// Set the current line number as a statement node attribute.
protected internal void SetLineNumber(ICodeNode node, Token token)
{
if (node != null)
{
node.SetAttribute(ICodeKeyImplementation.LINE, token.lineNumber);
}
}
public override ICodeNode Parse(Token token)
{
// Create the ASSIGN node.
ICodeNode assignNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.ASSIGN);
string targetName = token.text.ToLower();
SymbolTableEntry targetID = symbolTableStack.Lookup(targetName);
if (targetID == null)
{
targetID = symbolTableStack.EnterLocal(targetName);
}
targetID.AppendLineNumber(token.lineNumber);
token = NextToken();
ICodeNode variableNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.VARIABLE);
variableNode.SetAttribute(ICodeKeyImplementation.ID, targetID);
assignNode.AddChild(variableNode);
if (token.type == PascalTokenType.COLON_EQUALS)
{
token = NextToken();
}
else
{
errorHandler.flag(token, PascalErrorCode.MISSING_COLON_EQUALS, this);
}
ExpressionParser expressionParser = new ExpressionParser(this);
assignNode.AddChild(expressionParser.Parse(token));
return(assignNode);
}
// Set the current line number as a statement node attribute.
protected internal void SetLineNumber(ICodeNode node, Token token)
{
if (node != null)
node.SetAttribute(ICodeKeyImplementation.LINE, token.lineNumber);
}
private ICodeNode ParseFactor(Token token)
{
TokenType tokenType = token.type;
ICodeNode rootNode = null;
switch (tokenType.ToString())
{
case "IDENTIFIER":
{
// Look up the identifier in the symbol table stack.
// Flag the identifier as undefined if it's not found.
String name = token.text.ToLower();
SymbolTableEntry id = symbolTableStack.Lookup(name);
if (id == null)
{
errorHandler.flag(token, PascalErrorCode.IDENTIFIER_UNDEFINED, this);
id = symbolTableStack.EnterLocal(name);
}
rootNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.VARIABLE);
rootNode.SetAttribute(ICodeKeyImplementation.ID, id);
id.AppendLineNumber(token.lineNumber);
token = NextToken(); // consume the identifier
break;
}
case "INTEGER":
{
// Create an INTEGER_CONSTANT node as the root node.
rootNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.INTEGER_CONSTANT);
rootNode.SetAttribute(ICodeKeyImplementation.VALUE, token.value);
token = NextToken(); // consume the number
break;
}
case "REAL":
{
// Create an REAL_CONSTANT node as the root node.
rootNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.REAL_CONSTANT);
rootNode.SetAttribute(ICodeKeyImplementation.VALUE, token.value);
token = NextToken(); // consume the number
break;
}
case "STRING":
{
String value = (String)token.value;
// Create a STRING_CONSTANT node as the root node.
rootNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.STRING_CONSTANT);
rootNode.SetAttribute(ICodeKeyImplementation.VALUE, value);
token = NextToken(); // consume the string
break;
}
case "NOT":
{
token = NextToken(); // consume the NOT
// Create a NOT node as the root node.
rootNode = ICodeFactory.CreateICodeNode(ICodeNodeTypeImplementation.NOT);
// Parse the factor. The NOT node adopts the
// factor node as its child.
rootNode.AddChild(ParseFactor(token));
break;
}
case "LEFT_PAREN":
{
token = NextToken(); // consume the (
// Parse an expression and make its node the root node.
rootNode = ParseExpression(token);
// Look for the matching ) token.
token = CurrentToken();
if (token.type == PascalTokenType.RIGHT_PAREN)
{
token = NextToken(); // consume the )
}
else
{
errorHandler.flag(token, PascalErrorCode.MISSING_RIGHT_PAREN, this);
}
break;
}
default:
{
errorHandler.flag(token, PascalErrorCode.UNEXPECTED_TOKEN, this);
break;
}
}
return(rootNode);
}
