/// <summary>
/// Returns a factor (integer, string, boolean, unaryast)
/// </summary>
/// <returns>Factor AST</returns>
private AST Factor()
{
Token token = this.currentToken;
if (token.type == TokenType.INTEGER)
{
this.ConsumeToken(TokenType.INTEGER);
return(new NumericAST(token));
}
else if (token.type == TokenType.STRING)
{
this.ConsumeToken(TokenType.STRING);
return(new StringAST(token));
}
else if (token.type == TokenType.BOOL)
{
this.ConsumeToken(TokenType.BOOL);
return(new BooleanAST(token));
}
else if (token.type == TokenType.PARENLEFT)
{
this.ConsumeToken(TokenType.PARENLEFT);
AST ast = this.Expression();
this.ConsumeToken(TokenType.PARENRIGHT);
return(ast);
}
else if (token.type == TokenType.PLUS)
{
this.ConsumeToken(TokenType.PLUS);
AST ast = new OneOperatorAST(token, this.Factor());
return(ast);
}
else if (token.type == TokenType.MINUS)
{
this.ConsumeToken(TokenType.MINUS);
AST ast = new OneOperatorAST(token, this.Factor());
return(ast);
}
else if (token.type == TokenType.LOGICAL_NOT)
{
this.ConsumeToken(TokenType.LOGICAL_NOT);
AST ast = new OneOperatorAST(token, this.Factor());
return(ast);
}
else
{
AST ast = this.Variable();
return(ast);
}
}
/// <summary>
/// Traverses unary operation AST
/// </summary>
/// <param name="ast"></param>
/// <returns>OneOperatorAST</returns>
private object VisitOneOperatorAST(OneOperatorAST ast)
{
object component1 = this.VisitNode(ast.expression);
if (component1 is bool)
{
return(!(bool)component1);
}
else
{
if (ast.token.type == TokenType.MINUS)
{
return(-(int)this.VisitNode(ast.expression));
}
return(+(int)this.VisitNode(ast.expression));
}
}
