substituteFunctionsInValue() — tailwindcss Function Reference

Architecture documentation for the substituteFunctionsInValue() function in migrate-theme-to-var.ts from the tailwindcss codebase.

Function typescript OxideCore Extractor calls 4 called by 1

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OxideCore→ Extractor→ substituteFunctionsInValue() — tailwindcss Function Reference

Dependency Diagram

graph TD
  324d33ab_fbf5_0679_98c5_2192fd427d97["substituteFunctionsInValue()"]
  a5e6dda1_40ba_a775_d007_2d6576a30911["createConverter()"]
  a5e6dda1_40ba_a775_d007_2d6576a30911 -->|calls| 324d33ab_fbf5_0679_98c5_2192fd427d97
  c57928e0_95f9_bd68_c036_1186e1a4d345["toCss()"]
  324d33ab_fbf5_0679_98c5_2192fd427d97 -->|calls| c57928e0_95f9_bd68_c036_1186e1a4d345
  76c53890_d1d5_1797_39bd_61ec3a9419c4["eventuallyUnquote()"]
  324d33ab_fbf5_0679_98c5_2192fd427d97 -->|calls| 76c53890_d1d5_1797_39bd_61ec3a9419c4
  e5eb2faf_45a2_ac47_3404_8bd4e7eb6817["parse()"]
  324d33ab_fbf5_0679_98c5_2192fd427d97 -->|calls| e5eb2faf_45a2_ac47_3404_8bd4e7eb6817
  a32bba76_f60d_883f_1ff1_276a0bb9db9f["walk()"]
  324d33ab_fbf5_0679_98c5_2192fd427d97 -->|calls| a32bba76_f60d_883f_1ff1_276a0bb9db9f
  style 324d33ab_fbf5_0679_98c5_2192fd427d97 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

packages/@tailwindcss-upgrade/src/codemods/template/migrate-theme-to-var.ts lines 172–250

function substituteFunctionsInValue(
  ast: ValueParser.ValueAstNode[],
  handle: (value: string, fallback?: string) => string | null,
) {
  walk(ast, (node, ctx) => {
    if (node.kind === 'function' && node.value === 'theme') {
      if (node.nodes.length < 1) return

      // Ignore whitespace before the first argument
      if (node.nodes[0].kind === 'separator' && node.nodes[0].value.trim() === '') {
        node.nodes.shift()
      }

      let pathNode = node.nodes[0]
      if (pathNode.kind !== 'word') return

      let path = pathNode.value

      // For the theme function arguments, we require all separators to contain
      // comma (`,`), spaces alone should be merged into the previous word to
      // avoid splitting in this case:
      //
      // theme(--color-red-500 / 75%) theme(--color-red-500 / 75%, foo, bar)
      //
      // We only need to do this for the first node, as the fallback values are
      // passed through as-is.
      let skipUntilIndex = 1
      for (let i = skipUntilIndex; i < node.nodes.length; i++) {
        if (node.nodes[i].value.includes(',')) {
          break
        }
        path += ValueParser.toCss([node.nodes[i]])
        skipUntilIndex = i + 1
      }

      path = eventuallyUnquote(path)
      let fallbackValues = node.nodes.slice(skipUntilIndex + 1)

      let replacement =
        fallbackValues.length > 0 ? handle(path, ValueParser.toCss(fallbackValues)) : handle(path)
      if (replacement === null) return

      if (ctx.parent) {
        let idx = ctx.parent.nodes.indexOf(node) - 1
        while (idx !== -1) {
          let previous = ctx.parent.nodes[idx]
          // Skip the space separator
          if (previous.kind === 'separator' && previous.value.trim() === '') {
            idx -= 1
            continue
          }

          // If the previous node is a word and contains an operator, we need to
          // wrap the replacement in parentheses to make the output less
          // ambiguous.
          //
          // Input:
          // - `calc(100dvh-theme(spacing.2))`
          //
          // Output:
          // - `calc(100dvh-(--spacing(2)))`
          //
          // Not:
          // -`calc(100dvh---spacing(2))`
          //
          if (/^[-+*/]$/.test(previous.value.trim())) {
            replacement = `(${replacement})`
          }

          break
        }
      }

      return WalkAction.Replace(ValueParser.parse(replacement))
    }
  })

  return ValueParser.toCss(ast)
}