substituteAtImports() — tailwindcss Function Reference

Architecture documentation for the substituteAtImports() function in at-import.ts from the tailwindcss codebase.

Function typescript CompilerEngine ModuleResolution calls 5 called by 1

Entity Profile

CompilerEngine→ ModuleResolution→ substituteAtImports() — tailwindcss Function Reference

Dependency Diagram

graph TD
  761efede_46a5_5722_0699_0e1b0947c406["substituteAtImports()"]
  26086ff1_0d4f_fdb2_3fc4_d0c999f90a8c["parseCss()"]
  26086ff1_0d4f_fdb2_3fc4_d0c999f90a8c -->|calls| 761efede_46a5_5722_0699_0e1b0947c406
  e9d556bc_f22d_356c_1bd2_27442c34b5c7["walk()"]
  761efede_46a5_5722_0699_0e1b0947c406 -->|calls| e9d556bc_f22d_356c_1bd2_27442c34b5c7
  d4cb5436_afc5_b498_b798_03165e495710["parseImportParams()"]
  761efede_46a5_5722_0699_0e1b0947c406 -->|calls| d4cb5436_afc5_b498_b798_03165e495710
  5da7c62d_f734_2cbc_b10f_03c31a70d4f9["context()"]
  761efede_46a5_5722_0699_0e1b0947c406 -->|calls| 5da7c62d_f734_2cbc_b10f_03c31a70d4f9
  8b7b19eb_b2e9_7522_24fe_7d4dcb7d22a4["buildImportNodes()"]
  761efede_46a5_5722_0699_0e1b0947c406 -->|calls| 8b7b19eb_b2e9_7522_24fe_7d4dcb7d22a4
  257c4715_dc91_0c7f_fce8_433a757d9ce6["parse()"]
  761efede_46a5_5722_0699_0e1b0947c406 -->|calls| 257c4715_dc91_0c7f_fce8_433a757d9ce6
  style 761efede_46a5_5722_0699_0e1b0947c406 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/tailwindcss/src/at-import.ts lines 16–81

export async function substituteAtImports(
  ast: AstNode[],
  base: string,
  loadStylesheet: LoadStylesheet,
  recurseCount = 0,
  track = false,
) {
  let features = Features.None
  let promises: Promise<void>[] = []

  walk(ast, (node) => {
    if (node.kind === 'at-rule' && (node.name === '@import' || node.name === '@reference')) {
      let parsed = parseImportParams(ValueParser.parse(node.params))
      if (parsed === null) return
      if (node.name === '@reference') {
        parsed.media = 'reference'
      }

      features |= Features.AtImport

      let { uri, layer, media, supports } = parsed

      // Skip importing data or remote URIs
      if (uri.startsWith('data:')) return
      if (uri.startsWith('http://') || uri.startsWith('https://')) return

      let contextNode = context({}, [])

      promises.push(
        (async () => {
          // Since we do not have fully resolved paths in core, we can't
          // reliably detect circular imports. Instead, we try to limit the
          // recursion depth to a number that is too large to be reached in
          // practice.
          if (recurseCount > 100) {
            throw new Error(
              `Exceeded maximum recursion depth while resolving \`${uri}\` in \`${base}\`)`,
            )
          }

          let loaded = await loadStylesheet(uri, base)
          let ast = CSS.parse(loaded.content, { from: track ? loaded.path : undefined })
          await substituteAtImports(ast, loaded.base, loadStylesheet, recurseCount + 1, track)

          contextNode.nodes = buildImportNodes(
            node,
            [context({ base: loaded.base }, ast)],
            layer,
            media,
            supports,
          )
        })(),
      )

      // The resolved Stylesheets already have their transitive @imports
      // resolved, so we can skip walking them.
      return WalkAction.ReplaceSkip(contextNode)
    }
  })

  if (promises.length > 0) {
    await Promise.all(promises)
  }

  return features
}