91 lines
3.1 KiB
JavaScript
91 lines
3.1 KiB
JavaScript
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var composeArgs = require('./_composeArgs'),
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composeArgsRight = require('./_composeArgsRight'),
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replaceHolders = require('./_replaceHolders');
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/** Used as the internal argument placeholder. */
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var PLACEHOLDER = '__lodash_placeholder__';
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/** Used to compose bitmasks for function metadata. */
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var WRAP_BIND_FLAG = 1,
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WRAP_BIND_KEY_FLAG = 2,
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WRAP_CURRY_BOUND_FLAG = 4,
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WRAP_CURRY_FLAG = 8,
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WRAP_ARY_FLAG = 128,
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WRAP_REARG_FLAG = 256;
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/* Built-in method references for those with the same name as other `lodash` methods. */
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var nativeMin = Math.min;
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/**
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* Merges the function metadata of `source` into `data`.
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*
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* Merging metadata reduces the number of wrappers used to invoke a function.
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* This is possible because methods like `_.bind`, `_.curry`, and `_.partial`
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* may be applied regardless of execution order. Methods like `_.ary` and
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* `_.rearg` modify function arguments, making the order in which they are
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* executed important, preventing the merging of metadata. However, we make
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* an exception for a safe combined case where curried functions have `_.ary`
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* and or `_.rearg` applied.
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*
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* @private
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* @param {Array} data The destination metadata.
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* @param {Array} source The source metadata.
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* @returns {Array} Returns `data`.
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*/
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function mergeData(data, source) {
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var bitmask = data[1],
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srcBitmask = source[1],
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newBitmask = bitmask | srcBitmask,
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isCommon = newBitmask < (WRAP_BIND_FLAG | WRAP_BIND_KEY_FLAG | WRAP_ARY_FLAG);
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var isCombo =
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((srcBitmask == WRAP_ARY_FLAG) && (bitmask == WRAP_CURRY_FLAG)) ||
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((srcBitmask == WRAP_ARY_FLAG) && (bitmask == WRAP_REARG_FLAG) && (data[7].length <= source[8])) ||
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((srcBitmask == (WRAP_ARY_FLAG | WRAP_REARG_FLAG)) && (source[7].length <= source[8]) && (bitmask == WRAP_CURRY_FLAG));
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// Exit early if metadata can't be merged.
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if (!(isCommon || isCombo)) {
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return data;
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}
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// Use source `thisArg` if available.
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if (srcBitmask & WRAP_BIND_FLAG) {
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data[2] = source[2];
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// Set when currying a bound function.
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newBitmask |= bitmask & WRAP_BIND_FLAG ? 0 : WRAP_CURRY_BOUND_FLAG;
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}
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// Compose partial arguments.
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var value = source[3];
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if (value) {
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var partials = data[3];
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data[3] = partials ? composeArgs(partials, value, source[4]) : value;
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data[4] = partials ? replaceHolders(data[3], PLACEHOLDER) : source[4];
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}
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// Compose partial right arguments.
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value = source[5];
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if (value) {
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partials = data[5];
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data[5] = partials ? composeArgsRight(partials, value, source[6]) : value;
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data[6] = partials ? replaceHolders(data[5], PLACEHOLDER) : source[6];
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}
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// Use source `argPos` if available.
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value = source[7];
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if (value) {
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data[7] = value;
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}
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// Use source `ary` if it's smaller.
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if (srcBitmask & WRAP_ARY_FLAG) {
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data[8] = data[8] == null ? source[8] : nativeMin(data[8], source[8]);
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}
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// Use source `arity` if one is not provided.
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if (data[9] == null) {
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data[9] = source[9];
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}
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// Use source `func` and merge bitmasks.
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data[0] = source[0];
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data[1] = newBitmask;
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return data;
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}
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module.exports = mergeData;
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