ChunkMetadataMap Class — vite Architecture

Source Code

packages/vite/src/node/build.ts lines 1186–1235

export class ChunkMetadataMap {
  private _inner = new Map<string, ChunkMetadata | AssetMetadata>()
  private _resetChunks = new Set<string>()

  private _getKey(chunk: RenderedChunk | OutputChunk | OutputAsset): string {
    return 'preliminaryFileName' in chunk
      ? chunk.preliminaryFileName
      : chunk.fileName
  }

  private _getDefaultValue(
    chunk: RenderedChunk | OutputChunk | OutputAsset,
  ): ChunkMetadata | AssetMetadata {
    return chunk.type === 'chunk'
      ? {
          importedAssets: new Set(),
          importedCss: new Set(),
          // NOTE: adding this as a workaround for now ideally we'd want to remove this workaround
          // use shared `chunk.modules` object to allow mutation on js side plugins
          __modules: chunk.modules,
        }
      : {
          importedAssets: new Set(),
          importedCss: new Set(),
        }
  }

  get(
    chunk: RenderedChunk | OutputChunk | OutputAsset,
  ): ChunkMetadata | AssetMetadata {
    const key = this._getKey(chunk)
    if (!this._inner.has(key)) {
      this._inner.set(key, this._getDefaultValue(chunk))
    }
    return this._inner.get(key)!
  }

  // reset chunk metadata on the first RenderChunk call for watch mode
  reset(chunk: RenderedChunk | OutputChunk | OutputAsset): void {
    const key = this._getKey(chunk)
    if (this._resetChunks.has(key)) return

    this._resetChunks.add(key)
    this._inner.set(key, this._getDefaultValue(chunk))
  }

  clearResetChunks(): void {
    this._resetChunks.clear()
  }
}