private List <string> isNumaricAssigment(List <string> AssemblyList, AssignmentStatement aSimple)
{
NumericExpression Num = (NumericExpression)(aSimple.Value);
int value = Num.Value;
AssemblyList.Add("@" + value);
AssemblyList.Add("D = A");
AssemblyList.Add("@RETURN");
AssemblyList.Add("M = D");
computeVariabletoR0(AssemblyList, aSimple.Variable.Name);
updateDestinationWithResult(AssemblyList);
return(AssemblyList);
}
private Expression BinaryExpressionCreate(BinaryOperationExpression exp, ref Stack <Token> sTokens)
{
if (sTokens.Peek().Name == "-" || sTokens.Peek().Name == "+")
{
exp.Operator = sTokens.Pop().Name;
}
else
{
throw new SyntaxErrorException("Operator '+' or '-' expected", sTokens.Pop());
}
if (sTokens.Peek().Name == "(")
{
sTokens.Pop();
exp.Operand1 = BinaryExpressionCreate(new BinaryOperationExpression(), ref sTokens);
if (sTokens.Pop().Name != ")")
{
throw new SyntaxErrorException("Missing ')' symbol", sTokens.Pop());
}
}
else
{
if (Char.IsDigit(sTokens.Peek().Name, 0))
{
bool success = false;
NumericExpression num = new NumericExpression();
success = Int32.TryParse(sTokens.Pop().Name, out num.Value);
if (!success)
{
throw new SyntaxErrorException("Invalid number", sTokens.Pop());
}
exp.Operand1 = num;
}
else if (Char.IsLetter(sTokens.Peek().Name, 0))
{
VariableExpression var2 = new VariableExpression();
var2.Name = sTokens.Pop().Name;
exp.Operand1 = var2;
}
else
{
throw new SyntaxErrorException("Invalid variable or const", sTokens.Pop());
}
}
if (sTokens.Peek().Name == "(")
{
sTokens.Pop();
exp.Operand2 = BinaryExpressionCreate(new BinaryOperationExpression(), ref sTokens);
if (sTokens.Pop().Name != ")")
{
throw new SyntaxErrorException("Missing ')' symbol", sTokens.Pop());
}
}
else
{
if (Char.IsDigit(sTokens.Peek().Name, 0))
{
bool success = false;
NumericExpression num = new NumericExpression();
success = Int32.TryParse(sTokens.Pop().Name, out num.Value);
if (!success)
{
throw new SyntaxErrorException("Invalid number", sTokens.Pop());
}
exp.Operand2 = num;
}
else if (Char.IsLetter(sTokens.Peek().Name, 0))
{
VariableExpression var2 = new VariableExpression();
var2.Name = sTokens.Pop().Name;
exp.Operand2 = var2;
}
else
{
throw new SyntaxErrorException("Invalid variable or const", sTokens.Pop());
}
}
return(exp);
}
//Parses a stack of tokens, containing a single assignment statement.
//The structure must be "let <var> = <expression>;" where expression can be of an arbitrary complexity, i.e., any complex expression is allowed.
//Parsing must detect syntax problems (e.g. "let" or "=" are missing, opened parantheses are not closed, sentence does not end with a ;, and so forth).
//When syntax errors are detected, a SyntaxErrorException must be thrown, with an appropriate message explaining the problem.
public AssignmentStatement Parse(Stack <Token> sTokens)
{
Token popedToken = new Token();
popedToken = sTokens.Pop();
AssignmentStatement StatmentToReturn = new AssignmentStatement();
VariableExpression variableWorkingOn = new VariableExpression(),
SecondVariable = new VariableExpression();
NumericExpression num = new NumericExpression();
if (popedToken.Type != Token.TokenType.Keyword)
{
throw new SyntaxErrorException("We accept only LL(0) type, Unrecogmized KeyWord", popedToken);
}
popedToken = sTokens.Pop();
if ((popedToken.Type == Token.TokenType.ID) && (popedToken.Name.ElementAt(0) >= '0') && (popedToken.Name.ElementAt(0) <= '9'))
{
throw new SyntaxErrorException("All variables can not start with a number", popedToken);
}
else if (popedToken.Name.Contains("?") || popedToken.Name.Contains("#") || popedToken.Name.Contains("@"))
{
throw new SyntaxErrorException("Variable can not contain the '?,#,@' signs", popedToken);
}
else if ((popedToken.Type != Token.TokenType.ID))
{
throw new SyntaxErrorException("Expecting a variable name", popedToken);
}
else
{
variableWorkingOn.Name = popedToken.Name;
StatmentToReturn.Variable = variableWorkingOn;
}
popedToken = sTokens.Pop();
if (!popedToken.Name.Equals("="))
{
throw new SyntaxErrorException("Expecting a '=' sign", popedToken);
}
popedToken = sTokens.Pop();
if (Char.IsDigit(popedToken.Name, 0))
{
bool success = false;
success = Int32.TryParse(popedToken.Name, out num.Value);
if (!success)
{
throw new SyntaxErrorException("Invalid number", popedToken);
}
StatmentToReturn.Value = num;
}
else if (Char.IsLetter(popedToken.Name, 0))
{
SecondVariable.Name = popedToken.Name;
StatmentToReturn.Value = SecondVariable;
}
else if (popedToken.Name == "(")
{
StatmentToReturn.Value = BinaryExpressionCreate(new BinaryOperationExpression(), ref sTokens);
if ((sTokens.Count > 0))
{
if (sTokens.Pop().Name != ")")
{
throw new SyntaxErrorException("Missing ')' symbol", popedToken);
}
}
}
else
{
throw new SyntaxErrorException("Invalid value", popedToken);
}
if (sTokens.Count > 1)
{
throw new SyntaxErrorException("Invalid value", popedToken);
}
if (sTokens.Count == 0 || (sTokens.Count == 1 && (sTokens.Pop().Name != ";")))
{
throw new SyntaxErrorException("Expecting ';' at the end of the statement", popedToken);
}
if (sTokens.Count > 0)
{
throw new SyntaxErrorException("No code after ';'", popedToken);
}
return(StatmentToReturn);
}
private List <string> GenerateCodeForUnaryAssignment(LetStatement aSimple, Dictionary <string, int> dSymbolTable)
{
List <string> lAssembly = new List <string>();
//add here code for computing a single let statement containing only a simple expression
Expression value = aSimple.Value;
if (value is NumericExpression)
{
lAssembly.Add("//Numeric Value " + aSimple);
NumericExpression numExp = (NumericExpression)value;
//next 8 lines rep @var
lAssembly.Add("@LCL");
lAssembly.Add("D=M");
lAssembly.Add("@" + dSymbolTable[aSimple.Variable]);
lAssembly.Add("D=A+D");//D=a's address
lAssembly.Add("@_a");
lAssembly.Add("M=D");
lAssembly.Add("@" + RESULT);
lAssembly.Add("M=D");
lAssembly.Add("@" + numExp.Value);
lAssembly.Add("D=A");
lAssembly.Add("@_a");
lAssembly.Add("A=M");
lAssembly.Add("M=D");
lAssembly.Add("@" + RESULT);
lAssembly.Add("M=D");
}
else if (value is VariableExpression)
{
lAssembly.Add("//Variable value" + aSimple);
//Example: let a = b;
//LCL[a]=LCL[b]
VariableExpression valExp = (VariableExpression)value;
int valuesIndex = dSymbolTable[valExp.ToString()];
//first store value of LCL[b] in RESULT
lAssembly.Add("@LCL");
lAssembly.Add("D=M");
lAssembly.Add("@" + dSymbolTable[valExp.ToString()]);
lAssembly.Add("A=D+A");
lAssembly.Add("D=M");
lAssembly.Add("@" + RESULT);
lAssembly.Add("M=D");
//next store a's address in virtual register "_a"
lAssembly.Add("@LCL");
lAssembly.Add("D=M");
lAssembly.Add("@" + dSymbolTable[valExp.ToString()]);
lAssembly.Add("D=D+A");
lAssembly.Add("@_a");
lAssembly.Add("M=D");
//update "a"
lAssembly.Add("@" + RESULT);
lAssembly.Add("D=M");
lAssembly.Add("@_a");
lAssembly.Add("A=M");
lAssembly.Add("M=D");
}
return(lAssembly);
}
public List <string> GenerateCode(LetStatement aSimple, Dictionary <string, int> dSymbolTable)
{
List <string> lAssembly = new List <string>();
lAssembly.Add("//generation started" + aSimple);
//add here code for computing a single let statement containing only a simple expression
Expression value = aSimple.Value;
string variable = aSimple.Variable;
if (value is NumericExpression | value is VariableExpression)
{
lAssembly.AddRange(GenerateCodeForUnaryAssignment(aSimple, dSymbolTable));
}
else if (value is BinaryOperationExpression)
{
lAssembly.Add("//Binary Expression" + aSimple);
//
//Example: a = b <op> c
//first let a=b
//next let a=a <op> c
//
BinaryOperationExpression binExp = (BinaryOperationExpression)value;
Expression operand1 = binExp.Operand1;
Expression operand2 = binExp.Operand2;
LetStatement letAEqualB = makeLetStatement(variable, operand1);
//let a=b
lAssembly.AddRange(GenerateCodeForUnaryAssignment(letAEqualB, dSymbolTable));
lAssembly.Add("@" + RESULT);
lAssembly.Add("D=M");
lAssembly.Add("@" + OPERAND1);
lAssembly.Add("M=D");
//let a = a <op> c
if (operand2 is NumericExpression)
{
lAssembly.Add("//Opearand 2 is Numeric " + aSimple);
NumericExpression num = (NumericExpression)operand2;
lAssembly.Add("@" + num.Value);
lAssembly.Add("D=A");
lAssembly.Add("@_a");
lAssembly.Add("M=M" + binExp.Operator + "D");
lAssembly.Add("D=M");
lAssembly.Add("@" + RESULT);
lAssembly.Add("M=D");
}
else if (operand2 is VariableExpression)
{
lAssembly.Add("//Opearand 2 is a Variable " + aSimple);
VariableExpression c = (VariableExpression)operand2;
lAssembly.Add("@LCL");
lAssembly.Add("D=M");
lAssembly.Add("@" + dSymbolTable[c.Name]);
lAssembly.Add("D=M");
lAssembly.Add("@" + dSymbolTable[variable]);
lAssembly.Add("M=M" + binExp.Operator + "D");
lAssembly.Add("D=M");
lAssembly.Add("@" + RESULT);
lAssembly.Add("M=D");
}
}
return(lAssembly);
}
