createUtilitySignatureCache() — tailwindcss Function Reference

Source Code

packages/tailwindcss/src/canonicalize-candidates.ts lines 2026–2066

function createUtilitySignatureCache(
  designSystem: DesignSystem,
): DesignSystem['storage'][typeof UTILITY_SIGNATURE_KEY] {
  return new DefaultMap((options: SignatureOptions) => {
    return new DefaultMap<string, string | Symbol>((utility) => {
      try {
        // Ensure the prefix is added to the utility if it is not already present.
        utility =
          designSystem.theme.prefix && !utility.startsWith(designSystem.theme.prefix)
            ? `${designSystem.theme.prefix}:${utility}`
            : utility

        // Use `@apply` to normalize the selector to `.x`
        let ast: AstNode[] = [styleRule('.x', [atRule('@apply', utility)])]

        temporarilyDisableThemeInline(designSystem, () => {
          // There's separate utility caches for respect important vs not
          // so we want to compile them both with `@theme inline` disabled
          for (let candidate of designSystem.parseCandidate(utility)) {
            designSystem.compileAstNodes(candidate, CompileAstFlags.RespectImportant)
          }

          substituteAtApply(ast, designSystem)
        })

        // Optimize the AST. This is needed such that any internal intermediate
        // nodes are gone. This will also cleanup declaration nodes with undefined
        // values or `--tw-sort` declarations.
        canonicalizeAst(designSystem, ast, options)

        // Compute the final signature, by generating the CSS for the utility
        let signature = toCss(ast)
        return signature
      } catch {
        // A unique symbol is returned to ensure that 2 signatures resulting in
        // `null` are not considered equal.
        return Symbol()
      }
    })
  })
}