lex example test

lex.c

#include <stdio.h>
#include <stdlib.h>

#include "token.h"
#include "rhd/heap_string.h"
#include "rhd/linked_list.h"

struct lexer
{
    char *buf;
    int bufsz;
    int pos;
    struct token tk;
    int lineno;
    struct linked_list *tokens;
};

int next(struct lexer *lex)
{
    if(lex->pos + 1 >= lex->bufsz)
	return -1;
    return lex->buf[lex->pos++];
}

heap_string next_match(struct lexer *lex, int (*cmp)(int))
{
    //undo the fetch from before
    --lex->pos;
    
    heap_string s = NULL;
    while(1)
    {
	int ch = next(lex);
	if(ch == -1 || !cmp(ch))
	    return s;
	heap_string_push(&s, ch);
    }
    return s;
}

static int match_test_ident(int ch)
{
    return (ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z') || ch == '_';
}

static int match_test_integer(int ch)
{
    return ch >= '0' && ch <= '9';
}

int token(struct lexer *lex, struct token *tk)
{
    int ch;
retry:
    tk->type = TK_INVALID;
    ch = next(lex);
    if(ch == -1)
	return 1;
    
    switch(ch)
    {
	case ' ':
	case '\t':
	case '\r':
	case '\n':
	    goto retry;

	case '#':
	case '<':
	case '>':
	case '"':
	case '\'':
	case '{':
	case '}':
	case '/':
	case '*':
	case '[':
	case ']':
	case '&':
	case '^':
	case '|':
	case '!':
	case '-':
	case '+':
	case '(':
	case ')':
	case '=':
	case ';':
	case ':':
	case '\\':
	case ',':
	case '%':
	case '.':
	    tk->type = ch;
	    break;

	default:
	    if(match_test_integer(ch))
	    {
		tk->type = TK_INTEGER;
		heap_string s = next_match(lex, match_test_integer);
		tk->integer = atoi(s);
		heap_string_free(&s);
	    } else if(match_test_ident(ch))
	    {
		tk->type = TK_IDENT;
		heap_string s = next_match(lex, match_test_ident);
		//check whether this ident is a special ident
		if(!strcmp(s, "loop"))
		    tk->type = TK_LOOP;
		else if(!strcmp(s, "if"))
		    tk->type = TK_IF;
		snprintf(tk->string, sizeof(tk->string), "%s", s);
		heap_string_free(&s);
	    } else
	    {
		printf("got %c, unhandled error\n", ch);
		return 1; //error
	    }
	    break;
    }
    return 0;
}

void parse(heap_string data)
{
    int len = strlen(data);

    struct lexer lex = {
	.buf = data,
	.bufsz = strlen(data) + 1,
	.pos = 0,
	.lineno = 0,
	.tokens = NULL
    };

    lex.tokens = linked_list_create(struct token);

    struct token tk = {0};

    for(int i = 0; i < len; ++i)
    {
	int ret = token(&lex, &tk);
	if(ret)
	{
	    break;
	}
	//if(tk.type == TK_IDENT)
	//printf("token = %d (%s)\n", tk.type, tk.string);
	linked_list_append(lex.tokens, tk);
    }

    linked_list_reversed_foreach(lex.tokens, struct token*, it,
    {
	    if(it->type == TK_IDENT)
		printf("]%s\n", it->string);
    });

    linked_list_destroy(&lex.tokens);
}
/*
int main(int argc, char **argv)
{
    if(argc < 2)
	return 0;
    heap_string data = read_file(argv[1]);

    if(!data)
    {
	printf("failed to read file '%s'\n", argv[1]);
	return 1;
    }

    //printf("data = %s\n", data);
    parse(data);
    heap_string_free(&data);
    return 0;
}
*/