com.google.debugging.sourcemap.SourceMapObjectParser Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of closure-compiler-unshaded Show documentation

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.

There is a newer version: v20240317

Show newest version

/*
 * 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.debugging.sourcemap;

import com.google.common.collect.ImmutableList;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonNull;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import org.jspecify.nullness.Nullable;

/**
 * Java implementation of the source map parser.
 */
public class SourceMapObjectParser {
  // Gson objects are safe to share across threads and are somewhat expensive to construct. Use a
  // single instance.  This is Safe per gson docs:
  // https://google.github.io/gson/apidocs/com/google/gson/Gson.html
  private static final Gson gson = new Gson();

  public static SourceMapObject parse(String contents) throws SourceMapParseException {

    SourceMapObject.Builder builder = SourceMapObject.builder();

    try {
      JsonObject sourceMapRoot = gson.fromJson(contents, JsonObject.class);

      builder.setVersion(sourceMapRoot.get("version").getAsInt());
      builder.setFile(getStringOrNull(sourceMapRoot, "file"));
      builder.setLineCount(
          sourceMapRoot.has("lineCount") ? sourceMapRoot.get("lineCount").getAsInt() : -1);
      builder.setMappings(getStringOrNull(sourceMapRoot, "mappings"));
      builder.setSourceRoot(getStringOrNull(sourceMapRoot, "sourceRoot"));

      if (sourceMapRoot.has("sections")) {
        ImmutableList.Builder listBuilder = ImmutableList.builder();
        for (JsonElement each : sourceMapRoot.get("sections").getAsJsonArray()) {
          listBuilder.add(buildSection(each.getAsJsonObject()));
        }
        builder.setSections(listBuilder.build());
      }

      builder.setSources(getJavaStringArray(sourceMapRoot.get("sources")));
      builder.setSourcesContent(getJavaStringArray(sourceMapRoot.get("sourcesContent")));
      builder.setNames(getJavaStringArray(sourceMapRoot.get("names")));

      Map extensions = new LinkedHashMap<>();
      for (Map.Entry entry : sourceMapRoot.entrySet()) {
        if (entry.getKey().startsWith("x_")) {
          extensions.put(entry.getKey(), entry.getValue());
        }
      }
      builder.setExtensions(Collections.unmodifiableMap(extensions));

    } catch (JsonParseException ex) {
      throw new SourceMapParseException("JSON parse exception: " + ex);
    }

    return builder.build();
  }

  private static SourceMapSection buildSection(JsonObject section) throws SourceMapParseException {
    JsonObject offset = section.get("offset").getAsJsonObject();
    int line = offset.get("line").getAsInt();
    int column = offset.get("column").getAsInt();

    if (section.has("map") && section.has("url")) {
      throw new SourceMapParseException(
          "Invalid map format: section may not have both 'map' and 'url'");
    } else if (section.has("url")) {
      return SourceMapSection.forURL(section.get("url").getAsString(), line, column);
    } else if (section.has("map")) {
      return SourceMapSection.forMap(section.get("map").toString(), line, column);
    }

    throw new SourceMapParseException(
        "Invalid map format: section must have either 'map' or 'url'");
  }

  private static @Nullable String getStringOrNull(JsonObject object, String key) {
    return object.has(key) ? object.get(key).getAsString() : null;
  }

  private static String @Nullable [] getJavaStringArray(JsonElement element) {
    if (element == null || element instanceof JsonNull) {
      return null;
    }
    JsonArray array = element.getAsJsonArray();
    int len = array.size();
    String[] result = new String[len];
    for (int i = 0; i < len; i++) {
      JsonElement item = array.get(i);
      result[i] = item.isJsonNull() ? null : item.getAsString();
    }
    return result;
  }

  private SourceMapObjectParser() {}
}