public Node Clone()
{
Node n = new Node();
n.Attributes = Attributes;
n.Value = Value;
n.Left = Left;
n.Right = Right;
return n;
}
/// <summary>
/// Removes any empty child nodes of the specified node
/// </summary>
private void RemoveRecursive(Node node)
{
if (node.Left != null)
{
node.Left.RemoveEmptyChildren();
if (node.Left.IsEmpty())
node.Left = null;
}
if (node.Right != null)
{
node.Right.RemoveEmptyChildren();
if (node.Right.IsEmpty())
node.Right = null;
}
}
public void Print(Node node, String dash)
{
Console.Write("\n" + dash + "-> " + node.Value);
String attributes = "";
if (node.Attributes[0] != "")
attributes += " " + node.Attributes[0] + ",";
if (node.Attributes[1] != "")
attributes += " " + node.Attributes[1] + ",";
if (node.Attributes[2] != "")
attributes += " " + node.Attributes[2] + ",";
if (node.Left != null)
node.Left.Print(node.Left, dash + "-");
if (node.Right != null)
node.Right.Print(node.Right, dash + "-");
}
private void ParseBlock(ref Node node)
{
//A block is a number of statements enclosed in {...}
if (CurrentToken.Value.Equals("{"))
{
//Each block starts a new scope
Database.NewScope();
NextToken();
ParseStatements(ref node);
if (!CurrentToken.Value.Equals("}"))
Error("Expected ending of the block: }", CurrentToken.LineStart);
Database.ParentScope();
}
//Or it can just be a single statement
else
ParseStatement(ref node);
}
private void ParseAssign(ref Node node)
{
node = new Node();
node.Value = "ASSIGN";
node.Left = new Node();
//Parse the variable
Int32 type = ParseVariableFactor(ref node.Left);
node.Attributes[2] = Database.GetTypeName(type);
//Assignment statement must be followed by an equal sign
if (CurrentToken.Value != "=")
Error("Expected assignment operator: =", CurrentToken.LineStart);
NextToken();
//Expression is on the right child
Int32 exprType = ParseExpression(ref node.Right, 0);
//Check type match between variable and expression
if (!Database.CheckTypesAreEqual(exprType, type))
Error("Assignment types mismatched", CurrentToken.LineStart);
}
private void ParseVariableDeclaration(ref Node node)
{
VariableInfo var = new VariableInfo();
ParseDeclaration(ref var);
node = new Node();
node.Value = "DECLARE";
node.Attributes[0] = Database.GetVarId(var.Name, null);
node.Attributes[1] = Database.GetTypeName(var.Type);
}
private void ParseStatements(ref Node node)
{
if (CurrentToken.Value.Equals("}"))
return;
node = new Node();
node.Value = "STATEMENT";
if (!CurrentToken.Value.Equals(";"))
ParseStatement(ref node.Left);
//if (!CurrentToken.Value.Equals(";"))
//Error("Expected semicolon", CurrentToken.LineStart);
NextToken();
ParseStatements(ref node.Right);
}
private void ParseStatement(ref Node node)
{
//Check the first token to determine what to do
if (CurrentToken.Value.Equals("IF"))
ParseIf(ref node);
else if (CurrentToken.Value.Equals("WHILE"))
ParseWhile(ref node);
else if (CurrentToken.Value.Equals("RETURN"))
ParseReturn(ref node);
else if (Database.CheckType(CurrentToken.Value))
ParseVariableDeclaration(ref node);
else if (CheckAssignComing())
ParseAssign(ref node);
else
ParseFactorEx(ref node);//Error("Unknown statement", CurrentToken.LineStart);
}
private void ParseReturn(ref Node node)
{
node = new Node();
node.Value = "RETURN";
NextToken();
if (RetType != Database.GetType("VOID"))
{
if (!Database.CheckTypesAreEqual(ParseExpression(ref node.Right, 0), RetType))
{
Error("Return and function types mistmatched", CurrentToken.LineStart);
}
}
}
private void ParseIf(ref Node node)
{
node = new Node();
node.Value = "IF";
NextToken();
if (!CurrentToken.Value.Equals("("))
Error("Enclose the condition in (...)", CurrentToken.LineStart);
NextToken();
if (ParseExpression(ref node.Left, 0) != Database.GetType("BOOL"))
Error("IF expressions must be boolean in type", CurrentToken.LineStart);
if (!CurrentToken.Value.Equals(")"))
Error("Enclose the condition in (...)", CurrentToken.LineStart);
NextToken();
ParseBlock(ref node.Right);
//If followed by an else statement, parse the else tree
//Node's value is else
//If -> Else If then left and right are both if trees
//If -> Else, left child is previous IF tree and right child is the series of else statements
NextToken();
if (CurrentToken.Value.Equals("ELSE"))
{
NextToken();
NextToken();
Node temp = node;
node.Left = new Node();
node.Left = temp;
node.Value = "ELSE";
if (CurrentToken.Value.Equals("IF"))
ParseIf(ref node.Right);
else
ParseBlock(ref node.Right);
}
}
private void ParseFunctionsDefinitions(ref Node node)
{
RetType = -1;
Node currentNode;
Boolean firstFunc = true;
ResetToken();
while (CurrentToken.LineStart != Int32.MaxValue)
{
if (CheckFunctionIncoming())
{
Database.NewScope();
if (firstFunc)
{
node = new Node();
currentNode = node;
firstFunc = false;
}
else
{
node.Right = new Node();
node = node.Right;
}
ParseFunction(ref node);
Database.ParentScope();
}
NextToken();
}
}
private void ParseFunction(ref Node node)
{
RetType = ParseType();
node.Value = "FUNCTION";
node.Attributes[0] = CurrentToken.Value;
Database.AddFunctionToScope(CurrentToken.Value);
//Skip parameter list - preparser took care of this
while (!CurrentToken.Value.Equals(")"))
NextToken();
NextToken();
//{ must exist
if (!CurrentToken.Value.Equals("{"))
Error("Expected function block {...}", CurrentToken.LineStart);
NextToken();
ParseStatements(ref node.Left);
if (!CurrentToken.Value.Equals("}"))
Error("Invalid ending: expected '}'", CurrentToken.LineStart);
NextToken();
}
/// <summary>
/// Factors can be prefixed or postfixed with unary operators
/// </summary>
private Int32 ParseFactorEx(ref Node node)
{
//If a pre-unary operator exists
if (Database.CheckUnaryOperator(CurrentToken.Value, true))
{
node = new Node();
node.Value = CurrentToken.Value;
node.Attributes[0] = "UNARY_OPERATOR";
NextToken();
Int32 type = ParseFactorEx(ref node.Right);
node.Attributes[2] = Database.GetTypeName(Database.GetReturnType(node.Value, type, true));
return Database.GetType(node.Attributes[2]);
}
//No more pre-operators, parse the actual factor
ParseFactor(ref node);
//Check for post-unary operators
while (Database.CheckUnaryOperator(CurrentToken.Value, false))
{
Node temp;
temp = node;
node.Left = new Node();
node.Left = temp;
node.Value = CurrentToken.Value;
node.Attributes[0] = "UNARY_OPERATOR";
NextToken();
Int32 type = Database.GetReturnType(node.Value,
Database.GetType(node.Left.Attributes[2]),
false);
node.Attributes[2] = Database.GetTypeName(type);
}
return Database.GetType(node.Attributes[2]);
}
private Int32 ParseFactor(ref Node node)
{
//A factor can be an expression in brackets
if (CurrentToken.Value.Equals("("))
{
if (CurrentToken.Value.Equals("("))
NextToken();
Int32 type = ParseExpression(ref node, 0);
if (!CurrentToken.Value.Equals(")"))
Error("Expected ending parenthesis: )", CurrentToken.LineStart);
NextToken();
//A bracketed expression can also have a member
if (CurrentToken.Value.Equals("."))
type = ParseMember(ref node, type);
return type;
}
node = new Node();
if (CurrentToken.Type.Equals(TokenType.String))
{
node.Value = CurrentToken.Value;
node.Attributes[0] = "VALUE";
node.Attributes[2] = "STRING";
NextToken();
return Database.GetType(node.Attributes[2]);
}
else if (CurrentToken.Type.Equals(TokenType.Number))
{
node.Value = CurrentToken.Value;
node.Attributes[0] = "VALUE";
if (CurrentToken.Value.Contains('.'))
node.Attributes[2] = "DOUBLE";
else
node.Attributes[2] = "INT";
NextToken();
return Database.GetType(node.Attributes[2]);
}
else if (CurrentToken.Type.Equals(TokenType.Character))
{
node.Value = CurrentToken.Value;
node.Attributes[0] = "VALUE";
node.Attributes[2] = "CHAR";
NextToken();
return Database.GetType(node.Attributes[2]);
}
else if (CurrentToken.Value.Equals("TRUE") || CurrentToken.Value.Equals("FALSE"))
{
node.Value = CurrentToken.Value;
node.Attributes[0] = "VALUE";
node.Attributes[2] = "BOOL";
NextToken();
return Database.GetType(node.Attributes[2]);
}
else if (Database.CheckFunction(CurrentToken.Value))
{
node.Value = CurrentToken.Value;
NextToken();
if (!CurrentToken.Value.Equals("("))
Error("Expected parameters list for function: " + CurrentToken.Value,
CurrentToken.LineStart);
NextToken();
if (Database.GetParameterNumber(node.Value) != 0)
ParseParameters(ref node.Right, node.Value, 0);
if (!CurrentToken.Value.Equals(")"))
Error("Expected ending parenthesis: )", CurrentToken.LineStart);
NextToken();
node.Attributes[0] = "FUNCTION";
node.Attributes[2] = Database.GetTypeName(Database.GetFunctionType(node.Value));
return Database.GetType(node.Attributes[2]);
}
else
return ParseVariableFactor(ref node);
return -1;
}
private Int32 ParseVariableFactor(ref Node node)
{
//Not an identifier or variable name
if (!CurrentToken.Type.Equals(TokenType.Identifier))
Error("Invalid factor", CurrentToken.LineStart, CurrentToken.CharacterPosition);
if (!Database.CheckVariable(CurrentToken.Value))
Error("Invalid variable name", CurrentToken.LineStart, CurrentToken.CharacterPosition);
//The node's value is the variable's unique ID, the factor type is the variable's data type
node.Value = Database.GetVarId(CurrentToken.Value, null);
Int32 type = Database.GetVarType(CurrentToken.Value, null);
node.Attributes[0] = "VARIABLE";
node.Attributes[2] = Database.GetTypeName(type);
NextToken();
//A . means a member is incoming
if (CurrentToken.Value.Equals("."))
type = ParseMember(ref node, type);
return type;
}
private Int32 ParseMember(ref Node node, Int32 type)
{
//The node's value is MEMBER, the left is the parent factor, right the member
Node current = node;
node.Left = new Node();
node.Right = new Node();
node.Left = current;
node.Value = "MEMBER";
node.Attributes[0] = String.Empty;
//Check if it is a valid member and get the data type
NextToken();
if (!Database.CheckMember(type, CurrentToken.Value))
Error("Invalid member", CurrentToken.LineStart, CurrentToken.CharacterPosition);
Int32 memberType = Database.GetMemberType(type, CurrentToken.Value);
//The right value is the member's name
node.Right.Value = CurrentToken.Value;
NextToken();
//Check if another type is incoming
if (CurrentToken.Value.Equals("."))
memberType = ParseMember(ref node.Right, memberType);
node.Attributes[2] = Database.GetTypeName(memberType);
return memberType;
}
private void ParseWhile(ref Node node)
{
node = new Node();
node.Value = "WHILE";
NextToken();
if (!CurrentToken.Value.Equals("("))
Error("Enclose the condition in (...)", CurrentToken.LineStart);
NextToken();
if (ParseExpression(ref node.Left, 0) != Database.GetType("BOOL"))
Error("Expression must be a boolean in the while", CurrentToken.LineStart);
if (!CurrentToken.Value.Equals(")"))
Error("Enclose the condition in (...)", CurrentToken.LineStart);
NextToken();
ParseBlock(ref node.Right);
}
private void ParseParameters(ref Node node, String functionName, Int32 parameterIndex)
{
//If end of parameter parsing
if (CurrentToken.Value.Equals(")"))
return;
node = new Node();
node.Value = "PARAMETER";
//Parse the expression in the node's left child
Int32 type = ParseExpression(ref node.Left, 0);
//Check if the types of the expression and parameter match
if (!Database.CheckTypesAreEqual(type,
Database.GetParameterType(functionName, parameterIndex)))
Error("Invalid parameter type", CurrentToken.LineStart, CurrentToken.CharacterPosition);
//This parameter has been parsed, now check for future parameters
if (parameterIndex != Database.GetParameterNumber(functionName) - 1)
{
//Two parameters must be separated by a comma
if (!CurrentToken.Value.Equals(","))
Error("Expected comma to separate more parameters", CurrentToken.LineStart);
NextToken();
if (CurrentToken.Value.Equals(")"))
Error("Expected more parameters", CurrentToken.LineStart);
ParseParameters(ref node.Right, functionName, parameterIndex + 1);
}
}
private Int32 ParseExpression(ref Node node, int precedenceLevel)
{
Int32 type = ParseFactor(ref node);
if (Database.CheckOperator(CurrentToken.Value))
{
if (node == null)
node = new Node();
Node clonedNode = node.Clone();
node.Left = clonedNode;
node.Value = CurrentToken.Value;
NextToken();
ParseFactor(ref node.Right);
}
return type;
/*
//If we have reached over the maximum precedence level, we need to parse a factor
if (precedenceLevel > MaxPrecedenceLevel)
return ParseFactorEx(ref node);
//Parse another expression of higher precedence and set it to LType
Int32 lType = ParseExpression(ref node, precedenceLevel+1);
Int32 temporaryToken;
//Check if an operator of current precedence level exists
while (Database.CheckOperator(CurrentToken.Value, precedenceLevel))
{
//An operator exists but it may not be what we want, mark the token in case we want
//to return to it
temporaryToken = TokenIndex;
//Then the operator is the node and the previously parsed expression is the left child node
String op = CurrentToken.Value;
Node temp;
temp = node;
node.Left = new Node();
node.Left = temp.Clone();
node.Value = op;
node.Attributes[0] = "OPERATOR";
NextToken();
//Right child node is the other expression of high precedence level
Int32 rType = ParseExpression(ref node.Right, precedenceLevel + 1);
//Return type retrieved from database
Int32 retType = Database.GetReturnType(op, lType, rType, precedenceLevel);
//Catch here
//If retType == -1 then the operator with LType, RType and Precedence level DO NOT exist
//There may exist an operator with such LType and RType but a different precedence level
//do not match
//In such case, we parsed the operator in the wrong precedence level
//We have to reset the previously saved token's position and also the expression tree
if (retType.Equals(-1))
{
node.Right = null;
node = temp;
TokenIndex = temporaryToken;
CurrentToken = Tokens[TokenIndex];
break;
}
//Valid return type is the type of the expression
node.Attributes[2] = Database.GetTypeName(retType);
lType = retType;
}
return lType;
* */
}
public Node()
{
Left = Right = null;
Attributes[0] = Attributes[1] = Attributes[2] = Value = String.Empty;
}
