DevTools: Add syntax highlighting to ChangesView

third_party/WebKit/Source/devtools/front_end/changes/ChangesHighlighter.js

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @param {!Object} config
- * @param {{rows: !Array<!Changes.ChangesView.Row>}} parserConfig
+ * @param {{rows: !Array<!Changes.ChangesView.Row>, baselineLines: !Array<string>, currentLines: !Array<string>, mimeType: string}} parserConfig
  * @return {{
  *  startState: function():!Changes.ChangesHighlighter.DiffState,
  *  token: function({next: function()}, !Changes.ChangesHighlighter.DiffState):string,
  *  blankLine: function(!Changes.ChangesHighlighter.DiffState):string,
+ *  copyState: function(!Changes.ChangesHighlighter.DiffState):Changes.ChangesHighlighter.DiffState
  * }}
  */
 Changes.ChangesHighlighter = function(config, parserConfig) {
   var rows = parserConfig.rows;
+  var baselineLines = parserConfig.baselineLines;
+  var currentLines = parserConfig.currentLines;
+  var innerMode = CodeMirror.getMode({}, parserConfig.mimeType);
+
+  /**
+   * @param {!Changes.ChangesHighlighter.DiffState} state
+   * @param {number} baselineLineNumber
+   * @param {number} currentLineNumber
+   */
+  function fastForward(state, baselineLineNumber, currentLineNumber) {
+    if (baselineLineNumber > state.baselineLineNumber) {
+      fastForwardState(state.baselineState, state.baselineLineNumber, baselineLineNumber, baselineLines);
+      state.baselineLineNumber = baselineLineNumber;
+    }
+    if (currentLineNumber > state.currentLineNumber) {
+      fastForwardState(state.currentState, state.currentLineNumber, currentLineNumber, currentLines);
+      state.currentLineNumber = currentLineNumber;
+    }
+  }
+
+  /**
+   * @param {!Object} state
+   * @param {number} from
+   * @param {number} to
+   * @param {!Array<string>} lines
+   */
+  function fastForwardState(state, from, to, lines) {
+    var lineNumber = from;
+    while (lineNumber < to && lineNumber < lines.length) {
+      var stream = new CodeMirror.StringStream(lines[lineNumber]);
+      while (!stream.eol()) {
+        innerMode.token(stream, state);
+        stream.start = stream.pos;
+      }
+      lineNumber++;

[luoe, 2017/03/30 01:10:39]

Joel: Handle blank lines

[einbinder, 2017/03/30 02:22:44]

Done.

+    }
+  }
 
   return {
     /**
      * @return {!Changes.ChangesHighlighter.DiffState}
      */
     startState: function() {
-      return {lineNumber: 0, index: 0};
+      return {
+        lineNumber: 0,
+        index: 0,
+        currentLineNumber: 0,
+        baselineLineNumber: 0,
+        currentState: CodeMirror.startState(innerMode),
+        baselineState: CodeMirror.startState(innerMode),
+        mismatch: 0
+      };
     },
 
     /**
      * @param {!{next: function()}} stream
      * @param {!Changes.ChangesHighlighter.DiffState} state
      * @return {string}
      */
     token: function(stream, state) {
       var row = rows[state.lineNumber];
       if (!row) {
         stream.next();
         return '';
       }
+      fastForward(state, row.baselineLineNumber - 1, row.currentLineNumber - 1);

[luoe, 2017/03/30 01:10:39]

Joel: 0 indexed

[einbinder, 2017/03/30 02:22:43]

I misread, it is good the way it is.

       var classes = '';
       if (state.index === 0)
         classes += ' line-background-' + row.type + ' line-' + row.type;
-      stream.pos += row.content[state.index].text.length;
+      var chars = row.content[state.index].text.length;
+      if (state.mismatch > 0)

[luoe, 2017/03/30 01:10:40]

Replace mismatch with state.diffPos > state.syntaxPos

[einbinder, 2017/03/30 02:22:44]

Done.

+        chars = state.mismatch;
+      var pos = stream.pos;
+      var innerStyle = state.lastInnerStyle;
+      var innerPos = pos - state.mismatch;

[luoe, 2017/03/30 01:10:39]

Proposed names:
chars => diffPos
innerPos => syntaxPos

[einbinder, 2017/03/30 02:22:43]

Done.

+      if (state.mismatch >= 0) {
+        if (row.type === Changes.ChangesView.RowType.Deletion || row.type === Changes.ChangesView.RowType.Addition ||
+            row.type === Changes.ChangesView.RowType.Equal) {
+          innerStyle = innerMode.token(
+              stream, row.type === Changes.ChangesView.RowType.Deletion ? state.baselineState : state.currentState);
+          innerPos = stream.pos;
+        } else {
+          innerStyle = '';
+          innerPos = pos + chars;
+        }
+      }
+      stream.pos = Math.min(innerPos, pos + chars);
+      if (innerStyle)
+        classes += ' ' + innerStyle;
       classes += ' ' + row.content[state.index].className;
-      state.index++;
+      state.mismatch = pos + chars - innerPos;
+      if (state.mismatch <= 0) {
+        state.index++;

[luoe, 2017/03/30 01:10:39]

diffTokenIndex?

Perhaps consider moving the ` if (state.mismatch >= 0)` next to `if
(state.mismatch <= 0)`

[einbinder, 2017/03/30 02:22:43]

Done.

+        state.lastInnerStyle = innerStyle;
+      }
       if (state.index >= row.content.length) {
         state.lineNumber++;
+        if (row.type === Changes.ChangesView.RowType.Deletion)
+          state.baselineLineNumber++;
+        else
+          state.currentLineNumber++;

[luoe, 2017/03/30 01:10:39]

Spacers don't need to increment this?

[einbinder, 2017/03/30 02:22:43]

Done.

         state.index = 0;
       }
       return classes;
     },
 
     /**
      * @param {!Changes.ChangesHighlighter.DiffState} state
      * @return {string}
      */
     blankLine: function(state) {
       var row = rows[state.lineNumber];
       state.lineNumber++;
+      state.mismatch = 0;
       state.index = 0;
       if (!row)
         return '';
-      return 'line-background-' + row.type + ' line-' + row.type;
+      if (row.type === Changes.ChangesView.RowType.Deletion)
+        state.baselineLineNumber++;
+      else
+        state.currentLineNumber++;
+      var style = '';
+      if (innerMode.blankLine) {
+        style = innerMode.blankLine(
+            row.type === Changes.ChangesView.RowType.Deletion ? state.baselineState : state.currentState);
+      }
+      return style + ' line-background-' + row.type + ' line-' + row.type;
+    },
+
+    /**
+     * @param {!Changes.ChangesHighlighter.DiffState} state
+     * @return {!Changes.ChangesHighlighter.DiffState}
+     */
+    copyState: function(state) {
+      var newState = /** @type {!Changes.ChangesHighlighter.DiffState} */ ({});
+      for (var i in state)
+        newState[i] = state[i];
+      newState.currentState = CodeMirror.copyState(innerMode, state.currentState);
+      newState.baselineState = CodeMirror.copyState(innerMode, state.baselineState);
+      return newState;
     }
   };
 };
 
 /** @typedef {!{lineNumber: number, index: number}} */
 Changes.ChangesHighlighter.DiffState;
 
 CodeMirror.defineMode('devtools-diff', Changes.ChangesHighlighter);