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statement.cpp
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statement.cpp
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#include "statement.h"
Statement::Statement() {
}
Statement::Statement(QString n): name(n) {
error = new SyntaxError(QString("Unknown statement type \"%1\"").arg(name));
}
Statement* Statement::parse(const QString statement) {
QString content = statement.trimmed();
QString name = content.split(' ')[0];
QString body = content.section(' ', 1);
if (name == "REM") {
return new RemarkStatement(body);
} else if (name == "LET") {
return new LetStatement(body);
} else if (name == "PRINT") {
return new PrintStatement(body);
} else if (name == "PRINTF") {
return new PrintfStatement(body);
} else if (name == "INPUT") {
return new InputStatement(body);
} else if (name == "INPUTS") {
return new InputsStatement(body);
} else if (name == "GOTO") {
return new GotoStatement(body);
} else if (name == "IF") {
return new IfStatement(body);
} else if (name == "END") {
return new EndStatement();
}
return new Statement(name);
}
void Statement::execute(Runtime*) const {
throw error;
}
const QString Statement::ast() const {
return "ERROR";
}
Statement::~Statement() {
}
// REM
const QString RemarkStatement::ast() const {
return QString("REM\n " + body);
}
void RemarkStatement::execute(Runtime*) const {
return;
}
// LET
LetStatement::LetStatement(const QString body) {
try {
expression = Expression::parse(body);
} catch (Exception* exception) {
error = exception;
return;
}
if (expression->error) {
error = expression->error;
return;
}
// ensure an assignment expression
if (expression->getType() != COMPOUND_EXP || static_cast<const CompoundExpression*>(expression)->getOp() != "=") {
error = new SyntaxError(QString("Invalid expression \"%1\" for LET statement").arg(body));
}
}
void LetStatement::execute(Runtime* context) const {
expression->evaluate(context);
}
const QString LetStatement::ast() const {
if (error) {
return "ERROR";
}
return "LET " + expression->ast();
}
LetStatement::~LetStatement() {
delete expression;
}
// PRINT
PrintStatement::PrintStatement(const QString body) {
try {
expression = Expression::parse(body);
} catch (Exception* exception) {
error = exception;
return;
}
error = expression->error;
}
void PrintStatement::execute(Runtime* context) const {
const Value* value = expression->evaluate(context);
context->io->output(value);
}
const QString PrintStatement::ast() const {
if (error) {
return "ERROR";
}
return "PRINT" + indent("\n" + expression->ast());
}
PrintStatement::~PrintStatement() {
delete expression;
}
// PRINTF
PrintfStatement::PrintfStatement(const QString body) {
QList<QString> arguments = getArguments(body);
// Parse format string
if (arguments.size() < 1) {
error = new SyntaxError("Missing expression for PRINTF statement: " + body);
return;
}
const Expression* exp = Expression::parse(arguments.first().trimmed());
if (exp->getType() != CONST_EXP || !exp->ast().startsWith('"')) {
error = new SyntaxError("Invalid format string for PRINTF statement: " + formatString);
return;
}
formatString = exp->evaluate(nullptr)->toString();
arguments.pop_front();
// Parse arguments
for (QString argument : arguments) {
const Expression* arg;
try {
arg = Expression::parse(argument);
} catch (Exception* exception) {
error = exception;
return;
}
error = arg->error;
if (error) {
return;
}
args.append(arg);
}
// Validate number of arguments
int argCount = formatString.count(pattern);
if (argCount != args.size()) {
error = new SyntaxError(QString("Expecting %1 argument(s), found %2").arg(argCount).arg(args.size()));
return;
}
}
void PrintfStatement::execute(Runtime* context) const {
QString formattedString = formatString;
int index;
for (const Expression* arg : args) {
const Value* value = arg->evaluate(context);
index = formattedString.indexOf(pattern);
formattedString.replace(index, 2, value->toString());
}
context->io->output(formattedString);
}
const QString PrintfStatement::ast() const {
if (error) {
return "ERROR";
}
QString astString = "PRINTF" + indent("\n\"" + formatString + "\"");
for (const Expression* arg : args) {
astString += indent("\n" + arg->ast());
}
return astString;
}
QList<QString> PrintfStatement::getArguments(const QString body) const {
QList<QString> arguments;
bool inString = false;
QString current;
for (QChar c : body) {
// Don't treat commas inside strings as arguments delimiter
if (c == ',' && !inString) {
arguments.append(current);
current.clear();
} else {
current.append(c);
}
if (c == '"' || c == '\'') {
if (inString) {
inString = false;
} else {
inString = true;
}
}
}
if (!current.isEmpty()) {
arguments.append(current);
}
return arguments;
}
PrintfStatement::~PrintfStatement() {
for (const Expression* arg : args) {
delete arg;
}
}
// INPUT
InputStatement::InputStatement(const QString body): identifier(body) {
}
void InputStatement::execute(Runtime* context) const {
// ensure an identifier expression
const Expression* expression = Expression::parse(identifier);
if (expression->getType() != IDENTIFIER_EXP) {
throw new SyntaxError(QString("Invalid identifier \"%1\" for INPUT statement").arg(identifier));
}
context->io->requestInput(identifier);
if (context->status == OK) { // Console input
context->status = INTERRUPT;
}
}
const QString InputStatement::ast() const {
if (error) {
return "ERROR";
}
return QString("INPUT\n " + identifier);
}
// INPUTS
InputsStatement::InputsStatement(const QString body): InputStatement(body) {
}
void InputsStatement::execute(Runtime* context) const {
InputStatement::execute(context);
context->io->requestStringInput();
}
const QString InputsStatement::ast() const {
if (error) {
return "ERROR";
}
return QString("INPUTS\n " + identifier);
}
// GOTO
GotoStatement::GotoStatement(const QString body): destination(body.trimmed()) {
if (destination.isEmpty()) {
error = new SyntaxError("Missing jump destination for GOTO statement");
}
}
void GotoStatement::execute(Runtime* context) const {
bool ok;
int dest = destination.toInt(&ok);
if (!ok) {
throw new SyntaxError(QString("Invalid jump destination \"%1\"").arg(destination));
}
context->status = GOTO;
context->gotoDst = dest;
}
QString GotoStatement::getDestination() const {
return destination;
}
const QString GotoStatement::ast() const {
if (error) {
return "ERROR";
}
return QString("GOTO\n %1").arg(destination);
}
// IF
IfStatement::IfStatement(const QString body) {
int indexOfThen = body.indexOf("THEN");
if (indexOfThen == -1) {
error = new SyntaxError("Missing THEN clause for IF statement");
return;
}
gotoStmt = new GotoStatement(body.mid(indexOfThen + 4));
int indexOfOp = parseCondition(body);
if (error) {
return;
}
try {
lhs = Expression::parse(body.left(indexOfOp));
rhs = Expression::parse(body.mid(indexOfOp + 1, indexOfThen - indexOfOp - 1));
} catch (Exception* exception) {
error = exception;
return;
}
error = lhs->error ? lhs->error : rhs->error;
}
void IfStatement::execute(Runtime* context) const {
const Value &left = *lhs->evaluate(context), &right = *rhs->evaluate(context);
bool shouldJump = (conditionOp == '<' && left < right) || (conditionOp == '=' && left == right) ||
(conditionOp == '>' && left > right);
if (shouldJump) {
gotoStmt->execute(context);
}
}
const QString IfStatement::ast() const {
if (error) {
return "ERROR";
}
return QString("IF THEN\n %1\n %2\n %3\n %4")
.arg(lhs->ast())
.arg(conditionOp)
.arg(rhs->ast())
.arg(gotoStmt->getDestination());
}
int IfStatement::parseCondition(const QString condition) {
int index;
index = condition.indexOf('<');
if (index != -1) {
conditionOp = '<';
return index;
}
index = condition.indexOf('=');
if (index != -1) {
conditionOp = '=';
return index;
}
index = condition.indexOf('>');
if (index != -1) {
conditionOp = '>';
return index;
}
error = new SyntaxError("Invalid condition operator for IF statement");
return -1;
}
IfStatement::~IfStatement() {
delete lhs;
delete rhs;
delete gotoStmt;
}
// END
void EndStatement::execute(Runtime* context) const {
context->status = HALT;
}
const QString EndStatement::ast() const {
return QString("END");
}