void BuildOperand(ExpressionBuilder builder)
{
//literal or identifier
if (Accept (Category.Literal_Integer,
Category.Literal_String,
Category.Identifier)) {
builder.Offer(accepted);
//nested expression
} else if (Accept (Category.Left_Bracket)) {
builder.Offer(accepted);
BuildExpression (builder);
Expect (Category.Rigth_Bracket);
builder.Offer (accepted);
} else {
errors.AddError(token, ErrorType.SyntaxError, "Expecting an operand");
}
}
Expression ParseExpression(ISet<Category> follow, ISet<Category> starters)
{
ExpressionBuilder builder = new ExpressionBuilder(errors);
BuildExpression(builder);
return builder.Build();
}
void BuildExpression(ExpressionBuilder builder)
{
if (Accept (Category.Unary_Operator)) {
builder.Offer(accepted);
BuildOperand (builder);
} else {
BuildOperand (builder);
if (Accept (Category.Binary_Operator)) {
builder.Offer(accepted);
BuildOperand (builder);
}
}
}