205 lines
8.3 KiB
JavaScript
205 lines
8.3 KiB
JavaScript
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import { decodedMappings, traceSegment, TraceMap } from '@jridgewell/trace-mapping';
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import { GenMapping, addSegment, setSourceContent, decodedMap, encodedMap } from '@jridgewell/gen-mapping';
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const SOURCELESS_MAPPING = {
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source: null,
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column: null,
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line: null,
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name: null,
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content: null,
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};
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const EMPTY_SOURCES = [];
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function Source(map, sources, source, content) {
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return {
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map,
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sources,
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source,
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content,
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};
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}
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/**
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* MapSource represents a single sourcemap, with the ability to trace mappings into its child nodes
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* (which may themselves be SourceMapTrees).
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*/
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function MapSource(map, sources) {
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return Source(map, sources, '', null);
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}
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/**
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* A "leaf" node in the sourcemap tree, representing an original, unmodified source file. Recursive
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* segment tracing ends at the `OriginalSource`.
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*/
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function OriginalSource(source, content) {
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return Source(null, EMPTY_SOURCES, source, content);
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}
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/**
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* traceMappings is only called on the root level SourceMapTree, and begins the process of
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* resolving each mapping in terms of the original source files.
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*/
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function traceMappings(tree) {
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const gen = new GenMapping({ file: tree.map.file });
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const { sources: rootSources, map } = tree;
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const rootNames = map.names;
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const rootMappings = decodedMappings(map);
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for (let i = 0; i < rootMappings.length; i++) {
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const segments = rootMappings[i];
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let lastSource = null;
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let lastSourceLine = null;
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let lastSourceColumn = null;
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for (let j = 0; j < segments.length; j++) {
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const segment = segments[j];
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const genCol = segment[0];
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let traced = SOURCELESS_MAPPING;
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// 1-length segments only move the current generated column, there's no source information
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// to gather from it.
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if (segment.length !== 1) {
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const source = rootSources[segment[1]];
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traced = originalPositionFor(source, segment[2], segment[3], segment.length === 5 ? rootNames[segment[4]] : '');
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// If the trace is invalid, then the trace ran into a sourcemap that doesn't contain a
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// respective segment into an original source.
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if (traced == null)
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continue;
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}
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// So we traced a segment down into its original source file. Now push a
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// new segment pointing to this location.
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const { column, line, name, content, source } = traced;
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if (line === lastSourceLine && column === lastSourceColumn && source === lastSource) {
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continue;
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}
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lastSourceLine = line;
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lastSourceColumn = column;
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lastSource = source;
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// Sigh, TypeScript can't figure out source/line/column are either all null, or all non-null...
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addSegment(gen, i, genCol, source, line, column, name);
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if (content != null)
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setSourceContent(gen, source, content);
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}
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}
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return gen;
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}
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/**
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* originalPositionFor is only called on children SourceMapTrees. It recurses down into its own
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* child SourceMapTrees, until we find the original source map.
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*/
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function originalPositionFor(source, line, column, name) {
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if (!source.map) {
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return { column, line, name, source: source.source, content: source.content };
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}
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const segment = traceSegment(source.map, line, column);
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// If we couldn't find a segment, then this doesn't exist in the sourcemap.
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if (segment == null)
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return null;
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// 1-length segments only move the current generated column, there's no source information
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// to gather from it.
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if (segment.length === 1)
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return SOURCELESS_MAPPING;
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return originalPositionFor(source.sources[segment[1]], segment[2], segment[3], segment.length === 5 ? source.map.names[segment[4]] : name);
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}
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function asArray(value) {
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if (Array.isArray(value))
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return value;
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return [value];
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}
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/**
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* Recursively builds a tree structure out of sourcemap files, with each node
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* being either an `OriginalSource` "leaf" or a `SourceMapTree` composed of
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* `OriginalSource`s and `SourceMapTree`s.
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*
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* Every sourcemap is composed of a collection of source files and mappings
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* into locations of those source files. When we generate a `SourceMapTree` for
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* the sourcemap, we attempt to load each source file's own sourcemap. If it
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* does not have an associated sourcemap, it is considered an original,
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* unmodified source file.
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*/
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function buildSourceMapTree(input, loader) {
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const maps = asArray(input).map((m) => new TraceMap(m, ''));
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const map = maps.pop();
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for (let i = 0; i < maps.length; i++) {
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if (maps[i].sources.length > 1) {
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throw new Error(`Transformation map ${i} must have exactly one source file.\n` +
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'Did you specify these with the most recent transformation maps first?');
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}
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}
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let tree = build(map, loader, '', 0);
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for (let i = maps.length - 1; i >= 0; i--) {
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tree = MapSource(maps[i], [tree]);
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}
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return tree;
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}
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function build(map, loader, importer, importerDepth) {
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const { resolvedSources, sourcesContent } = map;
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const depth = importerDepth + 1;
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const children = resolvedSources.map((sourceFile, i) => {
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// The loading context gives the loader more information about why this file is being loaded
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// (eg, from which importer). It also allows the loader to override the location of the loaded
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// sourcemap/original source, or to override the content in the sourcesContent field if it's
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// an unmodified source file.
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const ctx = {
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importer,
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depth,
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source: sourceFile || '',
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content: undefined,
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};
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// Use the provided loader callback to retrieve the file's sourcemap.
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// TODO: We should eventually support async loading of sourcemap files.
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const sourceMap = loader(ctx.source, ctx);
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const { source, content } = ctx;
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// If there is a sourcemap, then we need to recurse into it to load its source files.
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if (sourceMap)
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return build(new TraceMap(sourceMap, source), loader, source, depth);
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// Else, it's an an unmodified source file.
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// The contents of this unmodified source file can be overridden via the loader context,
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// allowing it to be explicitly null or a string. If it remains undefined, we fall back to
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// the importing sourcemap's `sourcesContent` field.
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const sourceContent = content !== undefined ? content : sourcesContent ? sourcesContent[i] : null;
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return OriginalSource(source, sourceContent);
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});
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return MapSource(map, children);
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}
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/**
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* A SourceMap v3 compatible sourcemap, which only includes fields that were
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* provided to it.
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*/
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class SourceMap {
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constructor(map, options) {
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const out = options.decodedMappings ? decodedMap(map) : encodedMap(map);
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this.version = out.version; // SourceMap spec says this should be first.
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this.file = out.file;
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this.mappings = out.mappings;
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this.names = out.names;
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this.sourceRoot = out.sourceRoot;
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this.sources = out.sources;
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if (!options.excludeContent) {
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this.sourcesContent = out.sourcesContent;
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}
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}
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toString() {
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return JSON.stringify(this);
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}
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}
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/**
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* Traces through all the mappings in the root sourcemap, through the sources
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* (and their sourcemaps), all the way back to the original source location.
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*
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* `loader` will be called every time we encounter a source file. If it returns
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* a sourcemap, we will recurse into that sourcemap to continue the trace. If
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* it returns a falsey value, that source file is treated as an original,
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* unmodified source file.
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*
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* Pass `excludeContent` to exclude any self-containing source file content
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* from the output sourcemap.
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*
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* Pass `decodedMappings` to receive a SourceMap with decoded (instead of
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* VLQ encoded) mappings.
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*/
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function remapping(input, loader, options) {
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const opts = typeof options === 'object' ? options : { excludeContent: !!options, decodedMappings: false };
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const tree = buildSourceMapTree(input, loader);
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return new SourceMap(traceMappings(tree), opts);
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}
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export { remapping as default };
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//# sourceMappingURL=remapping.mjs.map
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