/// <summary>
/// <para>Handles *expression* "==" *expression</para>
/// <para>*expression* "!=" *expression*</para>
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression4()
{
ASTExpressionBase expression = ParseExpression5();
while (Match(TokenType.EQUALS_EQUALS) || Match(TokenType.NOT_EQUALS))
{
switch (_buffer[0].Type)
{
case TokenType.EQUALS_EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression5();
expression = new ASTCompare(ASTCompare.OperationType.EQUALS_EQUALS, expression, expressionRight);
}
break;
case TokenType.NOT_EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression5();
expression = new ASTCompare(ASTCompare.OperationType.NOT_EQUALS, expression, expressionRight);
}
break;
}
}
return(expression);
}
/// <summary>
/// <para>Handles *expression* "*" *expression*</para>
/// <para>*expression* "/" *expression*</para>
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression7()
{
ASTExpressionBase expression = ParseExpression8();
while (Match(TokenType.TIMES) || Match(TokenType.DIVIDE))
{
switch (_buffer[0].Type)
{
case TokenType.TIMES:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression8();
expression = new ASTBinaryMathOperation(ASTBinaryMathOperation.OperationType.TIMES, expression, expressionRight);
}
break;
case TokenType.DIVIDE:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression8();
expression = new ASTBinaryMathOperation(ASTBinaryMathOperation.OperationType.DIVIDE, expression, expressionRight);
}
break;
}
}
return(expression);
}
private ASTStatementBase ParseStatement()
{
switch (_buffer[0].Type)
{
case TokenType.LEFT_BRACE: return(ParseBlock());
case TokenType.IF: return(ParseIf());
case TokenType.WHILE: return(ParseWhile());
case TokenType.FOR: return(ParseFor());
case TokenType.SWITCH: return(ParseSwitch());
case TokenType.BREAK: return(ParseBreak());
case TokenType.CONTINUE: return(ParseContinue());
case TokenType.RETURN: return(ParseReturn());
default:
{
ASTExpressionBase expression = ParseExpression();
Require(TokenType.SEMICOLON);
return(new ASTStatementExpression(expression));
}
}
}
private ASTStatementBase ParseReturn()
{
Require(TokenType.RETURN);
ASTExpressionBase returnExpression = ParseExpression();
Require(TokenType.SEMICOLON);
return(new ASTReturn(returnExpression));
}
/// <summary>
/// Handles *leftValue* "=" *expression* (assignment)
/// *variable* "+=" *expression*
/// *variable* "-=" *expression*
/// *variable* *= *expression*
/// *variable* /= *expression*
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression1()
{
ASTExpressionBase expression = ParseExpression2();
while (Match(TokenType.EQUALS) || Match(TokenType.PLUS_EQUALS) || Match(TokenType.MINUS_EQUALS) || Match(TokenType.TIMES_EQUALS) || Match(TokenType.DIVIDE_EQUALS))
{
if (expression.Type != ExpressionType.IDENTIFIER)
{
throw new ParserException("left side of an assignment must be a variable.", _lexer.Line, _lexer.Character);
}
switch (_buffer[0].Type)
{
case TokenType.EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression1();
expression = GetASTAssignment(ASTAssignment.AssignmentType.ASSIGNMENT, (expression as ASTIdentifier).Name, expressionRight, expression as ASTMemberAccess);
}
break;
case TokenType.PLUS_EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression1();
expression = GetASTAssignment(ASTAssignment.AssignmentType.ADDITION, (expression as ASTIdentifier).Name, expressionRight, expression as ASTMemberAccess);
}
break;
case TokenType.MINUS_EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression1();
expression = GetASTAssignment(ASTAssignment.AssignmentType.SUBTRACTION, (expression as ASTIdentifier).Name, expressionRight, expression as ASTMemberAccess);
}
break;
case TokenType.TIMES_EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression1();
expression = GetASTAssignment(ASTAssignment.AssignmentType.MULTIPLICATION, (expression as ASTIdentifier).Name, expressionRight, expression as ASTMemberAccess);
}
break;
case TokenType.DIVIDE_EQUALS:
{
Consume();
ASTExpressionBase expressionRight = ParseExpression1();
expression = GetASTAssignment(ASTAssignment.AssignmentType.DIVISION, (expression as ASTIdentifier).Name, expressionRight, expression as ASTMemberAccess);
}
break;
}
}
return(expression);
}
/// <summary>
/// Handles *expression* "&&" *expression* (and)
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression3()
{
ASTExpressionBase expression = ParseExpression4();
while (Match(TokenType.AND))
{
Consume();
ASTExpressionBase expressionRight = ParseExpression4();
expression = new ASTCompare(ASTCompare.OperationType.AND, expression, expressionRight);
}
return(expression);
}
/// <summary>
/// Handles *expression* "," *expression*
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression()
{
ASTExpressionBase expression = ParseExpression1();
List <ASTExpressionBase> expressionList = new List <ASTExpressionBase>();
expressionList.Add(expression);
while (Match(TokenType.COMMA))
{
expressionList.Add(ParseExpression1());
}
return(new ASTExpressionBase(expressionList));
}
private ASTStatementBase ParseWhile()
{
Require(TokenType.WHILE);
Require(TokenType.LEFT_PARENTHESIS);
ASTExpressionBase condition = ParseExpression();
Require(TokenType.RIGHT_PARENTHESIS);
_loopLevel++;
ASTStatementBase body = ParseStatement();
_loopLevel--;
return(new ASTWhile(condition, body));
}
private ASTAssignment GetASTAssignment(ASTAssignment.AssignmentType type, string variable,
ASTExpressionBase expression, ASTMemberAccess memberAccess)
{
if (!_insideClass)
{
if (memberAccess != null)
{
// assigning a member variable from outside the class
return(new ASTMemberAssignmentInstance(type, variable, expression, memberAccess.InstanceName));
}
else
{
// assigning a local variable
return(new ASTAssignment(type, variable, expression));
}
}
else
{
// assigning a member variable from inside the class
return(new ASTMemberAssignment(type, variable, expression));
}
}
private ASTStatementBase ParseFor()
{
Require(TokenType.FOR);
Require(TokenType.LEFT_PARENTHESIS);
ASTExpressionBase initializer = ParseExpression();
Require(TokenType.SEMICOLON);
ASTExpressionBase condition = ParseExpression();
Require(TokenType.SEMICOLON);
ASTExpressionBase incrementer = ParseExpression();
Require(TokenType.RIGHT_PARENTHESIS);
_loopLevel++;
ASTStatementBase body = ParseStatement();
_loopLevel--;
return(new ASTFor(initializer, condition, incrementer, body));
}
private ASTStatementBase ParseIf()
{
Require(TokenType.IF);
Require(TokenType.LEFT_PARENTHESIS);
ASTExpressionBase condition = ParseExpression();
Require(TokenType.RIGHT_PARENTHESIS);
ASTStatementBase ifPart = ParseStatement();
ASTStatementBase elsePart = null;
if (Match(TokenType.ELSE))
{
Consume();
elsePart = ParseStatement();
}
if (elsePart == null)
{
return(new ASTIf(condition, ifPart));
}
return(new ASTIf(condition, ifPart, elsePart));
}
/// <summary>
/// <para>Handles *identifier* "[" *tableKey* "]"</para>
/// <para>*identifier* "(" *argumentList* ")"</para>
/// <para>*identifier* -> *identifier* "(" *argumentList* ")"</para>
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression9()
{
ASTExpressionBase expression = ParseExpression10();
while (Match(TokenType.LEFT_PARENTHESIS) || Match(TokenType.ARROW) || Match(TokenType.LEFT_BRACKET))
{
switch (_buffer[0].Type)
{
case TokenType.LEFT_BRACKET:
{
Consume();
if (expression.Type != ExpressionType.IDENTIFIER)
{
throw new ParserException($"Table expected.", _lexer.Line, _lexer.Character);
}
var indexes = new List <ASTExpressionBase>();
while (!Match(TokenType.RIGHT_BRACKET))
{
indexes.Add(ParseExpression1());
if (Match(TokenType.COMMA))
{
Consume();
}
}
Require(TokenType.RIGHT_BRACKET);
expression = new ASTTableGet(expression, indexes);
}
break;
case TokenType.LEFT_PARENTHESIS:
{
Consume();
if (expression.Type != ExpressionType.IDENTIFIER)
{
throw new ParserException($"Function call expected.", _lexer.Line, _lexer.Character);
}
List <ASTExpressionBase> arguments = new List <ASTExpressionBase>();
while (!Match(TokenType.RIGHT_PARENTHESIS))
{
arguments.Add(ParseExpression1());
if (Match(TokenType.COMMA))
{
Consume();
}
}
Require(TokenType.RIGHT_PARENTHESIS);
expression = new ASTGlobalFunctionCall((expression as ASTIdentifier).Name, arguments);
}
break;
case TokenType.ARROW:
{
Consume();
if (expression.Type != ExpressionType.IDENTIFIER)
{
throw new ParserException($"class object expected.", _lexer.Line, _lexer.Character);
}
string memberName = Require(TokenType.IDENTIFIER).Text;
if (!Match(TokenType.LEFT_PARENTHESIS))
{
// return class variable
expression = new ASTMemberAccess(memberName, (expression as ASTIdentifier).Name);
break;
}
Require(TokenType.LEFT_PARENTHESIS);
List <ASTExpressionBase> arguments = new List <ASTExpressionBase>();
while (!Match(TokenType.RIGHT_PARENTHESIS))
{
arguments.Add(ParseExpression1());
if (Match(TokenType.COMMA))
{
Consume();
}
}
Require(TokenType.RIGHT_PARENTHESIS);
expression = new ASTMemberFunctionCall(memberName, (expression as ASTIdentifier).Name, arguments);
}
break;
}
}
return(expression);
}
private ASTStatementBase ParseSwitch()
{
Require(TokenType.SWITCH);
if (_switchLevel > 0)
{
throw new ParserException("Nested switch statements are currently not supported.", _lexer.Line, _lexer.Character);
}
Require(TokenType.LEFT_PARENTHESIS);
ASTExpressionBase check = ParseExpression();
Require(TokenType.RIGHT_PARENTHESIS);
Require(TokenType.LEFT_BRACE);
ASTSwitch switchStatement = new ASTSwitch(check);
while (!Match(TokenType.RIGHT_BRACE))
{
if (Match(TokenType.END_OF_FILE))
{
throw new ParserException("'}' expected!", _lexer.Line, _lexer.Character);
}
if (Match(TokenType.DEFAULT))
{
Require(TokenType.DEFAULT);
Require(TokenType.COLON);
_switchLevel++;
switchStatement.AddCase(null, ParseStatement());
_switchLevel--;
if (!Match(TokenType.RIGHT_BRACE))
{
throw new ParserException("A default case must be the final case of a switch statement.", _lexer.Line, _lexer.Character);
}
break;
}
Require(TokenType.CASE);
ASTExpressionBase _case = ParseExpression();
if (_case == null)
{
throw new ParserException("Identifier expected.", _lexer.Line, _lexer.Character);
}
Require(TokenType.COLON);
if (Match(TokenType.CASE) || Match(TokenType.DEFAULT))
{
switchStatement.AddCase(_case, null);
}
else
{
_switchLevel++;
switchStatement.AddCase(_case, ParseStatement());
_switchLevel--;
}
/* for now, I don't think forcing the scripter to use braces to have a "break;" after a case is necessary, eg. in the situation of
* case 5:
* {
* print("hello");
* break;
* }
*
* you might as well just type
* case 5:
* print("hello");
* break;
*/
if (Match(TokenType.BREAK)) // so let's allow that
{
Consume(); // consume 'break'
Require(TokenType.SEMICOLON); // require ';'
var currentCase = switchStatement.Cases[switchStatement.Cases.Count - 1]; // get statement of current case
// and add the 'break' to the end of it
switchStatement.Cases[switchStatement.Cases.Count - 1] = (currentCase.expression,
new ASTBlock(new List <ASTStatementBase>
{
currentCase.statement, new ASTBreak()
}));
}
}
Require(TokenType.RIGHT_BRACE);
if (switchStatement.Cases.Count == 0)
{
throw new ParserException("Empty switch statements are not allowed.", _lexer.Line, _lexer.Character);
}
return(switchStatement);
}
/// <summary>
/// <para>Handles "{" *key = value* list "}"</para>
/// <para>"(" *expression* ")"</para>
/// <para>*identifier*</para>
/// <para>*number*</para>
/// <para>*string*</para>
/// <para>"null"</para>
/// <para>"true"</para>
/// <para>"false"</para>
/// </summary>
/// <returns></returns>
private ASTExpressionBase ParseExpression10()
{
switch (_buffer[0].Type)
{
case TokenType.LEFT_BRACE:
{
Consume();
ASTTable table = new ASTTable();
while (!Match(TokenType.RIGHT_BRACE))
{
bool good = true;
if (Match(TokenType.LEFT_BRACKET)) // [key] = value
{
Consume();
if (!Match(TokenType.NUMBER) && !Match(TokenType.STRING))
{
throw new ParserException("Expected string or number key for table.", _lexer.Line, _lexer.Character);
}
ASTExpressionBase key = ParseExpression10();
Require(TokenType.RIGHT_BRACKET);
Require(TokenType.EQUALS);
ASTExpressionBase value = ParseExpression2();
good = table.InsertValue(key, value);
}
else
{
ASTExpressionBase key = ParseExpression2();
if (key.Type == ExpressionType.IDENTIFIER) // key = expvalue || value
{
if (Match(TokenType.EQUALS))
{
Require(TokenType.EQUALS);
ASTExpressionBase value = ParseExpression2();
good = table.InsertValue(key, value);
}
else // expvalue
{
good = table.InsertValue(null, key);
}
}
else // value (no key)
{
good = table.InsertValue(null, key);
}
}
if (!good)
{
throw new ParserException("Invalid key/value pair for table (possible duplicate?).", _lexer.Line, _lexer.Character);
}
if (Match(TokenType.COMMA))
{
Consume();
}
}
table.NormalizeValues();
Require(TokenType.RIGHT_BRACE);
return(table);
}
case TokenType.LEFT_PARENTHESIS:
{
Consume();
ASTExpressionBase expression = ParseExpression1();
Require(TokenType.RIGHT_PARENTHESIS);
return(expression);
}
case TokenType.IDENTIFIER:
{
var variable = Require(TokenType.IDENTIFIER).Text;
return(new ASTIdentifier(variable));
}
case TokenType.NUMBER:
{
double num = Require(TokenType.NUMBER).Number;
return(new ASTNumber(num));
}
case TokenType.STRING:
{
var str = Require(TokenType.STRING).Text;
return(new ASTString(str));
}
case TokenType.NULL:
{
Consume();
return(new ASTNull());
}
case TokenType.TRUE:
{
Consume();
return(new ASTTrue());
}
case TokenType.FALSE:
{
Consume();
return(new ASTFalse());
}
case TokenType.COUNT:
{
Consume();
var identifier = Require(TokenType.IDENTIFIER).Text;
return(new ASTCount(identifier));
}
default:
throw new ParserException("Primary expression expected", _lexer.Line, _lexer.Character);
}
}
