xref: /expo/packages/expo-modules-core/ios/JSI/JavaScriptRuntime.swift (revision 419852c4)

// Copyright 2022-present 650 Industries. All rights reserved.

public extension JavaScriptRuntime {
  /**
   A type of the closure that you pass to the `createSyncFunction` function.
   */
  typealias SyncFunctionClosure = (_ this: JavaScriptValue, _ arguments: [JavaScriptValue]) throws -> Any

  /**
   Evaluates JavaScript code represented as a string.

   - Parameter source: A string representing a JavaScript expression, statement, or sequence of statements.
                       The expression can include variables and properties of existing objects.
   - Returns: The completion value of evaluating the given code represented as `JavaScriptValue`.
              If the completion value is empty, `undefined` is returned.
   - Throws: `JavaScriptEvalException` when evaluated code has invalid syntax or throws an error.
   - Note: It wraps the original `evaluateScript` to better handle and rethrow exceptions.
   */
  @discardableResult
  func eval(_ source: String) throws -> JavaScriptValue {
    do {
      var result: JavaScriptValue?
      try EXUtilities.catchException {
        result = self.__evaluateScript(source)
      }
      // There is no risk to force unwrapping as long as the `evaluateScript` returns nonnull value.
      return result!
    } catch {
      throw JavaScriptEvalException(error as NSError)
    }
  }

  /**
   Evaluates the JavaScript code made by joining an array of strings with a newline separator.
   See the other ``eval(_:)`` for more details.
   */
  @discardableResult
  func eval(_ source: [String]) throws -> JavaScriptValue {
    try eval(source.joined(separator: "\n"))
  }

  /**
   Creates a synchronous host function that runs the given closure when it's called.
   The value returned by the closure is synchronously returned to JS.
   - Returns: A JavaScript function represented as a `JavaScriptObject`.
   - Note: It refines the ObjC implementation from `EXJavaScriptRuntime` to properly catch Swift errors and rethrow them as ObjC `NSError`.
   */
  func createSyncFunction(_ name: String, argsCount: Int = 0, closure: @escaping SyncFunctionClosure) -> JavaScriptObject {
    return __createSyncFunction(name, argsCount: argsCount) { this, args, errorPointer in
      do {
        return try runWithErrorPointer(errorPointer) {
          return try closure(this, args)
        }
      } catch {
        // Nicely log all errors to the console.
        log.error(error)

        // Can return anything as the error will be caught through the error pointer already.
        return nil
      }
    }
  }
}

internal final class JavaScriptEvalException: GenericException<NSError> {
  override var reason: String {
    return param.userInfo["message"] as? String ?? "unknown reason"
  }
}