| var arrayCopy = require('./arrayCopy'), |
| composeArgs = require('./composeArgs'), |
| composeArgsRight = require('./composeArgsRight'), |
| replaceHolders = require('./replaceHolders'); |
| |
| /** Used to compose bitmasks for wrapper metadata. */ |
| var BIND_FLAG = 1, |
| CURRY_BOUND_FLAG = 4, |
| CURRY_FLAG = 8, |
| ARY_FLAG = 128, |
| REARG_FLAG = 256; |
| |
| /** Used as the internal argument placeholder. */ |
| var PLACEHOLDER = '__lodash_placeholder__'; |
| |
| /* Native 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 required 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` |
| * augment function arguments, making the order in which they are executed important, |
| * preventing the merging of metadata. However, we make an exception for a safe |
| * common 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 < ARY_FLAG; |
| |
| var isCombo = |
| (srcBitmask == ARY_FLAG && bitmask == CURRY_FLAG) || |
| (srcBitmask == ARY_FLAG && bitmask == REARG_FLAG && data[7].length <= source[8]) || |
| (srcBitmask == (ARY_FLAG | REARG_FLAG) && bitmask == CURRY_FLAG); |
| |
| // Exit early if metadata can't be merged. |
| if (!(isCommon || isCombo)) { |
| return data; |
| } |
| // Use source `thisArg` if available. |
| if (srcBitmask & BIND_FLAG) { |
| data[2] = source[2]; |
| // Set when currying a bound function. |
| newBitmask |= (bitmask & BIND_FLAG) ? 0 : CURRY_BOUND_FLAG; |
| } |
| // Compose partial arguments. |
| var value = source[3]; |
| if (value) { |
| var partials = data[3]; |
| data[3] = partials ? composeArgs(partials, value, source[4]) : arrayCopy(value); |
| data[4] = partials ? replaceHolders(data[3], PLACEHOLDER) : arrayCopy(source[4]); |
| } |
| // Compose partial right arguments. |
| value = source[5]; |
| if (value) { |
| partials = data[5]; |
| data[5] = partials ? composeArgsRight(partials, value, source[6]) : arrayCopy(value); |
| data[6] = partials ? replaceHolders(data[5], PLACEHOLDER) : arrayCopy(source[6]); |
| } |
| // Use source `argPos` if available. |
| value = source[7]; |
| if (value) { |
| data[7] = arrayCopy(value); |
| } |
| // Use source `ary` if it's smaller. |
| if (srcBitmask & 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; |