apply.js 13 KB

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  1. import { hasOnlyWinLineEndings, hasOnlyUnixLineEndings } from '../util/string.js';
  2. import { isWin, isUnix, unixToWin, winToUnix } from './line-endings.js';
  3. import { parsePatch } from './parse.js';
  4. import distanceIterator from '../util/distance-iterator.js';
  5. /**
  6. * attempts to apply a unified diff patch.
  7. *
  8. * Hunks are applied first to last.
  9. * `applyPatch` first tries to apply the first hunk at the line number specified in the hunk header, and with all context lines matching exactly.
  10. * 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.
  11. * 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.
  12. * 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.
  13. *
  14. * Once a hunk is successfully fitted, the process begins again with the next hunk.
  15. * Regardless of `fuzzFactor`, later hunks must be applied later in the file than earlier hunks.
  16. *
  17. * If a hunk cannot be successfully fitted *anywhere* with fewer than `fuzzFactor` mismatches, `applyPatch` fails and returns `false`.
  18. *
  19. * 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.
  20. * (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.)
  21. *
  22. * If the patch was applied successfully, returns a string containing the patched text.
  23. * 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.
  24. *
  25. * @param patch a string diff or the output from the `parsePatch` or `structuredPatch` methods.
  26. */
  27. export function applyPatch(source, patch, options = {}) {
  28. let patches;
  29. if (typeof patch === 'string') {
  30. patches = parsePatch(patch);
  31. }
  32. else if (Array.isArray(patch)) {
  33. patches = patch;
  34. }
  35. else {
  36. patches = [patch];
  37. }
  38. if (patches.length > 1) {
  39. throw new Error('applyPatch only works with a single input.');
  40. }
  41. return applyStructuredPatch(source, patches[0], options);
  42. }
  43. function applyStructuredPatch(source, patch, options = {}) {
  44. if (options.autoConvertLineEndings || options.autoConvertLineEndings == null) {
  45. if (hasOnlyWinLineEndings(source) && isUnix(patch)) {
  46. patch = unixToWin(patch);
  47. }
  48. else if (hasOnlyUnixLineEndings(source) && isWin(patch)) {
  49. patch = winToUnix(patch);
  50. }
  51. }
  52. // Apply the diff to the input
  53. const lines = source.split('\n'), hunks = patch.hunks, compareLine = options.compareLine || ((lineNumber, line, operation, patchContent) => line === patchContent), fuzzFactor = options.fuzzFactor || 0;
  54. let minLine = 0;
  55. if (fuzzFactor < 0 || !Number.isInteger(fuzzFactor)) {
  56. throw new Error('fuzzFactor must be a non-negative integer');
  57. }
  58. // Special case for empty patch.
  59. if (!hunks.length) {
  60. return source;
  61. }
  62. // Before anything else, handle EOFNL insertion/removal. If the patch tells us to make a change
  63. // to the EOFNL that is redundant/impossible - i.e. to remove a newline that's not there, or add a
  64. // newline that already exists - then we either return false and fail to apply the patch (if
  65. // fuzzFactor is 0) or simply ignore the problem and do nothing (if fuzzFactor is >0).
  66. // If we do need to remove/add a newline at EOF, this will always be in the final hunk:
  67. let prevLine = '', removeEOFNL = false, addEOFNL = false;
  68. for (let i = 0; i < hunks[hunks.length - 1].lines.length; i++) {
  69. const line = hunks[hunks.length - 1].lines[i];
  70. if (line[0] == '\\') {
  71. if (prevLine[0] == '+') {
  72. removeEOFNL = true;
  73. }
  74. else if (prevLine[0] == '-') {
  75. addEOFNL = true;
  76. }
  77. }
  78. prevLine = line;
  79. }
  80. if (removeEOFNL) {
  81. if (addEOFNL) {
  82. // This means the final line gets changed but doesn't have a trailing newline in either the
  83. // original or patched version. In that case, we do nothing if fuzzFactor > 0, and if
  84. // fuzzFactor is 0, we simply validate that the source file has no trailing newline.
  85. if (!fuzzFactor && lines[lines.length - 1] == '') {
  86. return false;
  87. }
  88. }
  89. else if (lines[lines.length - 1] == '') {
  90. lines.pop();
  91. }
  92. else if (!fuzzFactor) {
  93. return false;
  94. }
  95. }
  96. else if (addEOFNL) {
  97. if (lines[lines.length - 1] != '') {
  98. lines.push('');
  99. }
  100. else if (!fuzzFactor) {
  101. return false;
  102. }
  103. }
  104. /**
  105. * Checks if the hunk can be made to fit at the provided location with at most `maxErrors`
  106. * insertions, substitutions, or deletions, while ensuring also that:
  107. * - lines deleted in the hunk match exactly, and
  108. * - wherever an insertion operation or block of insertion operations appears in the hunk, the
  109. * immediately preceding and following lines of context match exactly
  110. *
  111. * `toPos` should be set such that lines[toPos] is meant to match hunkLines[0].
  112. *
  113. * If the hunk can be applied, returns an object with properties `oldLineLastI` and
  114. * `replacementLines`. Otherwise, returns null.
  115. */
  116. function applyHunk(hunkLines, toPos, maxErrors, hunkLinesI = 0, lastContextLineMatched = true, patchedLines = [], patchedLinesLength = 0) {
  117. let nConsecutiveOldContextLines = 0;
  118. let nextContextLineMustMatch = false;
  119. for (; hunkLinesI < hunkLines.length; hunkLinesI++) {
  120. const hunkLine = hunkLines[hunkLinesI], operation = (hunkLine.length > 0 ? hunkLine[0] : ' '), content = (hunkLine.length > 0 ? hunkLine.substr(1) : hunkLine);
  121. if (operation === '-') {
  122. if (compareLine(toPos + 1, lines[toPos], operation, content)) {
  123. toPos++;
  124. nConsecutiveOldContextLines = 0;
  125. }
  126. else {
  127. if (!maxErrors || lines[toPos] == null) {
  128. return null;
  129. }
  130. patchedLines[patchedLinesLength] = lines[toPos];
  131. return applyHunk(hunkLines, toPos + 1, maxErrors - 1, hunkLinesI, false, patchedLines, patchedLinesLength + 1);
  132. }
  133. }
  134. if (operation === '+') {
  135. if (!lastContextLineMatched) {
  136. return null;
  137. }
  138. patchedLines[patchedLinesLength] = content;
  139. patchedLinesLength++;
  140. nConsecutiveOldContextLines = 0;
  141. nextContextLineMustMatch = true;
  142. }
  143. if (operation === ' ') {
  144. nConsecutiveOldContextLines++;
  145. patchedLines[patchedLinesLength] = lines[toPos];
  146. if (compareLine(toPos + 1, lines[toPos], operation, content)) {
  147. patchedLinesLength++;
  148. lastContextLineMatched = true;
  149. nextContextLineMustMatch = false;
  150. toPos++;
  151. }
  152. else {
  153. if (nextContextLineMustMatch || !maxErrors) {
  154. return null;
  155. }
  156. // Consider 3 possibilities in sequence:
  157. // 1. lines contains a *substitution* not included in the patch context, or
  158. // 2. lines contains an *insertion* not included in the patch context, or
  159. // 3. lines contains a *deletion* not included in the patch context
  160. // The first two options are of course only possible if the line from lines is non-null -
  161. // i.e. only option 3 is possible if we've overrun the end of the old file.
  162. 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));
  163. }
  164. }
  165. }
  166. // Before returning, trim any unmodified context lines off the end of patchedLines and reduce
  167. // toPos (and thus oldLineLastI) accordingly. This allows later hunks to be applied to a region
  168. // that starts in this hunk's trailing context.
  169. patchedLinesLength -= nConsecutiveOldContextLines;
  170. toPos -= nConsecutiveOldContextLines;
  171. patchedLines.length = patchedLinesLength;
  172. return {
  173. patchedLines,
  174. oldLineLastI: toPos - 1
  175. };
  176. }
  177. const resultLines = [];
  178. // Search best fit offsets for each hunk based on the previous ones
  179. let prevHunkOffset = 0;
  180. for (let i = 0; i < hunks.length; i++) {
  181. const hunk = hunks[i];
  182. let hunkResult;
  183. const maxLine = lines.length - hunk.oldLines + fuzzFactor;
  184. let toPos;
  185. for (let maxErrors = 0; maxErrors <= fuzzFactor; maxErrors++) {
  186. toPos = hunk.oldStart + prevHunkOffset - 1;
  187. const iterator = distanceIterator(toPos, minLine, maxLine);
  188. for (; toPos !== undefined; toPos = iterator()) {
  189. hunkResult = applyHunk(hunk.lines, toPos, maxErrors);
  190. if (hunkResult) {
  191. break;
  192. }
  193. }
  194. if (hunkResult) {
  195. break;
  196. }
  197. }
  198. if (!hunkResult) {
  199. return false;
  200. }
  201. // Copy everything from the end of where we applied the last hunk to the start of this hunk
  202. for (let i = minLine; i < toPos; i++) {
  203. resultLines.push(lines[i]);
  204. }
  205. // Add the lines produced by applying the hunk:
  206. for (let i = 0; i < hunkResult.patchedLines.length; i++) {
  207. const line = hunkResult.patchedLines[i];
  208. resultLines.push(line);
  209. }
  210. // Set lower text limit to end of the current hunk, so next ones don't try
  211. // to fit over already patched text
  212. minLine = hunkResult.oldLineLastI + 1;
  213. // Note the offset between where the patch said the hunk should've applied and where we
  214. // applied it, so we can adjust future hunks accordingly:
  215. prevHunkOffset = toPos + 1 - hunk.oldStart;
  216. }
  217. // Copy over the rest of the lines from the old text
  218. for (let i = minLine; i < lines.length; i++) {
  219. resultLines.push(lines[i]);
  220. }
  221. return resultLines.join('\n');
  222. }
  223. /**
  224. * applies one or more patches.
  225. *
  226. * `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).
  227. *
  228. * 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:
  229. *
  230. * - `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.
  231. * - `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.
  232. *
  233. * Once all patches have been applied or an error occurs, the `options.complete(err)` callback is made.
  234. */
  235. export function applyPatches(uniDiff, options) {
  236. const spDiff = typeof uniDiff === 'string' ? parsePatch(uniDiff) : uniDiff;
  237. let currentIndex = 0;
  238. function processIndex() {
  239. const index = spDiff[currentIndex++];
  240. if (!index) {
  241. return options.complete();
  242. }
  243. options.loadFile(index, function (err, data) {
  244. if (err) {
  245. return options.complete(err);
  246. }
  247. const updatedContent = applyPatch(data, index, options);
  248. options.patched(index, updatedContent, function (err) {
  249. if (err) {
  250. return options.complete(err);
  251. }
  252. processIndex();
  253. });
  254. });
  255. }
  256. processIndex();
  257. }