public void Dispose()
{
if (!IsDisposed)
{
// Fixup break targets references
int loopEndIp = Writer.IP;
foreach (var ip in BreakFixups)
{
Writer.WriteAt(ip, loopEndIp);
}
// Fixup continue targets
foreach (var ip in ContinueFixups)
{
Writer.WriteAt(ip, ContinueIP);
}
// Remove this context from loop stack
Debug.Assert(Function.LoopContexts.Count > 0);
Debug.Assert(Function.LoopContexts.Peek() == this);
Function.LoopContexts.Pop();
IsDisposed = true;
}
}
/// <summary>
/// Parses arguments for a function call. If <paramref name="usingParentheses"/>
/// is true, assumes opening parenthesis has been read and reads up to and
/// including the closing parenthesis. Returns false on error.
/// </summary>
/// <param name="function">Function being called. May be null for user
/// functions. Used to verify argument count for intrinsic functions.</param>
private bool ParseFunctionArguments(Function function, bool usingParentheses)
{
Token token;
int count = 0;
// Save position and write placeholder for argument count
int argumentCountIP = Writer.Write(0);
if (ParseExpression(false))
{
count++;
token = Lexer.GetNext();
while (token.Type == TokenType.Comma)
{
if (!ParseExpression())
{
return(false);
}
count++;
token = Lexer.GetNext();
}
}
else
{
token = Lexer.GetNext();
}
if (usingParentheses)
{
if (token.Type != TokenType.RightParen)
{
Error(ErrorCode.ExpectedRightParen, token);
return(false);
}
}
else
{
Lexer.UngetToken(token);
}
// Enforce argument count for intrinsic functions
// (May be null for user functions not yet defined)
if (function is IntrinsicFunction intrinsicFunction)
{
if (!intrinsicFunction.IsParameterCountValid(count, out string error))
{
Error(ErrorCode.WrongNumberOfArguments, error);
return(false);
}
}
// Fixup argument count
Writer.WriteAt(argumentCountIP, count);
return(true);
}
/// <summary>
/// Parses a symbol. Expected to be either a label, an assignment, a function
/// definition, or function call.
/// </summary>
private void ParseSymbol(Token token)
{
Token nextToken = Lexer.GetNext();
switch (nextToken.Type)
{
case TokenType.Colon:
// Label definition
if (!InFunction)
{
Error(ErrorCode.CodeOutsideFunction, token);
NextLine();
return;
}
AddLabel(token.Value, Writer.IP);
// Allow another statement on same line
break;
case TokenType.LeftBracket:
// Assignment to list item
if (!InFunction)
{
Error(ErrorCode.CodeOutsideFunction, token);
NextLine();
return;
}
Writer.Write(ByteCode.AssignListVariableMulti, GetVariableId(token.Value));
int subscriptsIP = Writer.Write(0); //
int subscripts = 0;
do
{
// Parse list index
if (!ParseExpression())
{
return;
}
token = Lexer.GetNext();
if (token.Type != TokenType.RightBracket)
{
Error(ErrorCode.ExpectedRightBracket, token);
NextLine();
return;
}
subscripts++;
// Get next token
token = Lexer.GetNext();
} while (token.Type == TokenType.LeftBracket);
// Set index count
Writer.WriteAt(subscriptsIP, subscripts);
if (token.Type != TokenType.Equal)
{
Error(ErrorCode.ExpectedEquals, token);
NextLine();
return;
}
// Parse expression
if (!ParseExpression())
{
return;
}
VerifyEndOfLine();
break;
case TokenType.Equal:
// Assignment
if (!InFunction)
{
Error(ErrorCode.CodeOutsideFunction, token);
NextLine();
return;
}
// Test for read-only
int varId = GetVariableId(token.Value);
if (IsReadOnly(varId))
{
Error(ErrorCode.AssignToReadOnlyVariable, token);
NextLine();
return;
}
Writer.Write(ByteCode.Assign, varId);
if (!ParseExpression())
{
return;
}
VerifyEndOfLine();
break;
default:
if (InFunction)
{
// Function call
int functionId = GetFunctionId(token.Value);
Function?function = Functions[functionId];
Writer.Write(ByteCode.ExecFunction, functionId);
// Next token might be part of argument expression
Lexer.UngetToken(nextToken);
if (!ParseFunctionArguments(function, false))
{
return;
}
VerifyEndOfLine();
}
else
{
// Function definition requires parentheses
if (nextToken.Type != TokenType.LeftParen)
{
Error(ErrorCode.ExpectedLeftParen, nextToken);
break;
}
// Create function
var function = new CompileTimeUserFunction(token.Value, Writer.IP);
// Parse and add parameters
if (!ParseFunctionParameters(function))
{
return;
}
// Add user function
AddUserFunction(token.Value, function);
InHeader = false;
CurrentFunction = function;
token = Lexer.GetNextSkipNewLines();
if (token.Type != TokenType.LeftBrace)
{
Error(ErrorCode.ExpectedLeftBrace, token);
return;
}
// Parse statements in function
while (ParseStatement())
{
;
}
token = Lexer.GetNext();
if (token.Type != TokenType.RightBrace)
{
Error(ErrorCode.ExpectedRightBrace);
return;
}
// Write return (no return expression)
Writer.Write(ByteCode.Return, 0);
// Check for undefined labels
foreach (var labelInfo in function.Labels.GetKeyValuePairs())
{
if (labelInfo.Value.IP == null)
{
Error(ErrorCode.LabelNotDefined, labelInfo.Key.MakeQuoted());
return;
}
}
CurrentFunction = null;
}
break;
}
}
