cat-rs 0.0.9

/* SDSLib, A C dynamic strings library
 *
 * Copyright (c) 2006-2012, Salvatore Sanfilippo <antirez at gmail dot com>
 * 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.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>

#include "cat_sds.h"

/* Create a new sds string with the content specified by the 'init' pointer
 * and 'initlen'.
 * If NULL is used for 'init' the string is initialized with zero bytes.
 *
 * The string is always null-termined (all the sds strings are, always) so
 * even if you create an sds string with:
 *
 * mystring = catsdsnewlen("abc",3);
 *
 * You can print the string with printf() as there is an implicit \0 at the
 * end of the string. However the string is binary safe and can contain
 * \0 characters in the middle, as the length is stored in the sds messageType. */
sds catsdsnewlen(const void *init, size_t initlen) {
    sdshdr *sh;

    if (init) {
        sh = malloc(sizeof(sdshdr) + initlen + 1);
    } else {
        sh = calloc(sizeof(sdshdr) + initlen + 1, 1);
    }
    if (sh == NULL) return NULL;
    sh->len = initlen;
    sh->free = 0;
    if (initlen && init)
        memcpy(sh->buf, init, initlen);
    sh->buf[initlen] = '\0';
    return (char *) sh->buf;
}


sds catsdsnewEmpty(size_t preAlloclen) {
    sdshdr *sh;

    sh = malloc(sizeof(sdshdr) + preAlloclen + 1);
    if (sh == NULL) return NULL;
    sh->len = 0;
    sh->free = preAlloclen;
    sh->buf[0] = '\0';
    return (char *) sh->buf;
}


/* Create an empty (zero length) sds string. Even in this case the string
 * always has an implicit null term. */
sds catsdsempty(void) {
    return catsdsnewlen("", 0);
}

/* Create a new sds string starting from a null terminated C string. */
sds catsdsnew(const char *init) {
    size_t initlen = (init == NULL) ? 0 : strlen(init);
    return catsdsnewlen(init, initlen);
}

/* Duplicate an sds string. */
sds catsdsdup(const sds s) {
    if (s == NULL) return NULL;
    return catsdsnewlen(s, catsdslen(s));
}

/* Free an sds string. No operation is performed if 's' is NULL. */
void catsdsfree(sds s) {
    if (s == NULL) return;
    free(s - sizeof(sdshdr));
}

/* Set the sds string length to the length as obtained with strlen(), so
 * considering as content only up to the first null term character.
 *
 * This function is useful when the sds string is hacked manually in some
 * way, like in the following example:
 *
 * s = catsdsnew("foobar");
 * s[2] = '\0';
 * sdsupdatelen(s);
 * printf("%d\n", catsdslen(s));
 *
 * The output will be "2", but if we comment out the call to catsdsupdatelen()
 * the output will be "6" as the string was modified but the logical length
 * remains 6 bytes. */
void catsdsupdatelen(sds s) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    int reallen = strlen(s);
    sh->free += (sh->len - reallen);
    sh->len = reallen;
}

/* Modify an sds string in-place to make it empty (zero length).
 * However all the existing buffer is not discarded but set as free space
 * so that next append operations will not require allocations up to the
 * number of bytes previously available. */
void catsdsclear(sds s) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    sh->free += sh->len;
    sh->len = 0;
    sh->buf[0] = '\0';
}

/* Enlarge the free space at the end of the sds string so that the caller
 * is sure that after calling this function can overwrite up to addlen
 * bytes after the end of the string, plus one more byte for nul term.
 *
 * Note: this does not change the *length* of the sds string as returned
 * by catsdslen(), but only the free buffer space we have. */
sds catsdsMakeRoomFor(sds s, size_t addlen) {
    sdshdr *sh, *newsh;
    size_t free = catsdsavail(s);
    size_t len, newlen;

    if (free >= addlen) return s;
    len = catsdslen(s);
    sh = (void *) (s - (sizeof(sdshdr)));
    newlen = (len + addlen);
    if (newlen < SDS_MAX_PREALLOC)
        newlen *= 2;
    else
        newlen += SDS_MAX_PREALLOC;
    newsh = realloc(sh, sizeof(sdshdr) + newlen + 1);
    if (newsh == NULL) return NULL;

    newsh->free = newlen - len;
    return newsh->buf;
}

/* Reallocate the sds string so that it has no free space at the end. The
 * contained string remains not altered, but next concatenation operations
 * will require a reallocation.
 *
 * After the call, the passed sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call. */
sds catsdsRemoveFreeSpace(sds s) {
    sdshdr *sh;

    sh = (void *) (s - (sizeof(sdshdr)));
    sh = realloc(sh, sizeof(sdshdr) + sh->len + 1);
    sh->free = 0;
    return sh->buf;
}

/* Return the total size of the allocation of the specifed sds string,
 * including:
 * 1) The sds messageType before the pointer.
 * 2) The string.
 * 3) The free buffer at the end if any.
 * 4) The implicit null term.
 */
size_t catsdsAllocSize(sds s) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));

    return sizeof(*sh) + sh->len + sh->free + 1;
}

/* Increment the sds length and decrements the left free space at the
 * end of the string according to 'incr'. Also set the null term
 * in the new end of the string.
 *
 * This function is used in order to fix the string length after the
 * user calls sdsMakeRoomFor(), writes something after the end of
 * the current string, and finally needs to set the new length.
 *
 * Note: it is possible to use a negative increment in order to
 * right-trim the string.
 *
 * Usage example:
 *
 * Using sdsIncrLen() and sdsMakeRoomFor() it is possible to mount the
 * following schema, to cat bytes coming from the kernel to the end of an
 * sds string without copying into an intermediate buffer:
 *
 * oldlen = catsdslen(s);
 * s = catsdsMakeRoomFor(s, BUFFER_SIZE);
 * nread = read(fd, s+oldlen, BUFFER_SIZE);
 * ... check for nread <= 0 and handle it ...
 * catsdsIncrLen(s, nread);
 */
void catsdsIncrLen(sds s, int incr) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));

    if (incr >= 0)
        assert(sh->free >= (unsigned int) incr);
    else
        assert(sh->len >= (unsigned int) (-incr));
    sh->len += incr;
    sh->free -= incr;
    s[sh->len] = '\0';
}

/* Grow the sds to have the specified length. Bytes that were not part of
 * the original length of the sds will be set to zero.
 *
 * if the specified length is smaller than the current length, no operation
 * is performed. */
sds catsdsgrowzero(sds s, size_t len) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    size_t totlen, curlen = sh->len;

    if (len <= curlen) return s;
    s = catsdsMakeRoomFor(s, len - curlen);
    if (s == NULL) return NULL;

    /* Make sure added region doesn't contain garbage */
    sh = (void *) (s - (sizeof(sdshdr)));
    memset(s + curlen, 0, (len - curlen + 1)); /* also set trailing \0 byte */
    totlen = sh->len + sh->free;
    sh->len = len;
    sh->free = totlen - sh->len;
    return s;
}

/* Append the specified binary-safe string pointed by 't' of 'len' bytes to the
 * end of the specified sds string 's'.
 *
 * After the call, the passed sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call. */
sds catsdscatlen(sds s, const void *t, size_t len) {
    sdshdr *sh;
    size_t curlen = catsdslen(s);

    s = catsdsMakeRoomFor(s, len);
    if (s == NULL) return NULL;
    sh = (void *) (s - (sizeof(sdshdr)));
    memcpy(s + curlen, t, len);
    sh->len = curlen + len;
    sh->free = sh->free - len;
    s[curlen + len] = '\0';
    return s;
}


sds catsdscatchar(sds s, char c) {
    sdshdr *sh;
    size_t curlen = catsdslen(s);

    s = catsdsMakeRoomFor(s, 1);
    if (s == NULL) return NULL;
    sh = (void *) (s - (sizeof(sdshdr)));
    s[curlen] = c;
    s[curlen + 1] = '\0';
    ++sh->len;
    --sh->free;
    return s;
}


/* Append the specified null termianted C string to the sds string 's'.
 *
 * After the call, the passed sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call. */
sds catsdscat(sds s, const char *t) {
    if (s == NULL || t == NULL) {
        return s;
    }
    return catsdscatlen(s, t, strlen(t));
}

/* Append the specified sds 't' to the existing sds 's'.
 *
 * After the call, the modified sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call. */
sds catsdscatsds(sds s, const sds t) {
    return catsdscatlen(s, t, catsdslen(t));
}

/* Destructively modify the sds string 's' to hold the specified binary
 * safe string pointed by 't' of length 'len' bytes. */
sds catsdscpylen(sds s, const char *t, size_t len) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    size_t totlen = sh->free + sh->len;

    if (totlen < len) {
        s = catsdsMakeRoomFor(s, len - sh->len);
        if (s == NULL) return NULL;
        sh = (void *) (s - (sizeof(sdshdr)));
        totlen = sh->free + sh->len;
    }
    memcpy(s, t, len);
    s[len] = '\0';
    sh->len = len;
    sh->free = totlen - len;
    return s;
}

/* Like catsdscpylen() but 't' must be a null-termined string so that the length
 * of the string is obtained with strlen(). */
sds catsdscpy(sds s, const char *t) {
    return catsdscpylen(s, t, strlen(t));
}

/* Helper for sdscatlonglong() doing the actual number -> string
 * conversion. 's' must point to a string with room for at least
 * SDS_LLSTR_SIZE bytes.
 *
 * The function returns the length of the null-terminated string
 * representation stored at 's'. */
#define SDS_LLSTR_SIZE 21

int sdsll2str(char *s, long long value) {
    char *p, aux;
    unsigned long long v;
    size_t l;

    /* Generate the string representation, this method produces
     * an reversed string. */
    v = (value < 0) ? -value : value;
    p = s;
    do {
        *p++ = '0' + (v % 10);
        v /= 10;
    } while (v);
    if (value < 0) *p++ = '-';

    /* Compute length and add null term. */
    l = p - s;
    *p = '\0';

    /* Reverse the string. */
    p--;
    while (s < p) {
        aux = *s;
        *s = *p;
        *p = aux;
        s++;
        p--;
    }
    return l;
}

/* Identical sdsll2str(), but for unsigned long long type. */
int sdsull2str(char *s, unsigned long long v) {
    char *p, aux;
    size_t l;

    /* Generate the string representation, this method produces
     * an reversed string. */
    p = s;
    do {
        *p++ = '0' + (v % 10);
        v /= 10;
    } while (v);

    /* Compute length and add null term. */
    l = p - s;
    *p = '\0';

    /* Reverse the string. */
    p--;
    while (s < p) {
        aux = *s;
        *s = *p;
        *p = aux;
        s++;
        p--;
    }
    return l;
}

/* Create an sds string from a long long value. It is much faster than:
 *
 * catsdscatprintf(catsdsempty(),"%lld\n", value);
 */
sds catsdsfromlonglong(long long value) {
    char buf[SDS_LLSTR_SIZE];
    int len = sdsll2str(buf, value);

    return catsdsnewlen(buf, len);
}

/* Like catsdscatprintf() but gets va_list instead of being variadic. */
sds catsdscatvprintf(sds s, const char *fmt, va_list ap) {
    va_list cpy;
    char staticbuf[1024], *buf = staticbuf, *t;
    size_t buflen = strlen(fmt) * 2;

    /* We try to start using a static buffer for speed.
     * If not possible we revert to heap allocation. */
    if (buflen > sizeof(staticbuf)) {
        buf = malloc(buflen);
        if (buf == NULL) return NULL;
    } else {
        buflen = sizeof(staticbuf);
    }

    /* Try with buffers two times bigger every time we fail to
     * fit the string in the current buffer size. */
    while (1) {
        buf[buflen - 2] = '\0';
        va_copy(cpy, ap);
        vsnprintf(buf, buflen, fmt, cpy);
        va_end(cpy);
        if (buf[buflen - 2] != '\0') {
            if (buf != staticbuf) free(buf);
            buflen *= 2;
            buf = malloc(buflen);
            if (buf == NULL) return NULL;
            continue;
        }
        break;
    }

    /* Finally concat the obtained string to the SDS string and return it. */
    t = catsdscat(s, buf);
    if (buf != staticbuf) free(buf);
    return t;
}

/* Append to the sds string 's' a string obtained using printf-alike format
 * specifier.
 *
 * After the call, the modified sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call.
 *
 * Example:
 *
 * s = catsdsnew("Sum is: ");
 * s = sdscatprintf(s,"%d+%d = %d",a,b,a+b).
 *
 * Often you need to create a string from scratch with the printf-alike
 * format. When this is the need, just use sdsempty() as the target string:
 *
 * s = catsdscatprintf(catsdsempty(), "... your format ...", args);
 */
sds catsdscatprintf(sds s, const char *fmt, ...) {
    va_list ap;
    char *t;
    va_start(ap, fmt);
    t = catsdscatvprintf(s, fmt, ap);
    va_end(ap);
    return t;
}

/* This function is similar to catsdscatprintf, but much faster as it does
 * not rely on sprintf() family functions implemented by the libc that
 * are often very slow. Moreover directly handling the sds string as
 * new data is concatenated provides a performance improvement.
 *
 * However this function only handles an incompatible subset of printf-alike
 * format specifiers:
 *
 * %s - C String
 * %S - SDS string
 * %i - signed int
 * %I - 64 bit signed integer (long long, int64_t)
 * %u - unsigned int
 * %U - 64 bit unsigned integer (unsigned long long, uint64_t)
 * %% - Verbatim "%" character.
 */
sds catsdscatfmt(sds s, char const *fmt, ...) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    size_t initlen = catsdslen(s);
    const char *f = fmt;
    int i;
    va_list ap;

    va_start(ap, fmt);
    f = fmt;    /* Next format specifier byte to process. */
    i = initlen; /* Position of the next byte to write to dest str. */
    while (*f) {
        char next, *str;
        unsigned int l;
        long long num;
        unsigned long long unum;

        /* Make sure there is always space for at least 1 char. */
        if (sh->free == 0) {
            s = catsdsMakeRoomFor(s, 1);
            sh = (void *) (s - (sizeof(sdshdr)));
        }

        switch (*f) {
            case '%':
                next = *(f + 1);
                f++;
                switch (next) {
                    case 's':
                    case 'S':
                        str = va_arg(ap, char*);
                        l = (next == 's') ? strlen(str) : catsdslen(str);
                        if (sh->free < l) {
                            s = catsdsMakeRoomFor(s, l);
                            sh = (void *) (s - (sizeof(sdshdr)));
                        }
                        memcpy(s + i, str, l);
                        sh->len += l;
                        sh->free -= l;
                        i += l;
                        break;
                    case 'i':
                    case 'I':
                        if (next == 'i')
                            num = va_arg(ap, int);
                        else
                            num = va_arg(ap, long long);
                        {
                            char buf[SDS_LLSTR_SIZE];
                            l = sdsll2str(buf, num);
                            if (sh->free < l) {
                                s = catsdsMakeRoomFor(s, l);
                                sh = (void *) (s - (sizeof(sdshdr)));
                            }
                            memcpy(s + i, buf, l);
                            sh->len += l;
                            sh->free -= l;
                            i += l;
                        }
                        break;
                    case 'u':
                    case 'U':
                        if (next == 'u')
                            unum = va_arg(ap, unsigned int);
                        else
                            unum = va_arg(ap, unsigned long long);
                        {
                            char buf[SDS_LLSTR_SIZE];
                            l = sdsull2str(buf, unum);
                            if (sh->free < l) {
                                s = catsdsMakeRoomFor(s, l);
                                sh = (void *) (s - (sizeof(sdshdr)));
                            }
                            memcpy(s + i, buf, l);
                            sh->len += l;
                            sh->free -= l;
                            i += l;
                        }
                        break;
                    default: /* Handle %% and generally %<unknown>. */
                        s[i++] = next;
                        sh->len += 1;
                        sh->free -= 1;
                        break;
                }
                break;
            default:
                s[i++] = *f;
                sh->len += 1;
                sh->free -= 1;
                break;
        }
        f++;
    }
    va_end(ap);

    /* Add null-term */
    s[i] = '\0';
    return s;
}

/* Remove the part of the string from left and from right composed just of
 * contiguous characters found in 'cset', that is a null terminted C string.
 *
 * After the call, the modified sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call.
 *
 * Example:
 *
 * s = catsdsnew("AA...AA.a.aa.aHelloWorld     :::");
 * s = catsdstrim(s,"Aa. :");
 * printf("%s\n", s);
 *
 * Output will be just "Hello World".
 */
sds catsdstrim(sds s, const char *cset) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    char *start, *end, *sp, *ep;
    size_t len;

    sp = start = s;
    ep = end = s + catsdslen(s) - 1;
    while (sp <= end && strchr(cset, *sp)) sp++;
    while (ep > start && strchr(cset, *ep)) ep--;
    len = (sp > ep) ? 0 : ((ep - sp) + 1);
    if (sh->buf != sp) memmove(sh->buf, sp, len);
    sh->buf[len] = '\0';
    sh->free = sh->free + (sh->len - len);
    sh->len = len;
    return s;
}

/* Turn the string into a smaller (or equal) string containing only the
 * substring specified by the 'start' and 'end' indexes.
 *
 * start and end can be negative, where -1 means the last character of the
 * string, -2 the penultimate character, and so forth.
 *
 * The interval is inclusive, so the start and end characters will be part
 * of the resulting string.
 *
 * The string is modified in-place.
 *
 * Example:
 *
 * s = catsdsnew("Hello World");
 * catsdsrange(s,1,-1); => "ello World"
 */
void catsdsrange(sds s, int start, int end) {
    sdshdr *sh = (void *) (s - (sizeof(sdshdr)));
    size_t newlen, len = catsdslen(s);

    if (len == 0) return;
    if (start < 0) {
        start = len + start;
        if (start < 0) start = 0;
    }
    if (end < 0) {
        end = len + end;
        if (end < 0) end = 0;
    }
    newlen = (start > end) ? 0 : (end - start) + 1;
    if (newlen != 0) {
        if (start >= (signed) len) {
            newlen = 0;
        } else if (end >= (signed) len) {
            end = len - 1;
            newlen = (start > end) ? 0 : (end - start) + 1;
        }
    } else {
        start = 0;
    }
    if (start && newlen) memmove(sh->buf, sh->buf + start, newlen);
    sh->buf[newlen] = 0;
    sh->free = sh->free + (sh->len - newlen);
    sh->len = newlen;
}

/* Apply tolower() to every character of the sds string 's'. */
void catsdstolower(sds s) {
    int len = catsdslen(s), j;

    for (j = 0; j < len; j++) s[j] = tolower(s[j]);
}

/* Apply toupper() to every character of the sds string 's'. */
void catsdstoupper(sds s) {
    int len = catsdslen(s), j;

    for (j = 0; j < len; j++) s[j] = toupper(s[j]);
}

/* Compare two sds strings s1 and s2 with memcmp().
 *
 * Return value:
 *
 *     positive if s1 > s2.
 *     negative if s1 < s2.
 *     0 if s1 and s2 are exactly the same binary string.
 *
 * If two strings share exactly the same prefix, but one of the two has
 * additional characters, the longer string is considered to be greater than
 * the smaller one. */
int catsdscmp(const sds s1, const sds s2) {
    size_t l1, l2, minlen;
    int cmp;

    l1 = catsdslen(s1);
    l2 = catsdslen(s2);
    minlen = (l1 < l2) ? l1 : l2;
    cmp = memcmp(s1, s2, minlen);
    if (cmp == 0) return l1 - l2;
    return cmp;
}

/* Split 's' with separator in 'sep'. An array
 * of sds strings is returned. *count will be set
 * by reference to the number of tokens returned.
 *
 * On out of memory, zero length string, zero length
 * separator, NULL is returned.
 *
 * Note that 'sep' is able to split a string using
 * a multi-character separator. For example
 * sdssplit("foo_-_bar","_-_"); will return two
 * elements "foo" and "bar".
 *
 * This version of the function is binary-safe but
 * requires length arguments. sdssplit() is just the
 * same function but for zero-terminated strings.
 */
sds *catsdssplitlen(const char *s, int len, const char *sep, int seplen, int *count) {
    int elements = 0, slots = 5, start = 0, j;
    sds *tokens;

    if (seplen < 1 || len < 0) return NULL;

    tokens = malloc(sizeof(sds) * slots);
    if (tokens == NULL) return NULL;

    if (len == 0) {
        *count = 0;
        return tokens;
    }
    for (j = 0; j < (len - (seplen - 1)); j++) {
        /* make sure there is room for the next element and the final one */
        if (slots < elements + 2) {
            sds *newtokens;

            slots *= 2;
            newtokens = realloc(tokens, sizeof(sds) * slots);
            if (newtokens == NULL) goto cleanup;
            tokens = newtokens;
        }
        /* search the separator */
        if ((seplen == 1 && *(s + j) == sep[0]) || (memcmp(s + j, sep, seplen) == 0)) {
            tokens[elements] = catsdsnewlen(s + start, j - start);
            if (tokens[elements] == NULL) goto cleanup;
            elements++;
            start = j + seplen;
            j = j + seplen - 1; /* skip the separator */
        }
    }
    /* Add the final element. We are sure there is room in the tokens array. */
    tokens[elements] = catsdsnewlen(s + start, len - start);
    if (tokens[elements] == NULL) goto cleanup;
    elements++;
    *count = elements;
    return tokens;

    cleanup:
    {
        int i;
        for (i = 0; i < elements; i++) catsdsfree(tokens[i]);
        free(tokens);
        *count = 0;
        return NULL;
    }
}

/* Free the result returned by catsdssplitlen(), or do nothing if 'tokens' is NULL. */
void catsdsfreesplitres(sds *tokens, int count) {
    if (!tokens) return;
    while (count--)
        catsdsfree(tokens[count]);
    free(tokens);
}

/* Append to the sds string "s" an escaped string representation where
 * all the non-printable characters (tested with isprint()) are turned into
 * escapes in the form "\n\r\a...." or "\x<hex-number>".
 *
 * After the call, the modified sds string is no longer valid and all the
 * references must be substituted with the new pointer returned by the call. */
sds catsdscatrepr(sds s, const char *p, size_t len) {
    s = catsdscatlen(s, "\"", 1);
    while (len--) {
        switch (*p) {
            case '\\':
            case '"':
                s = catsdscatprintf(s, "\\%c", *p);
                break;
            case '\n':
                s = catsdscatlen(s, "\\n", 2);
                break;
            case '\r':
                s = catsdscatlen(s, "\\r", 2);
                break;
            case '\t':
                s = catsdscatlen(s, "\\t", 2);
                break;
            case '\a':
                s = catsdscatlen(s, "\\a", 2);
                break;
            case '\b':
                s = catsdscatlen(s, "\\b", 2);
                break;
            default:
                if (isprint(*p))
                    s = catsdscatprintf(s, "%c", *p);
                else
                    s = catsdscatprintf(s, "\\x%02x", (unsigned char) *p);
                break;
        }
        p++;
    }
    return catsdscatlen(s, "\"", 1);
}

/* Helper function for catsdssplitargs() that returns non zero if 'c'
 * is a valid hex digit. */
int is_hex_digit(char c) {
    return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') ||
           (c >= 'A' && c <= 'F');
}

/* Helper function for catsdssplitargs() that converts a hex digit into an
 * integer from 0 to 15 */
int hex_digit_to_int(char c) {
    switch (c) {
        case '0':
            return 0;
        case '1':
            return 1;
        case '2':
            return 2;
        case '3':
            return 3;
        case '4':
            return 4;
        case '5':
            return 5;
        case '6':
            return 6;
        case '7':
            return 7;
        case '8':
            return 8;
        case '9':
            return 9;
        case 'a':
        case 'A':
            return 10;
        case 'b':
        case 'B':
            return 11;
        case 'c':
        case 'C':
            return 12;
        case 'd':
        case 'D':
            return 13;
        case 'e':
        case 'E':
            return 14;
        case 'f':
        case 'F':
            return 15;
        default:
            return 0;
    }
}

/* Split a line into arguments, where every argument can be in the
 * following programming-language REPL-alike form:
 *
 * foo bar "newline are supported\n" and "\xff\x00otherstuff"
 *
 * The number of arguments is stored into *argc, and an array
 * of sds is returned.
 *
 * The caller should free the resulting array of sds strings with
 * catsdsfreesplitres().
 *
 * Note that catsdscatrepr() is able to convert back a string into
 * a quoted string in the same format catsdssplitargs() is able to parse.
 *
 * The function returns the allocated tokens on success, even when the
 * input string is empty, or NULL if the input contains unbalanced
 * quotes or closed quotes followed by non space characters
 * as in: "foo"bar or "foo'
 */
sds *catsdssplitargs(const char *line, int *argc) {
    const char *p = line;
    char *current = NULL;
    char **vector = NULL;

    *argc = 0;
    while (1) {
        /* skip blanks */
        while (*p && isspace(*p)) p++;
        if (*p) {
            /* get a token */
            int inq = 0;  /* set to 1 if we are in "quotes" */
            int insq = 0; /* set to 1 if we are in 'single quotes' */
            int done = 0;

            if (current == NULL) current = catsdsempty();
            while (!done) {
                if (inq) {
                    if (*p == '\\' && *(p + 1) == 'x' &&
                        is_hex_digit(*(p + 2)) &&
                        is_hex_digit(*(p + 3))) {
                        unsigned char byte;

                        byte = (hex_digit_to_int(*(p + 2)) * 16) +
                               hex_digit_to_int(*(p + 3));
                        current = catsdscatlen(current, (char *) &byte, 1);
                        p += 3;
                    } else if (*p == '\\' && *(p + 1)) {
                        char c;

                        p++;
                        switch (*p) {
                            case 'n':
                                c = '\n';
                                break;
                            case 'r':
                                c = '\r';
                                break;
                            case 't':
                                c = '\t';
                                break;
                            case 'b':
                                c = '\b';
                                break;
                            case 'a':
                                c = '\a';
                                break;
                            default:
                                c = *p;
                                break;
                        }
                        current = catsdscatlen(current, &c, 1);
                    } else if (*p == '"') {
                        /* closing quote must be followed by a space or
                         * nothing at all. */
                        if (*(p + 1) && !isspace(*(p + 1))) goto err;
                        done = 1;
                    } else if (!*p) {
                        /* unterminated quotes */
                        goto err;
                    } else {
                        current = catsdscatlen(current, p, 1);
                    }
                } else if (insq) {
                    if (*p == '\\' && *(p + 1) == '\'') {
                        p++;
                        current = catsdscatlen(current, "'", 1);
                    } else if (*p == '\'') {
                        /* closing quote must be followed by a space or
                         * nothing at all. */
                        if (*(p + 1) && !isspace(*(p + 1))) goto err;
                        done = 1;
                    } else if (!*p) {
                        /* unterminated quotes */
                        goto err;
                    } else {
                        current = catsdscatlen(current, p, 1);
                    }
                } else {
                    switch (*p) {
                        case ' ':
                        case '\n':
                        case '\r':
                        case '\t':
                        case '\0':
                            done = 1;
                            break;
                        case '"':
                            inq = 1;
                            break;
                        case '\'':
                            insq = 1;
                            break;
                        default:
                            current = catsdscatlen(current, p, 1);
                            break;
                    }
                }
                if (*p) p++;
            }
            /* add the token to the vector */
            vector = realloc(vector, ((*argc) + 1) * sizeof(char *));
            vector[*argc] = current;
            (*argc)++;
            current = NULL;
        } else {
            /* Even on empty input string return something not NULL. */
            if (vector == NULL) vector = malloc(sizeof(void *));
            return vector;
        }
    }

    err:
    while ((*argc)--)
        catsdsfree(vector[*argc]);
    free(vector);
    if (current) catsdsfree(current);
    *argc = 0;
    return NULL;
}

/* Modify the string substituting all the occurrences of the set of
 * characters specified in the 'from' string to the corresponding character
 * in the 'to' array.
 *
 * For instance: catsdsmapchars(mystring, "ho", "01", 2)
 * will have the effect of turning the string "hello" into "0ell1".
 *
 * The function returns the sds string pointer, that is always the same
 * as the input pointer since no resize is needed. */
sds catsdsmapchars(sds s, const char *from, const char *to, size_t setlen) {
    size_t j, i, l = catsdslen(s);

    for (j = 0; j < l; j++) {
        for (i = 0; i < setlen; i++) {
            if (s[j] == from[i]) {
                s[j] = to[i];
                break;
            }
        }
    }
    return s;
}

/* Join an array of C strings using the specified separator (also a C string).
 * Returns the result as an sds string. */
sds catsdsjoin(char **argv, int argc, char *sep) {
    sds join = catsdsempty();
    int j;

    for (j = 0; j < argc; j++) {
        join = catsdscat(join, argv[j]);
        if (j != argc - 1) join = catsdscat(join, sep);
    }
    return join;
}