first upload

Basic.pro

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+#-------------------------------------------------
+#
+# Project created by QtCreator 2019-11-10T23:30:15
+#
+#-------------------------------------------------
+
+QT       += core gui
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+TARGET = Basic
+TEMPLATE = app
+
+# The following define makes your compiler emit warnings if you use
+# any feature of Qt which has been marked as deprecated (the exact warnings
+# depend on your compiler). Please consult the documentation of the
+# deprecated API in order to know how to port your code away from it.
+DEFINES += QT_DEPRECATED_WARNINGS
+
+# You can also make your code fail to compile if you use deprecated APIs.
+# In order to do so, uncomment the following line.
+# You can also select to disable deprecated APIs only up to a certain version of Qt.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+CONFIG += c++11
+
+SOURCES += \
+        evaluation.cpp \
+        expression.cpp \
+        main.cpp \
+        parser.cpp \
+        program.cpp\
+        basic.cpp \
+        statement.cpp \
+        tokenizer.cpp
+
+HEADERS += \
+        evaluation.h \
+        expression.h \
+        parser.h \
+        program.h\
+        basic.h \
+        statement.h \
+        tokenizer.h
+
+# Default rules for deployment.
+qnx: target.path = /tmp/$${TARGET}/bin
+else: unix:!android: target.path = /opt/$${TARGET}/bin
+!isEmpty(target.path): INSTALLS += target

basic.cpp

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+#include "basic.h"
+
+#include <QKeyEvent>
+#include <QTextLine>
+#include <QTextCursor>
+#include <QDebug>
+#include <QFont>
+
+Basic::Basic(QWidget *parent) : QTextEdit(parent)
+{
+    program = new Program;
+    tokenizer = new Tokenizer;
+    parser = new Parser;
+    eval = new Evaluation();
+    this->setFont(QFont("Consolas",14));
+    this->write("MINIMAL BASIC -- Type HELP for help.\n");
+    resize(800,600);
+}
+
+void Basic::write(QString string)
+{
+    this->append(string);
+}
+
+QString Basic::getInputValue()
+{
+    if (runtimeInput == "")
+        return "";
+    tokenizer->scanLine(runtimeInput);
+    QString token = tokenizer->getNextToken();
+    token = tokenizer->getNextToken();
+    QString value = tokenizer->getNextToken();
+    if(tokenizer->getTokenType(value)!= NUMBER || tokenizer->hasMoreTokens()){
+        return "INVALID";
+    }
+    return value;
+}
+
+void Basic::inputGotten(){
+    runtimeInput = "";
+}
+
+void Basic::processLine(QString line)
+{
+        tokenizer->scanLine(line);
+        if (state == RUNNING){
+            runtimeInput = line;
+        }else{
+            QString firstTerm = tokenizer->getNextToken();
+            if(tokenizer->getTokenType(firstTerm) != NUMBER)
+                processCommand(firstTerm);
+            else
+                processCode(firstTerm.toInt(),line);
+        }
+
+}
+
+void Basic::processCode(int lineNum, QString line)
+{
+    if (lineNum <= 0)
+        throw QString("Line number should be greater than 0!");
+    if (tokenizer->hasMoreTokens()){
+        program->insertLine(lineNum, line);
+        parser->parseStatement(tokenizer,this);
+    } else {
+        if(program->map.contains(lineNum))
+            program->removeLine(lineNum);
+        else throw QString("No such line to remove!");
+    }
+}
+
+void Basic::processCommand(QString cmd)
+{
+   QString CMD = cmd.toUpper();
+   if(CMD == "RUN") {
+       run();
+   }else if(CMD == "LIST") {
+       listProgram();
+   } else if(CMD == "CLEAR") {
+       clear();
+   } else if(CMD == "HELP") {
+       printHelpMsg();
+   } else if(CMD == "QUIT") {
+       exit(0);
+   } else if(CMD == "PRINT") {
+       tokenizer->trackback();
+       parser->parseStatement(tokenizer,this);
+   } else {
+       throw "Invalid COMMAND: " + CMD + ". Type HELP for help.";
+   }
+}
+
+void Basic::run()
+{
+    state = RUNNING;
+    int index = program->getFirstLineNum();
+    while(index != -1){
+        try{
+            program->getParsedStatement(index)->execute(eval);
+        }catch(int){
+            break;
+        }catch(const QString error) {
+            this->write(error);
+            break;
+        }
+        if (eval->getNextLineNum() != -1){
+            index = eval->getNextLineNum();
+        }else {
+            index = program->getNextLineNum(index);
+        }
+    }
+    state = NOTRUNNING;
+}
+
+void Basic::listProgram()
+{
+    for (int i = 0; i < program->list.size(); ++i) {
+        if(program->list.at(i)->stm)
+            this->write(program->list.at(i)->statement);
+    }
+}
+
+void Basic::clear()
+{
+    program->clear();
+    eval->clear();
+}
+
+
+void Basic::printHelpMsg()
+{
+    this->write("The following commands are accepted by the interpreter:");
+    this->write("RUN - Runs the stored program.");
+    this->write("LIST - Lists the stored program.");
+    this->write("CLEAR - Deletes the stored program.");
+    this->write("HELP - Displays help information.");
+    this->write("QUIT - Exits the interpreter.\n");
+
+    this->write("The following statements are accepted by the interpreter:");
+    this->write("The LET, PRINT, and INPUT statements can be executed directly by typing them without a line number.");
+    this->write("Following commands cannot be part of a program and must therefore be entered without a line number. ");
+    this->write("[Usage: REM exp]: This statement is used for comments. Any text on the line after the keyword REM is ignored.");
+    this->write("[Usage: LET var = exp]: Assignment statement. Assigns the value of the expression to the variable, replacing any previous value.");
+    this->write("[Usage: PRINT exp]: Prints value of the expression to the console.");
+    this->write("[Usage: INPUT var]: Reads in a variable from the user. Prompts the user by printing \" ? \", and assigns the input value to the variable");
+    this->write("[Usage: GOTO n]: Forces program to execute line n instead of the next stored line.");
+    this->write("[Usage: IF exp1 op exp2 THEN n]*: Conditional operator op accepts =, <, and > to compare exp1 and exp2. If condition holds, executes line n. If not, program executes the next stored line.");
+    this->write("[Usage: END]: Halts program execution.\n");
+
+    this->write("Functions are supported with the following statements.");
+    this->write("[Usage: SUB function_name, Statements, End Sub ]: the function can use variables defined outside the function, and variables defined inside the function can also be accessed in other parts of the code.");
+    this->write("[Usage: CALL function_name]:  invoked the function.\n");
+}
+
+void Basic::keyPressEvent(QKeyEvent *event)
+{
+    QTextCursor cursor = this->textCursor();
+    cursor.movePosition(QTextCursor::End);
+    this->setTextCursor(cursor);
+    ensureCursorVisible();
+
+    if (event->key() == Qt::Key_Backspace){
+        cursor.deletePreviousChar();
+        return;
+    }
+    if (event->key() == Qt::Key_Delete){
+        cursor.deleteChar();
+        return;
+    }
+    if (this->textCursor().hasSelection())
+        return;
+    if (event->key() == Qt::Key_Return) {
+        cursor.select(QTextCursor::LineUnderCursor);
+        QString Line = cursor.selectedText();
+        try{
+            processLine(Line);
+        }catch (const QString error) {
+            this->write(error);
+        }
+    }
+    QTextEdit::keyPressEvent(event);
+}

basic.h

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+/*
+ * File: Basic.h
+ * -------------------
+ * Export a QTextEdit class to implement a console to interact
+ * with the user.Process the command and print information.
+ *
+ */
+
+#ifndef BASIC_H
+#define BASIC_H
+
+#include <QObject>
+#include <QTextEdit>
+#include <QWidget>
+
+#include "program.h"
+#include "tokenizer.h"
+#include "parser.h"
+
+/* Mark wheter the program is running */
+enum State{RUNNING,NOTRUNNING};
+
+class Basic : public QTextEdit
+{
+    Q_OBJECT
+
+public:
+    Program* program;
+    Tokenizer* tokenizer;
+    Parser* parser;
+    Evaluation *eval;
+
+private:
+    QString runtimeInput;
+    State state;
+
+public:
+    explicit Basic(QWidget *parent = nullptr);
+
+    /*
+     * Function: write
+     * Usage: basic->write(QString);
+     * -----------------------------------------
+     * Print the string on the widget.
+     */
+    void write(QString string);
+
+    /*
+     * Function: processLine
+     * -----------------------------------------
+     * Get a single line entered by the user and decide if it
+     * is a command or a line of code. Process accordingly.
+     */
+    void processLine(QString line);
+
+    /*
+     * Function: processCode
+     * -----------------------------------------
+     * Process the line with a line number with the help of parser.
+     * Store it in the program.
+     * If line only has a line number, delete it if this line already
+     * exsits, or print that this line does not exists.
+     */
+    void processCode(int lineNum, QString line);
+
+    /*
+     * Function: processCommand
+     * -----------------------------------------
+     * Get a single command and checks its validity.
+     * If valid, carries out the corresponding operation.
+     */
+    void processCommand(QString cmd);
+
+    /*
+     * Function: getInputValue
+     * -----------------------------------------
+     * Get the user input during the running of the program.
+     */
+    QString getInputValue();
+
+    /*
+     * Function: inputGotten
+     * -----------------------------------------
+     * Mark that the input is gotten by the evaluation.
+     */
+    void inputGotten();
+
+    /*
+     * Function: run
+     * -----------------------------------------
+     * Start executing the program.
+     */
+    void run();
+
+    /*
+     * Function: listProgram
+     * -----------------------------------------------
+     * Print the line stored in program out on the window.
+     */
+    void listProgram();
+
+    /*
+     * Function: clear
+     * -----------------------------------------------
+     * Delete all the previous information.
+     */
+    void clear();
+
+    /*
+     * Function: printHelpMsg
+     * -----------------------------------------------
+     * Support the PRINT command. Print all the help information.
+     */
+    void printHelpMsg();
+protected:
+    virtual void keyPressEvent(QKeyEvent *event) override;
+};
+
+
+#endif // BASIC_H