source: mainline/uspace/app/bdsh/tok.c@ eff10e03

/*
 * Copyright (c) 2011 Martin Sucha
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <str.h>
#include <assert.h>
#include <malloc.h>
#include <stdlib.h>
#include <errno.h>

#include "tok.h"

/* Forward declarations of static functions */
static wchar_t tok_get_char(tokenizer_t *);
static wchar_t tok_look_char(tokenizer_t *);
static int tok_push_char(tokenizer_t *, wchar_t);
static int tok_push_token(tokenizer_t *);
static bool tok_pending_chars(tokenizer_t *);
static int tok_finish_string(tokenizer_t *);

/** Initialize the token parser
 * 
 * @param tok the tokenizer structure to initialize
 * @param input the input string to tokenize
 * @param out_tokens array of strings where to store the result
 * @param max_tokens number of elements of the out_tokens array
 */
int tok_init(tokenizer_t *tok, char *input, char **out_tokens,
    size_t max_tokens)
{       
        tok->in = input;
        tok->in_offset = 0;
        
        tok->outtok = out_tokens;
        tok->outtok_offset = 0;
        /* Leave one slot for a null terminator */
        assert(max_tokens > 0);
        tok->outtok_size = max_tokens - 1;
        
        /* Prepare a buffer where all the token strings will be stored */
        size_t len = str_size(input) + max_tokens + 1;
        char *tmp = malloc(len);
        
        if (tmp == NULL) {
                return ENOMEM;
        }
        
        tok->outbuf = tmp;
        tok->outbuf_offset = 0;
        tok->outbuf_size = len;
        tok->outbuf_last_start = 0;
        
        return EOK;
}

/** Finalize the token parser */
void tok_fini(tokenizer_t *tok)
{
        if (tok->outbuf != NULL) {
                free(tok->outbuf);
        }
}

/** Tokenize the input string into the tokens */
int tok_tokenize(tokenizer_t *tok)
{
        int rc;
        wchar_t cur_char;
        
        /* Read the input line char by char and append tokens */
        while ((cur_char = tok_get_char(tok)) != 0) {
                if (cur_char == ' ') {
                        /* Spaces delimit tokens, but are not processed in any way
                         * Push the token if there is any.
                         * There may not be any pending char for a token in case
                         * there are several spaces in the input.
                         */
                        if (tok_pending_chars(tok)) {
                                rc = tok_push_token(tok);
                                if (rc != EOK) {
                                        return rc;
                                }
                        }
                }
                else if (cur_char == '|') {
                        /* Pipes are tokens that are delimiters and should be output
                         * as a separate token
                         */
                        if (tok_pending_chars(tok)) {
                                rc = tok_push_token(tok);
                                if (rc != EOK) {
                                        return rc;
                                }
                        }
                        
                        rc = tok_push_char(tok, '|');
                        if (rc != EOK) {
                                return rc;
                        }
                        
                        rc = tok_push_token(tok);
                        if (rc != EOK) {
                                return rc;
                        }
                }
                else if (cur_char == '\'') {
                        /* A string starts with a quote (') and ends again with a quote.
                         * A literal quote is written as ''
                         */
                        rc = tok_finish_string(tok);
                        if (rc != EOK) {
                                return rc;
                        }
                }
                else {
                        /* If we are handling any other character, just append it to
                         * the current token.
                         */
                        rc = tok_push_char(tok, cur_char);
                        if (rc != EOK) {
                                return rc;
                        }
                }
        }
        
        /* Push the last token */
        if (tok_pending_chars(tok)) {
                rc = tok_push_token(tok);
                if (rc != EOK) {
                        return rc;
                }
        }
        
        /* We always have a space for the terminator, as we
         * reserved it in tok_init */
        tok->outtok[tok->outtok_offset] = 0;
        
        return EOK;
}

/** Finish tokenizing an opened string */
int tok_finish_string(tokenizer_t *tok)
{
        int rc;
        wchar_t cur_char;
        
        while ((cur_char = tok_get_char(tok)) != 0) {
                if (cur_char == '\'') {
                        if (tok_look_char(tok) == '\'') {
                                /* Encode a single literal quote */
                                rc = tok_push_char(tok, '\'');
                                if (rc != EOK) {
                                        return rc;
                                }
                                
                                /* Swallow the additional one in the input */
                                tok_get_char(tok);
                        }
                        else {
                                /* The string end */
                                return tok_push_token(tok);
                        }
                }
                else {
                        rc = tok_push_char(tok, cur_char);
                        if (rc != EOK) {
                                return rc;
                        }
                }
        }
        
        /* If we are here, the string run to the end without being closed */
        return EINVAL;
}

/** Get a char from input, advancing the input position */
wchar_t tok_get_char(tokenizer_t *tok)
{
        return str_decode(tok->in, &tok->in_offset, STR_NO_LIMIT);
}

/** Get a char from input, while staying on the same input position */
wchar_t tok_look_char(tokenizer_t *tok)
{
        size_t old_offset = tok->in_offset;
        wchar_t ret = tok_get_char(tok);
        tok->in_offset = old_offset;
        return ret;
}

/** Append a char to the end of the current token */
int tok_push_char(tokenizer_t *tok, wchar_t ch)
{
        return chr_encode(ch, tok->outbuf, &tok->outbuf_offset, tok->outbuf_size);
}

/** Push the current token to the output array */
int tok_push_token(tokenizer_t *tok)
{
        if (tok->outtok_offset >= tok->outtok_size) {
                return EOVERFLOW;
        }
        
        if (tok->outbuf_offset >= tok->outbuf_size) {
                return EOVERFLOW;
        }
        
        tok->outbuf[tok->outbuf_offset++] = 0;
        tok->outtok[tok->outtok_offset++] = tok->outbuf + tok->outbuf_last_start;
        tok->outbuf_last_start = tok->outbuf_offset;
        
        return EOK;
}

/** Return true, if the current token is not empty */
bool tok_pending_chars(tokenizer_t *tok)
{
        assert(tok->outbuf_offset >= tok->outbuf_last_start);
        return (tok->outbuf_offset != tok->outbuf_last_start);
}