Function getLiterals

packages/effect/src/ParseResult.ts:1492–1534

(
  ast: AST.AST,
  isDecoding: boolean
)

/** @internal */
export const getLiterals = (
  ast: AST.AST,
  isDecoding: boolean
): ReadonlyArray<[PropertyKey, AST.Literal]> => {
  switch (ast._tag) {
    case "Declaration": {
      const annotation = AST.getSurrogateAnnotation(ast)
      if (Option.isSome(annotation)) {
        return getLiterals(annotation.value, isDecoding)
      }
      break
    }
    case "TypeLiteral": {
      const out: Array<[PropertyKey, AST.Literal]> = []
      for (let i = 0; i < ast.propertySignatures.length; i++) {
        const propertySignature = ast.propertySignatures[i]
        const type = isDecoding ? AST.encodedAST(propertySignature.type) : AST.typeAST(propertySignature.type)
        if (AST.isLiteral(type) && !propertySignature.isOptional) {
          out.push([propertySignature.name, type])
        }
      }
      return out
    }
    case "TupleType": {
      const out: Array<[PropertyKey, AST.Literal]> = []
      for (let i = 0; i < ast.elements.length; i++) {
        const element = ast.elements[i]
        const type = isDecoding ? AST.encodedAST(element.type) : AST.typeAST(element.type)
        if (AST.isLiteral(type) && !element.isOptional) {
          out.push([i, type])
        }
      }
      return out
    }
    case "Refinement":
      return getLiterals(ast.from, isDecoding)
    case "Suspend":
      return getLiterals(ast.f(), isDecoding)
    case "Transformation":
      return getLiterals(isDecoding ? ast.from : ast.to, isDecoding)
  }
  return []
}

/**
 * The purpose of the algorithm is to narrow down the pool of possible