source-map-generator.js 13.5 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413
/* -*- Mode: js; js-indent-level: 2; -*- */
/*
 * Copyright 2011 Mozilla Foundation and contributors
 * Licensed under the New BSD license. See LICENSE or:
 * http://opensource.org/licenses/BSD-3-Clause
 */

const base64VLQ = require("./base64-vlq");
const util = require("./util");
const ArraySet = require("./array-set").ArraySet;
const MappingList = require("./mapping-list").MappingList;

/**
 * An instance of the SourceMapGenerator represents a source map which is
 * being built incrementally. You may pass an object with the following
 * properties:
 *
 *   - file: The filename of the generated source.
 *   - sourceRoot: A root for all relative URLs in this source map.
 */
class SourceMapGenerator {
  constructor(aArgs) {
    if (!aArgs) {
      aArgs = {};
    }
    this._file = util.getArg(aArgs, "file", null);
    this._sourceRoot = util.getArg(aArgs, "sourceRoot", null);
    this._skipValidation = util.getArg(aArgs, "skipValidation", false);
    this._sources = new ArraySet();
    this._names = new ArraySet();
    this._mappings = new MappingList();
    this._sourcesContents = null;
  }

  /**
   * Creates a new SourceMapGenerator based on a SourceMapConsumer
   *
   * @param aSourceMapConsumer The SourceMap.
   */
  static fromSourceMap(aSourceMapConsumer) {
    const sourceRoot = aSourceMapConsumer.sourceRoot;
    const generator = new SourceMapGenerator({
      file: aSourceMapConsumer.file,
      sourceRoot
    });
    aSourceMapConsumer.eachMapping(function(mapping) {
      const newMapping = {
        generated: {
          line: mapping.generatedLine,
          column: mapping.generatedColumn
        }
      };

      if (mapping.source != null) {
        newMapping.source = mapping.source;
        if (sourceRoot != null) {
          newMapping.source = util.relative(sourceRoot, newMapping.source);
        }

        newMapping.original = {
          line: mapping.originalLine,
          column: mapping.originalColumn
        };

        if (mapping.name != null) {
          newMapping.name = mapping.name;
        }
      }

      generator.addMapping(newMapping);
    });
    aSourceMapConsumer.sources.forEach(function(sourceFile) {
      let sourceRelative = sourceFile;
      if (sourceRoot !== null) {
        sourceRelative = util.relative(sourceRoot, sourceFile);
      }

      if (!generator._sources.has(sourceRelative)) {
        generator._sources.add(sourceRelative);
      }

      const content = aSourceMapConsumer.sourceContentFor(sourceFile);
      if (content != null) {
        generator.setSourceContent(sourceFile, content);
      }
    });
    return generator;
  }

  /**
   * Add a single mapping from original source line and column to the generated
   * source's line and column for this source map being created. The mapping
   * object should have the following properties:
   *
   *   - generated: An object with the generated line and column positions.
   *   - original: An object with the original line and column positions.
   *   - source: The original source file (relative to the sourceRoot).
   *   - name: An optional original token name for this mapping.
   */
  addMapping(aArgs) {
    const generated = util.getArg(aArgs, "generated");
    const original = util.getArg(aArgs, "original", null);
    let source = util.getArg(aArgs, "source", null);
    let name = util.getArg(aArgs, "name", null);

    if (!this._skipValidation) {
      this._validateMapping(generated, original, source, name);
    }

    if (source != null) {
      source = String(source);
      if (!this._sources.has(source)) {
        this._sources.add(source);
      }
    }

    if (name != null) {
      name = String(name);
      if (!this._names.has(name)) {
        this._names.add(name);
      }
    }

    this._mappings.add({
      generatedLine: generated.line,
      generatedColumn: generated.column,
      originalLine: original != null && original.line,
      originalColumn: original != null && original.column,
      source,
      name
    });
  }

  /**
   * Set the source content for a source file.
   */
  setSourceContent(aSourceFile, aSourceContent) {
    let source = aSourceFile;
    if (this._sourceRoot != null) {
      source = util.relative(this._sourceRoot, source);
    }

    if (aSourceContent != null) {
      // Add the source content to the _sourcesContents map.
      // Create a new _sourcesContents map if the property is null.
      if (!this._sourcesContents) {
        this._sourcesContents = Object.create(null);
      }
      this._sourcesContents[util.toSetString(source)] = aSourceContent;
    } else if (this._sourcesContents) {
      // Remove the source file from the _sourcesContents map.
      // If the _sourcesContents map is empty, set the property to null.
      delete this._sourcesContents[util.toSetString(source)];
      if (Object.keys(this._sourcesContents).length === 0) {
        this._sourcesContents = null;
      }
    }
  }

  /**
   * Applies the mappings of a sub-source-map for a specific source file to the
   * source map being generated. Each mapping to the supplied source file is
   * rewritten using the supplied source map. Note: The resolution for the
   * resulting mappings is the minimium of this map and the supplied map.
   *
   * @param aSourceMapConsumer The source map to be applied.
   * @param aSourceFile Optional. The filename of the source file.
   *        If omitted, SourceMapConsumer's file property will be used.
   * @param aSourceMapPath Optional. The dirname of the path to the source map
   *        to be applied. If relative, it is relative to the SourceMapConsumer.
   *        This parameter is needed when the two source maps aren't in the same
   *        directory, and the source map to be applied contains relative source
   *        paths. If so, those relative source paths need to be rewritten
   *        relative to the SourceMapGenerator.
   */
  applySourceMap(aSourceMapConsumer, aSourceFile, aSourceMapPath) {
    let sourceFile = aSourceFile;
    // If aSourceFile is omitted, we will use the file property of the SourceMap
    if (aSourceFile == null) {
      if (aSourceMapConsumer.file == null) {
        throw new Error(
          "SourceMapGenerator.prototype.applySourceMap requires either an explicit source file, " +
          'or the source map\'s "file" property. Both were omitted.'
        );
      }
      sourceFile = aSourceMapConsumer.file;
    }
    const sourceRoot = this._sourceRoot;
    // Make "sourceFile" relative if an absolute Url is passed.
    if (sourceRoot != null) {
      sourceFile = util.relative(sourceRoot, sourceFile);
    }
    // Applying the SourceMap can add and remove items from the sources and
    // the names array.
    const newSources = this._mappings.toArray().length > 0
      ? new ArraySet()
      : this._sources;
    const newNames = new ArraySet();

    // Find mappings for the "sourceFile"
    this._mappings.unsortedForEach(function(mapping) {
      if (mapping.source === sourceFile && mapping.originalLine != null) {
        // Check if it can be mapped by the source map, then update the mapping.
        const original = aSourceMapConsumer.originalPositionFor({
          line: mapping.originalLine,
          column: mapping.originalColumn
        });
        if (original.source != null) {
          // Copy mapping
          mapping.source = original.source;
          if (aSourceMapPath != null) {
            mapping.source = util.join(aSourceMapPath, mapping.source);
          }
          if (sourceRoot != null) {
            mapping.source = util.relative(sourceRoot, mapping.source);
          }
          mapping.originalLine = original.line;
          mapping.originalColumn = original.column;
          if (original.name != null) {
            mapping.name = original.name;
          }
        }
      }

      const source = mapping.source;
      if (source != null && !newSources.has(source)) {
        newSources.add(source);
      }

      const name = mapping.name;
      if (name != null && !newNames.has(name)) {
        newNames.add(name);
      }

    }, this);
    this._sources = newSources;
    this._names = newNames;

    // Copy sourcesContents of applied map.
    aSourceMapConsumer.sources.forEach(function(srcFile) {
      const content = aSourceMapConsumer.sourceContentFor(srcFile);
      if (content != null) {
        if (aSourceMapPath != null) {
          srcFile = util.join(aSourceMapPath, srcFile);
        }
        if (sourceRoot != null) {
          srcFile = util.relative(sourceRoot, srcFile);
        }
        this.setSourceContent(srcFile, content);
      }
    }, this);
  }

  /**
   * A mapping can have one of the three levels of data:
   *
   *   1. Just the generated position.
   *   2. The Generated position, original position, and original source.
   *   3. Generated and original position, original source, as well as a name
   *      token.
   *
   * To maintain consistency, we validate that any new mapping being added falls
   * in to one of these categories.
   */
  _validateMapping(aGenerated, aOriginal, aSource, aName) {
    // When aOriginal is truthy but has empty values for .line and .column,
    // it is most likely a programmer error. In this case we throw a very
    // specific error message to try to guide them the right way.
    // For example: https://github.com/Polymer/polymer-bundler/pull/519
    if (aOriginal && typeof aOriginal.line !== "number" && typeof aOriginal.column !== "number") {
        throw new Error(
            "original.line and original.column are not numbers -- you probably meant to omit " +
            "the original mapping entirely and only map the generated position. If so, pass " +
            "null for the original mapping instead of an object with empty or null values."
        );
    }

    if (aGenerated && "line" in aGenerated && "column" in aGenerated
        && aGenerated.line > 0 && aGenerated.column >= 0
        && !aOriginal && !aSource && !aName) {
      // Case 1.

    } else if (aGenerated && "line" in aGenerated && "column" in aGenerated
             && aOriginal && "line" in aOriginal && "column" in aOriginal
             && aGenerated.line > 0 && aGenerated.column >= 0
             && aOriginal.line > 0 && aOriginal.column >= 0
             && aSource) {
      // Cases 2 and 3.

    } else {
      throw new Error("Invalid mapping: " + JSON.stringify({
        generated: aGenerated,
        source: aSource,
        original: aOriginal,
        name: aName
      }));
    }
  }

  /**
   * Serialize the accumulated mappings in to the stream of base 64 VLQs
   * specified by the source map format.
   */
  _serializeMappings() {
    let previousGeneratedColumn = 0;
    let previousGeneratedLine = 1;
    let previousOriginalColumn = 0;
    let previousOriginalLine = 0;
    let previousName = 0;
    let previousSource = 0;
    let result = "";
    let next;
    let mapping;
    let nameIdx;
    let sourceIdx;

    const mappings = this._mappings.toArray();
    for (let i = 0, len = mappings.length; i < len; i++) {
      mapping = mappings[i];
      next = "";

      if (mapping.generatedLine !== previousGeneratedLine) {
        previousGeneratedColumn = 0;
        while (mapping.generatedLine !== previousGeneratedLine) {
          next += ";";
          previousGeneratedLine++;
        }
      } else if (i > 0) {
        if (!util.compareByGeneratedPositionsInflated(mapping, mappings[i - 1])) {
          continue;
        }
        next += ",";
      }

      next += base64VLQ.encode(mapping.generatedColumn
                                 - previousGeneratedColumn);
      previousGeneratedColumn = mapping.generatedColumn;

      if (mapping.source != null) {
        sourceIdx = this._sources.indexOf(mapping.source);
        next += base64VLQ.encode(sourceIdx - previousSource);
        previousSource = sourceIdx;

        // lines are stored 0-based in SourceMap spec version 3
        next += base64VLQ.encode(mapping.originalLine - 1
                                   - previousOriginalLine);
        previousOriginalLine = mapping.originalLine - 1;

        next += base64VLQ.encode(mapping.originalColumn
                                   - previousOriginalColumn);
        previousOriginalColumn = mapping.originalColumn;

        if (mapping.name != null) {
          nameIdx = this._names.indexOf(mapping.name);
          next += base64VLQ.encode(nameIdx - previousName);
          previousName = nameIdx;
        }
      }

      result += next;
    }

    return result;
  }

  _generateSourcesContent(aSources, aSourceRoot) {
    return aSources.map(function(source) {
      if (!this._sourcesContents) {
        return null;
      }
      if (aSourceRoot != null) {
        source = util.relative(aSourceRoot, source);
      }
      const key = util.toSetString(source);
      return Object.prototype.hasOwnProperty.call(this._sourcesContents, key)
        ? this._sourcesContents[key]
        : null;
    }, this);
  }

  /**
   * Externalize the source map.
   */
  toJSON() {
    const map = {
      version: this._version,
      sources: this._sources.toArray(),
      names: this._names.toArray(),
      mappings: this._serializeMappings()
    };
    if (this._file != null) {
      map.file = this._file;
    }
    if (this._sourceRoot != null) {
      map.sourceRoot = this._sourceRoot;
    }
    if (this._sourcesContents) {
      map.sourcesContent = this._generateSourcesContent(map.sources, map.sourceRoot);
    }

    return map;
  }

  /**
   * Render the source map being generated to a string.
   */
  toString() {
    return JSON.stringify(this.toJSON());
  }
}

SourceMapGenerator.prototype._version = 3;
exports.SourceMapGenerator = SourceMapGenerator;