sdk/pkg/js_ast/test/deferred_expression_test.dart

// Copyright (c) 2019, 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.

import 'package:expect/expect.dart';
import 'package:js_ast/js_ast.dart';
import 'package:js_ast/src/precedence.dart';

void main() {
  Map<Expression, DeferredExpression> map = {};
  VariableUse variableUse = VariableUse('variable');
  DeferredExpression deferred = map[variableUse] = _DeferredExpression(
    variableUse,
  );
  VariableUse variableUseAlias = VariableUse('variable');
  map[variableUseAlias] = _DeferredExpression(variableUseAlias);

  map[deferred] = _DeferredExpression(deferred);
  Literal literal = LiteralString('literal');
  map[literal] = _DeferredExpression(literal);

  test(map, '#', [variableUse], 'variable');
  test(map, '#', [deferred], 'variable');
  test(map, '{#: #}', [literal, variableUse], '{literal: variable}');
  test(map, '{#: #}', [literal, deferred], '{literal: variable}');
  test(map, '#.#', [variableUse, literal], 'variable.literal');
  test(map, '#.#', [deferred, literal], 'variable.literal');
  test(map, '# = # + 1', [variableUse, variableUseAlias], '++variable');
  test(map, '# = # + 1', [deferred, variableUseAlias], '++variable');
  test(map, '# = # - 1', [variableUse, variableUseAlias], '--variable');
  test(map, '# = # - 1', [deferred, variableUseAlias], '--variable');
  test(map, '# = # + 2', [variableUse, variableUseAlias], 'variable += 2');
  test(map, '# = # + 2', [deferred, variableUseAlias], 'variable += 2');
  test(map, '# = # * 2', [variableUse, variableUseAlias], 'variable *= 2');
  test(map, '# = # * 2', [deferred, variableUseAlias], 'variable *= 2');

  test(map, '# += # + 1', [
    variableUse,
    variableUseAlias,
  ], 'variable += variable + 1');
  test(map, '# += # + 1', [
    deferred,
    variableUseAlias,
  ], 'variable += variable + 1');
  test(map, '# += # - 1', [
    variableUse,
    variableUseAlias,
  ], 'variable += variable - 1');
  test(map, '# += # - 1', [
    deferred,
    variableUseAlias,
  ], 'variable += variable - 1');
  test(map, '# += # + 2', [
    variableUse,
    variableUseAlias,
  ], 'variable += variable + 2');
  test(map, '# += # + 2', [
    deferred,
    variableUseAlias,
  ], 'variable += variable + 2');
  test(map, '# += # * 2', [
    variableUse,
    variableUseAlias,
  ], 'variable += variable * 2');
  test(map, '# += # * 2', [
    deferred,
    variableUseAlias,
  ], 'variable += variable * 2');
}

void test(
  Map<Expression, DeferredExpression> map,
  String template,
  List<Expression> arguments,
  String expectedOutput,
) {
  Expression directExpression =
      js.expressionTemplateFor(template).instantiate(arguments) as Expression;
  _Context directContext = _Context();
  Printer directPrinter = Printer(
    const JavaScriptPrintingOptions(),
    directContext,
  );
  directPrinter.visit(directExpression);
  Expect.equals(expectedOutput, directContext.text);

  Expression deferredExpression =
      js
              .expressionTemplateFor(template)
              .instantiate(arguments.map((e) => map[e]).toList())
          as Expression;
  _Context deferredContext = _Context();
  Printer deferredPrinter = Printer(
    const JavaScriptPrintingOptions(),
    deferredContext,
  );
  deferredPrinter.visit(deferredExpression);
  Expect.equals(expectedOutput, deferredContext.text);

  for (Expression argument in arguments) {
    DeferredExpression deferred = map[argument]!;
    Expect.isTrue(
      directContext.enterPositions.containsKey(argument),
      'Argument ${DebugPrint(argument)} not found in direct enter positions: '
      '${directContext.enterPositions.keys}',
    );
    Expect.isTrue(
      deferredContext.enterPositions.containsKey(argument),
      'Argument ${DebugPrint(argument)} not found in '
      'deferred enter positions: '
      '${deferredContext.enterPositions.keys}',
    );
    Expect.isTrue(
      deferredContext.enterPositions.containsKey(deferred),
      'Argument ${DebugPrint(deferred)} not found in '
      'deferred enter positions: '
      '${deferredContext.enterPositions.keys}',
    );
    Expect.equals(
      directContext.enterPositions[argument],
      deferredContext.enterPositions[argument],
    );
    Expect.equals(
      directContext.enterPositions[argument],
      deferredContext.enterPositions[deferred],
    );

    Expect.isTrue(
      directContext.exitPositions.containsKey(argument),
      'Argument ${DebugPrint(argument)} not found in direct enter positions: '
      '${directContext.exitPositions.keys}',
    );
    Expect.isTrue(
      deferredContext.exitPositions.containsKey(argument),
      'Argument ${DebugPrint(argument)} not found in '
      'deferred enter positions: '
      '${deferredContext.exitPositions.keys}',
    );
    Expect.isTrue(
      deferredContext.exitPositions.containsKey(deferred),
      'Argument ${DebugPrint(deferred)} not found in '
      'deferred enter positions: '
      '${deferredContext.exitPositions.keys}',
    );
    Expect.equals(
      directContext.exitPositions[argument],
      deferredContext.exitPositions[argument],
    );
    Expect.equals(
      directContext.exitPositions[argument],
      deferredContext.exitPositions[deferred],
    );
  }
}

class _DeferredExpression extends DeferredExpression {
  @override
  final Expression value;

  _DeferredExpression(this.value);

  @override
  Precedence get precedenceLevel => value.precedenceLevel;
}

class _Context implements JavaScriptPrintingContext {
  StringBuffer sb = StringBuffer();
  List<String> errors = [];
  Map<Node, int> enterPositions = {};
  Map<Node, _Position> exitPositions = {};

  @override
  bool get isDebugContext => false;

  @override
  void emit(String string) {
    sb.write(string);
  }

  @override
  void enterNode(Node node, int startPosition) {
    enterPositions[node] = startPosition;
  }

  @override
  void exitNode(
    Node node,
    int startPosition,
    int endPosition,
    int? closingPosition,
  ) {
    exitPositions[node] = _Position(
      startPosition,
      endPosition,
      closingPosition,
    );
    Expect.equals(enterPositions[node], startPosition);
  }

  @override
  void error(String message) {
    errors.add(message);
  }

  String get text => sb.toString();
}

class _Position {
  final int startPosition;
  final int endPosition;
  final int? closingPosition;

  _Position(this.startPosition, this.endPosition, this.closingPosition);

  @override
  int get hashCode =>
      13 * startPosition.hashCode +
      17 * endPosition.hashCode +
      19 * closingPosition.hashCode;

  @override
  bool operator ==(Object other) {
    if (identical(this, other)) return true;
    return other is _Position &&
        startPosition == other.startPosition &&
        endPosition == other.endPosition &&
        closingPosition == other.closingPosition;
  }

  @override
  String toString() {
    return '_Position(start=$startPosition,'
        'end=$endPosition,closing=$closingPosition)';
  }
}