// TOP

#ifndef FCPP_NEW_LEXER_INC
#define FCPP_NEW_LEXER_INC

#include "4cpp_lexer_fsms.h"
#include "4cpp_lexer_tables.c"

#define lexer_link static

// TODO(allen): revisit this keyword data declaration system
struct String_List{
	String_And_Flag *data;
	int count;
};

struct Sub_Match_List_Result{
	int index;
	fcpp_i32 new_pos;
};

#define lexer_string_list(x) {x, (sizeof(x)/sizeof(*x))}

static String_And_Flag bool_lit_strings[] = {
	{"true"}, {"false"}
};
static String_List bool_lits = lexer_string_list(bool_lit_strings);

static String_And_Flag keyword_strings[] = {
    {"and", CPP_TOKEN_AND},
    {"and_eq", CPP_TOKEN_ANDEQ},
    {"bitand", CPP_TOKEN_BIT_AND},
    {"bitor", CPP_TOKEN_BIT_OR},
    {"or", CPP_TOKEN_OR},
    {"or_eq", CPP_TOKEN_OREQ},
    {"sizeof", CPP_TOKEN_SIZEOF},
    {"alignof", CPP_TOKEN_ALIGNOF},
    {"decltype", CPP_TOKEN_DECLTYPE},
    {"throw", CPP_TOKEN_THROW},
    {"new", CPP_TOKEN_NEW},
    {"delete", CPP_TOKEN_DELETE},
    {"xor", CPP_TOKEN_BIT_XOR},
    {"xor_eq", CPP_TOKEN_XOREQ},
    {"not", CPP_TOKEN_NOT},
    {"not_eq", CPP_TOKEN_NOTEQ},
    {"typeid", CPP_TOKEN_TYPEID},
    {"compl", CPP_TOKEN_BIT_NOT},
    
    {"void", CPP_TOKEN_KEY_TYPE},
    {"bool", CPP_TOKEN_KEY_TYPE},
    {"char", CPP_TOKEN_KEY_TYPE},
    {"int", CPP_TOKEN_KEY_TYPE},
    {"float", CPP_TOKEN_KEY_TYPE},
    {"double", CPP_TOKEN_KEY_TYPE},
    
    {"long", CPP_TOKEN_KEY_MODIFIER},
    {"short", CPP_TOKEN_KEY_MODIFIER},
    {"unsigned", CPP_TOKEN_KEY_MODIFIER},
    
    {"const", CPP_TOKEN_KEY_QUALIFIER},
    {"volatile", CPP_TOKEN_KEY_QUALIFIER},
    
    {"asm", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"break", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"case", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"catch", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"continue", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"default", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"do", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"else", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"for", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"goto", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"if", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"return", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"switch", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"try", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"while", CPP_TOKEN_KEY_CONTROL_FLOW},
    {"static_assert", CPP_TOKEN_KEY_CONTROL_FLOW},
    
    {"const_cast", CPP_TOKEN_KEY_CAST},
    {"dynamic_cast", CPP_TOKEN_KEY_CAST},
    {"reinterpret_cast", CPP_TOKEN_KEY_CAST},
    {"static_cast", CPP_TOKEN_KEY_CAST},
    
    {"class", CPP_TOKEN_KEY_TYPE_DECLARATION},
    {"enum", CPP_TOKEN_KEY_TYPE_DECLARATION},
    {"struct", CPP_TOKEN_KEY_TYPE_DECLARATION},
    {"typedef", CPP_TOKEN_KEY_TYPE_DECLARATION},
    {"union", CPP_TOKEN_KEY_TYPE_DECLARATION},
    {"template", CPP_TOKEN_KEY_TYPE_DECLARATION},
    {"typename", CPP_TOKEN_KEY_TYPE_DECLARATION},
    
    {"friend", CPP_TOKEN_KEY_ACCESS},
    {"namespace", CPP_TOKEN_KEY_ACCESS},
    {"private", CPP_TOKEN_KEY_ACCESS},
    {"protected", CPP_TOKEN_KEY_ACCESS},
    {"public", CPP_TOKEN_KEY_ACCESS},
    {"using", CPP_TOKEN_KEY_ACCESS},
    
    {"extern", CPP_TOKEN_KEY_LINKAGE},
    {"export", CPP_TOKEN_KEY_LINKAGE},
    {"inline", CPP_TOKEN_KEY_LINKAGE},
    {"static", CPP_TOKEN_KEY_LINKAGE},
    {"virtual", CPP_TOKEN_KEY_LINKAGE},
    
    {"alignas", CPP_TOKEN_KEY_OTHER},
    {"explicit", CPP_TOKEN_KEY_OTHER},
    {"noexcept", CPP_TOKEN_KEY_OTHER},
    {"nullptr", CPP_TOKEN_KEY_OTHER},
    {"operator", CPP_TOKEN_KEY_OTHER},
    {"register", CPP_TOKEN_KEY_OTHER},
    {"this", CPP_TOKEN_KEY_OTHER},
    {"thread_local", CPP_TOKEN_KEY_OTHER},
};
static String_List keywords = lexer_string_list(keyword_strings);

lexer_link Sub_Match_List_Result
sub_match_list(char *chunk, int size, int pos, String_List list, int sub_size){
	Sub_Match_List_Result result;
    String str_main;
    char *str_check;
    int i,l;
    
    result.index = -1;
    result.new_pos = pos;
    str_main = make_string(chunk + pos, size - pos);
    if (sub_size > 0){
        str_main = substr(str_main, 0, sub_size);
        for (i = 0; i < list.count; ++i){
            str_check = list.data[i].str;
            if (match(str_main, str_check)){
                result.index = i;
                result.new_pos = pos + sub_size;
                break;
            }
        }
    }
    else{
        for (i = 0; i < list.count; ++i){
            str_check = list.data[i].str;
            if (match_part(str_main, str_check, &l)){
                result.index = i;
                result.new_pos = pos + l;
                break;
            }
        }
    }
	return result;
}


lexer_link Cpp_Get_Token_Result
cpp_get_token(Cpp_Token_Stack *token_stack, int pos){
    Cpp_Get_Token_Result result = {};
    Cpp_Token *token_array = token_stack->tokens;
    Cpp_Token *token = 0;
	int first = 0;
    int count = token_stack->count;
    int last = count;
    int this_start = 0, next_start = 0;
    
    if (count > 0){
        for (;;){
            result.token_index = (first + last)/2;
            token = token_array + result.token_index;
            
            this_start = token->start;
            
            if (result.token_index + 1 < count){
                next_start = (token + 1)->start;
            }
            else{
                next_start = this_start + token->size;
            }
            if (this_start <= pos && pos < next_start){
                break;
            }
            else if (pos < this_start){
                last = result.token_index;
            }
            else{
                first = result.token_index + 1;
            }
            if (first == last){
                result.token_index = first;
                break;
            }
        }
        
        if (result.token_index == count){
            --result.token_index;
            result.in_whitespace = 1;
        }
        else{
            if (token->start + token->size <= pos){
                result.in_whitespace = 1;
            }
        }
    }
    else{
        result.token_index = -1;
        result.in_whitespace = 1;
    }
	
    return(result);
}

lexer_link void
cpp_shift_token_starts(Cpp_Token_Stack *stack, int from_token_i, int shift_amount){
    Cpp_Token *token = stack->tokens + from_token_i;
    int count = stack->count, i;
    
    for (i = from_token_i; i < count; ++i, ++token){
        token->start += shift_amount;
    }
}

enum Pos_Update_Rule{
    PUR_none,
    PUR_back_one,
    PUR_unget_whitespace,
};

lexer_link Lex_PP_State
cpp_pp_directive_to_state(Cpp_Token_Type type){
    Lex_PP_State result = LSPP_default;
    switch (type){
        case CPP_PP_INCLUDE:
        case CPP_PP_IMPORT:
        case CPP_PP_USING:
        result = LSPP_include;
        break;
        
        case CPP_PP_DEFINE:
        result = LSPP_macro_identifier;
        break;
        
        case CPP_PP_UNDEF:
        case CPP_PP_IFDEF:
        case CPP_PP_IFNDEF:
        result = LSPP_identifier;
        break;
        
        case CPP_PP_IF:
        case CPP_PP_ELIF:
        result = LSPP_body_if;
        break;
        
        case CPP_PP_PRAGMA:
        result = LSPP_body;
        break;
        
        case CPP_PP_LINE:
        result = LSPP_number;
        break;
        
        case CPP_PP_ERROR:
        result = LSPP_error;
        break;

        case CPP_PP_UNKNOWN:
        case CPP_PP_ELSE:
        case CPP_PP_ENDIF:
        result = LSPP_junk;
        break;
    }
    return(result);
}

lexer_link Cpp_Token_Merge
cpp_attempt_token_merge(Cpp_Token prev_token, Cpp_Token next_token){
    Cpp_Token_Merge result = {(Cpp_Token_Type)0};
	if (next_token.type == CPP_TOKEN_COMMENT && prev_token.type == CPP_TOKEN_COMMENT &&
		next_token.flags == prev_token.flags && next_token.state_flags == prev_token.state_flags){
		result.did_merge = 1;
		prev_token.size = next_token.start + next_token.size - prev_token.start;
		result.new_token = prev_token;
	}
	else if (next_token.type == CPP_TOKEN_JUNK && prev_token.type == CPP_TOKEN_JUNK &&
			 next_token.flags == prev_token.flags && next_token.state_flags == prev_token.state_flags){
		result.did_merge = 1;
		prev_token.size = next_token.start + next_token.size - prev_token.start;
		result.new_token = prev_token;
	}
	return result;
}

lexer_link void
cpp_push_token_nonalloc(Cpp_Token *out_tokens, int *token_i, Cpp_Token token){
    Cpp_Token_Merge merge = {(Cpp_Token_Type)0};
    Cpp_Token prev_token = {(Cpp_Token_Type)0};
    
    if (*token_i > 0){
        prev_token = out_tokens[*token_i - 1];
        merge = new_lex::cpp_attempt_token_merge(prev_token, token);
        if (merge.did_merge){
            out_tokens[*token_i - 1] = merge.new_token;
        }
    }
    
    if (!merge.did_merge){
        out_tokens[(*token_i)++] = token;
    }
}

struct Lex_Data{
    char *tb;
    int tb_pos;
    int token_start;
    
    int pos;
    int pos_overide;
    
    Lex_FSM fsm;
    Whitespace_FSM wfsm;
    unsigned char pp_state;
    unsigned char completed;
    
    Cpp_Token token;
    
    int __pc__;
};

#define DrCase(PC) case PC: goto resumespot_##PC

#define DrYield(PC, n) {\
    token_stack_out->count = token_i;\
    *S_ptr = S; S_ptr->__pc__ = PC; return(n); resumespot_##PC:; }

#define DrReturn(n) {\
    token_stack_out->count = token_i;\
    *S_ptr = S; S_ptr->__pc__ = -1; return(n); }

lexer_link int
cpp_lex_nonalloc(Lex_Data *S_ptr, char *chunk, int size, Cpp_Token_Stack *token_stack_out){
    Lex_Data S = *S_ptr;

    Cpp_Token *out_tokens = token_stack_out->tokens;
    int token_i = token_stack_out->count;
    int max_token_i = token_stack_out->max_count;

    Pos_Update_Rule pos_update_rule = PUR_none;

    char c = 0;

    int end_pos = size + S.pos;
    chunk -= S.pos;
    
    switch (S.__pc__){
        DrCase(1);
        DrCase(2);
        DrCase(3);
        DrCase(4);
        DrCase(5);
        DrCase(6);
    }
    
    for (;;){
        S.wfsm.white_done = 0;
        S.wfsm.pp_state = S.pp_state;
        for(;;){
            for (; S.wfsm.pp_state < LSPP_count && S.pos < end_pos;){
                c = chunk[S.pos++];
                int i = S.wfsm.pp_state + whitespace_fsm_eq_classes[c];
                S.wfsm.pp_state = whitespace_fsm_table[i];
            }
            S.wfsm.white_done = (S.wfsm.pp_state >= LSPP_count);
            
            if (S.wfsm.white_done == 0){
                DrYield(4, 1);
            }
            else break;
        }
        --S.pos;
        S.pp_state = S.wfsm.pp_state;
        if (S.pp_state >= LSPP_count){
            S.pp_state -= LSPP_count;
		}
        
        S.token_start = S.pos;
        S.tb_pos = 0;
        S.fsm = {0};
        for(;;){
            unsigned short *eq_classes = get_eq_classes[S.pp_state];
            unsigned char *fsm_table = get_table[S.pp_state];

            for (; S.fsm.state < LS_count && S.pos < end_pos;){
                c = chunk[S.pos++];
                S.tb[S.tb_pos++] = c;

                int i = S.fsm.state + eq_classes[c];
                S.fsm.state = fsm_table[i];
                S.fsm.multi_line |= multiline_state_table[S.fsm.state];
            }
            S.fsm.emit_token = (S.fsm.state >= LS_count);

            if (S.fsm.emit_token == 0){
                DrYield(3, 1);
            }
            else break;
        }
        
        Assert(S.fsm.emit_token == 1);
        
        if (c != 0){
            if (S.fsm.state >= LS_count) S.fsm.state -= LS_count;
            pos_update_rule = PUR_none;
            if (S.pp_state == LSPP_include){
                switch (S.fsm.state){
                    case LSINC_default:break;

                    case LSINC_quotes:
                    case LSINC_pointy:
                    S.token.type = CPP_TOKEN_INCLUDE_FILE;
                    S.token.flags = 0;
                    break;

                    case LSINC_junk:
                    S.token.type = CPP_TOKEN_JUNK;
                    S.token.flags = 0;
                    break;
                }
            }
            else{
                switch (S.fsm.state){
                    case LS_default:
                    switch (c){
#define OperCase(op,t) case op: S.token.type = t; break;
                        OperCase('{', CPP_TOKEN_BRACE_OPEN);
                        OperCase('}', CPP_TOKEN_BRACE_CLOSE);

                        OperCase('[', CPP_TOKEN_BRACKET_OPEN);
                        OperCase(']', CPP_TOKEN_BRACKET_CLOSE);

                        OperCase('(', CPP_TOKEN_PARENTHESE_OPEN);
                        OperCase(')', CPP_TOKEN_PARENTHESE_CLOSE);

                        OperCase('~', CPP_TOKEN_TILDE);
                        OperCase(',', CPP_TOKEN_COMMA);
                        OperCase(';', CPP_TOKEN_SEMICOLON);
                        OperCase('?', CPP_TOKEN_TERNARY_QMARK);

                        OperCase('@', CPP_TOKEN_JUNK);
                        OperCase('$', CPP_TOKEN_JUNK);
#undef OperCase

                        case '\\':
                        if (S.pp_state == LSPP_default){
                            S.token.type = CPP_TOKEN_JUNK;
                        }
                        else{
                            S.pos_overide = S.pos;
                            S.wfsm.white_done = 0;
                            for (;;){
                                for (; S.wfsm.white_done == 0 && S.pos < end_pos;){
                                    c = chunk[S.pos++];
                                    if (!(c == ' ' || c == '\t' || c == '\r' || c == '\v' || c == '\f')) S.wfsm.white_done = 1;
                                }

                                if (S.wfsm.white_done == 0){
                                    DrYield(1, 1);
                                }
                                else break;
                            }

                            if (c == '\n'){
                                S.fsm.emit_token = 0;
                                S.pos_overide = 0;
                            }
                            else{
                                S.token.type = CPP_TOKEN_JUNK;
                            }
                        }
                        break;
                    }
                    if (c != '@' && c != '$' && c != '\\'){
                        S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    }
                    break;

                    case LS_identifier:
                    {
                        --S.pos;

                        int word_size = S.pos - S.token_start;

                        if (S.pp_state == LSPP_body_if){
                            if (match(make_string(S.tb, word_size), make_lit_string("defined"))){
                                S.token.type = CPP_TOKEN_DEFINED;
                                S.token.flags = CPP_TFLAG_IS_OPERATOR | CPP_TFLAG_IS_KEYWORD;
                                break;
                            }
                        }

                        Sub_Match_List_Result sub_match;
                        sub_match = sub_match_list(S.tb, S.tb_pos, 0, bool_lits, word_size);

                        if (sub_match.index != -1){
                            S.token.type = CPP_TOKEN_BOOLEAN_CONSTANT;
                            S.token.flags = CPP_TFLAG_IS_KEYWORD;
                        }
                        else{
                            sub_match = sub_match_list(S.tb, S.tb_pos, 0, keywords, word_size);

                            if (sub_match.index != -1){
                                String_And_Flag data = keywords.data[sub_match.index];
                                S.token.type = (Cpp_Token_Type)data.flags;
                                S.token.flags = CPP_TFLAG_IS_KEYWORD;
                            }
                            else{
                                S.token.type = CPP_TOKEN_IDENTIFIER;
                                S.token.flags = 0;
                            }
                        }
                    }break;

                    case LS_pound:
                    S.token.flags = 0;
                    switch (c){
                        case '#': S.token.type = CPP_PP_CONCAT; break;
                        default:
                        S.token.type = CPP_PP_STRINGIFY;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_pp:
                    {
                        S.fsm.directive_state = LSDIR_default;
                        S.fsm.emit_token = 0;
                        for (;;){
                            for (; S.fsm.directive_state < LSDIR_count && S.pos < end_pos;){
                                c = chunk[S.pos++];
                                S.fsm.directive_state = pp_directive_table[S.fsm.directive_state + pp_directive_eq_classes[c]];
                            }
                            S.fsm.emit_token = (S.fsm.int_state >= LSDIR_count);

                            if (S.fsm.emit_token == 0){
                                DrYield(6, 1);
                            }
                            else break;
                        }
                        --S.pos;
                        
                        Cpp_Token_Type type = (Cpp_Token_Type)(S.fsm.directive_state - pp_directive_terminal_base);
                        S.token.type = type;
                        if (type == CPP_TOKEN_JUNK){
                            S.token.flags = 0;
						}
                        else{
                            S.token.flags = CPP_TFLAG_PP_DIRECTIVE;
                            S.pp_state = (unsigned char)cpp_pp_directive_to_state(S.token.type);
						}
                    }break;

                    case LS_number:
                    case LS_number0:
                    case LS_hex:
                    {
                        S.fsm.int_state = LSINT_default;
                        S.fsm.emit_token = 0;
                        --S.pos;
                        for (;;){
                            for (; S.fsm.int_state < LSINT_count && S.pos < end_pos;){
                                c = chunk[S.pos++];
                                S.fsm.int_state = int_fsm_table[S.fsm.int_state + int_fsm_eq_classes[c]];
                            }
                            S.fsm.emit_token = (S.fsm.int_state >= LSINT_count);

                            if (S.fsm.emit_token == 0){
                                DrYield(5, 1);
                            }
                            else break;
                        }
                        --S.pos;
                    }

                    S.token.type = CPP_TOKEN_INTEGER_CONSTANT;
                    S.token.flags = 0;
                    break;

                    case LS_float:
                    case LS_crazy_float0:
                    case LS_crazy_float1:
                    S.token.type = CPP_TOKEN_FLOATING_CONSTANT;
                    S.token.flags = 0;
                    switch (c){
                        case 'f': case 'F':
                        case 'l': case 'L':break;
                        default:
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_char:
                    S.token.type = CPP_TOKEN_CHARACTER_CONSTANT;
                    S.token.flags = 0;
                    break;

                    case LS_char_multiline:
                    S.token.type = CPP_TOKEN_CHARACTER_CONSTANT;
                    S.token.flags = CPP_TFLAG_MULTILINE;
                    break;

                    case LS_string:
                    S.token.type = CPP_TOKEN_STRING_CONSTANT;
                    S.token.flags = 0;
                    break;

                    case LS_string_multiline:
                    S.token.type = CPP_TOKEN_STRING_CONSTANT;
                    S.token.flags = CPP_TFLAG_MULTILINE;
                    break;

                    case LS_comment_pre:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_DIVEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_DIV;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_comment: case LS_comment_block_ending:
                    S.token.type = CPP_TOKEN_COMMENT;
                    S.token.flags = 0;
                    pos_update_rule = PUR_unget_whitespace;
                    break;

                    case LS_error_message:
                    S.token.type = CPP_TOKEN_ERROR_MESSAGE;
                    S.token.flags = 0;
                    pos_update_rule = PUR_unget_whitespace;
                    break;

                    case LS_dot:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '*': S.token.type = CPP_TOKEN_PTRDOT; break;
                        default:
                        S.token.type = CPP_TOKEN_DOT;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_ellipsis:
                    switch (c){
                        case '.':
                        S.token.flags = CPP_TFLAG_IS_OPERATOR;
                        S.token.type = CPP_TOKEN_ELLIPSIS;
                        break;

                        default:
                        S.token.type = CPP_TOKEN_JUNK;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_less:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_LESSEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_LESS;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_less_less:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_LSHIFTEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_LSHIFT;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_more:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_GRTREQ; break;
                        default:
                        S.token.type = CPP_TOKEN_GRTR;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_more_more:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_RSHIFTEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_RSHIFT;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_minus:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '-': S.token.type = CPP_TOKEN_DECREMENT; break;
                        case '=': S.token.type = CPP_TOKEN_SUBEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_MINUS;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_arrow:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '*': S.token.type = CPP_TOKEN_PTRARROW; break;
                        default:
                        S.token.type = CPP_TOKEN_ARROW;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_and:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '&': S.token.type = CPP_TOKEN_AND; break;
                        case '=': S.token.type = CPP_TOKEN_ANDEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_AMPERSAND;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_or:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '|': S.token.type = CPP_TOKEN_OR; break;
                        case '=': S.token.type = CPP_TOKEN_OREQ; break;
                        default:
                        S.token.type = CPP_TOKEN_BIT_OR;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_plus:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '+': S.token.type = CPP_TOKEN_INCREMENT; break;
                        case '=': S.token.type = CPP_TOKEN_ADDEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_PLUS;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_colon:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case ':': S.token.type = CPP_TOKEN_SCOPE; break;
                        default:
                        S.token.type = CPP_TOKEN_COLON;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_star:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_MULEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_STAR;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_modulo:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_MODEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_MOD;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_caret:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_XOREQ; break;
                        default:
                        S.token.type = CPP_TOKEN_BIT_XOR;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_eq:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_EQEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_EQ;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;

                    case LS_bang:
                    S.token.flags = CPP_TFLAG_IS_OPERATOR;
                    switch (c){
                        case '=': S.token.type = CPP_TOKEN_NOTEQ; break;
                        default:
                        S.token.type = CPP_TOKEN_NOT;
                        pos_update_rule = PUR_back_one;
                        break;
                    }
                    break;
                }

                switch (pos_update_rule){
                    case PUR_back_one:
                    --S.pos;
                    break;

                    case PUR_unget_whitespace:
                    c = chunk[--S.pos];
                    while (c == ' ' || c == '\n' || c == '\t' || c == '\r' || c == '\v' || c == '\f'){
                        c = chunk[--S.pos];
                    }
                    ++S.pos;
                    break;
                }

                if ((S.token.flags & CPP_TFLAG_PP_DIRECTIVE) == 0){
                    switch (S.pp_state){
                        case LSPP_include:
                        if (S.token.type != CPP_TOKEN_INCLUDE_FILE){
                            S.token.type = CPP_TOKEN_JUNK;
                        }
                        S.pp_state = LSPP_junk;
                        break;

                        case LSPP_macro_identifier:
                        if (S.fsm.state != LS_identifier){
                            S.token.type = CPP_TOKEN_JUNK;
                            S.pp_state = LSPP_junk;
                        }
                        else{
                            S.pp_state = LSPP_body;
                        }
                        break;

                        case LSPP_identifier:
                        if (S.fsm.state != LS_identifier){
                            S.token.type = CPP_TOKEN_JUNK;
                        }
                        S.pp_state = LSPP_junk;
                        break;

                        case LSPP_number:
                        if (S.token.type != CPP_TOKEN_INTEGER_CONSTANT){
                            S.token.type = CPP_TOKEN_JUNK;
                            S.pp_state = LSPP_junk;
                        }
                        else{
                            S.pp_state = LSPP_include;
                        }
                        break;

                        case LSPP_junk:
                        S.token.type = CPP_TOKEN_JUNK;
                        break;
                    }
                }
            }

            if (S.fsm.emit_token){
                S.token.start = S.token_start;
                if (S.pos_overide){
                    S.token.size = S.pos_overide - S.token_start;
                    S.pos_overide = 0;
                }
                else{
                    S.token.size = S.pos - S.token_start;
                }
                if ((S.token.flags & CPP_TFLAG_PP_DIRECTIVE) == 0){
                    S.token.flags |= (S.pp_state != LSPP_default)?(CPP_TFLAG_PP_BODY):(0);
                }
                S.token.state_flags = S.pp_state;
                
                cpp_push_token_nonalloc(out_tokens, &token_i, S.token);
                if (token_i == max_token_i){
                    DrYield(2, 2);
                }
            }
        }
        // NOTE(allen): else case for "if (c != 0) {...}
        else{
            S.completed = 1;
            break;
        }
    }
    
    DrReturn(0);
}

#undef DrYield
#undef DrReturn
#undef DrCase

#endif

// BOTTOM