front_end/models/text_utils/CodeMirrorUtils.ts

/*
 * Copyright (C) 2022 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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import * as CodeMirror from '../../third_party/codemirror.next/codemirror.next.js';
type Tokenizer = (line: string, callback: (value: string, style: string|null) => void) => void;

export function createCssTokenizer(): Tokenizer {
  async function tokenize(line: string, callback: (value: string, style: string|null) => void): Promise<void> {
    const streamParser = await CodeMirror.cssStreamParser();
    const stream = new CodeMirror.StringStream();
    stream.string = line;

    const startState = streamParser.startState();
    let lastPos = stream.pos;
    while (!stream.eol()) {
      const token = streamParser.token(stream, startState);
      const segment = stream.current().substring(lastPos, stream.pos);
      callback(segment, token);
      lastPos = stream.pos;
    }
  }
  return tokenize;
}