private void ParseFactor()
{
var token = CurrentToken();
switch (token.m_Type)
{
case PascalTokenType.Unsigned:
int value = (int)token.m_Value;
CodeGenerator.Emit(Operation.LoadLiteral, 0, value);
ConsumeCurrentToken();
break;
case PascalTokenType.Identifier:
var result = m_SymbolTableStack.Lookup(token.m_Text);
if (result == null)
{
//TODO: error
ErrorReporter.RecordError(4, m_Scanner.m_CurrentToken.m_LineNumber);
throw new Exception();
}
var type = (result as SymbolTableEntry).GetAttribute(SymbolTableAttributeKeyType.Type);
switch (type)
{
case SymbolTableEntryType.Constant:
int const_value = (int)(result as SymbolTableEntry).GetAttribute(SymbolTableAttributeKeyType.ConstantValue);
CodeGenerator.Emit(Operation.LoadLiteral, 0, const_value);
break;
case SymbolTableEntryType.Variable:
var current_nesting_level = m_SymbolTableStack.GetCurrentNestingLevel();
var reference_nesting_level = result.GetSymbolTable().GetNestingLevel();
int offset = (int)(result as SymbolTableEntry).GetAttribute(SymbolTableAttributeKeyType.Offset);
CodeGenerator.Emit(Operation.LoadVariable, current_nesting_level - reference_nesting_level, offset);
break;
default:
break;
}
ConsumeCurrentToken();
break;
case PascalTokenType.LeftParenthesis:
ConsumeCurrentToken(); //skip (
var expression_parser = new ExpressionParser(this);
expression_parser.ParseExpression();
token = CurrentToken();
if (token.m_Text != ")")
{
//TODO: error
ErrorReporter.RecordError(5, m_Scanner.m_CurrentToken.m_LineNumber);
throw new Exception();
}
ConsumeCurrentToken(); //skip )
break;
default:
//TODO: error
ErrorReporter.RecordError(0, m_Scanner.m_CurrentToken.m_LineNumber);
throw new Exception();
}
}
public override void Parse()
{
try
{
var token = CurrentToken();
switch (token.m_Type)
{
case PascalTokenType.Begin:
var compound_parser = new CompoundParser(this);
compound_parser.Parse();
break;
case PascalTokenType.Identifier:
var assignment_parser = new AssignmentParser(this);
assignment_parser.Parse();
break;
case PascalTokenType.If:
var if_parser = new IfStatementParser(this);
if_parser.Parse();
break;
case PascalTokenType.Call:
var procedure_parser = new ProcedureParser(this);
procedure_parser.Parse();
break;
case PascalTokenType.While:
var while_parser = new WhileStatementParser(this);
while_parser.Parse();
break;
case PascalTokenType.Read:
var read_parser = new ReadParser(this);
read_parser.Parse();
break;
case PascalTokenType.Write:
var write_parser = new WriteParser(this);
write_parser.Parse();
break;
case PascalTokenType.Repeat:
var repeat_parser = new RepeatStatementParser(this);
repeat_parser.Parse();
break;
//case PascalTokenType.Semicolon:
// ConsumeCurrentToken();
// break;
default:
if (!FollowStatement.Contains(token.m_Text))
{
//TODO: error
ErrorReporter.RecordError(0, m_Scanner.m_CurrentToken.m_LineNumber, ",possibility: missing ;");
throw new Exception();
}
break;
}
}
catch (Exception)
{
}
}