 * 创建一个函数，该函数可以创建或调用func用可选的this和部分应用的参数.
 *
 * @param {Function|string} func 需要包装的函数.
 * @param {number} bitmask 位掩码标识
 * @param {*} [thisArg] .
 * @param {Array} [partials] .
 * @param {Array} [holders] .
 * @param {Array} [argPos] .
 * @param {number} [ary] .
 * @param {number} [arity] 可用参数数量.
 * @returns {Function} 返回包装之后的函数.
 */
 //lodash使用BitMask来进行各种方法的表示，BitMask使用方法可以看 http://geek.csdn.net/news/detail/73343

function createWrap(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {
  var isBindKey = bitmask & WRAP_BIND_KEY_FLAG;//是否是bindKey方法（不是，跳过）
  if (!isBindKey && typeof func != ‘function‘) {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  var length = partials ? partials.length : 0;//length=0
  if (!length) {
    bitmask &= ~(WRAP_PARTIAL_FLAG | WRAP_PARTIAL_RIGHT_FLAG);//清除WRAP_PARTIAL_FLAG和WRAP_PARTIAL_RIGHT_FLAG
    partials = holders = undefined;
  }
  ary = ary === undefined ? ary : nativeMax(toInteger(ary), 0);
  arity = arity === undefined ? arity : toInteger(arity);//处理一下arity
  length -= holders ? holders.length : 0;

  if (bitmask & WRAP_PARTIAL_RIGHT_FLAG) {//是否是WRAP_PARTIAL_RIGHT_FLAG(不是，跳过)
    var partialsRight = partials,
        holdersRight = holders;

    partials = holders = undefined;
  }
  var data = isBindKey ? undefined : getData(func);//得到func的元数据（没有，跳过）

  var newData = [
    func, bitmask, thisArg, partials, holders, partialsRight, holdersRight,
    argPos, ary, arity
  ];//将所有参数赋值给newData

  if (data) {
    mergeData(newData, data);
  }
  func = newData[0];
  bitmask = newData[1];
  thisArg = newData[2];
  partials = newData[3];
  holders = newData[4];
  arity = newData[9] = newData[9] === undefined
    ? (isBindKey ? 0 : func.length)
    : nativeMax(newData[9] - length, 0);//再次处理一下arity

  if (!arity && bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG)) {
    bitmask &= ~(WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG);
  }
  if (!bitmask || bitmask == WRAP_BIND_FLAG) {
    var result = createBind(func, bitmask, thisArg);
  } else if (bitmask == WRAP_CURRY_FLAG || bitmask == WRAP_CURRY_RIGHT_FLAG) {
    result = createCurry(func, bitmask, arity);
  } else if ((bitmask == WRAP_PARTIAL_FLAG || bitmask == (WRAP_BIND_FLAG | WRAP_PARTIAL_FLAG)) && !holders.length) {
    result = createPartial(func, bitmask, thisArg, partials);
  } else {
    result = createHybrid.apply(undefined, newData);//调用createHybrid方法，传入所有参数
  }
  var setter = data ? baseSetData : setData;//设置data的元数据（暂不分析）
  return setWrapToString(setter(result, newData), func, bitmask);//给包装之后的方法添加元数据（用于优化），添加toStirng方法，并返回func(具体实现暂不分析)
}

module.exports = createWrap;

//_createHybrid.js

var composeArgs = require(‘./_composeArgs‘),
    composeArgsRight = require(‘./_composeArgsRight‘),
    countHolders = require(‘./_countHolders‘),
    createCtor = require(‘./_createCtor‘),
    createRecurry = require(‘./_createRecurry‘),
    getHolder = require(‘./_getHolder‘),
    reorder = require(‘./_reorder‘),
    replaceHolders = require(‘./_replaceHolders‘),
    root = require(‘./_root‘);

//位掩码标识
var WRAP_BIND_FLAG = 1,
    WRAP_BIND_KEY_FLAG = 2,
    WRAP_CURRY_FLAG = 8,
    WRAP_CURRY_RIGHT_FLAG = 16,
    WRAP_ARY_FLAG = 128,
    WRAP_FLIP_FLAG = 512;

/**
 * 创建一个包装函数，调用func使用可选的thisArg，应用部分参数和柯里化.
 *
 * @param {Function|string} func 需要包装的方法.
 * @param {number} bitmask 位掩码标识
 * @param {*} [thisArg] .
 * @param {Array} [partials] .
 * @param {Array} [holders] .
 * @param {Array} [partialsRight] .
 * @param {Array} [holdersRight] .
 * @param {Array} [argPos] .
 * @param {number} [ary] .
 * @param {number} [arity] 可用函数参数数量.
 * @returns {Function} 返回新的包装函数.
 */
function createHybrid(func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity) {
  var isAry = bitmask & WRAP_ARY_FLAG,//是否是ary（是的）
      isBind = bitmask & WRAP_BIND_FLAG,
      isBindKey = bitmask & WRAP_BIND_KEY_FLAG,
      isCurried = bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG),
      isFlip = bitmask & WRAP_FLIP_FLAG,
      Ctor = isBindKey ? undefined : createCtor(func);

  function wrapper() {
    var length = arguments.length,//参数个数
        args = Array(length),//保存所有参数
        index = length;//参数数组索引

    while (index--) {//遍历参数，将所有参数存入args
      args[index] = arguments[index];
    }
    if (isCurried) {
      var placeholder = getHolder(wrapper),
          holdersCount = countHolders(args, placeholder);
    }
    if (partials) {
      args = composeArgs(args, partials, holders, isCurried);
    }
    if (partialsRight) {
      args = composeArgsRight(args, partialsRight, holdersRight, isCurried);
    }
    length -= holdersCount;
    if (isCurried && length < arity) {
      var newHolders = replaceHolders(args, placeholder);
      return createRecurry(
        func, bitmask, createHybrid, wrapper.placeholder, thisArg,
        args, newHolders, argPos, ary, arity - length
      );
    }
    var thisBinding = isBind ? thisArg : this,
        fn = isBindKey ? thisBinding[func] : func;

    length = args.length;//参数长度
    if (argPos) {
      args = reorder(args, argPos);
    } else if (isFlip && length > 1) {
      args.reverse();
    }
    if (isAry && ary < length) {//进入这里，将参数的长度缩减到ary的数量
      args.length = ary;
    }
    if (this && this !== root && this instanceof wrapper) {
      fn = Ctor || createCtor(fn);
    }
    return fn.apply(thisBinding, args);//调用func，并且传入的参数个数为ary个
  }
  return wrapper;
}
module.exports = createHybrid;

//before.js

var toInteger = require(‘./toInteger‘);//转化为整型

var FUNC_ERROR_TEXT = ‘Expected a function‘;

/**
 *
 *
 * @param {number} n func不再被调用的执行次数上限.
 * @param {Function} func 需要限制的方法.
 * @returns {Function} Returns the new restricted function.
 * @example
 *
 * jQuery(element).on(‘click‘, _.before(5, addContactToList));
 * // => Allows adding up to 4 contacts to the list.
 */
function before(n, func) {
  var result;
  if (typeof func != ‘function‘) {//不是方法，抛出错误
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  n = toInteger(n);//还可以执行的n值
  return function() {
    if (--n > 0) {//如果n-1比0大,也就是n>=1,调用func,并将结果赋值给result
      result = func.apply(this, arguments);
    }
    if (n <= 1) {//销毁func
      func = undefined;
    }
    return result;//返回result
  };
}

module.exports = before;

//bind.js


var baseRest = require(‘./_baseRest‘),//生产具有rest参数的方法
    createWrap = require(‘./_createWrap‘),//函数包装方法
    getHolder = require(‘./_getHolder‘),//得到占位符标识
    replaceHolders = require(‘./_replaceHolders‘);//替换占位符

var WRAP_BIND_FLAG = 1,//bind位掩码
    WRAP_PARTIAL_FLAG = 32;//partial位掩码

/**
 * 
 *
 * _.bind.placeholder的值默认为`_`
 *
 *
 * @param {Function} func 需要绑定的函数.
 * @param {*} thisArg The func的this对象.
 * @param {...*} [partials] 提前传入的参数.
 * @returns {Function} 返回新的已绑定的方法.
 * @example
 *
 * function greet(greeting, punctuation) {
 *   return greeting + ‘ ‘ + this.user + punctuation;
 * }
 *
 * var object = { ‘user‘: ‘fred‘ };
 *
 * var bound = _.bind(greet, object, ‘hi‘);
 * bound(‘!‘);
 * // => ‘hi fred!‘
 *
 * // Bound with placeholders.
 * var bound = _.bind(greet, object, _, ‘!‘);
 * bound(‘hi‘);
 * // => ‘hi fred!‘
 */
var bind = baseRest(function(func, thisArg, partials) {
  var bitmask = WRAP_BIND_FLAG;//位掩码为bind
  if (partials.length) {//如果有传入参数
    var holders = replaceHolders(partials, getHolder(bind));//得到占位符的索引
    bitmask |= WRAP_PARTIAL_FLAG;//位掩码加上partial的标识
  }
  return createWrap(func, bitmask, thisArg, partials, holders);//调用createWrap方法，返回包装之后的方法
});

// 对默认的placeholder赋值.
bind.placeholder = {};

module.exports = bind;

//_createWrap.js

var baseSetData = require(‘./_baseSetData‘),
    createBind = require(‘./_createBind‘),//创建bind方法
    createCurry = require(‘./_createCurry‘),
    createHybrid = require(‘./_createHybrid‘),
    createPartial = require(‘./_createPartial‘),//创建部分参数方法
    getData = require(‘./_getData‘),
    mergeData = require(‘./_mergeData‘),
    setData = require(‘./_setData‘),
    setWrapToString = require(‘./_setWrapToString‘),
    toInteger = require(‘./toInteger‘);

var FUNC_ERROR_TEXT = ‘Expected a function‘;

//各种方法的位掩码标识
var WRAP_BIND_FLAG = 1,
    WRAP_BIND_KEY_FLAG = 2,
    WRAP_CURRY_FLAG = 8,
    WRAP_CURRY_RIGHT_FLAG = 16,
    WRAP_PARTIAL_FLAG = 32,
    WRAP_PARTIAL_RIGHT_FLAG = 64;

var nativeMax = Math.max;//原生最大值方法

/**
 * 创建一个函数，该函数可以创建或调用func用可选的this和部分应用的参数.
 *
 * @param {Function|string} func 需要包装的函数.
 * @param {number} bitmask 位掩码标识
 * @param {*} [thisArg] func的this对象
 * @param {Array} [partials] 应用的参数
 * @param {Array} [holders] 占位符的索引
 * @param {Array} [argPos] .
 * @param {number} [ary] .
 * @param {number} [arity] 可用参数数量.
 * @returns {Function} 返回包装之后的函数.
 */
 //lodash使用BitMask来进行各种方法的表示，BitMask使用方法可以看 http://geek.csdn.net/news/detail/73343

function createWrap(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {
  var isBindKey = bitmask & WRAP_BIND_KEY_FLAG;//是否是bindKey方法（不是，跳过）
  if (!isBindKey && typeof func != ‘function‘) {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  var length = partials ? partials.length : 0;//应用的参数个数，不传为0
  if (!length) {
    bitmask &= ~(WRAP_PARTIAL_FLAG | WRAP_PARTIAL_RIGHT_FLAG);//清除WRAP_PARTIAL_FLAG和WRAP_PARTIAL_RIGHT_FLAG
    partials = holders = undefined;//部分参数和占位符索引都为undefined
  }
  ary = ary === undefined ? ary : nativeMax(toInteger(ary), 0);//没传，跳过
  arity = arity === undefined ? arity : toInteger(arity);//跳过
  length -= holders ? holders.length : 0;//如果有占位符，参数长度减去占位符长度

  if (bitmask & WRAP_PARTIAL_RIGHT_FLAG) {//是否是WRAP_PARTIAL_RIGHT_FLAG(不是，跳过)
    var partialsRight = partials,
        holdersRight = holders;

    partials = holders = undefined;
  }
  var data = isBindKey ? undefined : getData(func);//得到func的元数据（没有，跳过）

  var newData = [
    func, bitmask, thisArg, partials, holders, partialsRight, holdersRight,
    argPos, ary, arity
  ];//将所有参数赋值给newData

  if (data) {
    mergeData(newData, data);
  }
  func = newData[0];
  bitmask = newData[1];
  thisArg = newData[2];
  partials = newData[3];
  holders = newData[4];
  arity = newData[9] = newData[9] === undefined
    ? (isBindKey ? 0 : func.length)
    : nativeMax(newData[9] - length, 0);

  if (!arity && bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG)) {
    bitmask &= ~(WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG);
  }
  if (!bitmask || bitmask == WRAP_BIND_FLAG) {//如果没传partials，调用createBind方法，并且将包装函数赋值给result
    var result = createBind(func, bitmask, thisArg);
  } else if (bitmask == WRAP_CURRY_FLAG || bitmask == WRAP_CURRY_RIGHT_FLAG) {
    result = createCurry(func, bitmask, arity);
  } else if ((bitmask == WRAP_PARTIAL_FLAG || bitmask == (WRAP_BIND_FLAG | WRAP_PARTIAL_FLAG)) && !holders.length) {//如果传了partials，但是没有传占位符，调用createPartial方法，并且将包装函数赋值给result
    result = createPartial(func, bitmask, thisArg, partials);
  } else {//如果传了partials和holders，调用createHybrid方法
    result = createHybrid.apply(undefined, newData);
  }
  var setter = data ? baseSetData : setData;//设置data的元数据（暂不分析）
  return setWrapToString(setter(result, newData), func, bitmask);//给包装之后的方法添加元数据（用于优化），添加toStirng方法，并返回func(具体实现暂不分析)
}

module.exports = createWrap;

//_createBind.js

var createCtor = require(‘./_createCtor‘),//创建一个可以创建函数实例的方法
    root = require(‘./_root‘);//根元素，node环境为global,浏览器环境为window

var WRAP_BIND_FLAG = 1;//bind位掩码标识

/**
 * 创建一个包装func的方法，调用这个方法可以使用可选的this对象.
 *
 * @private
 * @param {Function} func 需要包装的函数.
 * @param {number} bitmask 位掩码标识.
 * @param {*} [thisArg] func的this对象.
 * @returns {Function} 返回新的包装函数.
 */
function createBind(func, bitmask, thisArg) {
  var isBind = bitmask & WRAP_BIND_FLAG,//是否是bind方法
      Ctor = createCtor(func);//用于创建实例的构造器

  function wrapper() {
    var fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;//如果是根元素调用，使用func，否则使用Ctor
    return fn.apply(isBind ? thisArg : this, arguments);//调用fn,传入this对象和参数
  }
  return wrapper;//返回wrapper方法
}

module.exports = createBind;

//_createPartial.js

var apply = require(‘./_apply‘),//同Function.apply
    createCtor = require(‘./_createCtor‘),//创建一个可以创建函数实例的方法
    root = require(‘./_root‘);//根元素

var WRAP_BIND_FLAG = 1;//bind方法位掩码

/**
 * 创建一个func的包装方法，调用这个方法可以使用可选的this对象和提前传入部分参数.
 *
 * @private
 * @param {Function} func 需要包装的方法.
 * @param {number} 位掩码标识.
 * @param {*} thisArg func的this对象.
 * @param {Array} partials 提前传入的参数.
 * @returns {Function} 返回新的包装方法.
 */
function createPartial(func, bitmask, thisArg, partials) {
  var isBind = bitmask & WRAP_BIND_FLAG,//是否是bind方法
      Ctor = createCtor(func);//用于创建实例的构造器

  function wrapper() {
    var argsIndex = -1,//参数索引
        argsLength = arguments.length,//传入参数个数
        leftIndex = -1,//提前传入参数索引
        leftLength = partials.length,//提前传入参数个数
        args = Array(leftLength + argsLength),//总参数
        fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;//如果是根元素调用，使用func，否则使用Ctor

    while (++leftIndex < leftLength) {//遍历partials,将参数作为调用方法的前面的参数
      args[leftIndex] = partials[leftIndex];
    }
    while (argsLength--) {//遍历传入的参数，将其作为调用方法的后面的参数
      args[leftIndex++] = arguments[++argsIndex];
    }
    return apply(fn, isBind ? thisArg : this, args);//调用fn,传入this对象和参数
  }
  return wrapper;//返回wrapper方法
}

module.exports = createPartial;

//_createHybrid.js

var composeArgs = require(‘./_composeArgs‘),//组合参数方法
    composeArgsRight = require(‘./_composeArgsRight‘),
    countHolders = require(‘./_countHolders‘),
    createCtor = require(‘./_createCtor‘),
    createRecurry = require(‘./_createRecurry‘),
    getHolder = require(‘./_getHolder‘),
    reorder = require(‘./_reorder‘),
    replaceHolders = require(‘./_replaceHolders‘),
    root = require(‘./_root‘);

//位掩码标识
var WRAP_BIND_FLAG = 1,
    WRAP_BIND_KEY_FLAG = 2,
    WRAP_CURRY_FLAG = 8,
    WRAP_CURRY_RIGHT_FLAG = 16,
    WRAP_ARY_FLAG = 128,
    WRAP_FLIP_FLAG = 512;

/**
 * 创建一个包装函数，调用func使用可选的thisArg，应用部分参数和柯里化.
 *
 * @param {Function|string} func 需要包装的方法.
 * @param {number} bitmask 位掩码标识
 * @param {*} [thisArg] this对象.
 * @param {Array} [partials] 实现传入的参数.
 * @param {Array} [holders] 占位符.
 * @param {Array} [partialsRight] .
 * @param {Array} [holdersRight] .
 * @param {Array} [argPos] .
 * @param {number} [ary] .
 * @param {number} [arity] 可用函数参数数量.
 * @returns {Function} 返回新的包装函数.
 */
function createHybrid(func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity) {
  var isAry = bitmask & WRAP_ARY_FLAG,
      isBind = bitmask & WRAP_BIND_FLAG,//是否具有bind标识
      isBindKey = bitmask & WRAP_BIND_KEY_FLAG,
      isCurried = bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG),
      isFlip = bitmask & WRAP_FLIP_FLAG,
      Ctor = isBindKey ? undefined : createCtor(func);

  function wrapper() {
    var length = arguments.length,//参数个数
        args = Array(length),//保存所有参数
        index = length;//参数数组索引

    while (index--) {//遍历参数，将所有参数存入args
      args[index] = arguments[index];
    }
    if (isCurried) {
      var placeholder = getHolder(wrapper),
          holdersCount = countHolders(args, placeholder);
    }
    if (partials) {//执行composeArgs，对参数进行组合
      args = composeArgs(args, partials, holders, isCurried);
    }
    if (partialsRight) {
      args = composeArgsRight(args, partialsRight, holdersRight, isCurried);
    }
    length -= holdersCount;
    if (isCurried && length < arity) {
      var newHolders = replaceHolders(args, placeholder);
      return createRecurry(
        func, bitmask, createHybrid, wrapper.placeholder, thisArg,
        args, newHolders, argPos, ary, arity - length
      );
    }
    var thisBinding = isBind ? thisArg : this,//设置this为thisArg
        fn = isBindKey ? thisBinding[func] : func;//设置fn为func

    length = args.length;//参数长度
    if (argPos) {
      args = reorder(args, argPos);
    } else if (isFlip && length > 1) {
      args.reverse();
    }
    if (isAry && ary < length) {
      args.length = ary;
    }
    if (this && this !== root && this instanceof wrapper) {
      fn = Ctor || createCtor(fn);
    }
    return fn.apply(thisBinding, args);//调用fn，并且传入args
  }
  return wrapper;//返回包装方法
}
module.exports = createHybrid;

//composeArgs.js

var nativeMax = Math.max;//原生求最大值方法

/**
 * 创建一个由提前传入的参数，占位符和传入的参数组成的一维数组.
 *
 * @private
 * @param {Array} args 提供的参数.
 * @param {Array} partials 提前传入的参数.
 * @param {Array} holders 提前传入参数中的占位符索引.
 * @params {boolean} [isCurried] 指定是否组成一个柯里化函数.
 * @returns {Array} 返回新的参数集合.
 */
function composeArgs(args, partials, holders, isCurried) {
  var argsIndex = -1,//传入参数索引
      argsLength = args.length,//参数个数
      holdersLength = holders.length,//占位符个数
      leftIndex = -1,//提前传入参数索引
      leftLength = partials.length,//提前传入参数个数
      rangeLength = nativeMax(argsLength - holdersLength, 0),//实际参数个数
      result = Array(leftLength + rangeLength),//返回结果数组
      isUncurried = !isCurried;//是否并未柯里化

  while (++leftIndex < leftLength) {//遍历partials，将其传入result
    result[leftIndex] = partials[leftIndex];
  }
  while (++argsIndex < holdersLength) {//遍历holders,将result中对应索引的值，换成传入的参数对应的值
    if (isUncurried || argsIndex < argsLength) {
      result[holders[argsIndex]] = args[argsIndex];
    }
  }
  while (rangeLength--) {//遍历args，将剩余的参数传入reslut
    result[leftIndex++] = args[argsIndex++];
  }
  return result;//返回生产的完整参数数组
}

module.exports = composeArgs;

//bindKey.js

var baseRest = require(‘./_baseRest‘),//创建具有rest参数的方法
    createWrap = require(‘./_createWrap‘),//函数包装方法
    getHolder = require(‘./_getHolder‘),//得到占位符标识
    replaceHolders = require(‘./_replaceHolders‘);//替换占位符

var WRAP_BIND_FLAG = 1,//bind位掩码
    WRAP_BIND_KEY_FLAG = 2,//bindKey位掩码
    WRAP_PARTIAL_FLAG = 32;//partial位掩码

/**
 *
 *
 * _.bind.placeholder的值默认为`_`
 *
 * @static
 * @memberOf _
 * @since 0.10.0
 * @category Function
 * @param {Object} object 调用该方法的对象.
 * @param {string} key 方法的key值.
 * @param {...*} [partials] 需要提前传入的参数.
 * @returns {Function} 返回新的已绑定的方法.
 * @example
 *
 * var object = {
 *   ‘user‘: ‘fred‘,
 *   ‘greet‘: function(greeting, punctuation) {
 *     return greeting + ‘ ‘ + this.user + punctuation;
 *   }
 * };
 *
 * var bound = _.bindKey(object, ‘greet‘, ‘hi‘);
 * bound(‘!‘);
 * // => ‘hi fred!‘
 *
 * object.greet = function(greeting, punctuation) {
 *   return greeting + ‘ya ‘ + this.user + punctuation;
 * };
 *
 * bound(‘!‘);
 * // => ‘hiya fred!‘
 *
 * // Bound with placeholders.
 * var bound = _.bindKey(object, ‘greet‘, _, ‘!‘);
 * bound(‘hi‘);
 * // => ‘hiya fred!‘
 */
var bindKey = baseRest(function(object, key, partials) {//创建使用rest参数的方法
  var bitmask = WRAP_BIND_FLAG | WRAP_BIND_KEY_FLAG;//位掩码为bind和bindKey
  if (partials.length) {//如果传入了partials
    var holders = replaceHolders(partials, getHolder(bindKey));//得到占位符的索引
    bitmask |= WRAP_PARTIAL_FLAG;//位掩码加上partial的标识
  }
  return createWrap(key, bitmask, object, partials, holders);//调用createWrap方法，返回包装之后的方法
});

// Assign default placeholders.
bindKey.placeholder = {};

module.exports = bindKey;

//_createWrap.js

var baseSetData = require(‘./_baseSetData‘),
    createBind = require(‘./_createBind‘),//创建bind方法
    createCurry = require(‘./_createCurry‘),
    createHybrid = require(‘./_createHybrid‘),
    createPartial = require(‘./_createPartial‘),//创建部分参数方法
    getData = require(‘./_getData‘),
    mergeData = require(‘./_mergeData‘),
    setData = require(‘./_setData‘),
    setWrapToString = require(‘./_setWrapToString‘),
    toInteger = require(‘./toInteger‘);

var FUNC_ERROR_TEXT = ‘Expected a function‘;

//各种方法的位掩码标识
var WRAP_BIND_FLAG = 1,
    WRAP_BIND_KEY_FLAG = 2,
    WRAP_CURRY_FLAG = 8,
    WRAP_CURRY_RIGHT_FLAG = 16,
    WRAP_PARTIAL_FLAG = 32,
    WRAP_PARTIAL_RIGHT_FLAG = 64;

var nativeMax = Math.max;//原生最大值方法

/**
 * 创建一个函数，该函数可以创建或调用func用可选的this和部分应用的参数.
 *
 * @param {Function|string} func 需要包装的函数.
 * @param {number} bitmask 位掩码标识
 * @param {*} [thisArg] func的this对象
 * @param {Array} [partials] 应用的参数
 * @param {Array} [holders] 占位符的索引
 * @param {Array} [argPos] .
 * @param {number} [ary] .
 * @param {number} [arity] 可用参数数量.
 * @returns {Function} 返回包装之后的函数.
 */
 //lodash使用BitMask来进行各种方法的表示，BitMask使用方法可以看 http://geek.csdn.net/news/detail/73343

function createWrap(func, bitmask, thisArg, partials, holders, argPos, ary, arity) {
  var isBindKey = bitmask & WRAP_BIND_KEY_FLAG;//是否是bindKey方法（是的）
  if (!isBindKey && typeof func != ‘function‘) {
    throw new TypeError(FUNC_ERROR_TEXT);
  }
  var length = partials ? partials.length : 0;//应用的参数个数，不传为0
  if (!length) {
    bitmask &= ~(WRAP_PARTIAL_FLAG | WRAP_PARTIAL_RIGHT_FLAG);//清除WRAP_PARTIAL_FLAG和WRAP_PARTIAL_RIGHT_FLAG
    partials = holders = undefined;//部分参数和占位符索引都为undefined
  }
  ary = ary === undefined ? ary : nativeMax(toInteger(ary), 0);//没传，跳过
  arity = arity === undefined ? arity : toInteger(arity);//跳过
  length -= holders ? holders.length : 0;//如果有占位符，参数长度减去占位符长度

  if (bitmask & WRAP_PARTIAL_RIGHT_FLAG) {//是否是WRAP_PARTIAL_RIGHT_FLAG(不是，跳过)
    var partialsRight = partials,
        holdersRight = holders;

    partials = holders = undefined;
  }
  var data = isBindKey ? undefined : getData(func);//得到func的元数据（没有，跳过）

  var newData = [
    func, bitmask, thisArg, partials, holders, partialsRight, holdersRight,
    argPos, ary, arity
  ];//将所有参数赋值给newData

  if (data) {
    mergeData(newData, data);
  }
  func = newData[0];
  bitmask = newData[1];
  thisArg = newData[2];
  partials = newData[3];
  holders = newData[4];
  arity = newData[9] = newData[9] === undefined
    ? (isBindKey ? 0 : func.length)
    : nativeMax(newData[9] - length, 0);

  if (!arity && bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG)) {
    bitmask &= ~(WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG);
  }
  if (!bitmask || bitmask == WRAP_BIND_FLAG) {//
    var result = createBind(func, bitmask, thisArg);
  } else if (bitmask == WRAP_CURRY_FLAG || bitmask == WRAP_CURRY_RIGHT_FLAG) {
    result = createCurry(func, bitmask, arity);
  } else if ((bitmask == WRAP_PARTIAL_FLAG || bitmask == (WRAP_BIND_FLAG | WRAP_PARTIAL_FLAG)) && !holders.length) {
    result = createPartial(func, bitmask, thisArg, partials);
  } else {//进入这里，调用createHybrid方法。
    result = createHybrid.apply(undefined, newData);
  }
  var setter = data ? baseSetData : setData;//设置data的元数据（暂不分析）
  return setWrapToString(setter(result, newData), func, bitmask);//给包装之后的方法添加元数据（用于优化），添加toStirng方法，并返回func(具体实现暂不分析)
}

module.exports = createWrap;

//_createHybrid.js

var composeArgs = require(‘./_composeArgs‘),//组合参数方法
    composeArgsRight = require(‘./_composeArgsRight‘),
    countHolders = require(‘./_countHolders‘),
    createCtor = require(‘./_createCtor‘),
    createRecurry = require(‘./_createRecurry‘),
    getHolder = require(‘./_getHolder‘),
    reorder = require(‘./_reorder‘),
    replaceHolders = require(‘./_replaceHolders‘),
    root = require(‘./_root‘);

//位掩码标识
var WRAP_BIND_FLAG = 1,
    WRAP_BIND_KEY_FLAG = 2,
    WRAP_CURRY_FLAG = 8,
    WRAP_CURRY_RIGHT_FLAG = 16,
    WRAP_ARY_FLAG = 128,
    WRAP_FLIP_FLAG = 512;

/**
 * 创建一个包装函数，调用func使用可选的thisArg，应用部分参数和柯里化.
 *
 * @param {Function|string} func 需要包装的方法.
 * @param {number} bitmask 位掩码标识
 * @param {*} [thisArg] this对象.
 * @param {Array} [partials] 实现传入的参数.
 * @param {Array} [holders] 占位符.
 * @param {Array} [partialsRight] .
 * @param {Array} [holdersRight] .
 * @param {Array} [argPos] .
 * @param {number} [ary] .
 * @param {number} [arity] 可用函数参数数量.
 * @returns {Function} 返回新的包装函数.
 */
function createHybrid(func, bitmask, thisArg, partials, holders, partialsRight, holdersRight, argPos, ary, arity) {
  var isAry = bitmask & WRAP_ARY_FLAG,
      isBind = bitmask & WRAP_BIND_FLAG,//是否具有bind标识（有）
      isBindKey = bitmask & WRAP_BIND_KEY_FLAG,//是否具有BindKey标识（有）
      isCurried = bitmask & (WRAP_CURRY_FLAG | WRAP_CURRY_RIGHT_FLAG),
      isFlip = bitmask & WRAP_FLIP_FLAG,
      Ctor = isBindKey ? undefined : createCtor(func);

  function wrapper() {
    var length = arguments.length,//参数个数
        args = Array(length),//保存所有参数
        index = length;//参数数组索引

    while (index--) {//遍历参数，将所有参数存入args
      args[index] = arguments[index];
    }
    if (isCurried) {
      var placeholder = getHolder(wrapper),
          holdersCount = countHolders(args, placeholder);
    }
    if (partials) {//执行composeArgs，对参数进行组合
      args = composeArgs(args, partials, holders, isCurried);
    }
    if (partialsRight) {
      args = composeArgsRight(args, partialsRight, holdersRight, isCurried);
    }
    length -= holdersCount;
    if (isCurried && length < arity) {
      var newHolders = replaceHolders(args, placeholder);
      return createRecurry(
        func, bitmask, createHybrid, wrapper.placeholder, thisArg,
        args, newHolders, argPos, ary, arity - length
      );
    }
    var thisBinding = isBind ? thisArg : this,//设置this为thisArg
        fn = isBindKey ? thisBinding[func] : func;//设置fn为thisBinding[func]

    length = args.length;//参数长度
    if (argPos) {
      args = reorder(args, argPos);
    } else if (isFlip && length > 1) {
      args.reverse();
    }
    if (isAry && ary < length) {
      args.length = ary;
    }
    if (this && this !== root && this instanceof wrapper) {
      fn = Ctor || createCtor(fn);
    }
    return fn.apply(thisBinding, args);//调用fn，并且传入args
  }
  return wrapper;//返回包装方法
}
module.exports = createHybrid;