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Diffstat (limited to 'src/util/sugar.js')
| -rw-r--r-- | src/util/sugar.js | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/src/util/sugar.js b/src/util/sugar.js index 70749d8..46c4879 100644 --- a/src/util/sugar.js +++ b/src/util/sugar.js @@ -406,6 +406,219 @@ export function bindOpts(fn, bind) { bindOpts.bindIndex = Symbol(); +// Sorts multiple arrays by an arbitrary function (which is the last argument). +// Paired values from each array are provided to the callback sequentially: +// +// (a_fromFirstArray, b_fromFirstArray, +// a_fromSecondArray, b_fromSecondArray, +// a_fromThirdArray, b_fromThirdArray) => +// relative positioning (negative, positive, or zero) +// +// Like native single-array sort, this is a mutating function. +export function sortMultipleArrays(...args) { + const arrays = args.slice(0, -1); + const fn = args.at(-1); + + const length = arrays[0].length; + const symbols = new Array(length).fill(null).map(() => Symbol()); + const indexes = Object.fromEntries(symbols.map((symbol, index) => [symbol, index])); + + symbols.sort((a, b) => { + const indexA = indexes[a]; + const indexB = indexes[b]; + + const args = []; + for (let i = 0; i < arrays.length; i++) { + args.push(arrays[i][indexA]); + args.push(arrays[i][indexB]); + } + + return fn(...args); + }); + + for (const array of arrays) { + // Note: We're mutating this array pulling values from itself, but only all + // at once after all those values have been pulled. + array.splice(0, array.length, ...symbols.map(symbol => array[indexes[symbol]])); + } + + return arrays; +} + +// Filters multiple arrays by an arbitrary function (which is the last argument). +// Values from each array are provided to the callback sequentially: +// +// (value_fromFirstArray, +// value_fromSecondArray, +// value_fromThirdArray, +// index, +// [firstArray, secondArray, thirdArray]) => +// true or false +// +// Please be aware that this is a mutating function, unlike native single-array +// filter. The mutated arrays are returned. Also attached under `.removed` are +// corresponding arrays of items filtered out. +export function filterMultipleArrays(...args) { + const arrays = args.slice(0, -1); + const fn = args.at(-1); + + const removed = new Array(arrays.length).fill(null).map(() => []); + + for (let i = arrays[0].length - 1; i >= 0; i--) { + const args = arrays.map(array => array[i]); + args.push(i, arrays); + + if (!fn(...args)) { + for (let j = 0; j < arrays.length; j++) { + const item = arrays[j][i]; + arrays[j].splice(i, 1); + removed[j].unshift(item); + } + } + } + + Object.assign(arrays, {removed}); + return arrays; +} + +// Corresponding filter function for sortByCount. By default, items whose +// corresponding count is zero will be removed. +export function filterByCount(data, counts, { + min = 1, + max = Infinity, +} = {}) { + filterMultipleArrays(data, counts, (data, count) => + count >= min && count <= max); +} + +// Reduces multiple arrays with an arbitrary function (which is the last +// argument). Note that this reduces into multiple accumulators, one for +// each input array, not just a single value. That's reflected in both the +// callback parameters: +// +// (accumulator1, +// accumulator2, +// value_fromFirstArray, +// value_fromSecondArray, +// index, +// [firstArray, secondArray]) => +// [newAccumulator1, newAccumulator2] +// +// As well as the final return value of reduceMultipleArrays: +// +// [finalAccumulator1, finalAccumulator2] +// +// This is not a mutating function. +export function reduceMultipleArrays(...args) { + const [arrays, fn, initialAccumulators] = + (typeof args.at(-1) === 'function' + ? [args.slice(0, -1), args.at(-1), null] + : [args.slice(0, -2), args.at(-2), args.at(-1)]); + + if (empty(arrays[0])) { + throw new TypeError(`Reduce of empty arrays with no initial value`); + } + + let [accumulators, i] = + (initialAccumulators + ? [initialAccumulators, 0] + : [arrays.map(array => array[0]), 1]); + + for (; i < arrays[0].length; i++) { + const args = [...accumulators, ...arrays.map(array => array[i])]; + args.push(i, arrays); + accumulators = fn(...args); + } + + return accumulators; +} + +export function chunkByConditions(array, conditions) { + if (empty(array)) { + return []; + } + + if (empty(conditions)) { + return [array]; + } + + const out = []; + let cur = [array[0]]; + for (let i = 1; i < array.length; i++) { + const item = array[i]; + const prev = array[i - 1]; + let chunk = false; + for (const condition of conditions) { + if (condition(item, prev)) { + chunk = true; + break; + } + } + if (chunk) { + out.push(cur); + cur = [item]; + } else { + cur.push(item); + } + } + out.push(cur); + return out; +} + +export function chunkByProperties(array, properties) { + return chunkByConditions( + array, + properties.map((p) => (a, b) => { + if (a[p] instanceof Date && b[p] instanceof Date) return +a[p] !== +b[p]; + + if (a[p] !== b[p]) return true; + + // Not sure if this line is still necessary with the specific check for + // d8tes a8ove, 8ut, uh, keeping it anyway, just in case....? + if (a[p] != b[p]) return true; + + return false; + }) + ).map((chunk) => ({ + ...Object.fromEntries(properties.map((p) => [p, chunk[0][p]])), + chunk, + })); +} + +export function chunkMultipleArrays(...args) { + const arrays = args.slice(0, -1); + const fn = args.at(-1); + + if (arrays[0].length === 0) { + return []; + } + + const newChunk = index => arrays.map(array => [array[index]]); + const results = [newChunk(0)]; + + for (let i = 1; i < arrays[0].length; i++) { + const current = results.at(-1); + + const args = []; + for (let j = 0; j < arrays.length; j++) { + const item = arrays[j][i]; + const previous = current[j].at(-1); + args.push(item, previous); + } + + if (fn(...args)) { + results.push(newChunk(i)); + continue; + } + + for (let j = 0; j < arrays.length; j++) { + current[j].push(arrays[j][i]); + } + } + + return results; +} + // Delicious function annotations, such as: // // (*bound) soWeAreBackInTheMine |