private SyntaxTreeNode AddOp()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode() { Token = curToken };
if (curToken.TokenType == TokenType.Plus)
Match(TokenType.Plus);
else if (curToken.TokenType == TokenType.Minus)
Match(TokenType.Minus);
return node;
}
private SyntaxTreeNode AssignStatement()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode();
if (curToken.TokenType == TokenType.Identifier)
{
node.Left = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Identifier);
}
if (curToken.TokenType == TokenType.Assignment)
{
node.Token = curToken;
Match(TokenType.Assignment);
}
node.Right = Expression();
return node;
}
private SyntaxTreeNode ComparisonOp()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode() { Token = curToken };
if (curToken.TokenType == TokenType.Greater)
Match(TokenType.Greater);
else if (curToken.TokenType == TokenType.LessThan)
Match(TokenType.LessThan);
else if (curToken.TokenType == TokenType.LessThanOrEqual)
Match(TokenType.LessThanOrEqual);
else if (curToken.TokenType == TokenType.GreaterThanOrEqual)
Match(TokenType.GreaterThanOrEqual);
else if (curToken.TokenType == TokenType.Equal)
Match(TokenType.Equal);
return node;
}
private SyntaxTreeNode Term()
{
SyntaxTreeNode node = Factor();
while (curToken.TokenType == TokenType.Multiply || curToken.TokenType == TokenType.Division)
{
SyntaxTreeBinaryNode temp = new SyntaxTreeBinaryNode() { Token = curToken };
temp.Left = node;
Match(curToken.TokenType);
temp.Right = Factor();
node = temp;
}
return node;
}
private SyntaxTreeNode WriteStatement()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Write);
node.Left = Expression();
return node;
}
private SyntaxTreeNode RepeatStatement()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Repeat);
SyntaxTreeNode statements = StatementSequence();
Match(TokenType.Until);
SyntaxTreeNode condition = Expression();
node.Left = condition;
node.Right = statements;
return node;
}
private SyntaxTreeNode SimpleExpression()
{
SyntaxTreeNode node = Term();
while (curToken.TokenType == TokenType.Plus || curToken.TokenType == TokenType.Minus)
{
SyntaxTreeBinaryNode temp = new SyntaxTreeBinaryNode() { Token = curToken };
temp.Left = node;
Match(curToken.TokenType);
temp.Right = Term();
node = temp;
}
return node;
}
private SyntaxTreeNode ReadStatement()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Read);
if (curToken.TokenType == TokenType.Identifier)
{
node.Left = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Identifier);
}
return node;
}
private SyntaxTreeNode MulOp()
{
SyntaxTreeBinaryNode node = new SyntaxTreeBinaryNode() { Token = curToken };
if (curToken.TokenType == TokenType.Multiply)
Match(TokenType.Multiply);
else if (curToken.TokenType == TokenType.Division)
Match(TokenType.Division);
return node;
}
private SyntaxTreeNode IfStatement()
{
SyntaxTreeBinaryNode ifNode = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.If);
ifNode.Left = Expression();
Match(TokenType.Then);
SyntaxTreeNode thenPart = StatementSequence();
SyntaxTreeBinaryNode ifParts = new SyntaxTreeBinaryNode() { Left = thenPart };
if (curToken.TokenType == TokenType.Else)
{
Match(TokenType.Else);
ifParts.Right = StatementSequence();
}
ifNode.Right = ifParts;
Match(TokenType.End);
return ifNode;
}
private SyntaxTreeNode Factor()
{
SyntaxTreeNode node = null;
if (curToken.TokenType == TokenType.LeftParenthesis)
{
Match(TokenType.LeftParenthesis);
node = Expression();
Match(TokenType.RightParenthesis);
}
else if (curToken.TokenType == TokenType.Number)
{
node = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Number);
}
else
{
node = new SyntaxTreeBinaryNode() { Token = curToken };
Match(TokenType.Identifier);
}
return node;
}
private SyntaxTreeNode Expression()
{
SyntaxTreeNode node = SimpleExpression();
if (IsComparison(curToken.TokenType))
{
SyntaxTreeBinaryNode temp = new SyntaxTreeBinaryNode() { Token = curToken };
Match(curToken.TokenType);
temp.Left = node;
temp.Right = SimpleExpression();
node = temp;
}
return node;
}
