Function isVariableUsed

packages/tailwindcss/src/ast.ts:906–932

(
  variable: string,
  theme: Theme,
  variableDependencies: Map<string, Set<string>>,
  alreadySeenVariables: Set<string> = new Set(),
)

// Find out if a variable is either used directly or if any of the variables that depend on it are
// used
function isVariableUsed(
  variable: string,
  theme: Theme,
  variableDependencies: Map<string, Set<string>>,
  alreadySeenVariables: Set<string> = new Set(),
): boolean {
  // Break recursions when visiting a variable twice
  if (alreadySeenVariables.has(variable)) {
    return true
  } else {
    alreadySeenVariables.add(variable)
  }

  let options = theme.getOptions(variable)
  if (options & (ThemeOptions.STATIC | ThemeOptions.USED)) {
    return true
  } else {
    let dependencies = variableDependencies.get(variable) ?? []
    for (let dependency of dependencies) {
      if (isVariableUsed(dependency, theme, variableDependencies, alreadySeenVariables)) {
        return true
      }
    }
  }

  return false
}

function extractKeyframeNames(value: string): string[] {
  return value.split(/[\s,]+/)