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