258 lines
13 KiB
JavaScript
258 lines
13 KiB
JavaScript
import { hasOnlyWinLineEndings, hasOnlyUnixLineEndings } from '../util/string.js';
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import { isWin, isUnix, unixToWin, winToUnix } from './line-endings.js';
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import { parsePatch } from './parse.js';
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import distanceIterator from '../util/distance-iterator.js';
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/**
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* attempts to apply a unified diff patch.
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*
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* Hunks are applied first to last.
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* `applyPatch` first tries to apply the first hunk at the line number specified in the hunk header, and with all context lines matching exactly.
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* If that fails, it tries scanning backwards and forwards, one line at a time, to find a place to apply the hunk where the context lines match exactly.
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* If that still fails, and `fuzzFactor` is greater than zero, it increments the maximum number of mismatches (missing, extra, or changed context lines) that there can be between the hunk context and a region where we are trying to apply the patch such that the hunk will still be considered to match.
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* Regardless of `fuzzFactor`, lines to be deleted in the hunk *must* be present for a hunk to match, and the context lines *immediately* before and after an insertion must match exactly.
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*
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* Once a hunk is successfully fitted, the process begins again with the next hunk.
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* Regardless of `fuzzFactor`, later hunks must be applied later in the file than earlier hunks.
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*
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* If a hunk cannot be successfully fitted *anywhere* with fewer than `fuzzFactor` mismatches, `applyPatch` fails and returns `false`.
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*
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* If a hunk is successfully fitted but not at the line number specified by the hunk header, all subsequent hunks have their target line number adjusted accordingly.
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* (e.g. if the first hunk is applied 10 lines below where the hunk header said it should fit, `applyPatch` will *start* looking for somewhere to apply the second hunk 10 lines below where its hunk header says it goes.)
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*
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* If the patch was applied successfully, returns a string containing the patched text.
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* If the patch could not be applied (because some hunks in the patch couldn't be fitted to the text in `source`), `applyPatch` returns false.
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*
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* @param patch a string diff or the output from the `parsePatch` or `structuredPatch` methods.
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*/
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export function applyPatch(source, patch, options = {}) {
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let patches;
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if (typeof patch === 'string') {
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patches = parsePatch(patch);
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}
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else if (Array.isArray(patch)) {
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patches = patch;
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}
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else {
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patches = [patch];
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}
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if (patches.length > 1) {
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throw new Error('applyPatch only works with a single input.');
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}
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return applyStructuredPatch(source, patches[0], options);
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}
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function applyStructuredPatch(source, patch, options = {}) {
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if (options.autoConvertLineEndings || options.autoConvertLineEndings == null) {
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if (hasOnlyWinLineEndings(source) && isUnix(patch)) {
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patch = unixToWin(patch);
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}
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else if (hasOnlyUnixLineEndings(source) && isWin(patch)) {
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patch = winToUnix(patch);
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}
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}
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// Apply the diff to the input
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const lines = source.split('\n'), hunks = patch.hunks, compareLine = options.compareLine || ((lineNumber, line, operation, patchContent) => line === patchContent), fuzzFactor = options.fuzzFactor || 0;
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let minLine = 0;
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if (fuzzFactor < 0 || !Number.isInteger(fuzzFactor)) {
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throw new Error('fuzzFactor must be a non-negative integer');
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}
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// Special case for empty patch.
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if (!hunks.length) {
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return source;
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}
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// Before anything else, handle EOFNL insertion/removal. If the patch tells us to make a change
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// to the EOFNL that is redundant/impossible - i.e. to remove a newline that's not there, or add a
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// newline that already exists - then we either return false and fail to apply the patch (if
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// fuzzFactor is 0) or simply ignore the problem and do nothing (if fuzzFactor is >0).
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// If we do need to remove/add a newline at EOF, this will always be in the final hunk:
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let prevLine = '', removeEOFNL = false, addEOFNL = false;
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for (let i = 0; i < hunks[hunks.length - 1].lines.length; i++) {
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const line = hunks[hunks.length - 1].lines[i];
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if (line[0] == '\\') {
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if (prevLine[0] == '+') {
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removeEOFNL = true;
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}
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else if (prevLine[0] == '-') {
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addEOFNL = true;
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}
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}
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prevLine = line;
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}
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if (removeEOFNL) {
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if (addEOFNL) {
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// This means the final line gets changed but doesn't have a trailing newline in either the
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// original or patched version. In that case, we do nothing if fuzzFactor > 0, and if
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// fuzzFactor is 0, we simply validate that the source file has no trailing newline.
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if (!fuzzFactor && lines[lines.length - 1] == '') {
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return false;
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}
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}
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else if (lines[lines.length - 1] == '') {
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lines.pop();
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}
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else if (!fuzzFactor) {
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return false;
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}
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}
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else if (addEOFNL) {
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if (lines[lines.length - 1] != '') {
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lines.push('');
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}
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else if (!fuzzFactor) {
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return false;
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}
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}
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/**
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* Checks if the hunk can be made to fit at the provided location with at most `maxErrors`
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* insertions, substitutions, or deletions, while ensuring also that:
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* - lines deleted in the hunk match exactly, and
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* - wherever an insertion operation or block of insertion operations appears in the hunk, the
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* immediately preceding and following lines of context match exactly
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*
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* `toPos` should be set such that lines[toPos] is meant to match hunkLines[0].
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*
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* If the hunk can be applied, returns an object with properties `oldLineLastI` and
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* `replacementLines`. Otherwise, returns null.
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*/
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function applyHunk(hunkLines, toPos, maxErrors, hunkLinesI = 0, lastContextLineMatched = true, patchedLines = [], patchedLinesLength = 0) {
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let nConsecutiveOldContextLines = 0;
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let nextContextLineMustMatch = false;
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for (; hunkLinesI < hunkLines.length; hunkLinesI++) {
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const hunkLine = hunkLines[hunkLinesI], operation = (hunkLine.length > 0 ? hunkLine[0] : ' '), content = (hunkLine.length > 0 ? hunkLine.substr(1) : hunkLine);
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if (operation === '-') {
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if (compareLine(toPos + 1, lines[toPos], operation, content)) {
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toPos++;
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nConsecutiveOldContextLines = 0;
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}
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else {
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if (!maxErrors || lines[toPos] == null) {
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return null;
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}
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patchedLines[patchedLinesLength] = lines[toPos];
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return applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI, false, patchedLines, patchedLinesLength + 1);
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}
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}
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if (operation === '+') {
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if (!lastContextLineMatched) {
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return null;
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}
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patchedLines[patchedLinesLength] = content;
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patchedLinesLength++;
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nConsecutiveOldContextLines = 0;
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nextContextLineMustMatch = true;
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}
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if (operation === ' ') {
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nConsecutiveOldContextLines++;
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patchedLines[patchedLinesLength] = lines[toPos];
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if (compareLine(toPos + 1, lines[toPos], operation, content)) {
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patchedLinesLength++;
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lastContextLineMatched = true;
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nextContextLineMustMatch = false;
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toPos++;
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}
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else {
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if (nextContextLineMustMatch || !maxErrors) {
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return null;
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}
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// Consider 3 possibilities in sequence:
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// 1. lines contains a *substitution* not included in the patch context, or
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// 2. lines contains an *insertion* not included in the patch context, or
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// 3. lines contains a *deletion* not included in the patch context
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// The first two options are of course only possible if the line from lines is non-null -
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// i.e. only option 3 is possible if we've overrun the end of the old file.
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return (lines[toPos] && (applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI + 1, false, patchedLines, patchedLinesLength + 1) || applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI, false, patchedLines, patchedLinesLength + 1)) || applyHunk(hunkLines, toPos, maxErrors - 1, hunkLinesI + 1, false, patchedLines, patchedLinesLength));
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}
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}
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}
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// Before returning, trim any unmodified context lines off the end of patchedLines and reduce
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// toPos (and thus oldLineLastI) accordingly. This allows later hunks to be applied to a region
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// that starts in this hunk's trailing context.
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patchedLinesLength -= nConsecutiveOldContextLines;
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toPos -= nConsecutiveOldContextLines;
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patchedLines.length = patchedLinesLength;
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return {
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patchedLines,
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oldLineLastI: toPos - 1
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};
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}
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const resultLines = [];
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// Search best fit offsets for each hunk based on the previous ones
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let prevHunkOffset = 0;
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for (let i = 0; i < hunks.length; i++) {
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const hunk = hunks[i];
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let hunkResult;
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const maxLine = lines.length - hunk.oldLines + fuzzFactor;
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let toPos;
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for (let maxErrors = 0; maxErrors <= fuzzFactor; maxErrors++) {
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toPos = hunk.oldStart + prevHunkOffset - 1;
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const iterator = distanceIterator(toPos, minLine, maxLine);
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for (; toPos !== undefined; toPos = iterator()) {
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hunkResult = applyHunk(hunk.lines, toPos, maxErrors);
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if (hunkResult) {
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break;
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}
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}
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if (hunkResult) {
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break;
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}
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}
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if (!hunkResult) {
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return false;
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}
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// Copy everything from the end of where we applied the last hunk to the start of this hunk
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for (let i = minLine; i < toPos; i++) {
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resultLines.push(lines[i]);
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}
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// Add the lines produced by applying the hunk:
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for (let i = 0; i < hunkResult.patchedLines.length; i++) {
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const line = hunkResult.patchedLines[i];
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resultLines.push(line);
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}
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// Set lower text limit to end of the current hunk, so next ones don't try
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// to fit over already patched text
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minLine = hunkResult.oldLineLastI + 1;
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// Note the offset between where the patch said the hunk should've applied and where we
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// applied it, so we can adjust future hunks accordingly:
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prevHunkOffset = toPos + 1 - hunk.oldStart;
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}
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// Copy over the rest of the lines from the old text
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for (let i = minLine; i < lines.length; i++) {
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resultLines.push(lines[i]);
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}
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return resultLines.join('\n');
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}
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/**
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* applies one or more patches.
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*
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* `patch` may be either an array of structured patch objects, or a string representing a patch in unified diff format (which may patch one or more files).
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*
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* This method will iterate over the contents of the patch and apply to data provided through callbacks. The general flow for each patch index is:
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*
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* - `options.loadFile(index, callback)` is called. The caller should then load the contents of the file and then pass that to the `callback(err, data)` callback. Passing an `err` will terminate further patch execution.
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* - `options.patched(index, content, callback)` is called once the patch has been applied. `content` will be the return value from `applyPatch`. When it's ready, the caller should call `callback(err)` callback. Passing an `err` will terminate further patch execution.
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*
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* Once all patches have been applied or an error occurs, the `options.complete(err)` callback is made.
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*/
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export function applyPatches(uniDiff, options) {
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const spDiff = typeof uniDiff === 'string' ? parsePatch(uniDiff) : uniDiff;
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let currentIndex = 0;
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function processIndex() {
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const index = spDiff[currentIndex++];
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if (!index) {
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return options.complete();
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}
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options.loadFile(index, function (err, data) {
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if (err) {
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return options.complete(err);
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}
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const updatedContent = applyPatch(data, index, options);
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options.patched(index, updatedContent, function (err) {
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if (err) {
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return options.complete(err);
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}
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processIndex();
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});
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});
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}
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processIndex();
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}
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