public override void Visit(ReadStmt readStmt)
{
string userInput = Console.ReadLine();
Symbol inputSymbol = SymbolTable.GetSymbol(readStmt.Variable.IdentifierName);
switch (readStmt.Variable.Type)
{
case ExprType.IntType: inputSymbol.Value = int.Parse(userInput); break;
case ExprType.StringType: inputSymbol.Value = userInput; break;
case ExprType.BoolType:
userInput = userInput.ToLower();
if (userInput == "false" || userInput == "0")
inputSymbol.Value = false;
else
inputSymbol.Value = true;
break;
}
}
public void Visit(ReadStmt node)
{
Symbol variable = SymbolTable [node.Children [0].Name];
string userInput = Console.ReadLine ().Trim ();
if (variable.Type == "Int") {
try {
Int32.Parse (userInput);
} catch (Exception e) {
throw new RuntimeError ("Expected input value " + userInput + " to be integer", 0, 0);
}
}
SymbolTable [variable.Name].Value = userInput;
}
public void Visit(ReadStmt node)
{
try {
if (!SymbolTable.ContainsKey (node.Children [0].Name)) {
throw new SemanticError ("Variable " + node.Children [0].Name + " must be declared" +
" before it can be assigned a value", node.Children [0].Row,
node.Children [0].Column);
}
} catch (SemanticError error) {
Errors.Add (error);
TypeStack.Clear ();
}
}
public override void Visit(ReadStmt readStmt)
{
readStmt.Variable.Accept(this);
}
private Statement Stmt()
{
switch ((Token.Types)currentToken.Type) {
case Token.Types.Var:
VarDeclStmt varDeclStmt = new VarDeclStmt ("VarDecl", currentToken.Row, currentToken.Column);
Match (Token.Types.Var);
varDeclStmt.AddChild (IdentifierNameStmt ());
Match (Token.Types.Colon);
varDeclStmt.AddChild (Type ());
if ((Token.Types)currentToken.Type == Token.Types.Assign) {
Match (Token.Types.Assign);
varDeclStmt.AddChild (Expr ());
return varDeclStmt;
} else if ((Token.Types)currentToken.Type == Token.Types.Semicolon) {
return varDeclStmt;
}
throw new SyntaxError ("Expected Assign, got: " + currentToken.Type, currentToken.Row, currentToken.Column);
case Token.Types.Identifier:
AssignmentStmt assignmentStmt = new AssignmentStmt ("AssignmentStmt", currentToken.Row, currentToken.Column);
assignmentStmt.AddChild (IdentifierNameStmt ());
Match (Token.Types.Assign);
assignmentStmt.AddChild (Expr ());
return assignmentStmt;
case Token.Types.For:
ForStmt forStmt = new ForStmt ("ForStmt", currentToken.Row, currentToken.Column);
Match (Token.Types.For);
forStmt.AddChild (IdentifierNameStmt ());
Match (Token.Types.In);
forStmt.AddChild (Expr ());
Match (Token.Types.Range);
forStmt.AddChild (Expr ());
Match (Token.Types.Do);
forStmt.AddChild (Stmts ());
Match (Token.Types.End);
Match (Token.Types.For);
return forStmt;
case Token.Types.Read:
ReadStmt readStmt = new ReadStmt ("ReadStmt", currentToken.Row, currentToken.Column);
Match (Token.Types.Read);
readStmt.AddChild (IdentifierNameStmt ());
return readStmt;
case Token.Types.Print:
PrintStmt printStmt = new PrintStmt ("PrintStmt", currentToken.Row, currentToken.Column);
Match (Token.Types.Print);
printStmt.AddChild (Expr ());
return printStmt;
case Token.Types.Assert:
AssertStmt assertStmt = new AssertStmt ("AssertStmt", currentToken.Row, currentToken.Column);
Match (Token.Types.Assert);
Match (Token.Types.LeftParenthesis);
assertStmt.AddChild (Expr ());
Match (Token.Types.RightParenthesis);
return assertStmt;
default:
throw new SyntaxError ("invalid start symbol for statement " + currentToken.Lexeme,
currentToken.Row, currentToken.Column);
}
}
private Statement ParseStatement()
{
if (Accept(Token.Types.KwVar))
{
DeclarationStmt declaration = new DeclarationStmt(AcceptedToken.Line, AcceptedToken.Column);
Token id = Match(Token.Types.Identifier);
declaration.Identifier = new IdentifierExpr(id.Line, id.Column, id.Content);
Match(Token.Types.Colon);
TypeNode typeNode = ParseType();
declaration.Type = typeNode;
if (Accept(Token.Types.OpAssignment))
{
declaration.AssignmentExpr = ParseExpression();
}
return declaration;
}
else if (Accept(Token.Types.Identifier))
{
AssignmentStmt statement = new AssignmentStmt(AcceptedToken.Line, AcceptedToken.Column);
statement.Identifier = new IdentifierExpr(AcceptedToken.Line, AcceptedToken.Column, AcceptedToken.Content);
Match(Token.Types.OpAssignment);
statement.AssignmentExpr = ParseExpression();
return statement;
}
else if (Accept(Token.Types.KwFor))
{
ForStmt statement = new ForStmt(AcceptedToken.Line, AcceptedToken.Column);
Token idToken = Match(Token.Types.Identifier);
statement.LoopVar = new IdentifierExpr(idToken.Line, idToken.Column, idToken.Content);
Match(Token.Types.KwIn);
statement.StartExpr = ParseExpression();
Match(Token.Types.OpRange);
statement.EndExpr = ParseExpression();
Match(Token.Types.KwDo);
statement.Body = ParseStatements(new StmtList(CurrentToken.Line, CurrentToken.Column));
Match(Token.Types.KwEnd);
Match(Token.Types.KwFor);
return statement;
}
else if (Accept(Token.Types.KwRead))
{
ReadStmt statement = new ReadStmt(AcceptedToken.Line, AcceptedToken.Column);
Token idToken = Match(Token.Types.Identifier);
statement.Variable = new IdentifierExpr(idToken.Line, idToken.Column, idToken.Content);
return statement;
}
else if (Accept(Token.Types.KwPrint))
{
PrintStmt statement = new PrintStmt(AcceptedToken.Line, AcceptedToken.Column);
statement.PrintExpr = ParseExpression();
return statement;
}
else if (Accept(Token.Types.KwAssert))
{
AssertStmt statement = new AssertStmt(AcceptedToken.Line, AcceptedToken.Column);
Match(Token.Types.LParen);
statement.AssertExpr = ParseExpression();
Match(Token.Types.RParen);
return statement;
}
throw new ParserException(String.Format("Expected statement, got {0} instead at line {1} column {2}.",
CurrentToken.Type, CurrentToken.Line, CurrentToken.Column));
}