pkg/front_end/lib/src/fasta/type_inference/type_inference_listener.dart

// Copyright (c) 2017, 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.md file.

import 'package:kernel/ast.dart';

/// Base class for [TypeInferenceListener] that defines the API for debugging.
///
/// By default no debug info is printed.  To enable debug printing, mix in
/// [TypeInferenceDebugging].
class TypeInferenceBase {
  bool debugExpressionEnter(
      String expressionType, Expression expression, DartType typeContext) {
    return false;
  }

  debugExpressionExit(
      String expressionType, Expression expression, DartType inferredType) {}
}

/// Mixin which can be applied to [TypeInferenceListener] to cause debug info to
/// be printed.
class TypeInferenceDebugging implements TypeInferenceBase {
  bool debugExpressionEnter(
      String expressionType, Expression expression, DartType typeContext) {
    print('Enter $expressionType($expression) (context=$typeContext)');
    return true;
  }

  debugExpressionExit(
      String expressionType, Expression expression, DartType inferredType) {
    print('Exit $expressionType($expression) (type=$inferredType)');
  }
}

/// Callback interface used by [TypeInferrer] to report the results of type
/// inference to a client.
///
/// The interface is structured as a set of enter/exit methods.  The enter
/// methods are called as the inferrer recurses down through the AST, and the
/// exit methods are called on the way back up.  The enter methods take a
/// [DartType] argument representing the downwards inference context, and return
/// a bool indicating whether the TypeInferenceListener needs to know the final
/// inferred type; the exit methods take [DartType] argument representing the
/// final inferred type.
///
/// The default implementation (in this base class) does nothing, however it can
/// be used to debug type inference by uncommenting the
/// "with TypeInferenceDebugging" clause below.
class TypeInferenceListener
    extends TypeInferenceBase // with TypeInferenceDebugging
{
  bool asExpressionEnter(AsExpression expression, DartType typeContext) =>
      debugExpressionEnter("asExpression", expression, typeContext);

  void asExpressionExit(AsExpression expression, DartType inferredType) =>
      debugExpressionExit("asExpression", expression, inferredType);

  bool boolLiteralEnter(BoolLiteral expression, DartType typeContext) =>
      debugExpressionEnter("boolLiteral", expression, typeContext);

  void boolLiteralExit(BoolLiteral expression, DartType inferredType) =>
      debugExpressionExit("boolLiteral", expression, inferredType);

  bool conditionalExpressionEnter(
          ConditionalExpression expression, DartType typeContext) =>
      debugExpressionEnter("conditionalExpression", expression, typeContext);

  void conditionalExpressionExit(
          ConditionalExpression expression, DartType inferredType) =>
      debugExpressionExit("conditionalExpression", expression, inferredType);

  bool constructorInvocationEnter(
          ConstructorInvocation expression, DartType typeContext) =>
      debugExpressionEnter("constructorInvocation", expression, typeContext);

  void constructorInvocationExit(
          ConstructorInvocation expression, DartType inferredType) =>
      debugExpressionExit("constructorInvocation", expression, inferredType);

  bool doubleLiteralEnter(DoubleLiteral expression, DartType typeContext) =>
      debugExpressionEnter("doubleLiteral", expression, typeContext);

  void doubleLiteralExit(DoubleLiteral expression, DartType inferredType) =>
      debugExpressionExit("doubleLiteral", expression, inferredType);

  bool functionExpressionEnter(
          FunctionExpression expression, DartType typeContext) =>
      debugExpressionEnter("functionExpression", expression, typeContext);

  void functionExpressionExit(
          FunctionExpression expression, DartType inferredType) =>
      debugExpressionExit("functionExpression", expression, inferredType);

  bool intLiteralEnter(IntLiteral expression, DartType typeContext) =>
      debugExpressionEnter("intLiteral", expression, typeContext);

  void intLiteralExit(IntLiteral expression, DartType inferredType) =>
      debugExpressionExit("intLiteral", expression, inferredType);

  bool isExpressionEnter(IsExpression expression, DartType typeContext) =>
      debugExpressionEnter("isExpression", expression, typeContext);

  void isExpressionExit(IsExpression expression, DartType inferredType) =>
      debugExpressionExit("isExpression", expression, inferredType);

  bool isNotExpressionEnter(Not expression, DartType typeContext) =>
      debugExpressionEnter("isNotExpression", expression, typeContext);

  void isNotExpressionExit(Not expression, DartType inferredType) =>
      debugExpressionExit("isNotExpression", expression, inferredType);

  bool listLiteralEnter(ListLiteral expression, DartType typeContext) =>
      debugExpressionEnter("listLiteral", expression, typeContext);

  void listLiteralExit(ListLiteral expression, DartType inferredType) =>
      debugExpressionExit("listLiteral", expression, inferredType);

  bool methodInvocationEnter(
          MethodInvocation expression, DartType typeContext) =>
      debugExpressionEnter("methodInvocation", expression, typeContext);

  void methodInvocationExit(
          MethodInvocation expression, DartType inferredType) =>
      debugExpressionExit("methodInvocation", expression, inferredType);

  bool nullLiteralEnter(NullLiteral expression, DartType typeContext) =>
      debugExpressionEnter("nullLiteral", expression, typeContext);

  void nullLiteralExit(NullLiteral expression, DartType inferredType) =>
      debugExpressionExit("nullLiteral", expression, inferredType);

  bool staticGetEnter(StaticGet expression, DartType typeContext) =>
      debugExpressionEnter("staticGet", expression, typeContext);

  void staticGetExit(StaticGet expression, DartType inferredType) =>
      debugExpressionExit("staticGet", expression, inferredType);

  bool staticInvocationEnter(
          StaticInvocation expression, DartType typeContext) =>
      debugExpressionEnter("staticInvocation", expression, typeContext);

  void staticInvocationExit(
          StaticInvocation expression, DartType inferredType) =>
      debugExpressionExit("staticInvocation", expression, inferredType);

  bool stringConcatenationEnter(
          StringConcatenation expression, DartType typeContext) =>
      debugExpressionEnter("stringConcatenation", expression, typeContext);

  void stringConcatenationExit(
          StringConcatenation expression, DartType inferredType) =>
      debugExpressionExit("stringConcatenation", expression, inferredType);

  bool stringLiteralEnter(StringLiteral expression, DartType typeContext) =>
      debugExpressionEnter("StringLiteral", expression, typeContext);

  void stringLiteralExit(StringLiteral expression, DartType inferredType) =>
      debugExpressionExit("StringLiteral", expression, inferredType);

  bool variableGetEnter(VariableGet expression, DartType typeContext) =>
      debugExpressionEnter("variableGet", expression, typeContext);

  void variableGetExit(VariableGet expression, DartType inferredType) =>
      debugExpressionExit("variableGet", expression, inferredType);

  bool variableSetEnter(VariableSet expression, DartType typeContext) =>
      debugExpressionEnter("variableSet", expression, typeContext);

  void variableSetExit(VariableSet expression, DartType inferredType) =>
      debugExpressionExit("variableSet", expression, inferredType);
}