public ITreeNode Program()
{
ITreeNode programNode = new ErrorNode();
switch (curTokenType)
{
case TokenType.BEGINBL:
Match(ref matchToken, TokenType.BEGINBL);
ITreeNode someStatement = Program();
BlockNode block = new BlockNode();
block.addStatement(someStatement);
while (curTokenType != TokenType.ENDBL)
{
someStatement = Program();
block.addStatement(someStatement);
}
Match(ref matchToken, TokenType.ENDBL);
programNode = block;
break;
case TokenType.LABEL:
Match(ref matchToken, TokenType.LABEL);
LabelNode labeledBlock = new LabelNode(matchToken.getValue());
ITreeNode labeledStatement;
do
{
labeledStatement = Program();
labeledBlock.addStatement(labeledStatement);
}
while (curTokenType != TokenType.EOF);
programNode = labeledBlock;
break;
case TokenType.INTDEC:
Match(ref matchToken, TokenType.INTDEC);
Match(ref matchToken, TokenType.ID);
programNode = new IdentifierDeclarationNode(IdentifierType.INT, matchToken.getValue());
Match(ref matchToken, TokenType.EOS);
break;
case TokenType.BOOLDEC:
Match(ref matchToken, TokenType.BOOLDEC);
Match(ref matchToken, TokenType.ID);
programNode = new IdentifierDeclarationNode(IdentifierType.BOOL, matchToken.getValue());
Match(ref matchToken, TokenType.EOS);
break;
case TokenType.FOR:
Match(ref matchToken, TokenType.FOR);
Match(ref matchToken, TokenType.LPAREN);
AssignmentNode init = (AssignmentNode)Program();
AssignmentNode step = (AssignmentNode)Program();
BooleanExpressionNode condition = (BooleanExpressionNode)BooleanExpression();
Match(ref matchToken, TokenType.RPAREN);
BlockNode forBody = (BlockNode)Program();
programNode = new ForNode(init, step, condition, forBody);
break;
/*case TokenType.FUN:
Match(ref matchToken, TokenType.FUN);
IdentifierNode id = (IdentifierNode)Factor();
programNode = new FunctionNode(id);
Match(ref matchToken, TokenType.EOS);
break;*/
case TokenType.GOTO:
Match(ref matchToken, TokenType.GOTO);
Match(ref matchToken, TokenType.ID);
IdentifierNode gotoLabel = new IdentifierNode(matchToken.getValue(), IdentifierType.LABEL);
programNode = new GotoNode(gotoLabel);
Match(ref matchToken, TokenType.EOS);
break;
case TokenType.ID:
Match(ref matchToken, TokenType.ID);
IdentifierNode assignId = new IdentifierNode(matchToken.getValue(), IdentifierType.UNKNOWN);
Match(ref matchToken, TokenType.ASSIGN);
BooleanExpressionNode assignValue = (BooleanExpressionNode)BooleanExpression();
programNode = new AssignmentNode(assignId, assignValue);
Match(ref matchToken, TokenType.EOS);
break;
case TokenType.IF:
Match(ref matchToken, TokenType.IF);
ITreeNode thenBranch;
ITreeNode elseBranch;
Match(ref matchToken, TokenType.LPAREN);
BooleanExpressionNode ifCondition = (BooleanExpressionNode)BooleanExpression();
Match(ref matchToken, TokenType.RPAREN);
Match(ref matchToken, TokenType.THEN);
thenBranch = (BlockNode)Program();
if (curTokenType == TokenType.ELSE)
{
Match(ref matchToken, TokenType.ELSE);
elseBranch = (BlockNode)Program();
}
else
{
elseBranch = new BlankNode();
}
programNode = new IfNode(ifCondition, thenBranch, elseBranch);
break;
/*case TokenType.LET:
Match(ref matchToken, TokenType.LET);
IdentifierNode shortId = (IdentifierNode)Factor();
Match(ref matchToken, TokenType.ASSIGN);
BooleanExpressionNode subst = (BooleanExpressionNode)BooleanExpression();
Match(ref matchToken, TokenType.IN);
BooleanExpressionNode target = (BooleanExpressionNode)BooleanExpression();
programNode = new LetNode(shortId, subst, target);
Match(ref matchToken, TokenType.EOS);
break;*/
case TokenType.PRINT:
Match(ref matchToken, TokenType.PRINT);
Match(ref matchToken, TokenType.LPAREN);
BooleanExpressionNode printArgument = (BooleanExpressionNode)BooleanExpression();
Match(ref matchToken, TokenType.RPAREN);
programNode = new PrintNode(printArgument);
Match(ref matchToken, TokenType.EOS);
break;
case TokenType.WHILE:
Match(ref matchToken, TokenType.WHILE);
Match(ref matchToken, TokenType.LPAREN);
BooleanExpressionNode whileCondition = (BooleanExpressionNode)BooleanExpression();
Match(ref matchToken, TokenType.RPAREN);
BlockNode whileBody = (BlockNode)Program();
programNode = new WhileNode(whileCondition, whileBody);
break;
case TokenType.EOF:
programNode = new BlankNode();
break;
default:
Expect(TokenType.UNKNOWN, lookAheadToken);
break;
}
return programNode;
}