boxscript-interperter-c/source/lexer.cpp

#include "lexer.hpp"
namespace BoxScript::Lexer
{
LexToken::LexToken()
{
    this->text="";
    this->type = ERROR;
}
LexToken::LexToken(std::string _text)
{
    this->text = _text;
    if(_text.size() > 0)
    {
        this->type=_text[0] >= '0' && _text[0] <= '9' ? NUMBER : IDENTIFER;
    }
    else{
        this->type = ERROR;
    }
}   
class Lexer
{
    private:
    std::string text;
    int filePos;
    void read_char(char* chr,bool* esc)
    {
        int txt = text[filePos++];
        if(txt == '\\')
        {
            txt = text[filePos++];
            if(txt == 'x')
            {
                std::string txt="0x";
                filePos+=2;
                for(int i = 0;i<2;i++)
                {
                    txt += text[filePos++];
                }
                *chr= (char)std::stol(txt,0,0);
            }else
            {
                if(txt == 'n')
                {
                    *chr= '\n';
                }else
                if(txt == 'r')
                {
                    *chr='\r';
                }else
                if(txt == 't')
                {
                    *chr='\t';
                }else{
                    *chr = (char)txt;
                }
            }
            *esc=true;
        }
        else{
            *esc=false;
            *chr=(char)txt;
        }
    }
    std::string read_string()
    {
        std::string b="";
        while(true)
        {
            char chr='\0';
            bool esc=false;
            read_char(&chr,&esc);
            if(chr == '\"' && !esc)
            {
                break;
            }
            b+=chr;
        }
        return b;
    }
    public:
    Lexer(std::string _text)
    {   
        this->text=_text;
        this->filePos=0;
    }
    std::vector<LexToken> Lex()
    {
        std::vector<LexToken> tokens;
        std::string b="";
        while(filePos < text.length())
        {
            char c = text[filePos++];
            if(c == '\"')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                std::string str = read_string();
                LexToken token;
                token.text = str;
                token.type = STRING;
                tokens.push_back(token);
            }else if(c == '#')
            {
                while(text[filePos++] != '\n');
            }
            else
            if(c == '\'')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                char chr='\0';
                bool esc;
                read_char(&chr,&esc);
                LexToken token;
                token.text="";
                token.text += chr;
                token.type = NUMBER;
                tokens.push_back(token);
                      
            }else if(c == '+')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="+";
                token.type = PLUS;
                tokens.push_back(token);
            }else if(c == '-')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="-";
                token.type = MINUS;
                tokens.push_back(token);
            }else if(c == '+')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="*";
                token.type = MULTIPLY;
                tokens.push_back(token);
            }
            else if(c == '/')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="/";
                token.type = DIVIDE;
                tokens.push_back(token);
            }else if(c == '%')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="%";
                token.type = MOD;
                tokens.push_back(token);
            }
            else if(c == '{')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="{";
                token.type = LBRACE;
                tokens.push_back(token);
            }
            else if(c == '}')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="}";
                token.type = RBRACE;
                tokens.push_back(token);
            }
            else if(c == '(')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="(";
                token.type = LPAREN;
                tokens.push_back(token);
            }
            else if(c == ')')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text=")";
                token.type = RPAREN;
                tokens.push_back(token);
            }
            else if(c == '=')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text="=";
                token.type = EQUALS;
                tokens.push_back(token);
            }
            else if(c == ',')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text=",";
                token.type = COMMA;
                tokens.push_back(token);
            }
            else if(c == ';')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
                LexToken token;
                token.text=";";
                token.type = SEMI;
                tokens.push_back(token);
            }
            else if(c == '\n' || c == ' ' || c == '\t')
            {
                if(b.length() > 0)
                {
                    tokens.push_back(LexToken(b));
                    b="";
                }
               
            }else{
                b += c;
            }
        }
        if(b.length() > 0)
        {
            tokens.push_back(LexToken(b));
            b="";
        }
        return tokens;
    }

};
std::vector<LexToken> Lex(std::string text)
{
    Lexer l(text);
    return l.Lex();
}
};