public void InterpretLine(List <Statement> statement)
{
if (InterpreterMode == InterpreterMode.Running)
{
return;
}
ContinueRunning = true;
CurrentImmediateModeStatementMarker = new ImmediateModeStatementMarker(statement);
try
{
while (CurrentImmediateModeStatementMarker.Valid && CurrentImmediateModeStatementMarker.StatementIndex < statement.Count)
{
var currentStatement = CurrentImmediateModeStatementMarker.Statement;
var commandToken = currentStatement.Tokens[0] as Commands.CommandToken;
var isVariableAssignment = currentStatement.Tokens[0] is VariableNameToken;
if (commandToken == null && !isVariableAssignment)
{
throw new SyntaxErrorException();
}
CurrentCommandToken = commandToken;
TokenMarker marker = new TokenMarker(currentStatement.Tokens);
if (isVariableAssignment)
{
commandToken = (CommandToken)TokensProvider.GetBuiltinToken("LET");
}
else
{
marker.MoveNext();
}
commandToken.Execute(this, marker);
CurrentImmediateModeStatementMarker.MoveToNextStatement();
}
}
catch (RetroBASIC.Exceptions.RetroBASICException basicException)
{
ExpressionEvaluator.Clear();
string outputMessage = $"{ErrorMessages.errorStart} {basicException.Message}{ErrorMessages.error}";
Console.OutputTextWriter.WriteLine();
Console.OutputTextWriter.WriteLine(outputMessage);
}
finally
{
ContinueRunning = false;
CurrentImmediateModeStatementMarker = null;
InterpreterMode = InterpreterMode.Immmediate;
}
}
// Evalute the X(A,...Z ) part of the expression LET X(A,...Z)=[expression].
public ValueTokenArray EvaluateVariableArrayAssignment(TokenMarker tokenMarker)
{
if (!(tokenMarker.Token is VariableNameToken))
{
throw new Exceptions.SyntaxErrorException();
}
// Push the token and a custom action to be performed when the closing ")" is evaluated.
operatorTokens.Push(tokenMarker.Token);
operatorActions.Push(x => EvaluateVariableAssignmentToken(x));
arrayCount.Push(0);
tokenMarker.MoveNext();
// Have the Evaluate function return when the closing ")" is evaluated.
var result = EvaluateInternal(tokenMarker, () => (this.arrayCount.Count > 0));
return((ValueTokenArray)result);
}
public ValueToken ReadNextDataValue()
{
if (DataTokenMarker == null)
{
FindDataStatement();
if (DataStatementMarker.Valid == false)
{
return(null);
}
DataTokenMarker = new TokenMarker(DataStatementMarker.Statement.Tokens);
DataTokenMarker.MoveNext();
}
if (DataTokenMarker.Token == null)
{
while (DataTokenMarker.Token == null)
{
DataStatementMarker.MoveToNextStatement();
FindDataStatement();
if (DataStatementMarker.Valid == false)
{
return(null);
}
DataTokenMarker = new TokenMarker(DataStatementMarker.Statement.Tokens);
DataTokenMarker.MoveNext();
}
}
var result = (ValueToken)DataTokenMarker.Token;
DataTokenMarker.MoveNext();
if (DataTokenMarker.Token is CommaToken)
{
DataTokenMarker.MoveNext();
}
return(result);
}
private ValueToken EvaluateInternal(TokenMarker tokenMarker, Func <bool> ContinueIfTrue = null)
{
Token token = null;
Token prevToken = null;
if (ContinueIfTrue == null)
{
ContinueIfTrue = () => true;
}
while (tokenMarker.Token != null && ContinueIfTrue())
{
prevToken = token;
token = tokenMarker.Token;
tokenMarker.MoveNext();
// Push a number on to the result stack.
if (token is ValueToken valueToken)
{
if (prevToken != null && ((prevToken is VariableNameToken) || (prevToken is CloseParenToken)))
{
// A variable token directly follows a quote. Let the caller decide if this an error.
tokenMarker.MovePrev();
break;
}
valueTokens.Push(valueToken);
continue;
}
// Return value of the variable
if (token is VariableNameToken variableNameToken)
{
// Make sure the previous token was an operator, if not let the caller decide if it's an error
if (prevToken != null && ((prevToken is VariableNameToken) || (prevToken is ValueToken)))
{
tokenMarker.MovePrev();
break;
}
var nextToken = tokenMarker.Token;
if (nextToken == null || !(nextToken is OpenParenToken))
{
// For non-array variables, get the value now and push the resultt.
var value = interpreterEnvironment.GetVariableValue(variableNameToken);
valueTokens.Push(value);
continue;
}
// For array variables, push the token and setup for evaluation later.
operatorTokens.Push(token);
operatorActions.Push(x => EvaluateGetArrayVariableToken(x));
arrayCount.Push(0);
continue;
}
// Push opening brack to operator stack
if (token is OpenParenToken)
{
operatorTokens.Push(token);
continue;
}
// Handle Unary operators
if ((prevToken == null || prevToken is OperatorToken || prevToken is OpenParenToken) &&
token is OperatorToken)
{
switch (token)
{
// Push the unary minus token
case MinusToken minusToken:
token = tokensProvider.UnaryMinusToken;
operatorTokens.Push(token);
operatorActions.Push(x => EvaluateUnaryOperatorToken(x));
continue;
// A unary plus does nothing, so also do nothing.
case PlusToken plusToken:
continue;
default:
throw new Exceptions.SyntaxErrorException();
}
}
// If a closing parenthesis is found, solve until opening brace
if (token is CloseParenToken)
{
if (operatorTokens.Count > 0)
{
/* Evaluate the expression back to the opening brace or last comma
* to properly handle Fn(x-1, x-2) */
FinishEvaluatingExpressionChunk();
// Remove opening brace
operatorTokens.Pop();
if (arrayCount.Count > 0 && operatorTokens.TryPeek(out Token topToken) &&
((topToken is FunctionToken) || (topToken is VariableNameToken)))
{
if (prevToken is CommaToken)
{
// Not in a function or in an array dimension, so let the caller decide if this is an error.
tokenMarker.MovePrev();
break;
}
// Found a closing parenthesis for a function or an array variable. Add one to the array count.
var count = arrayCount.Pop();
arrayCount.Push(count + 1);
// Now remove the operator token and call the lambda function to finish
// evaluating the function or array reference.
PerformEvaluationAction();
}
continue;
}
// Too many closing parenthesis is a syntax error.
throw new Exceptions.SyntaxErrorException();
}
// As long as precedence allows, evaluate the operator tokens.
while (operatorTokens.TryPeek(out Token stackToken) &&
(stackToken is OperatorToken operatorStackToken) &&
(token is OperatorToken currentOperatorToken) &&
operatorStackToken.Precedence >= currentOperatorToken.Precedence)
{
PerformEvaluationAction();
continue;
}
// Handle a comma in a function parameter or a dimension
if (token is CommaToken)
{
if (arrayCount.Count > 0)
{
/* Evaluate the expression back to the opening brace or last comma
* to properly handle Fn(x-1, x-2) */
FinishEvaluatingExpressionChunk();
var count = arrayCount.Pop();
arrayCount.Push(count + 1);
continue;
}
else
{
// Let the caller decide if this is an error
tokenMarker.MovePrev();
break;
}
}
// Setup evaluation of a function
if (token is FunctionToken)
{
if (tokenMarker.Token == null || !(tokenMarker.Token is OpenParenToken))
{
throw new Exceptions.SyntaxErrorException();
}
// Add the token to the stack and setup to finish the function evaluation.
arrayCount.Push(0); // args count
operatorTokens.Push(token);
operatorActions.Push((x) => EvaluateFunctionToken(x));
continue;
}
//Setup evaluation of a user defined function
if (token is FnToken)
{
if (tokenMarker.Token is WhitespacesToken)
{
tokenMarker.MoveNext();
}
if (tokenMarker.Token == null || !(tokenMarker.Token is VariableNameToken userDefinedFunctionName))
{
throw new Exceptions.SyntaxErrorException();
}
tokenMarker.MoveNext();
arrayCount.Push(0);
operatorTokens.Push(userDefinedFunctionName);
operatorActions.Push((x) => EvaluateUserDefinedFunctionToken(x));
continue;
}
// Push an operator token on to the operator tokens stack
if (token is OperatorToken)
{
operatorTokens.Push(token);
// Setup to finish evaluating an operator.
operatorActions.Push((x) => EvaluateBinaryOperatorToken(x));
continue;
}
// An unrecognized token. Let the caller decide what to do about it, if anything.
// Move tokenMarker back by one since it had already been bumped up by one
// above and it should be pointing at the unrecognized character.
tokenMarker.MovePrev();
break;
}
// Finishing evaluating all the pending operations. FinishPendingOperations()
while (operatorTokens.TryPeek(out Token lastOperator))
{
// Check for non-matching right parenthesis
if (lastOperator is OpenParenToken)
{
throw new Exceptions.SyntaxErrorException();
}
PerformEvaluationAction();
}
var finalResult = valueTokens.Pop();
return(finalResult);
}
protected void InterpetLines()
{
InterpreterMode = InterpreterMode.Running;
ContinueRunning = true;
try
{
while (ContinueRunning)
{
var currentStatement = CurrentStatementMarker.Statement;
if (currentStatement == null)
{
break;
}
var commandToken = currentStatement.Tokens[0] as Commands.CommandToken;
var isVariableAssignment = (currentStatement.Tokens[0] as VariableNameToken) != null;
if (commandToken == null && !isVariableAssignment)
{
throw new SyntaxErrorException();
}
CurrentCommandToken = commandToken;
TokenMarker marker = new TokenMarker(currentStatement.Tokens);
if (isVariableAssignment)
{
commandToken = TokensProvider.GetBuiltinToken("LET") as Commands.CommandToken;
}
else
{
marker.MoveNext();
}
#if DEBUG
if (CurrentStatementMarker.LineNumber == 630)
{
CurrentStatementMarker = CurrentStatementMarker;
}
if (CurrentStatementMarker.LineNumber == 770)
{
CurrentStatementMarker = CurrentStatementMarker;
}
#endif
commandToken.Execute(this, marker);
if (!ContinueRunning)
{
break;
}
CurrentCommandToken = null;
if (NextStatementMarker != null)
{
CurrentStatementMarker.MoveTo(NextStatementMarker);
NextStatementMarker = null;
}
else
{
CurrentStatementMarker.MoveToNextStatement();
}
if (CurrentStatementMarker.Valid == false)
{
ContinueRunning = false;
}
}
}
catch (RetroBASIC.Exceptions.RetroBASICException basicException)
{
string outputMessage = $"{ErrorMessages.errorStart} {basicException.Message}{ErrorMessages.error}{ErrorMessages.inMsg}{CurrentStatementMarker.LineNumber}";
Console.OutputTextWriter.WriteLine();
Console.OutputTextWriter.WriteLine(outputMessage);
}
finally
{
ContinueRunning = false;
InterpreterMode = InterpreterMode.Immmediate;
}
}