1 files changed, 89 insertions, 0 deletions
diff --git a/node_modules/@jridgewell/remapping/src/build-source-map-tree.ts b/node_modules/@jridgewell/remapping/src/build-source-map-tree.ts
new file mode 100644
index 0000000..3e0262b
--- /dev/null
+++ b/node_modules/@jridgewell/remapping/src/build-source-map-tree.ts
@@ -0,0 +1,89 @@
+import { TraceMap } from '@jridgewell/trace-mapping';
+
+import { OriginalSource, MapSource } from './source-map-tree';
+
+import type { Sources, MapSource as MapSourceType } from './source-map-tree';
+import type { SourceMapInput, SourceMapLoader, LoaderContext } from './types';
+
+function asArray<T>(value: T | T[]): T[] {
+  if (Array.isArray(value)) return value;
+  return [value];
+}
+
+/**
+ * Recursively builds a tree structure out of sourcemap files, with each node
+ * being either an `OriginalSource` "leaf" or a `SourceMapTree` composed of
+ * `OriginalSource`s and `SourceMapTree`s.
+ *
+ * Every sourcemap is composed of a collection of source files and mappings
+ * into locations of those source files. When we generate a `SourceMapTree` for
+ * the sourcemap, we attempt to load each source file's own sourcemap. If it
+ * does not have an associated sourcemap, it is considered an original,
+ * unmodified source file.
+ */
+export default function buildSourceMapTree(
+  input: SourceMapInput | SourceMapInput[],
+  loader: SourceMapLoader,
+): MapSourceType {
+  const maps = asArray(input).map((m) => new TraceMap(m, ''));
+  const map = maps.pop()!;
+
+  for (let i = 0; i < maps.length; i++) {
+    if (maps[i].sources.length > 1) {
+      throw new Error(
+        `Transformation map ${i} must have exactly one source file.\n` +
+          'Did you specify these with the most recent transformation maps first?',
+      );
+    }
+  }
+
+  let tree = build(map, loader, '', 0);
+  for (let i = maps.length - 1; i >= 0; i--) {
+    tree = MapSource(maps[i], [tree]);
+  }
+  return tree;
+}
+
+function build(
+  map: TraceMap,
+  loader: SourceMapLoader,
+  importer: string,
+  importerDepth: number,
+): MapSourceType {
+  const { resolvedSources, sourcesContent, ignoreList } = map;
+
+  const depth = importerDepth + 1;
+  const children = resolvedSources.map((sourceFile: string | null, i: number): Sources => {
+    // The loading context gives the loader more information about why this file is being loaded
+    // (eg, from which importer). It also allows the loader to override the location of the loaded
+    // sourcemap/original source, or to override the content in the sourcesContent field if it's
+    // an unmodified source file.
+    const ctx: LoaderContext = {
+      importer,
+      depth,
+      source: sourceFile || '',
+      content: undefined,
+      ignore: undefined,
+    };
+
+    // Use the provided loader callback to retrieve the file's sourcemap.
+    // TODO: We should eventually support async loading of sourcemap files.
+    const sourceMap = loader(ctx.source, ctx);
+
+    const { source, content, ignore } = ctx;
+
+    // If there is a sourcemap, then we need to recurse into it to load its source files.
+    if (sourceMap) return build(new TraceMap(sourceMap, source), loader, source, depth);
+
+    // Else, it's an unmodified source file.
+    // The contents of this unmodified source file can be overridden via the loader context,
+    // allowing it to be explicitly null or a string. If it remains undefined, we fall back to
+    // the importing sourcemap's `sourcesContent` field.
+    const sourceContent =
+      content !== undefined ? content : sourcesContent ? sourcesContent[i] : null;
+    const ignored = ignore !== undefined ? ignore : ignoreList ? ignoreList.includes(i) : false;
+    return OriginalSource(source, sourceContent, ignored);
+  });
+
+  return MapSource(map, children);
+}