public void ExecuteConstantExpression()
{
ConstantExpression expr = new ConstantExpression(1);
ExpressionCommand command = new ExpressionCommand(expr);
Assert.AreEqual(1, command.Execute(null));
Assert.AreEqual(expr, command.Expression);
}
public ICommand ParseCommand()
{
Token token = this.NextToken();
if (token == null)
return null;
if (token.Type == TokenType.Separator)
{
if (token.Value == ";")
return NullCommand.Instance;
if (token.Value == "{")
{
ICommand commands = new CompositeCommand(this.ParseCommands());
this.ParseToken("}", TokenType.Separator);
return commands;
}
}
if (token.Type == TokenType.Name)
{
if (token.Value == "if")
return this.ParseIfCommand();
if (token.Value == "while")
return this.ParseWhileCommand();
if (token.Value == "class")
return this.ParseDefineClassCommand();
if (token.Value == "return")
{
var expr = this.ParseExpression();
this.ParseToken(";", TokenType.Separator);
return new ReturnCommand(expr);
}
if (token.Value == "void")
return this.ParseDefineFunction(this.ParseName());
if (token.Value == "main")
return this.ParseDefineFunction(token.Value);
}
this.PushToken(token);
IExpression expression = this.ParseExpression();
if (expression == null)
return null;
token = this.NextToken();
if (token != null && token.Type == TokenType.Name && this.IsTypeExpression(expression))
{
if (this.TryPeekToken("(", TokenType.Separator))
return this.ParseDefineFunction(token.Value);
return this.ParseDefineVariableCommand(expression, token.Value);
}
ICommand command = null;
if (expression is VariableExpression && token.Type == TokenType.Operator && token.Value == "=")
{
string name = ((VariableExpression)expression).Name;
IExpression expr = this.ParseExpression();
command = new SetVariableCommand(name, expr);
token = this.NextToken();
}
else
command = new ExpressionCommand(expression);
if (token == null || token.Type != TokenType.Separator || token.Value != ";")
throw new ParserException("Expected ';'");
return command;
}
