Skip to content

Instantly share code, notes, and snippets.

@bcoe
Created September 29, 2019 20:42
Embed
What would you like to do?
SourceMap.js
// This file is a modified version of:
// https://cs.chromium.org/chromium/src/v8/tools/SourceMap.js?rcl=dd10454c1d
// from the V8 codebase. Logic specific to WebInspector is removed and linting
// is made to match the Node.js style guide.
// Copyright 2013 the V8 project authors. 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.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// 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,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// This is a copy from blink dev tools, see:
// http://src.chromium.org/viewvc/blink/trunk/Source/devtools/front_end/SourceMap.js
// revision: 153407
/*
* Copyright (C) 2012 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.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* 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,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
'use strict';
let base64Map;
const VLQ_BASE_SHIFT = 5;
const VLQ_BASE_MASK = (1 << 5) - 1;
const VLQ_CONTINUATION_MASK = 1 << 5;
/**
* Implements Source Map V3 model. See http://code.google.com/p/closure-compiler/wiki/SourceMaps
* for format description.
* @constructor
* @param {string} sourceMappingURL
* @param {SourceMapV3} payload
*/
class SourceMap {
#reverseMappingsBySourceURL = [];
#mappings = [];
#sources = {};
#sourceContentByURL = {};
/**
* @constructor
* @param {SourceMapV3} payload
*/
constructor(payload) {
if (!base64Map) {
const base64Digits =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
base64Map = {};
for (let i = 0; i < base64Digits.length; ++i)
base64Map[base64Digits.charAt(i)] = i;
}
this.#parseMappingPayload(payload);
}
/**
* @param {SourceMapV3} mappingPayload
*/
#parseMappingPayload = (mappingPayload) => {
if (mappingPayload.sections)
this.#parseSections(mappingPayload.sections);
else
this.#parseMap(mappingPayload, 0, 0);
}
/**
* @param {Array.<SourceMapV3.Section>} sections
*/
#parseSections = (sections) => {
for (let i = 0; i < sections.length; ++i) {
const section = sections[i];
this.#parseMap(section.map, section.offset.line, section.offset.column);
}
}
/**
* @param {number} lineNumber in compiled resource
* @param {number} columnNumber in compiled resource
* @return {?Array}
*/
findEntry(lineNumber, columnNumber) {
let first = 0;
let count = this.#mappings.length;
while (count > 1) {
const step = count >> 1;
const middle = first + step;
const mapping = this.#mappings[middle];
if (lineNumber < mapping[0] ||
(lineNumber === mapping[0] && columnNumber < mapping[1])) {
count = step;
} else {
first = middle;
count -= step;
}
}
const entry = this.#mappings[first];
if (!first && entry && (lineNumber < entry[0] ||
(lineNumber === entry[0] && columnNumber < entry[1]))) {
return null;
}
return entry;
}
/**
* @param {string} sourceURL of the originating resource
* @param {number} lineNumber in the originating resource
* @return {Array}
*/
findEntryReversed(sourceURL, lineNumber) {
const mappings = this.#reverseMappingsBySourceURL[sourceURL];
for (; lineNumber < mappings.length; ++lineNumber) {
const mapping = mappings[lineNumber];
if (mapping)
return mapping;
}
return this.#mappings[0];
}
/**
* @override
*/
#parseMap = (map, lineNumber, columnNumber) => {
let sourceIndex = 0;
let sourceLineNumber = 0;
let sourceColumnNumber = 0;
const sources = [];
const originalToCanonicalURLMap = {};
for (let i = 0; i < map.sources.length; ++i) {
const url = map.sources[i];
originalToCanonicalURLMap[url] = url;
sources.push(url);
this.#sources[url] = true;
if (map.sourcesContent && map.sourcesContent[i])
this.#sourceContentByURL[url] = map.sourcesContent[i];
}
const stringCharIterator = new StringCharIterator(map.mappings);
let sourceURL = sources[sourceIndex];
while (true) {
if (stringCharIterator.peek() === ',')
stringCharIterator.next();
else {
while (stringCharIterator.peek() === ';') {
lineNumber += 1;
columnNumber = 0;
stringCharIterator.next();
}
if (!stringCharIterator.hasNext())
break;
}
columnNumber += decodeVLQ(stringCharIterator);
if (isSeparator(stringCharIterator.peek())) {
this.#mappings.push([lineNumber, columnNumber]);
continue;
}
const sourceIndexDelta = decodeVLQ(stringCharIterator);
if (sourceIndexDelta) {
sourceIndex += sourceIndexDelta;
sourceURL = sources[sourceIndex];
}
sourceLineNumber += decodeVLQ(stringCharIterator);
sourceColumnNumber += decodeVLQ(stringCharIterator);
if (!isSeparator(stringCharIterator.peek()))
// Unused index into the names list.
decodeVLQ(stringCharIterator);
this.#mappings.push([lineNumber, columnNumber, sourceURL,
sourceLineNumber, sourceColumnNumber]);
}
for (let i = 0; i < this.#mappings.length; ++i) {
const mapping = this.#mappings[i];
const url = mapping[2];
if (!url)
continue;
if (!this.#reverseMappingsBySourceURL[url])
this.#reverseMappingsBySourceURL[url] = [];
const reverseMappings = this.#reverseMappingsBySourceURL[url];
const sourceLine = mapping[3];
if (!reverseMappings[sourceLine])
reverseMappings[sourceLine] = [mapping[0], mapping[1]];
}
};
}
/**
* @param {string} char
* @return {boolean}
*/
function isSeparator(char) {
return char === ',' || char === ';';
}
/**
* @param {SourceMap.StringCharIterator} stringCharIterator
* @return {number}
*/
function decodeVLQ(stringCharIterator) {
// Read unsigned value.
let result = 0;
let shift = 0;
let digit;
do {
digit = base64Map[stringCharIterator.next()];
result += (digit & VLQ_BASE_MASK) << shift;
shift += VLQ_BASE_SHIFT;
} while (digit & VLQ_CONTINUATION_MASK);
// Fix the sign.
const negative = result & 1;
result >>= 1;
return negative ? -result : result;
}
class StringCharIterator {
/**
* @constructor
* @param {string} string
*/
constructor(string) {
this._string = string;
this._position = 0;
}
/**
* @return {string}
*/
next() {
return this._string.charAt(this._position++);
}
/**
* @return {string}
*/
peek() {
return this._string.charAt(this._position);
}
/**
* @return {boolean}
*/
hasNext() {
return this._position < this._string.length;
}
}
module.exports = {
SourceMap
};
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment