Implement patch parser

kpdecker · kpdecker · commit 532bcf9315a3 · 2015-08-08T13:40:47.000-05:00
This provides better support of multiple indexes, etc and will allow for multi-file patching.
diff --git a/src/index.js b/src/index.js
@@ -24,6 +24,7 @@ import {diffCss} from './diff/css';
 import {diffJson, canonicalize} from './diff/json';
 
 import {applyPatch} from './patch/apply';
+import {parsePatch} from './patch/parse';
 import {structuredPatch, createTwoFilesPatch, createPatch} from './patch/create';
 
 import {convertChangesToDMP} from './convert/dmp';
@@ -46,6 +47,7 @@ export {
   createTwoFilesPatch,
   createPatch,
   applyPatch,
+  parsePatch,
   convertChangesToDMP,
   convertChangesToXML,
   canonicalize
diff --git a/src/patch/parse.js b/src/patch/parse.js
@@ -0,0 +1,128 @@
+export function parsePatch(uniDiff, options = {}) {
+  let diffstr = uniDiff.split('\n'),
+      list = [],
+      i = 0;
+
+  function parseIndex() {
+    let index = {};
+    list.push(index);
+
+    let header = (/^Index: (.*)/.exec(diffstr[i]));
+    if (header) {
+      index.index = header[1];
+      i++;
+
+      if (/^===/.test(diffstr[i])) {
+        i++;
+      }
+
+      parseFileHeader(index);
+      parseFileHeader(index);
+    } else {
+      // Ignore erant header components that might occur at the start of the file
+      parseFileHeader({});
+      parseFileHeader({});
+    }
+
+    index.hunks = [];
+
+    while (i < diffstr.length) {
+      if (/^Index:/.test(diffstr[i])) {
+        break;
+      } else if (/^@@/.test(diffstr[i])) {
+        index.hunks.push(parseHunk(index));
+      } else if (!diffstr[i]) {
+        i++;
+      } else {
+        throw new Error('Unknown line ' + (i + 1) + ' ' + JSON.stringify(diffstr[i]));
+      }
+    }
+  }
+
+  // Parses the --- and +++ headers, if none are found, no lines
+  // are consumed.
+  function parseFileHeader(index) {
+    let fileHeader = (/^(\-\-\-|\+\+\+)\s(\S+)\s?(.*)/.exec(diffstr[i]));
+    if (fileHeader) {
+      index[fileHeader[1] === '---' ? 'from' : 'to'] = {
+        file: fileHeader[2],
+        header: fileHeader[3]
+      };
+      i++;
+    }
+  }
+
+  // Parses a hunk
+  // This assumes that we are at the start of a hunk.
+  function parseHunk(index) {
+    let chunkHeaderIndex = i,
+        chunkHeaderLine = diffstr[i++],
+        chunkHeader = chunkHeaderLine.split(/@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@/);
+
+    let hunk = {
+      from: {
+        line: +chunkHeader[1],
+        count: +chunkHeader[2] || 1
+      },
+      to: {
+        line: +chunkHeader[3],
+        count: +chunkHeader[4] || 1
+      },
+      lines: []
+    };
+
+    let addCount = 0,
+        removeCount = 0;
+    for (; i < diffstr.length; i++) {
+      let operation = diffstr[i][0],
+          content = diffstr[i].substr(1);
+
+      if (operation === '+' || operation === '-' || operation === ' ') {
+        hunk.lines.push({operation, content});
+
+        if (operation === '+') {
+          addCount++;
+        } else if (operation === '-') {
+          removeCount++;
+        } else {
+          addCount++;
+          removeCount++;
+        }
+      } else if (operation === '\\') {
+        if (diffstr[i - 1][0] === '+') {
+          index.removeEOFNL = true;
+        } else if (diffstr[i - 1][0] === '-') {
+          index.addEOFNL = true;
+        }
+      } else {
+        break;
+      }
+    }
+
+    // Handle the empty block count case
+    if (!addCount && hunk.to.count === 1) {
+      hunk.to.count = 0;
+    }
+    if (!removeCount && hunk.from.count === 1) {
+      hunk.from.count = 0;
+    }
+
+    // Perform optional sanity checking
+    if (options.strict) {
+      if (addCount !== hunk.to.count) {
+        throw new Error('Added line count did not match for hunk at line ' + (chunkHeaderIndex + 1));
+      }
+      if (removeCount !== hunk.from.count) {
+        throw new Error('Removed line count did not match for hunk at line ' + (chunkHeaderIndex + 1));
+      }
+    }
+
+    return hunk;
+  }
+
+  while (i < diffstr.length) {
+    parseIndex();
+  }
+
+  return list;
+}
diff --git a/test/patch/parse.js b/test/patch/parse.js
