public static Node ParseStatement()
{
//Console.WriteLine("parsing expression");
//Diagram rules
//1st - Identfier
//identifier - =
//= - expression
//1st - print
//print - expression
//1st - statements
Node root;
//TODO- condense this code by replacing similar code with some functions (expect line end for example)
switch (tokens.actual.type)
{
case "END":
return(new NoOp());
case "IDENTIFIER":
// IDENTIFIER - = - EXPRESSION
// get identifier
Identifier ident = new Identifier((string)tokens.actual.value);
tokens.SelectNext();
if (tokens.actual.type != "EQUAL") //expecting a EQUAL
{
throw new SystemException($"Identifier with no assignment ({tokens.actual.value}) (position {tokens.position}) [Line: {CurrentLine}]");
}
root = new BinOp(); //create the assign biop node
root.value = '=';
root.children[0] = ident; //left is the identfier
tokens.SelectNext();
root.children[1] = ParseExpression(); //right is a expression
if (tokens.actual.type != "LINEBREAK") //expect linebreak after the expression;
{
throw new SystemException($"No LINEBREAK after assignment (position {tokens.position}) [Line: {CurrentLine}]");
}
CurrentLine++;
tokens.SelectNext(); //go to next token after linebreak
return(root);
case "PRINT":
//print - expression
root = new UnOp();
root.value = "print";
tokens.SelectNext();
root.children[0] = ParseExpression();
if (tokens.actual.type != "LINEBREAK") //expect linebreak after the expression;
{
throw new SystemException($"No LINEBREAK after PRINT (position {tokens.position}) [Line: {CurrentLine}]");
}
CurrentLine++;
tokens.SelectNext(); //go to next token after linebreak
return(root);
case "WHILE":
root = new WhileNode();
tokens.SelectNext();
root.children[0] = ParseRelExpression();
if (tokens.actual.type != "LINEBREAK") //expect linebreak after the expression;
{
throw new SystemException($"No LINEBREAK after Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
}
CurrentLine++;
tokens.SelectNext(); //go to next token after linebreak
root.children[1] = ParseStatements(); //already goes to next line, no select next required
return(root);
case "IF":
root = new IfNode();
tokens.SelectNext();
root.children[0] = ParseRelExpression();
if (tokens.actual.type != "THEN") //expect THEN after the rel expression;
{
throw new SystemException($"THEN is required after an IF's Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
}
tokens.SelectNext();
if (tokens.actual.type != "LINEBREAK") //expect linebreak after THEN;
{
throw new SystemException($"No LINEBREAK after Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
}
CurrentLine++;
tokens.SelectNext(); //go to next token after linebreak
root.children[1] = ParseStatements(); //already goes to next line, no select next required
if (tokens.actual.type == "ELSE")
{
tokens.SelectNext();
if (tokens.actual.type != "LINEBREAK") //expect linebreak after ELSE;
{
throw new SystemException($"No LINEBREAK after ELSE (position {tokens.position}) [Line: {CurrentLine}]");
}
CurrentLine++;
tokens.SelectNext(); //go to next token after linebreak
root.children[2] = ParseStatements(); //left the token after the END, so it is probably on IF (END IF\n)
}
if (tokens.actual.type != "IF") //expect IF after the statements END for END IF\n construction;
{
throw new SystemException($"IF section end symbol not found, found END instead of END IF (position {tokens.position}) [Line: {CurrentLine}]");
}
tokens.SelectNext();
if (tokens.actual.type != "LINEBREAK") //expect linebreak after THEN;
{
throw new SystemException($"No LINEBREAK after Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
}
CurrentLine++;
tokens.SelectNext(); //go to next token after linebreak
return(root);
default:
return(new NoOp());
}
}
//public static Node ParseStatements(string poi){
// return ParseStatements("none");
// }
public static Node ParseStatement()
{
//Console.WriteLine("parsing expression");
Node root;
//TODO- condense this code by replacing similar code with some functions (expect line end for example)
switch (tokens.actual.type)
{
case "END":
return(new NoOp());
//assing, start wuth put
case "PUT":
root = new BinOp();
root.value = "=";
tokens.SelectNext();
root.children[1] = ParseRelExpression();
Expect("IN", true);
Expect("IDENTIFIER", false);
Identifier ident = new Identifier((string)tokens.actual.value);
root.children[0] = ident;
tokens.SelectNext();
return(root);
/*case "IDENTIFIER":
* // IDENTIFIER - = - EXPRESSION
* // get identifier
* Identifier ident = new Identifier((string)tokens.actual.value);
* tokens.SelectNext();
* if(tokens.actual.type != "EQUAL"){ //expecting a EQUAL
* throw new SystemException ($"Identifier with no assignment ({tokens.actual.value}) (position {tokens.position}) [Line: {CurrentLine}]");
* }
* root = new BinOp(); //create the assign biop node
* root.value = '=';
* root.children[0] = ident; //left is the identfier
* tokens.SelectNext();
* root.children[1] = ParseRelExpression(); //right is a relative expression
*
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after the expression;
* throw new SystemException ($"No LINEBREAK after assignment (position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
* return root;*/
case "DO":
tokens.SelectNext();
Expect("IDENTIFIER", false);
FuncCall call = new FuncCall();
call.value = (string)tokens.actual.value;
tokens.SelectNext();
if (tokens.actual.type == "WITH")
{
tokens.SelectNext();
do
{
if (tokens.actual.type == "COMMA")
{
tokens.SelectNext();
}
call.Add(ParseRelExpression());
}while (tokens.actual.type == "COMMA");
}
return(call);
case "TO":
tokens.SelectNext();
return(ParseFunction());
/*
* case "CALL":
* tokens.SelectNext();
* Expect("IDENTIFIER",false);
*
* FuncCall call = new FuncCall();
* call.value = (string)tokens.actual.value;
*
* tokens.SelectNext();
* Expect("POPEN",true);
* if(tokens.actual.type != "PCLOSE"){
* do{
* if(tokens.actual.type == "COMMA"){
* tokens.SelectNext();
* }
* call.Add(ParseRelExpression());
* }while (tokens.actual.type == "COMMA");
* }
* Expect("PCLOSE",true);
* return call;
*/
case "PRINT":
//print - expression
root = new UnOp();
root.value = "print";
tokens.SelectNext();
root.children[0] = ParseRelExpression();
return(root); //cl change
/*
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after the expression;
* throw new SystemException ($"No LINEBREAK after PRINT (position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
* return root;
*/
case "WHILE":
root = new WhileNode();
tokens.SelectNext();
root.children[0] = ParseRelExpression();
Expect("DO", true);
root.children[1] = ParseStatements("while");
Expect("PERIOD", true);
return(root);
/*
* root = new WhileNode();
* tokens.SelectNext();
* root.children[0] = ParseRelExpression();
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after the expression;
* throw new SystemException ($"No LINEBREAK after Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
* root.children[1] = ParseStatements("while"); //already goes to next line, no select next required
* return root;
*/
/*
* case "DIM":
* root = new BinOp();
* root.value = "vardec";
* tokens.SelectNext();
*
* if(tokens.actual.type != "IDENTIFIER"){
* throw new SystemException ($"IDENTIFIER is required after an variable declaration declaration (position {tokens.position}) [Line: {CurrentLine}]");
* }
* root.children[0] = new NoOp();
* root.children[0].value = (string)tokens.actual.value;
* tokens.SelectNext();
*
* if(tokens.actual.type != "AS"){
* throw new SystemException ($"'As' is required in an variable declaration (position {tokens.position}) [Line: {CurrentLine}]");
* }
* tokens.SelectNext();
*
* root.children[1] = parseType();
*
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after the expression;
* throw new SystemException ($"No LINEBREAK after Variable declaration(position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
*
* return root;
*/
case "IF":
root = new IfNode();
tokens.SelectNext();
root.children[0] = ParseRelExpression();
Expect("DO", true);
root.children[1] = ParseStatements("if");
Expect("PERIOD", true);
if (tokens.actual.type == "ELSE")
{
tokens.SelectNext();
root.children[2] = ParseStatements("else");
}
return(root);
/*
* if(tokens.actual.type != "THEN"){ //expect THEN after the rel expression;
* throw new SystemException ($"THEN is required after an IF's Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
* }
* tokens.SelectNext();
*
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after THEN;
* throw new SystemException ($"No LINEBREAK after Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
*
* root.children[1] = ParseStatements("if"); //already goes to next line, no select next required
*
* if(tokens.actual.type == "ELSE"){
* tokens.SelectNext();
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after ELSE;
* throw new SystemException ($"No LINEBREAK after ELSE (position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
* root.children[2] = ParseStatements("else"); //left the token after the END, so it is probably on IF (END IF\n)
* }
*
* if(tokens.actual.type != "IF"){ //expect IF after the statements END for END IF\n construction;
* throw new SystemException ($"IF section end symbol not found, found END instead of END IF (position {tokens.position}) [Line: {CurrentLine}]");
* }
* tokens.SelectNext();
*
* if(tokens.actual.type != "LINEBREAK"){ //expect linebreak after THEN;
* throw new SystemException ($"No LINEBREAK after Relative Expression (position {tokens.position}) [Line: {CurrentLine}]");
* }
* CurrentLine++;
* tokens.SelectNext(); //go to next token after linebreak
*
* return root; */
default:
return(new NoOp());
}
}