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 {{diffRows: !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,
+ *  token: function(!CodeMirror.StringStream, !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 diffRows = parserConfig.diffRows;
+  var baselineLines = parserConfig.baselineLines;
+  var currentLines = parserConfig.currentLines;
+  var syntaxHighlightMode = CodeMirror.getMode({}, parserConfig.mimeType);
+
+  /**
+   * @param {!Changes.ChangesHighlighter.DiffState} state
+   * @param {number} baselineLineNumber
+   * @param {number} currentLineNumber
+   */
+  function fastForward(state, baselineLineNumber, currentLineNumber) {
+    if (baselineLineNumber > state.baselineLineNumber) {
+      fastForwardSyntaxHighlighter(state.baselineSyntaxState, state.baselineLineNumber, baselineLineNumber, baselineLines);
+      state.baselineLineNumber = baselineLineNumber;
+    }
+    if (currentLineNumber > state.currentLineNumber) {
+      fastForwardSyntaxHighlighter(state.currentSyntaxState, state.currentLineNumber, currentLineNumber, currentLines);
+      state.currentLineNumber = currentLineNumber;
+    }
+  }
+
+  /**
+   * @param {!Object} syntaxState
+   * @param {number} from
+   * @param {number} to
+   * @param {!Array<string>} lines
+   */
+  function fastForwardSyntaxHighlighter(syntaxState, from, to, lines) {
+    var lineNumber = from;
+    while (lineNumber < to && lineNumber < lines.length) {
+      var stream = new CodeMirror.StringStream(lines[lineNumber]);
+      if (stream.eol() && syntaxHighlightMode.blankLine)
+        syntaxHighlightMode.blankLine(syntaxState);
+      while (!stream.eol()) {
+        syntaxHighlightMode.token(stream, syntaxState);
+        stream.start = stream.pos;
+      }
+      lineNumber++;
+    }
+  }
 
   return {
     /**
      * @return {!Changes.ChangesHighlighter.DiffState}
      */
     startState: function() {
-      return {lineNumber: 0, index: 0};
+      return {
+        rowNumber: 0,
+        diffTokenIndex: 0,
+        currentLineNumber: 0,
+        baselineLineNumber: 0,
+        currentSyntaxState: CodeMirror.startState(syntaxHighlightMode),
+        baselineSyntaxState: CodeMirror.startState(syntaxHighlightMode),
+        syntaxPosition: 0,
+        diffPosition: 0,
+        syntaxStyle: '',
+        diffStyle: ''
+      };
     },
 
     /**
-     * @param {!{next: function()}} stream
+     * @param {!CodeMirror.StringStream} stream
      * @param {!Changes.ChangesHighlighter.DiffState} state
      * @return {string}
      */
     token: function(stream, state) {
-      var row = rows[state.lineNumber];
-      if (!row) {
+      var diffRow = diffRows[state.rowNumber];
+      if (!diffRow) {
         stream.next();
         return '';
       }
+      fastForward(state, diffRow.baselineLineNumber - 1, diffRow.currentLineNumber - 1);
       var classes = '';
-      if (state.index === 0)
-        classes += ' line-background-' + row.type + ' line-' + row.type;
-      stream.pos += row.content[state.index].text.length;
-      classes += ' ' + row.content[state.index].className;
-      state.index++;
-      if (state.index >= row.content.length) {
-        state.lineNumber++;
-        state.index = 0;
+      if (stream.pos === 0)
+        classes += ' line-background-' + diffRow.type + ' line-' + diffRow.type;
+
+      var syntaxHighlighterNeedsRefresh = state.diffPosition >= state.syntaxPosition;
+      if (state.diffPosition <= state.syntaxPosition) {
+        state.diffPosition += diffRow.tokens[state.diffTokenIndex].text.length;
+        state.diffStyle = diffRow.tokens[state.diffTokenIndex].className;
+        state.diffTokenIndex++;
+      }
+
+      if (syntaxHighlighterNeedsRefresh) {
+        if (diffRow.type === Changes.ChangesView.RowType.Deletion || diffRow.type === Changes.ChangesView.RowType.Addition ||
+            diffRow.type === Changes.ChangesView.RowType.Equal) {
+          state.syntaxStyle = syntaxHighlightMode.token(
+              stream, diffRow.type === Changes.ChangesView.RowType.Deletion ? state.baselineSyntaxState : state.currentSyntaxState);
+          state.syntaxPosition = stream.pos;
+        } else {
+          state.syntaxStyle = '';
+          state.syntaxPosition = Infinity;
+        }
+      }
+
+      stream.pos = Math.min(state.syntaxPosition, state.diffPosition);
+      classes += ' ' + state.syntaxStyle;
+      classes += ' ' + state.diffStyle;
+
+      if (stream.eol()) {
+        state.rowNumber++;
+        if (diffRow.type === Changes.ChangesView.RowType.Deletion)
+          state.baselineLineNumber++;
+        else
+          state.currentLineNumber++;
+        state.diffPosition = 0;
+        state.syntaxPosition = 0;
+        state.diffTokenIndex = 0;
       }
       return classes;
     },
 
     /**
      * @param {!Changes.ChangesHighlighter.DiffState} state
      * @return {string}
      */
     blankLine: function(state) {
-      var row = rows[state.lineNumber];
-      state.lineNumber++;
-      state.index = 0;
-      if (!row)
+      var diffRow = diffRows[state.rowNumber];
+      state.rowNumber++;
+      state.syntaxPosition = 0;
+      state.diffPosition = 0;
+      state.diffTokenIndex = 0;
+      if (!diffRow)
         return '';
-      return 'line-background-' + row.type + ' line-' + row.type;
+
+      var style = '';
+      if (syntaxHighlightMode.blankLine) {
+        if (diffRow.type === Changes.ChangesView.RowType.Equal || diffRow.type === Changes.ChangesView.RowType.Addition) {
+          style = syntaxHighlightMode.blankLine(state.currentSyntaxState);
+          state.currentLineNumber++;
+        } else if (diffRow.type === Changes.ChangesView.RowType.Deletion) {
+          style = syntaxHighlightMode.blankLine(state.baselineSyntaxState);
+          state.baselineLineNumber++;
+        }
+      }
+      return style + ' line-background-' + diffRow.type + ' line-' + diffRow.type;
+    },
+
+    /**
+     * @param {!Changes.ChangesHighlighter.DiffState} state
+     * @return {!Changes.ChangesHighlighter.DiffState}
+     */
+    copyState: function(state) {
+      var newState = Object.assign({}, state);
+      newState.currentSyntaxState = CodeMirror.copyState(syntaxHighlightMode, state.currentSyntaxState);
+      newState.baselineSyntaxState = CodeMirror.copyState(syntaxHighlightMode, state.baselineSyntaxState);
+      return /** @type {!Changes.ChangesHighlighter.DiffState} */ (newState);
     }
   };
 };
 
-/** @typedef {!{lineNumber: number, index: number}} */
+/**
+ * @typedef {!{
+ *  rowNumber: number,
+ *  diffTokenIndex: number,
+ *  currentLineNumber: number,
+ *  baselineLineNumber: number,
+ *  currentSyntaxState: !Object,
+ *  baselineSyntaxState: !Object,
+ *  syntaxPosition: number,
+ *  diffPosition: number,
+ *  syntaxStyle: string,
+ *  diffStyle: string
+ * }}
+ */
 Changes.ChangesHighlighter.DiffState;
 
 CodeMirror.defineMode('devtools-diff', Changes.ChangesHighlighter);