/// <summary>
///
/// </summary>
/// <returns></returns>
public static new EXPRESSION parse(Token first, iSCOPE context)
{
EXPRESSION result = null;
Token token = (first == null) ? get() : first;
Token begin = token;
switch (token.code)
{
case TokenCode.This:
forget();
UNIT unit = Context.unit();
if (unit == null)
{
// Error message!
result = new THIS(null);
}
else
{
result = new THIS(unit);
result.setSpan(token);
}
break;
case TokenCode.Return:
if (!ENTITY.weAreWithinEnsure)
{
break;
}
forget();
ROUTINE routine = Context.routine();
if (routine == null)
{
} // error
else
{
result = new RETURN_EXPR(routine);
result.setSpan(token);
}
break;
case TokenCode.Old:
forget();
result = EXPRESSION.parse(null, context);
Span end = result.span;
OLD old = new OLD(result);
result.parent = old;
result = old;
result.setSpan(begin.span, end);
break;
case TokenCode.If:
result = CONDITIONAL.parse(context);
break;
case TokenCode.LParen:
forget();
Span start_tuple = token.span;
result = EXPRESSION.parse(null, context);
token = get();
if (token.code == TokenCode.Comma)
{
// Seems to be a tuple
forget();
TUPLE_EXPR tuple = new TUPLE_EXPR();
tuple.add(result);
while (true)
{
EXPRESSION expr = EXPRESSION.parse(null, context);
tuple.add(expr);
token = get();
if (token.code != TokenCode.Comma)
{
break;
}
forget();
}
result = tuple;
}
end = expect(TokenCode.RParen).span;
result.setSpan(token.span, end);
break;
case TokenCode.Identifier:
if (first == null)
{
forget(); ////// perhaps the same condition should be added for all cases?
}
DECLARATION d = Context.find(token);
if (d == null)
{
result = new UNRESOLVED(context, new IDENTIFIER(token));
}
else
{
result = new REFERENCE(d);
}
Token token2 = get();
if (token2.code == TokenCode.LBracket)
{
UNIT_REF unitRef = UNIT_REF.parse(token, false, context);
result = new NEW(unitRef);
result.setSpan(unitRef.span);
}
else
{
result.setSpan(token);
}
break;
case TokenCode.Integer:
case TokenCode.Real:
case TokenCode.String:
case TokenCode.Character:
result = new LITERAL(token.value, token.span, token.code);
result.setSpan(token);
forget();
break;
default:
return(null);
}
// result.setSpan(token);
return(result);
}
public void add(DECLARATION d)
{
body.Add(d);
}
public REFERENCE(DECLARATION d)
{
declaration = d;
}
/// <summary>
/// The function processes all kinds of statements including
/// assignments, calls, and variable/constant declarations.
/// </summary>
/// <param name="context"></param>
/// <returns>true, if any construct (a statement, or a simple declaration)
/// was processed, and false otherwise.</returns>
public static bool parse(iSCOPE context, TokenCode stop1, TokenCode stop2, TokenCode stop3)
{
Debug.Indent();
Debug.WriteLine("Entering STATEMENT.parse");
bool result = true;
Token token = get();
Token begin = token;
if (token.code == stop1 && stop1 != TokenCode.ERROR)
{
goto Finish;
}
if (token.code == stop2 && stop2 != TokenCode.ERROR)
{
goto Finish;
}
if (token.code == stop3 && stop3 != TokenCode.ERROR)
{
goto Finish;
}
switch (token.code)
{
// case TokenCode.Pure: -- doesn't make any sense
case TokenCode.Safe:
case TokenCode.Routine:
ROUTINE.parse(token, false, false, false, 0, context);
break;
case TokenCode.If:
IF.parse(context);
break;
case TokenCode.While:
case TokenCode.Loop:
LOOP.parse(null, context);
break;
// Break
// : break [ Label ]
//
// Label
// : Identifier
case TokenCode.Break:
BREAK.parse(context);
break;
// Statement
// : ...
// | raise [ Expression ]
case TokenCode.Raise:
forget();
RAISE.parse(token.span, context);
break;
// Statement
// : ...
// | check PredicatesList end
// | ...
case TokenCode.Check:
CHECK.parse(context);
break;
// Statement
// : ...
// | return [ Expression ]
// | ...
case TokenCode.Return:
forget();
EXPRESSION expr = EXPRESSION.parse(null, context); // can be null
RETURN ret = new RETURN(expr);
if (expr != null)
{
expr.parent = ret;
ret.setSpan(begin.span, expr.span);
}
else
{
ret.setSpan(begin);
}
context.add(ret);
break;
// Statement
// : ...
// | Try
// | ...
//
// Try
// : try { Statement } Catches [ Else ] end
//
// Catches
// : catch [ "(" [ Identifier ":" ] Type ")" ] { Statement }
//
// Else
// : else { Statement }
case TokenCode.Try:
TRY.parse(context);
break;
// Statement
// : ...
// | ? Identifier
// | ...
//
case TokenCode.Question:
break;
case TokenCode.Init:
// Initializer call
forget();
Token start = token;
DECLARATION init = Context.find(INITIALIZER.initName);
EXPRESSION initRef;
if (init != null)
{
initRef = new REFERENCE(init);
}
else
{
initRef = new UNRESOLVED(context, new IDENTIFIER(INITIALIZER.initName));
}
CALL call = new CALL(initRef);
token = expect(TokenCode.LParen);
while (true)
{
EXPRESSION argument = EXPRESSION.parse(null, context);
call.add(argument);
argument.parent = call;
token = get();
if (token.code == TokenCode.Comma)
{
forget(); continue;
}
break;
}
token = expect(TokenCode.RParen);
call.setSpan(start.span, token.span);
context.add(call);
break;
case TokenCode.Identifier:
{
// Several different cases:
// - a label in front of while/loop
// - a declaration
// - a statement
forget();
Token next = get();
if (next.code == TokenCode.LParen)
{
forget();
TokenCode codeAfter = saveTokensUntilRightParenth(next);
switch (codeAfter)
{
case TokenCode.Colon:
case TokenCode.Is:
// case TokenCode.Do:
case TokenCode.Arrow:
//This as a routine declaration!!
ROUTINE.parse(token, false, false, false, 0, context);
goto Weiter;
}
}
EXPRESSION attempt = EXPRESSION.parse(token, context);
if (attempt is UNRESOLVED)
{
// Might be a label or a declaration...
Token idd = new Token(attempt.span, TokenCode.Identifier,
(attempt as UNRESOLVED).name.identifier,
new Category(CategoryCode.identifier));
token = get();
switch (token.code)
{
case TokenCode.Is:
case TokenCode.Comma:
// This is definitely a declaration
forget();
VARIABLE.parse(false, false, false, false, idd, token, context);
goto Weiter;
case TokenCode.Colon:
forget();
Token token2 = get();
if (token2.code == TokenCode.While || token2.code == TokenCode.Loop)
{
// This is a real label! Don't 'forget()'.
LOOP.parse(idd, context);
}
else
{
// This is definitely a variable declaration.
// Don't forget()
VARIABLE.parse(false, false, false, false, idd, token, context);
}
goto Weiter;
default:
// Nothing to do; just going further
break;
}
}
// 'attempt' is something else: a call or the left part of an assignment
token = get();
if (token.code == TokenCode.Assign)
{
forget();
EXPRESSION right = EXPRESSION.parse(null, context);
ASSIGNMENT res = new ASSIGNMENT(attempt, right);
res.setSpan(attempt.span, right.span);
context.add(res);
}
else
{
if (!(attempt is CALL)) // something's wrong
{
result = false;
}
context.add(attempt);
}
Weiter:
break;
}
case TokenCode.Const:
// Something like
// const a is 5...
// OR
// const is a, b, ... end
forget(); token = get();
if (token.code == TokenCode.Is)
{
forget();
CONSTANT.parse(context);
}
else
{
VARIABLE.parse(false, false, true, false, null, null, context);
}
break;
default:
// Something else, e.g., (a... or this...
// Either a function call or an assignment.
//
// this := ...
// (if cond then a else b).f ...
// ^
EXPRESSION e = EXPRESSION.parse(null, context);
if (e == null)
{
// Either an error or just the end of statement sequence
result = false;
break;
}
token = get();
if (token.code == TokenCode.Assign)
{
forget();
EXPRESSION right = EXPRESSION.parse(null, context);
ASSIGNMENT assignment = new ASSIGNMENT(e, right);
assignment.setSpan(e.span, right.span);
context.add(assignment);
}
else
{
context.add(e);
}
break;
}
Finish:
Debug.WriteLine("Exiting STATEMENT.parse");
Debug.Unindent();
return(result);
}
