front_end/text_editor/SyntaxHighlighter.ts

// Copyright 2021 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.

/* eslint-disable rulesdir/no_underscored_properties */

import * as TextUtils from '../text_utils/text_utils.js';
import * as UI from '../ui/legacy/legacy.js';

export class SyntaxHighlighter {
  _mimeType: string;
  _stripExtraWhitespace: boolean;

  constructor(mimeType: string, stripExtraWhitespace: boolean) {
    this._mimeType = mimeType;
    this._stripExtraWhitespace = stripExtraWhitespace;
  }

  createSpan(content: string, className: string): Element {
    const span = document.createElement('span');
    span.className = className.replace(/\S+/g, 'cm-$&');
    if (this._stripExtraWhitespace && className !== 'whitespace') {
      content = content.replace(/^[\n\r]*/, '').replace(/\s*$/, '');
    }
    UI.UIUtils.createTextChild(span, content);
    return span;
  }

  syntaxHighlightNode(node: Element): Promise<void> {
    const lines = node.textContent ? node.textContent.split('\n') : [];
    let plainTextStart: number;
    let line: string;

    node.removeChildren();
    const tokenize = TextUtils.CodeMirrorUtils.TokenizerFactory.instance().createTokenizer(this._mimeType);
    for (let i = 0; i < lines.length; ++i) {
      line = lines[i];
      plainTextStart = 0;
      tokenize(line, processToken.bind(this));
      if (plainTextStart < line.length) {
        const plainText = line.substring(plainTextStart, line.length);
        UI.UIUtils.createTextChild(node, plainText);
      }
      if (i < lines.length - 1) {
        UI.UIUtils.createTextChild(node, '\n');
      }
    }
    return Promise.resolve();

    function processToken(
        this: SyntaxHighlighter, token: string, tokenType: string|null, column: number, newColumn: number): void {
      if (!tokenType) {
        return;
      }

      if (column > plainTextStart) {
        const plainText = line.substring(plainTextStart, column);
        UI.UIUtils.createTextChild(node, plainText);
      }
      node.appendChild(this.createSpan(token, tokenType));
      plainTextStart = newColumn;
    }
  }
}