com.google.javascript.jscomp.deps.JsFunctionParser Maven / Gradle / Ivy

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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

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/*
 * Copyright 2008 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.javascript.jscomp.deps;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.CharMatcher;
import com.google.javascript.jscomp.ErrorManager;

import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collection;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * A parser that can extract dependency information from a .js file.
 *
 * @author [email protected] (Andrew Grieve)
 */
@GwtIncompatible("java.util.regex")
public final class JsFunctionParser extends JsFileLineParser {

  public static class SymbolInfo {
    public final String functionName;
    public final String symbol;

    private SymbolInfo(String functionName, String symbol) {
      this.functionName = functionName;
      this.symbol = symbol;
    }
  }

  private static Logger logger =
      Logger.getLogger(JsFunctionParser.class.getName());

  /** Pattern for matching functions. */
  private Pattern pattern;

  /** Matcher used in the parsing. */
  private Matcher matcher;

  /** Symbols parsed. */
  private Collection symbols;

  /** Functions to parse */
  private Collection functionsToParse;

  /**
   * Constructor
   *
   * @param functions Functions to parse.
   * @param errorManager Handles parse errors.
   */
  public JsFunctionParser(
      Collection functions, ErrorManager errorManager) {
    super(errorManager);
    functionsToParse = functions;
    pattern = getPattern(functions);
    matcher = pattern.matcher("");
  }

  /**
   * Constructs a pattern to extract the arguments of the given functions.
   *
   * @param functions Functions to parse.
   * @return A pattern to extract {@code functions}' arguments.
   */
  private static Pattern getPattern(Collection functions) {
    StringBuilder sb = new StringBuilder("(?:^|;)\\s*(");

    for (String function : functions) {
      sb.append(Pattern.quote(function)).append("|");
    }

    // remove last '|'
    sb.deleteCharAt(sb.length() - 1);
    sb.append(")\\s*\\((.*?)\\)");

    return Pattern.compile(sb.toString());
  }

  /**
   * Parses the given file and returns the dependency information that it
   * contained.
   *
   * @param filePath Path to the file to parse.
   * @param fileContents The contents to parse.
   * @return A collection containing all symbols found in the
   *     file.
   */
  public Collection parseFile(
      String filePath, String fileContents) {
    return parseReader(filePath, new StringReader(fileContents));
  }

  private Collection parseReader(
      String filePath, Reader fileContents) {
    symbols = new ArrayList<>();

    logger.fine("Parsing Source: " + filePath);
    doParse(filePath, fileContents);

    return symbols;
  }

  /**
   * Parses a line of JavaScript, extracting dependency information.
   */
  @Override
  protected boolean parseLine(String line) throws ParseException {
    boolean hasFunctions = false;
    boolean parseLine = false;

    // Quick sanity check that will catch most cases. This is a performance
    // win for people with a lot of JS.
    for (String function : functionsToParse) {
      if (line.contains(function)) {
        parseLine = true;
        break;
      }
    }

    if (parseLine) {
      matcher.reset(line);
      while (matcher.find()) {
        hasFunctions = true;
        String functionName = matcher.group(1);
        String arg = parseJsString(matcher.group(2)); // Parse the param.
        symbols.add(new SymbolInfo(functionName, arg));
      }
    }

    return !shortcutMode || hasFunctions ||
        CharMatcher.whitespace().matchesAllOf(line);
  }
}