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204 lines
8.3 KiB
204 lines
8.3 KiB
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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