// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

library dart2js.constant_system;

import '../dart_types.dart';
import '../compiler.dart' show
    Compiler;
import '../resolution/operators.dart';
import '../tree/tree.dart' show
    DartString;
import 'values.dart';

abstract class Operation {
  String get name;
}

abstract class UnaryOperation extends Operation {
  /** Returns [:null:] if it was unable to fold the operation. */
  ConstantValue fold(ConstantValue constant);
}

abstract class BinaryOperation extends Operation {
  /** Returns [:null:] if it was unable to fold the operation. */
  ConstantValue fold(ConstantValue left, ConstantValue right);
  apply(left, right);
}

/**
 * A [ConstantSystem] is responsible for creating constants and folding them.
 */
abstract class ConstantSystem {
  BinaryOperation get add;
  BinaryOperation get bitAnd;
  UnaryOperation get bitNot;
  BinaryOperation get bitOr;
  BinaryOperation get bitXor;
  BinaryOperation get booleanAnd;
  BinaryOperation get booleanOr;
  BinaryOperation get divide;
  BinaryOperation get equal;
  BinaryOperation get greaterEqual;
  BinaryOperation get greater;
  BinaryOperation get identity;
  BinaryOperation get ifNull;
  BinaryOperation get lessEqual;
  BinaryOperation get less;
  BinaryOperation get modulo;
  BinaryOperation get multiply;
  UnaryOperation get negate;
  UnaryOperation get not;
  BinaryOperation get shiftLeft;
  BinaryOperation get shiftRight;
  BinaryOperation get subtract;
  BinaryOperation get truncatingDivide;

  BinaryOperation get codeUnitAt;

  const ConstantSystem();

  ConstantValue createInt(int i);
  ConstantValue createDouble(double d);
  ConstantValue createString(DartString string);
  ConstantValue createBool(bool value);
  ConstantValue createNull();
  ConstantValue createList(InterfaceType type,
                           List<ConstantValue> values);
  // TODO(johnniwinther): Remove the need for [compiler].
  ConstantValue createMap(Compiler compiler,
                          InterfaceType type,
                          List<ConstantValue> keys,
                          List<ConstantValue> values);
  // TODO(johnniwinther): Remove the need for [compiler].
  ConstantValue createType(Compiler compiler,
                           DartType type);

  // We need to special case the subtype check for JavaScript constant
  // system because an int is a double at runtime.
  bool isSubtype(DartTypes types, DartType s, DartType t);

  /** Returns true if the [constant] is an integer at runtime. */
  bool isInt(ConstantValue constant);
  /** Returns true if the [constant] is a double at runtime. */
  bool isDouble(ConstantValue constant);
  /** Returns true if the [constant] is a string at runtime. */
  bool isString(ConstantValue constant);
  /** Returns true if the [constant] is a boolean at runtime. */
  bool isBool(ConstantValue constant);
  /** Returns true if the [constant] is null at runtime. */
  bool isNull(ConstantValue constant);

  UnaryOperation lookupUnary(UnaryOperator operator) {
    switch (operator.kind) {
      case UnaryOperatorKind.COMPLEMENT: return bitNot;
      case UnaryOperatorKind.NEGATE: return negate;
      case UnaryOperatorKind.NOT: return not;
      default:  return null;
    }
  }

  BinaryOperation lookupBinary(BinaryOperator operator) {
    switch (operator.kind) {
      case BinaryOperatorKind.ADD:   return add;
      case BinaryOperatorKind.SUB:   return subtract;
      case BinaryOperatorKind.MUL:   return multiply;
      case BinaryOperatorKind.DIV:   return divide;
      case BinaryOperatorKind.MOD:   return modulo;
      case BinaryOperatorKind.IDIV:  return truncatingDivide;
      case BinaryOperatorKind.OR:   return bitOr;
      case BinaryOperatorKind.AND:   return bitAnd;
      case BinaryOperatorKind.XOR:   return bitXor;
      case BinaryOperatorKind.LOGICAL_OR:  return booleanOr;
      case BinaryOperatorKind.LOGICAL_AND:  return booleanAnd;
      case BinaryOperatorKind.SHL:  return shiftLeft;
      case BinaryOperatorKind.SHR:  return shiftRight;
      case BinaryOperatorKind.LT:   return less;
      case BinaryOperatorKind.LTEQ:  return lessEqual;
      case BinaryOperatorKind.GT:   return greater;
      case BinaryOperatorKind.GTEQ:  return greaterEqual;
      case BinaryOperatorKind.EQ:  return equal;
      case BinaryOperatorKind.IF_NULL: return ifNull;
      default:    return null;
    }
  }
}