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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. This binary checks for style issues such as incorrect or missing JSDoc usage, and missing goog.require() statements. It does not do more advanced checks such as typechecking.

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/*
 * Copyright 2016 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;

import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.javascript.rhino.Node;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;

/** A class to get a raw and gzip'ed size estimate; it doesn't generate code. */
final class PerformanceTrackerCodeSizeEstimator extends CodeConsumer {
  private int size = 0;
  private char lastChar = '\0';
  private final ByteArrayOutputStream output;
  private final GZIPOutputStream stream;
  private final boolean trackGzSize;

  static PerformanceTrackerCodeSizeEstimator estimate(Node jsRoot, boolean trackGzSize) {
    PerformanceTrackerCodeSizeEstimator estimator = new PerformanceTrackerCodeSizeEstimator(
        trackGzSize);
    CodeGenerator.forCostEstimation(estimator).add(jsRoot);
    return estimator;
  }

  private PerformanceTrackerCodeSizeEstimator(boolean trackGzSize) {
    this.trackGzSize = trackGzSize;
    if (trackGzSize) {
      try {
        output = new ByteArrayOutputStream();
        stream = new GZIPOutputStream(output);
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    } else {
      output = null;
      stream = null;
    }
  }

  @Override
  void append(String str) {
    int len = str.length();
    if (len > 0) {
      size += len;
      lastChar = str.charAt(len - 1);
      if (trackGzSize) {
        try {
          stream.write(str.getBytes(UTF_8));
        } catch (IOException e) {
          throw new RuntimeException(e);
        }
      }
    }
  }

  @Override
  char getLastChar() {
    return lastChar;
  }

  int getCodeSize() {
    return size;
  }

  int getZippedCodeSize() {
    if (trackGzSize) {
      try {
        stream.finish();
        stream.close();
        return output.size();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
    } else {
      return 0;
    }
  }
}