use std.io;

var lexer = func(file) {
    var (ptr,token)=(0,[]);
    var s=io.readfile(file);
    var len=size(s);
    var line=0;
    var gen = func(tok) {
        append(token,{
            line:line,
            token:tok
        });
    }
    return {
        jmp_note:func() {
            while(ptr<len and s[ptr]!='\n'[0])
                ptr+=1;
            if (ptr<len and s[ptr]=='\n'[0])
                line+=1;
            ptr+=1;
        },
        id_gen:func() {
            var tmp="";
            while(ptr<len) {
                var c=s[ptr];
                if (('a'[0]<=c and c<='z'[0])
                or ('A'[0]<=c and c<='Z'[0])
                or ('0'[0]<=c and c<='9'[0])
                or c=='_'[0])
                    tmp~=chr(c);
                else
                    break;
                ptr+=1;
            }
            gen(tmp);
        },
        str_gen:func() {
            var str="";
            var mark=chr(s[ptr]);
            ptr+=1;
            while(ptr<len and chr(s[ptr])!=mark) {
                if (chr(s[ptr])=='\\') {
                    ptr+=1;
                    var c=chr(s[ptr]);
                    if   (c=='a' ) str~='\a';
                    elsif (c=='b' ) str~='\b';
                    elsif (c=='e' ) str~='\e';
                    elsif (c=='f' ) str~='\f';
                    elsif (c=='n' ) str~='\n';
                    elsif (c=='r' ) str~='\r';
                    elsif (c=='t' ) str~='\t';
                    elsif (c=='v' ) str~='\v';
                    elsif (c=='?' ) str~='\?';
                    elsif (c=='0' ) str~='\0';
                    elsif (c=='\\') str~='\\';
                    elsif (c=='\'') str~='\'';
                    elsif (c=='\"') str~='\"';
                    else           str~=c;
                } else {
                    if (s[ptr]=='\n'[0])
                        line+=1;
                    str~=chr(s[ptr]);
                }
                ptr+=1;
            }
            if (ptr>=len)
                print("read eof when generating string.\n");
            ptr+=1;
            gen(str);
        },
        num_gen:func() {
            var number=chr(s[ptr]);
            ptr+=1;
            if (ptr<len and chr(s[ptr])=='x') {
                ptr+=1;
                while(ptr<len and
                ('a'[0]<=s[ptr] and s[ptr]<='f'[0]
                or '0'[0]<=s[ptr] and s[ptr]<='9'[0])) {
                    number~=chr(s[ptr]);
                    ptr+=1;
                }
                gen(num(number));
                return;
            } elsif (ptr<len and chr(s[ptr])=='o') {
                ptr+=1;
                while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='7'[0])) {
                    number~=chr(s[ptr]);
                    ptr+=1;
                }
                gen(num(number));
                return;
            }
            while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='9'[0])) {
                number~=chr(s[ptr]);
                ptr+=1;
            }
            if (ptr<len and chr(s[ptr])=='.') {
                number~=chr(s[ptr]);
                ptr+=1;
                while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='9'[0])) {
                    number~=chr(s[ptr]);
                    ptr+=1;
                }
            }
            if (chr(s[ptr])=='e' or chr(s[ptr])=='E') {
                number~=chr(s[ptr]);
                ptr+=1;
                if (chr(s[ptr])=='-' or chr(s[ptr])=='+') {
                    number~=chr(s[ptr]);
                    ptr+=1;
                }
                while(ptr<len and ('0'[0]<=s[ptr] and s[ptr]<='9'[0])) {
                    number~=chr(s[ptr]);
                    ptr+=1;
                }
            }
            var last_c=chr(number[-1]);
            if (last_c=='.' or last_c=='e' or last_c=='E' or last_c=='-' or last_c=='+')
                println("error number: ",number);
            gen(num(number));
        },
        opr_gen:func() {
            var c=chr(s[ptr]);
            if (c=='+' or c=='-' or c=='~' or c=='/' or c=='*' or c=='>' or c=='<' or c=='!' or c=='=') {
                var tmp=c;
                ptr+=1;
                if (ptr<len and chr(s[ptr])=='=') {
                    tmp~=chr(s[ptr]);
                    ptr+=1;
                }
                gen(tmp);
                return;
            } elsif (c=='.') {
                if (ptr+2<len and chr(s[ptr+1])=='.' and chr(s[ptr+2])=='.') {
                    gen("...");
                    ptr+=3;
                }
                else {
                    gen(".");
                    ptr+=1;
                }
                return;
            }
            elsif (c!=' ' and c!='\t' and c!='\n' and c!='\r' and s[ptr]>0)
                gen(c);
            ptr+=1;
            return;
        },
        compile:func() {
            line=1;
            while(ptr<len) {
                var c=s[ptr];
                if (c=='#'[0])
                    me.jmp_note();
                elsif (c=='\n'[0]) {
                    line+=1;
                    ptr+=1;
                }
                elsif ('a'[0]<=c and c<='z'[0]
                    or 'A'[0]<=c and c<='Z'[0]
                    or c=='_'[0])
                    me.id_gen();
                elsif (c=='\''[0] or c=='\"'[0])
                    me.str_gen();
                elsif ('0'[0]<=c and c<='9'[0])
                    me.num_gen();
                else
                    me.opr_gen();
            }
            return;
        },
        get_token:func() {return token;}
    };
}

var lex=lexer("std/fg_env.nas");
lex.compile();
foreach(var tok;lex.get_token())
    print('(',tok.line,' | ',tok.token,')\n');