Merge branch 'development'

Author: saiyam-sandhir

main.cpp

@@ -0,0 +1,169 @@
+#include<iostream>
+#include<string>
+#include<vector>
+#include<sstream>
+#include<map>
+
+using namespace std;
+
+enum TokenType
+{
+    GET,
+    SET,
+    GO,
+    EQUAL,
+    VARIABLE,
+    NUMERIC,
+    END,
+    INVALID
+};
+
+class Token
+{
+    private:
+        TokenType type;
+        string value;
+
+    public:
+        Token(TokenType typ, string val) : type(typ), value(val){};
+
+        friend void parser(const vector<Token> &input_tokens);
+};
+
+bool isAlpha(const string &str)
+{
+    for (char ch : str)
+    {
+        if (!isalpha(ch))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+bool isNumeric(const string &str)
+{
+    for (char ch : str)
+    {
+        if (!isdigit(ch))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+vector<Token> lexer(string input)
+{
+    vector<Token> tokens;
+    istringstream iss(input);
+    string word;
+
+    while(iss >> word)
+    {
+        if(word == "GET")
+        {
+            tokens.emplace_back(Token(GET, "GET"));
+        }
+        else if(word == "SET")
+        {
+            tokens.emplace_back(Token(SET, "SET"));
+        }
+        else if(word == "GO")
+        {
+            tokens.emplace_back(Token(GO, "GO"));
+        }
+        else if(isNumeric(word))
+        {
+            tokens.emplace_back(Token(NUMERIC, word));
+        }
+        else if(word == "END")
+        {
+            tokens.emplace_back(Token(END, "END"));
+        }
+        else if(word == "=")
+        {
+            tokens.emplace_back(Token(EQUAL, "="));
+        }
+        else if(isAlpha(word))
+        {
+            tokens.emplace_back(Token(VARIABLE, word));
+        }
+        else
+        {
+            tokens.emplace_back(Token(INVALID, word));
+        }
+    }
+
+    return tokens;
+}
+
+map<string, int> variables;
+bool interpreter_running = true;
+void parser(const vector<Token> &input_tokens)
+{
+    for(auto itr = input_tokens.begin(); itr != input_tokens.end(); ++itr)
+    {
+        switch ((*itr).type)
+        {
+            case GET:
+                if((*(itr + 1)).type == VARIABLE)
+                {
+                    cout << ": ";
+                    string input_line;
+                    getline(cin, input_line);
+                    stringstream(input_line) >> variables[(*(itr + 1)).value];
+                }
+                
+                break;
+
+            case SET:
+                if((*(itr + 1)).type == VARIABLE && (*(itr + 2)).type == EQUAL && (*(itr + 3)).type == NUMERIC)
+                {
+                    variables[(*(itr + 1)).value] = stoi((*(itr + 3)).value);
+                }
+
+                break;
+
+            case GO:
+                if((*(itr + 1)).type == VARIABLE)
+                {
+                    cout << variables[(*(itr + 1)).value] << endl;
+                }
+
+                break;
+                
+            case INVALID:
+                break;
+
+            case END:
+                interpreter_running = false;
+
+                break;
+
+            default:
+                break;
+        }
+    }
+}
+
+int main()
+{
+    while(interpreter_running)
+    {
+        string input;
+        char ch;
+        cout << ">>> ";
+
+        while((ch = cin.get()) != '\n')
+        {
+            input += ch;
+        }
+
+        parser(lexer(input));
+        input = "";
+    }
+
+    return 0;
+}