void processLine(string line, Program & program, EvalState & state) {
TokenScanner scanner;
scanner.ignoreWhitespace();
scanner.scanNumbers();
scanner.setInput(line);
string str=scanner.nextToken();
if (scanner.getTokenType(str)==NUMBER) {
int lineNumber=stringToInteger(str);
string token=scanner.nextToken();
scanner.saveToken(token);
if (token!="") {
program.addSourceLine(lineNumber, line);
program.setParsedStatement(lineNumber, parseStatement(scanner));
}
else {
program.removeSourceLine(lineNumber);
}
}
else if (str=="LIST") {
for (int i=program.getFirstLineNumber(); i!=-1; i=program.getNextLineNumber(i)) {
cout << program.getSourceLine(i)<<endl;
}
}
else if (str=="CLEAR") {
program.clear();
}
else if(str=="QUIT") exit(0);
else if (str=="HELP") cout<<"This is a minimal BASIC interpreter."<<endl;
else if (str=="RUN") {
int currentLine=program.getFirstLineNumber();
state.setCurrentLine(currentLine);
while (currentLine!=-1) {
program.getParsedStatement(currentLine)->execute(state);
if(currentLine!=state.getCurrentLine()) {
currentLine=state.getCurrentLine();
}
else {
currentLine=program.getNextLineNumber(currentLine);
state.setCurrentLine(currentLine);
}
}
}
}
/*
* Function: processLine
* Usage: processLine(line, program, state);
* -----------------------------------------
* Processes a single line entered by the user. In this version,
* the implementation does exactly what the interpreter program
* does in Chapter 19: read a line, parse it as an expression,
* and then print the result. In your implementation, you will
* need to replace this method with one that can respond correctly
* when the user enters a program line (which begins with a number)
* or one of the BASIC commands, such as LIST or RUN.
*/
void processLine(string line, Program & program, EvalState & state) {
TokenScanner scanner;
scanner.ignoreWhitespace();
scanner.scanNumbers();
scanner.setInput(line);
string token=scanner.nextToken();
TokenType type=scanner.getTokenType(token);
int lineNumb;
int priorLineNumb;
if(type==NUMBER){
if(scanner.hasMoreTokens()){
program.addSourceLine(stringToInteger(token),line);
Statement *stmt=parseStatement(scanner);
program.setParsedStatement(stringToInteger(token),stmt); //link statement to line number
}
else
program.removeSourceLine(stringToInteger(token));
}
if(type==WORD){
if(token=="LIST"){
lineNumb=program.getFirstLineNumber();
while(lineNumb!=-1){
cout<<program.getSourceLine(lineNumb)<<endl;
lineNumb=program.getNextLineNumber(lineNumb);
}
}
else if(token=="RUN"){
state.setCurrentLine(program.getFirstLineNumber());
lineNumb=state.getCurrentLine();
while(lineNumb!=-1){
if(program.hasLineNumber(lineNumb)==false)
error("Invalid line reference at program line "+integerToString(priorLineNumb));
Statement *stmt=program.getParsedStatement(lineNumb);
state.setCurrentLine(program.getNextLineNumber(lineNumb));
stmt->execute(state);
priorLineNumb=lineNumb;
lineNumb=state.getCurrentLine();
}
}
else if(token=="CLEAR"){
program.clear();
}
else if(token=="HELP"){
cout<<"Minimal Basic Statements"<<endl;
cout<<"REM This statement used for comments"<<endl;
cout<<"LET This statement is BASIC's assigment statement"<<endl;
cout<<"PRINT In minimal BASIC, the PRINT statement has the form: "<<endl;
cout<<" PRINT exp"<<endl;
cout<<" where exp is an expression."<<endl;
cout<<"INPUT In the minimal version of the BASIC interpreter, the INPUT statement has the form:"<<endl;
cout<<" INPUT var"<<endl;
cout<<" where var is a variable read in from the user"<<endl;
cout<<"GOTO This statement has the syntax"<<endl;
cout<<" GOTO n"<<endl;
cout<<" which forces the program to continue from line n instead of continuing with the next statement"<<endl;
cout<<"IF This statement provides conditional control. The syntax for this statement is: "<<endl;
cout<<" IF exp1 op exp2 THEN n"<<endl;
cout<<" where exp1 and exp2 are expressions and op is one of the conditional operators =, <, or >."<<endl;
cout<<"END This statment marks the end of the program."<<endl;
cout<<"Commands to control the BASIC interpreter"<<endl;
cout<<"RUN This command starts program execution beginning at the lowest-numbered line. "<<endl;
cout<<"LIST This command lists the steps in the program in numerical sequence."<<endl;
cout<<"CLEAR This command deletes the program so the user can start entering a new one."<<endl;
cout<<"HELP This command provides a simple help message describing the interpreter."<<endl;
cout<<"QUIT Typing QUIT exits from the BASIC interpreter by calling exit(0)."<<endl;
}
else if(token=="QUIT"){
exit(0);
}
else
cout<<"Invalid command"<<endl;
}
}
void processLine(string line, Program & program, EvalState & state) {
/* TokenScanner scanner;
scanner.ignoreWhitespace();
scanner.scanNumbers();
scanner.setInput(line);
Expression *exp = parseExp(scanner);
int value = exp->eval(state);
cout << value << endl;
delete exp;*/
TokenScanner scanner;
scanner.ignoreWhitespace();
scanner.scanNumbers();
scanner.setInput(line);
string token = scanner.nextToken();
TokenType type = scanner.getTokenType(token);
if (type == WORD){
if (token == "RUN")
{
int current_line=program.getFirstLineNumber();
while (current_line>=0)
{
int next_line = program.getNextLineNumber(current_line);
Statement* stat=program.getParsedStatement(current_line);
StatementType type = stat->get_type();
if (type == END)
break;
if (type == GOTO)
{
((Gotostmt*)stat)->execute(state,current_line);
continue;
}
if (type == IF)
{
((Ifstmt*)stat)->execute(state, current_line);
if (current_line != -2)
continue;
}
stat->execute(state);
current_line = next_line;
}
}
if (token == "QUIT")
{
exit(0);
}
if (token == "CLEAR")
{
program.clear();
EvalState state1;
state = state1;
}
if (token == "HELP")
{
}
if (token == "LIST")
{
int current_line = program.getFirstLineNumber();
while (current_line != -1)
{
cout << program.getSourceLine(current_line) << endl;
current_line = program.getNextLineNumber(current_line);
}
}
if (token == "INPUT"){
string st = scanner.nextToken();
if (scanner.hasMoreTokens())
error("SYNTAX ERROR");
Inputstmt inputst(st);
inputst.execute(state);
}
if (token == "PRINT"){
Printstmt printst(scanner);
printst.execute(state);
}
if (token == "LET")
{
Letstmt lets(scanner);
lets.execute(state);
}
if (token != "RUN"&&token != "CLEAR"&&token != "HELP"&&token != "LIST"&&token != "QUIT"&&token != "PRINT"&&token != "LET"&&token != "INPUT")
error("SYNTAX ERROR");
}
else if (type == NUMBER){
int line_num = atoi(token.c_str());
string token2 = scanner.nextToken();
if (token2 == "")
{
program.removeSourceLine(line_num);
return;
}
if (token2 == "REM")
{
string str, temp;
while (scanner.hasMoreTokens())
{
temp = scanner.nextToken();
str += temp;
}
Statement* remst = new Remstmt(str);
program.setParsedStatement(line_num, remst);
program.addSourceLine(line_num, line);
return;
}
if (token2 == "LET")
{
Statement *letst = new Letstmt(scanner);
program.setParsedStatement(line_num, letst);
program.addSourceLine(line_num, line);
return;
}
if (token2 == "PRINT")
{
Statement *printst = new Printstmt(scanner);
program.setParsedStatement(line_num, printst);
program.addSourceLine(line_num, line);
return;
}
if (token2 == "INPUT")
{
string st = scanner.nextToken();
if (scanner.hasMoreTokens())
error("SYNTAX ERROR");
Statement* inputstat = new Inputstmt(st);
program.setParsedStatement(line_num, inputstat);
program.addSourceLine(line_num, line);
return;
}
if (token2 == "GOTO")
{
string token_tmp = scanner.nextToken();
TokenType type = scanner.getTokenType(token_tmp);
if (type != NUMBER)
error("SYNTAX ERROR");
if (scanner.hasMoreTokens())
error("SYNTAX ERROR");
int linenum = atoi(token_tmp.c_str());
Statement* gotostat = new Gotostmt(linenum);
program.setParsedStatement(line_num, gotostat);
program.addSourceLine(line_num, line);
return;
}
if (token2 == "IF")
{
TokenScanner Lscanner;
TokenScanner Rscanner;
string left, right, tmp, cmp;
while (scanner.hasMoreTokens())
{
tmp = scanner.nextToken();
if (tmp == "=" || tmp == ">" || tmp == "<")
{
cmp = tmp;
break;
}
else left = left + tmp;
}
if (cmp != "="&&cmp != "<"&&cmp != ">")
error("SYNTAX ERROR");
while (scanner.hasMoreTokens())
{
tmp = scanner.nextToken();
if (tmp == "THEN")
break;
else right = right + tmp;
}
if (tmp != "THEN")
error("SYNTAX ERROR");
string token_tmp = scanner.nextToken();
TokenType type = scanner.getTokenType(token_tmp);
if (type != NUMBER)
error("SYNTAX ERROR");
if (scanner.hasMoreTokens())
error("SYNTAX ERROR");
int linenum = atoi(token_tmp.c_str());
Lscanner.setInput(left);
Rscanner.setInput(right);
Expression *lexp = parseExp(Lscanner);
Expression *rexp = parseExp(Rscanner);
Statement* ifstat = new Ifstmt(lexp, rexp, cmp, linenum);
program.setParsedStatement(line_num, ifstat);
program.addSourceLine(line_num, line);
return;
}
if (token2 == "END")
{
Statement* endstat=new Endstmt();
program.setParsedStatement(line_num, endstat);
program.addSourceLine(line_num, line);
return;
}
error("SYNTAX ERROR");
}
else error("SYNTAX ERROR");
}