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- 'use strict';
- Object.defineProperty(exports, '__esModule', {
- value: true
- });
- exports.default = void 0;
- /**
- * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- *
- */
- // This diff-sequences package implements the linear space variation in
- // An O(ND) Difference Algorithm and Its Variations by Eugene W. Myers
- // Relationship in notation between Myers paper and this package:
- // A is a
- // N is aLength, aEnd - aStart, and so on
- // x is aIndex, aFirst, aLast, and so on
- // B is b
- // M is bLength, bEnd - bStart, and so on
- // y is bIndex, bFirst, bLast, and so on
- // Δ = N - M is negative of baDeltaLength = bLength - aLength
- // D is d
- // k is kF
- // k + Δ is kF = kR - baDeltaLength
- // V is aIndexesF or aIndexesR (see comment below about Indexes type)
- // index intervals [1, N] and [1, M] are [0, aLength) and [0, bLength)
- // starting point in forward direction (0, 0) is (-1, -1)
- // starting point in reverse direction (N + 1, M + 1) is (aLength, bLength)
- // The “edit graph” for sequences a and b corresponds to items:
- // in a on the horizontal axis
- // in b on the vertical axis
- //
- // Given a-coordinate of a point in a diagonal, you can compute b-coordinate.
- //
- // Forward diagonals kF:
- // zero diagonal intersects top left corner
- // positive diagonals intersect top edge
- // negative diagonals insersect left edge
- //
- // Reverse diagonals kR:
- // zero diagonal intersects bottom right corner
- // positive diagonals intersect right edge
- // negative diagonals intersect bottom edge
- // The graph contains a directed acyclic graph of edges:
- // horizontal: delete an item from a
- // vertical: insert an item from b
- // diagonal: common item in a and b
- //
- // The algorithm solves dual problems in the graph analogy:
- // Find longest common subsequence: path with maximum number of diagonal edges
- // Find shortest edit script: path with minimum number of non-diagonal edges
- // Input callback function compares items at indexes in the sequences.
- // Output callback function receives the number of adjacent items
- // and starting indexes of each common subsequence.
- // Either original functions or wrapped to swap indexes if graph is transposed.
- // Indexes in sequence a of last point of forward or reverse paths in graph.
- // Myers algorithm indexes by diagonal k which for negative is bad deopt in V8.
- // This package indexes by iF and iR which are greater than or equal to zero.
- // and also updates the index arrays in place to cut memory in half.
- // kF = 2 * iF - d
- // kR = d - 2 * iR
- // Division of index intervals in sequences a and b at the middle change.
- // Invariant: intervals do not have common items at the start or end.
- const pkg = 'diff-sequences'; // for error messages
- const NOT_YET_SET = 0; // small int instead of undefined to avoid deopt in V8
- // Return the number of common items that follow in forward direction.
- // The length of what Myers paper calls a “snake” in a forward path.
- const countCommonItemsF = (aIndex, aEnd, bIndex, bEnd, isCommon) => {
- let nCommon = 0;
- while (aIndex < aEnd && bIndex < bEnd && isCommon(aIndex, bIndex)) {
- aIndex += 1;
- bIndex += 1;
- nCommon += 1;
- }
- return nCommon;
- }; // Return the number of common items that precede in reverse direction.
- // The length of what Myers paper calls a “snake” in a reverse path.
- const countCommonItemsR = (aStart, aIndex, bStart, bIndex, isCommon) => {
- let nCommon = 0;
- while (aStart <= aIndex && bStart <= bIndex && isCommon(aIndex, bIndex)) {
- aIndex -= 1;
- bIndex -= 1;
- nCommon += 1;
- }
- return nCommon;
- }; // A simple function to extend forward paths from (d - 1) to d changes
- // when forward and reverse paths cannot yet overlap.
- const extendPathsF = (d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF) => {
- // Unroll the first iteration.
- let iF = 0;
- let kF = -d; // kF = 2 * iF - d
- let aFirst = aIndexesF[iF]; // in first iteration always insert
- let aIndexPrev1 = aFirst; // prev value of [iF - 1] in next iteration
- aIndexesF[iF] += countCommonItemsF(
- aFirst + 1,
- aEnd,
- bF + aFirst - kF + 1,
- bEnd,
- isCommon
- ); // Optimization: skip diagonals in which paths cannot ever overlap.
- const nF = d < iMaxF ? d : iMaxF; // The diagonals kF are odd when d is odd and even when d is even.
- for (iF += 1, kF += 2; iF <= nF; iF += 1, kF += 2) {
- // To get first point of path segment, move one change in forward direction
- // from last point of previous path segment in an adjacent diagonal.
- // In last possible iteration when iF === d and kF === d always delete.
- if (iF !== d && aIndexPrev1 < aIndexesF[iF]) {
- aFirst = aIndexesF[iF]; // vertical to insert from b
- } else {
- aFirst = aIndexPrev1 + 1; // horizontal to delete from a
- if (aEnd <= aFirst) {
- // Optimization: delete moved past right of graph.
- return iF - 1;
- }
- } // To get last point of path segment, move along diagonal of common items.
- aIndexPrev1 = aIndexesF[iF];
- aIndexesF[iF] =
- aFirst +
- countCommonItemsF(aFirst + 1, aEnd, bF + aFirst - kF + 1, bEnd, isCommon);
- }
- return iMaxF;
- }; // A simple function to extend reverse paths from (d - 1) to d changes
- // when reverse and forward paths cannot yet overlap.
- const extendPathsR = (d, aStart, bStart, bR, isCommon, aIndexesR, iMaxR) => {
- // Unroll the first iteration.
- let iR = 0;
- let kR = d; // kR = d - 2 * iR
- let aFirst = aIndexesR[iR]; // in first iteration always insert
- let aIndexPrev1 = aFirst; // prev value of [iR - 1] in next iteration
- aIndexesR[iR] -= countCommonItemsR(
- aStart,
- aFirst - 1,
- bStart,
- bR + aFirst - kR - 1,
- isCommon
- ); // Optimization: skip diagonals in which paths cannot ever overlap.
- const nR = d < iMaxR ? d : iMaxR; // The diagonals kR are odd when d is odd and even when d is even.
- for (iR += 1, kR -= 2; iR <= nR; iR += 1, kR -= 2) {
- // To get first point of path segment, move one change in reverse direction
- // from last point of previous path segment in an adjacent diagonal.
- // In last possible iteration when iR === d and kR === -d always delete.
- if (iR !== d && aIndexesR[iR] < aIndexPrev1) {
- aFirst = aIndexesR[iR]; // vertical to insert from b
- } else {
- aFirst = aIndexPrev1 - 1; // horizontal to delete from a
- if (aFirst < aStart) {
- // Optimization: delete moved past left of graph.
- return iR - 1;
- }
- } // To get last point of path segment, move along diagonal of common items.
- aIndexPrev1 = aIndexesR[iR];
- aIndexesR[iR] =
- aFirst -
- countCommonItemsR(
- aStart,
- aFirst - 1,
- bStart,
- bR + aFirst - kR - 1,
- isCommon
- );
- }
- return iMaxR;
- }; // A complete function to extend forward paths from (d - 1) to d changes.
- // Return true if a path overlaps reverse path of (d - 1) changes in its diagonal.
- const extendOverlappablePathsF = (
- d,
- aStart,
- aEnd,
- bStart,
- bEnd,
- isCommon,
- aIndexesF,
- iMaxF,
- aIndexesR,
- iMaxR,
- division
- ) => {
- const bF = bStart - aStart; // bIndex = bF + aIndex - kF
- const aLength = aEnd - aStart;
- const bLength = bEnd - bStart;
- const baDeltaLength = bLength - aLength; // kF = kR - baDeltaLength
- // Range of diagonals in which forward and reverse paths might overlap.
- const kMinOverlapF = -baDeltaLength - (d - 1); // -(d - 1) <= kR
- const kMaxOverlapF = -baDeltaLength + (d - 1); // kR <= (d - 1)
- let aIndexPrev1 = NOT_YET_SET; // prev value of [iF - 1] in next iteration
- // Optimization: skip diagonals in which paths cannot ever overlap.
- const nF = d < iMaxF ? d : iMaxF; // The diagonals kF = 2 * iF - d are odd when d is odd and even when d is even.
- for (let iF = 0, kF = -d; iF <= nF; iF += 1, kF += 2) {
- // To get first point of path segment, move one change in forward direction
- // from last point of previous path segment in an adjacent diagonal.
- // In first iteration when iF === 0 and kF === -d always insert.
- // In last possible iteration when iF === d and kF === d always delete.
- const insert = iF === 0 || (iF !== d && aIndexPrev1 < aIndexesF[iF]);
- const aLastPrev = insert ? aIndexesF[iF] : aIndexPrev1;
- const aFirst = insert
- ? aLastPrev // vertical to insert from b
- : aLastPrev + 1; // horizontal to delete from a
- // To get last point of path segment, move along diagonal of common items.
- const bFirst = bF + aFirst - kF;
- const nCommonF = countCommonItemsF(
- aFirst + 1,
- aEnd,
- bFirst + 1,
- bEnd,
- isCommon
- );
- const aLast = aFirst + nCommonF;
- aIndexPrev1 = aIndexesF[iF];
- aIndexesF[iF] = aLast;
- if (kMinOverlapF <= kF && kF <= kMaxOverlapF) {
- // Solve for iR of reverse path with (d - 1) changes in diagonal kF:
- // kR = kF + baDeltaLength
- // kR = (d - 1) - 2 * iR
- const iR = (d - 1 - (kF + baDeltaLength)) / 2; // If this forward path overlaps the reverse path in this diagonal,
- // then this is the middle change of the index intervals.
- if (iR <= iMaxR && aIndexesR[iR] - 1 <= aLast) {
- // Unlike the Myers algorithm which finds only the middle “snake”
- // this package can find two common subsequences per division.
- // Last point of previous path segment is on an adjacent diagonal.
- const bLastPrev = bF + aLastPrev - (insert ? kF + 1 : kF - 1); // Because of invariant that intervals preceding the middle change
- // cannot have common items at the end,
- // move in reverse direction along a diagonal of common items.
- const nCommonR = countCommonItemsR(
- aStart,
- aLastPrev,
- bStart,
- bLastPrev,
- isCommon
- );
- const aIndexPrevFirst = aLastPrev - nCommonR;
- const bIndexPrevFirst = bLastPrev - nCommonR;
- const aEndPreceding = aIndexPrevFirst + 1;
- const bEndPreceding = bIndexPrevFirst + 1;
- division.nChangePreceding = d - 1;
- if (d - 1 === aEndPreceding + bEndPreceding - aStart - bStart) {
- // Optimization: number of preceding changes in forward direction
- // is equal to number of items in preceding interval,
- // therefore it cannot contain any common items.
- division.aEndPreceding = aStart;
- division.bEndPreceding = bStart;
- } else {
- division.aEndPreceding = aEndPreceding;
- division.bEndPreceding = bEndPreceding;
- }
- division.nCommonPreceding = nCommonR;
- if (nCommonR !== 0) {
- division.aCommonPreceding = aEndPreceding;
- division.bCommonPreceding = bEndPreceding;
- }
- division.nCommonFollowing = nCommonF;
- if (nCommonF !== 0) {
- division.aCommonFollowing = aFirst + 1;
- division.bCommonFollowing = bFirst + 1;
- }
- const aStartFollowing = aLast + 1;
- const bStartFollowing = bFirst + nCommonF + 1;
- division.nChangeFollowing = d - 1;
- if (d - 1 === aEnd + bEnd - aStartFollowing - bStartFollowing) {
- // Optimization: number of changes in reverse direction
- // is equal to number of items in following interval,
- // therefore it cannot contain any common items.
- division.aStartFollowing = aEnd;
- division.bStartFollowing = bEnd;
- } else {
- division.aStartFollowing = aStartFollowing;
- division.bStartFollowing = bStartFollowing;
- }
- return true;
- }
- }
- }
- return false;
- }; // A complete function to extend reverse paths from (d - 1) to d changes.
- // Return true if a path overlaps forward path of d changes in its diagonal.
- const extendOverlappablePathsR = (
- d,
- aStart,
- aEnd,
- bStart,
- bEnd,
- isCommon,
- aIndexesF,
- iMaxF,
- aIndexesR,
- iMaxR,
- division
- ) => {
- const bR = bEnd - aEnd; // bIndex = bR + aIndex - kR
- const aLength = aEnd - aStart;
- const bLength = bEnd - bStart;
- const baDeltaLength = bLength - aLength; // kR = kF + baDeltaLength
- // Range of diagonals in which forward and reverse paths might overlap.
- const kMinOverlapR = baDeltaLength - d; // -d <= kF
- const kMaxOverlapR = baDeltaLength + d; // kF <= d
- let aIndexPrev1 = NOT_YET_SET; // prev value of [iR - 1] in next iteration
- // Optimization: skip diagonals in which paths cannot ever overlap.
- const nR = d < iMaxR ? d : iMaxR; // The diagonals kR = d - 2 * iR are odd when d is odd and even when d is even.
- for (let iR = 0, kR = d; iR <= nR; iR += 1, kR -= 2) {
- // To get first point of path segment, move one change in reverse direction
- // from last point of previous path segment in an adjacent diagonal.
- // In first iteration when iR === 0 and kR === d always insert.
- // In last possible iteration when iR === d and kR === -d always delete.
- const insert = iR === 0 || (iR !== d && aIndexesR[iR] < aIndexPrev1);
- const aLastPrev = insert ? aIndexesR[iR] : aIndexPrev1;
- const aFirst = insert
- ? aLastPrev // vertical to insert from b
- : aLastPrev - 1; // horizontal to delete from a
- // To get last point of path segment, move along diagonal of common items.
- const bFirst = bR + aFirst - kR;
- const nCommonR = countCommonItemsR(
- aStart,
- aFirst - 1,
- bStart,
- bFirst - 1,
- isCommon
- );
- const aLast = aFirst - nCommonR;
- aIndexPrev1 = aIndexesR[iR];
- aIndexesR[iR] = aLast;
- if (kMinOverlapR <= kR && kR <= kMaxOverlapR) {
- // Solve for iF of forward path with d changes in diagonal kR:
- // kF = kR - baDeltaLength
- // kF = 2 * iF - d
- const iF = (d + (kR - baDeltaLength)) / 2; // If this reverse path overlaps the forward path in this diagonal,
- // then this is a middle change of the index intervals.
- if (iF <= iMaxF && aLast - 1 <= aIndexesF[iF]) {
- const bLast = bFirst - nCommonR;
- division.nChangePreceding = d;
- if (d === aLast + bLast - aStart - bStart) {
- // Optimization: number of changes in reverse direction
- // is equal to number of items in preceding interval,
- // therefore it cannot contain any common items.
- division.aEndPreceding = aStart;
- division.bEndPreceding = bStart;
- } else {
- division.aEndPreceding = aLast;
- division.bEndPreceding = bLast;
- }
- division.nCommonPreceding = nCommonR;
- if (nCommonR !== 0) {
- // The last point of reverse path segment is start of common subsequence.
- division.aCommonPreceding = aLast;
- division.bCommonPreceding = bLast;
- }
- division.nChangeFollowing = d - 1;
- if (d === 1) {
- // There is no previous path segment.
- division.nCommonFollowing = 0;
- division.aStartFollowing = aEnd;
- division.bStartFollowing = bEnd;
- } else {
- // Unlike the Myers algorithm which finds only the middle “snake”
- // this package can find two common subsequences per division.
- // Last point of previous path segment is on an adjacent diagonal.
- const bLastPrev = bR + aLastPrev - (insert ? kR - 1 : kR + 1); // Because of invariant that intervals following the middle change
- // cannot have common items at the start,
- // move in forward direction along a diagonal of common items.
- const nCommonF = countCommonItemsF(
- aLastPrev,
- aEnd,
- bLastPrev,
- bEnd,
- isCommon
- );
- division.nCommonFollowing = nCommonF;
- if (nCommonF !== 0) {
- // The last point of reverse path segment is start of common subsequence.
- division.aCommonFollowing = aLastPrev;
- division.bCommonFollowing = bLastPrev;
- }
- const aStartFollowing = aLastPrev + nCommonF; // aFirstPrev
- const bStartFollowing = bLastPrev + nCommonF; // bFirstPrev
- if (d - 1 === aEnd + bEnd - aStartFollowing - bStartFollowing) {
- // Optimization: number of changes in forward direction
- // is equal to number of items in following interval,
- // therefore it cannot contain any common items.
- division.aStartFollowing = aEnd;
- division.bStartFollowing = bEnd;
- } else {
- division.aStartFollowing = aStartFollowing;
- division.bStartFollowing = bStartFollowing;
- }
- }
- return true;
- }
- }
- }
- return false;
- }; // Given index intervals and input function to compare items at indexes,
- // divide at the middle change.
- //
- // DO NOT CALL if start === end, because interval cannot contain common items
- // and because this function will throw the “no overlap” error.
- const divide = (
- nChange,
- aStart,
- aEnd,
- bStart,
- bEnd,
- isCommon,
- aIndexesF,
- aIndexesR,
- division // output
- ) => {
- const bF = bStart - aStart; // bIndex = bF + aIndex - kF
- const bR = bEnd - aEnd; // bIndex = bR + aIndex - kR
- const aLength = aEnd - aStart;
- const bLength = bEnd - bStart; // Because graph has square or portrait orientation,
- // length difference is minimum number of items to insert from b.
- // Corresponding forward and reverse diagonals in graph
- // depend on length difference of the sequences:
- // kF = kR - baDeltaLength
- // kR = kF + baDeltaLength
- const baDeltaLength = bLength - aLength; // Optimization: max diagonal in graph intersects corner of shorter side.
- let iMaxF = aLength;
- let iMaxR = aLength; // Initialize no changes yet in forward or reverse direction:
- aIndexesF[0] = aStart - 1; // at open start of interval, outside closed start
- aIndexesR[0] = aEnd; // at open end of interval
- if (baDeltaLength % 2 === 0) {
- // The number of changes in paths is 2 * d if length difference is even.
- const dMin = (nChange || baDeltaLength) / 2;
- const dMax = (aLength + bLength) / 2;
- for (let d = 1; d <= dMax; d += 1) {
- iMaxF = extendPathsF(d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF);
- if (d < dMin) {
- iMaxR = extendPathsR(d, aStart, bStart, bR, isCommon, aIndexesR, iMaxR);
- } else if (
- // If a reverse path overlaps a forward path in the same diagonal,
- // return a division of the index intervals at the middle change.
- extendOverlappablePathsR(
- d,
- aStart,
- aEnd,
- bStart,
- bEnd,
- isCommon,
- aIndexesF,
- iMaxF,
- aIndexesR,
- iMaxR,
- division
- )
- ) {
- return;
- }
- }
- } else {
- // The number of changes in paths is 2 * d - 1 if length difference is odd.
- const dMin = ((nChange || baDeltaLength) + 1) / 2;
- const dMax = (aLength + bLength + 1) / 2; // Unroll first half iteration so loop extends the relevant pairs of paths.
- // Because of invariant that intervals have no common items at start or end,
- // and limitation not to call divide with empty intervals,
- // therefore it cannot be called if a forward path with one change
- // would overlap a reverse path with no changes, even if dMin === 1.
- let d = 1;
- iMaxF = extendPathsF(d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF);
- for (d += 1; d <= dMax; d += 1) {
- iMaxR = extendPathsR(
- d - 1,
- aStart,
- bStart,
- bR,
- isCommon,
- aIndexesR,
- iMaxR
- );
- if (d < dMin) {
- iMaxF = extendPathsF(d, aEnd, bEnd, bF, isCommon, aIndexesF, iMaxF);
- } else if (
- // If a forward path overlaps a reverse path in the same diagonal,
- // return a division of the index intervals at the middle change.
- extendOverlappablePathsF(
- d,
- aStart,
- aEnd,
- bStart,
- bEnd,
- isCommon,
- aIndexesF,
- iMaxF,
- aIndexesR,
- iMaxR,
- division
- )
- ) {
- return;
- }
- }
- }
- /* istanbul ignore next */
- throw new Error(
- `${pkg}: no overlap aStart=${aStart} aEnd=${aEnd} bStart=${bStart} bEnd=${bEnd}`
- );
- }; // Given index intervals and input function to compare items at indexes,
- // return by output function the number of adjacent items and starting indexes
- // of each common subsequence. Divide and conquer with only linear space.
- //
- // The index intervals are half open [start, end) like array slice method.
- // DO NOT CALL if start === end, because interval cannot contain common items
- // and because divide function will throw the “no overlap” error.
- const findSubsequences = (
- nChange,
- aStart,
- aEnd,
- bStart,
- bEnd,
- transposed,
- callbacks,
- aIndexesF,
- aIndexesR,
- division // temporary memory, not input nor output
- ) => {
- if (bEnd - bStart < aEnd - aStart) {
- // Transpose graph so it has portrait instead of landscape orientation.
- // Always compare shorter to longer sequence for consistency and optimization.
- transposed = !transposed;
- if (transposed && callbacks.length === 1) {
- // Lazily wrap callback functions to swap args if graph is transposed.
- const _callbacks$ = callbacks[0],
- foundSubsequence = _callbacks$.foundSubsequence,
- isCommon = _callbacks$.isCommon;
- callbacks[1] = {
- foundSubsequence: (function(_foundSubsequence) {
- function foundSubsequence(_x, _x2, _x3) {
- return _foundSubsequence.apply(this, arguments);
- }
- foundSubsequence.toString = function() {
- return _foundSubsequence.toString();
- };
- return foundSubsequence;
- })((nCommon, bCommon, aCommon) => {
- foundSubsequence(nCommon, aCommon, bCommon);
- }),
- isCommon: (function(_isCommon) {
- function isCommon(_x4, _x5) {
- return _isCommon.apply(this, arguments);
- }
- isCommon.toString = function() {
- return _isCommon.toString();
- };
- return isCommon;
- })((bIndex, aIndex) => isCommon(aIndex, bIndex))
- };
- }
- const tStart = aStart;
- const tEnd = aEnd;
- aStart = bStart;
- aEnd = bEnd;
- bStart = tStart;
- bEnd = tEnd;
- }
- const _callbacks = callbacks[transposed ? 1 : 0],
- foundSubsequence = _callbacks.foundSubsequence,
- isCommon = _callbacks.isCommon; // Divide the index intervals at the middle change.
- divide(
- nChange,
- aStart,
- aEnd,
- bStart,
- bEnd,
- isCommon,
- aIndexesF,
- aIndexesR,
- division
- );
- const nChangePreceding = division.nChangePreceding,
- aEndPreceding = division.aEndPreceding,
- bEndPreceding = division.bEndPreceding,
- nCommonPreceding = division.nCommonPreceding,
- aCommonPreceding = division.aCommonPreceding,
- bCommonPreceding = division.bCommonPreceding,
- nCommonFollowing = division.nCommonFollowing,
- aCommonFollowing = division.aCommonFollowing,
- bCommonFollowing = division.bCommonFollowing,
- nChangeFollowing = division.nChangeFollowing,
- aStartFollowing = division.aStartFollowing,
- bStartFollowing = division.bStartFollowing; // Unless either index interval is empty, they might contain common items.
- if (aStart < aEndPreceding && bStart < bEndPreceding) {
- // Recursely find and return common subsequences preceding the division.
- findSubsequences(
- nChangePreceding,
- aStart,
- aEndPreceding,
- bStart,
- bEndPreceding,
- transposed,
- callbacks,
- aIndexesF,
- aIndexesR,
- division
- );
- } // Return common subsequences that are adjacent to the middle change.
- if (nCommonPreceding !== 0) {
- foundSubsequence(nCommonPreceding, aCommonPreceding, bCommonPreceding);
- }
- if (nCommonFollowing !== 0) {
- foundSubsequence(nCommonFollowing, aCommonFollowing, bCommonFollowing);
- } // Unless either index interval is empty, they might contain common items.
- if (aStartFollowing < aEnd && bStartFollowing < bEnd) {
- // Recursely find and return common subsequences following the division.
- findSubsequences(
- nChangeFollowing,
- aStartFollowing,
- aEnd,
- bStartFollowing,
- bEnd,
- transposed,
- callbacks,
- aIndexesF,
- aIndexesR,
- division
- );
- }
- };
- const validateLength = (name, arg) => {
- const type = typeof arg;
- if (type !== 'number') {
- throw new TypeError(`${pkg}: ${name} typeof ${type} is not a number`);
- }
- if (!Number.isSafeInteger(arg)) {
- throw new RangeError(`${pkg}: ${name} value ${arg} is not a safe integer`);
- }
- if (arg < 0) {
- throw new RangeError(`${pkg}: ${name} value ${arg} is a negative integer`);
- }
- };
- const validateCallback = (name, arg) => {
- const type = typeof arg;
- if (type !== 'function') {
- throw new TypeError(`${pkg}: ${name} typeof ${type} is not a function`);
- }
- }; // Compare items in two sequences to find a longest common subsequence.
- // Given lengths of sequences and input function to compare items at indexes,
- // return by output function the number of adjacent items and starting indexes
- // of each common subsequence.
- var _default = (aLength, bLength, isCommon, foundSubsequence) => {
- validateLength('aLength', aLength);
- validateLength('bLength', bLength);
- validateCallback('isCommon', isCommon);
- validateCallback('foundSubsequence', foundSubsequence); // Count common items from the start in the forward direction.
- const nCommonF = countCommonItemsF(0, aLength, 0, bLength, isCommon);
- if (nCommonF !== 0) {
- foundSubsequence(nCommonF, 0, 0);
- } // Unless both sequences consist of common items only,
- // find common items in the half-trimmed index intervals.
- if (aLength !== nCommonF || bLength !== nCommonF) {
- // Invariant: intervals do not have common items at the start.
- // The start of an index interval is closed like array slice method.
- const aStart = nCommonF;
- const bStart = nCommonF; // Count common items from the end in the reverse direction.
- const nCommonR = countCommonItemsR(
- aStart,
- aLength - 1,
- bStart,
- bLength - 1,
- isCommon
- ); // Invariant: intervals do not have common items at the end.
- // The end of an index interval is open like array slice method.
- const aEnd = aLength - nCommonR;
- const bEnd = bLength - nCommonR; // Unless one sequence consists of common items only,
- // therefore the other trimmed index interval consists of changes only,
- // find common items in the trimmed index intervals.
- const nCommonFR = nCommonF + nCommonR;
- if (aLength !== nCommonFR && bLength !== nCommonFR) {
- const nChange = 0; // number of change items is not yet known
- const transposed = false; // call the original unwrapped functions
- const callbacks = [
- {
- foundSubsequence,
- isCommon
- }
- ]; // Indexes in sequence a of last points in furthest reaching paths
- // from outside the start at top left in the forward direction:
- const aIndexesF = [NOT_YET_SET]; // from the end at bottom right in the reverse direction:
- const aIndexesR = [NOT_YET_SET]; // Initialize one object as output of all calls to divide function.
- const division = {
- aCommonFollowing: NOT_YET_SET,
- aCommonPreceding: NOT_YET_SET,
- aEndPreceding: NOT_YET_SET,
- aStartFollowing: NOT_YET_SET,
- bCommonFollowing: NOT_YET_SET,
- bCommonPreceding: NOT_YET_SET,
- bEndPreceding: NOT_YET_SET,
- bStartFollowing: NOT_YET_SET,
- nChangeFollowing: NOT_YET_SET,
- nChangePreceding: NOT_YET_SET,
- nCommonFollowing: NOT_YET_SET,
- nCommonPreceding: NOT_YET_SET
- }; // Find and return common subsequences in the trimmed index intervals.
- findSubsequences(
- nChange,
- aStart,
- aEnd,
- bStart,
- bEnd,
- transposed,
- callbacks,
- aIndexesF,
- aIndexesR,
- division
- );
- }
- if (nCommonR !== 0) {
- foundSubsequence(nCommonR, aEnd, bEnd);
- }
- }
- };
- exports.default = _default;
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