Function intersectTypeLiterals

packages/effect/src/Schema.ts:3271–3299

(
  x: AST.AST,
  y: AST.AST,
  path: ReadonlyArray<PropertyKey>
)

export const mutable = <S extends Schema.Any>(schema: S): mutable<S> => make(AST.mutable(schema.ast))

const intersectTypeLiterals = (
  x: AST.AST,
  y: AST.AST,
  path: ReadonlyArray<PropertyKey>
): AST.TypeLiteral => {
  if (AST.isTypeLiteral(x) && AST.isTypeLiteral(y)) {
    const propertySignatures = [...x.propertySignatures]
    for (const ps of y.propertySignatures) {
      const name = ps.name
      const i = propertySignatures.findIndex((ps) => ps.name === name)
      if (i === -1) {
        propertySignatures.push(ps)
      } else {
        const { isOptional, type } = propertySignatures[i]
        propertySignatures[i] = new AST.PropertySignature(
          name,
          extendAST(type, ps.type, path.concat(name)),
          isOptional,
          true
        )
      }
    }
    return new AST.TypeLiteral(
      propertySignatures,
      x.indexSignatures.concat(y.indexSignatures)
    )
  }
  throw new Error(errors_.getSchemaExtendErrorMessage(x, y, path))
}

const preserveRefinementAnnotations = AST.omitAnnotations([AST.IdentifierAnnotationId])