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 /*

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

  *

  * Copyright 2021 Mike Becker, Olaf Wintermann All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are met:

  *

  *   1. Redistributions of source code must retain the above copyright

  *      notice, this list of conditions and the following disclaimer.

  *

  *   2. 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.

  *

  * 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 HOLDER 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 "cx/string.h"

 #include "cx/utils.h"

 #include <string.h>

 #include <stdarg.h>

 #include <ctype.h>

 #ifndef _WIN32

 #include <strings.h> // for strncasecmp()

 #endif // _WIN32

 cxmutstr cx_mutstr(char *cstring) {

     return (cxmutstr) {cstring, strlen(cstring)};

 }

 cxmutstr cx_mutstrn(

         char *cstring,

         size_t length

 ) {

     return (cxmutstr) {cstring, length};

 }

 cxstring cx_str(const char *cstring) {

     return (cxstring) {cstring, strlen(cstring)};

 }

 cxstring cx_strn(

         const char *cstring,

         size_t length

 ) {

     return (cxstring) {cstring, length};

 }

 cxstring cx_strcast(cxmutstr str) {

     return (cxstring) {str.ptr, str.length};

 }

 void cx_strfree(cxmutstr *str) {

     free(str->ptr);

     str->ptr = NULL;

     str->length = 0;

 }

 void cx_strfree_a(

         CxAllocator *alloc,

         cxmutstr *str

 ) {

     cxFree(alloc, str->ptr);

     str->ptr = NULL;

     str->length = 0;

 }

 size_t cx_strlen(

         size_t count,

         ...

 ) {

     if (count == 0) return 0;

     va_list ap;

     va_start(ap, count);

     size_t size = 0;

     cx_for_n(i, count) {

         cxstring str = va_arg(ap, cxstring);

         size += str.length;

     }

     va_end(ap);

     return size;

 }

 cxmutstr cx_strcat_a(

         CxAllocator *alloc,

         size_t count,

         ...

 ) {

     cxstring *strings = calloc(count, sizeof(cxstring));

     if (!strings) abort();

     va_list ap;

     va_start(ap, count);

     // get all args and overall length

     size_t slen = 0;

     cx_for_n(i, count) {

         cxstring s = va_arg (ap, cxstring);

         strings[i] = s;

         slen += s.length;

     }

     // create new string

     cxmutstr result;

     result.ptr = cxMalloc(alloc, slen + 1);

     result.length = slen;

     if (result.ptr == NULL) abort();

     // concatenate strings

     size_t pos = 0;

     cx_for_n(i, count) {

         cxstring s = strings[i];

         memcpy(result.ptr + pos, s.ptr, s.length);

         pos += s.length;

     }

     // terminate string

     result.ptr[result.length] = '\0';

     // free temporary array

     free(strings);

     return result;

 }

 cxstring cx_strsubs(

         cxstring string,

         size_t start

 ) {

     return cx_strsubsl(string, start, string.length - start);

 }

 cxmutstr cx_strsubs_m(

         cxmutstr string,

         size_t start

 ) {

     return cx_strsubsl_m(string, start, string.length - start);

 }

 cxstring cx_strsubsl(

         cxstring string,

         size_t start,

         size_t length

 ) {

     if (start > string.length) {

         return (cxstring) {NULL, 0};

     }

     size_t rem_len = string.length - start;

     if (length > rem_len) {

         length = rem_len;

     }

     return (cxstring) {string.ptr + start, length};

 }

 cxmutstr cx_strsubsl_m(

         cxmutstr string,

         size_t start,

         size_t length

 ) {

     cxstring result = cx_strsubsl(cx_strcast(string), start, length);

     return (cxmutstr) {(char *) result.ptr, result.length};

 }

 cxstring cx_strchr(

         cxstring string,

         int chr

 ) {

     chr = 0xFF & chr;

     // TODO: improve by comparing multiple bytes at once

     cx_for_n(i, string.length) {

         if (string.ptr[i] == chr) {

             return cx_strsubs(string, i);

         }

     }

     return (cxstring) {NULL, 0};

 }

 cxmutstr cx_strchr_m(

         cxmutstr string,

         int chr

 ) {

     cxstring result = cx_strchr(cx_strcast(string), chr);

     return (cxmutstr) {(char *) result.ptr, result.length};

 }

 cxstring cx_strrchr(

         cxstring string,

         int chr

 ) {

     chr = 0xFF & chr;

     size_t i = string.length;

     while (i > 0) {

         i--;

         // TODO: improve by comparing multiple bytes at once

         if (string.ptr[i] == chr) {

             return cx_strsubs(string, i);

         }

     }

     return (cxstring) {NULL, 0};

 }

 cxmutstr cx_strrchr_m(

         cxmutstr string,

         int chr

 ) {

     cxstring result = cx_strrchr(cx_strcast(string), chr);

     return (cxmutstr) {(char *) result.ptr, result.length};

 }

 #define STRSTR_SBO_BUFLEN 512

 cxstring cx_strstr(

         cxstring haystack,

         cxstring needle

 ) {

     if (needle.length == 0) {

         return haystack;

     }

     // optimize for single-char needles

     if (needle.length == 1) {

         return cx_strchr(haystack, *needle.ptr);

     }

     /*

      * IMPORTANT:

      * Our prefix table contains the prefix length PLUS ONE

      * this is our decision, because we want to use the full range of size_t.

      * The original algorithm needs a (-1) at one single place,

      * and we want to avoid that.

      */

     // local prefix table

     size_t s_prefix_table[STRSTR_SBO_BUFLEN];

     // check needle length and use appropriate prefix table

     // if the pattern exceeds static prefix table, allocate on the heap

     bool useheap = needle.length >= STRSTR_SBO_BUFLEN;

     register size_t *ptable = useheap ? calloc(needle.length + 1,

                                                sizeof(size_t)) : s_prefix_table;

     // keep counter in registers

     register size_t i, j;

     // fill prefix table

     i = 0;

     j = 0;

     ptable[i] = j;

     while (i < needle.length) {

         while (j >= 1 && needle.ptr[j - 1] != needle.ptr[i]) {

             j = ptable[j - 1];

         }

         i++;

         j++;

         ptable[i] = j;

     }

     // search

     cxstring result = {NULL, 0};

     i = 0;

     j = 1;

     while (i < haystack.length) {

         while (j >= 1 && haystack.ptr[i] != needle.ptr[j - 1]) {

             j = ptable[j - 1];

         }

         i++;

         j++;

         if (j - 1 == needle.length) {

             size_t start = i - needle.length;

             result.ptr = haystack.ptr + start;

             result.length = haystack.length - start;

             break;

         }

     }

     // if prefix table was allocated on the heap, free it

     if (ptable != s_prefix_table) {

         free(ptable);

     }

     return result;

 }

 cxmutstr cx_strstr_m(

         cxmutstr haystack,

         cxstring needle

 ) {

     cxstring result = cx_strstr(cx_strcast(haystack), needle);

     return (cxmutstr) {(char *) result.ptr, result.length};

 }

 size_t cx_strsplit(

         cxstring string,

         cxstring delim,

         size_t limit,

         cxstring *output

 ) {

     // special case: output limit is zero

     if (limit == 0) return 0;

     // special case: delimiter is empty

     if (delim.length == 0) {

         output[0] = string;

         return 1;

     }

     // special cases: delimiter is at least as large as the string

     if (delim.length >= string.length) {

         // exact match

         if (cx_strcmp(string, delim) == 0) {

             output[0] = cx_strn(string.ptr, 0);

             output[1] = cx_strn(string.ptr + string.length, 0);

             return 2;

         } else {

             // no match possible

             output[0] = string;

             return 1;

         }

     }

     size_t n = 0;

     cxstring curpos = string;

     while (1) {

         ++n;

         cxstring match = cx_strstr(curpos, delim);

         if (match.length > 0) {

             // is the limit reached?

             if (n < limit) {

                 // copy the current string to the array

                 cxstring item = cx_strn(curpos.ptr, match.ptr - curpos.ptr);

                 output[n - 1] = item;

                 size_t processed = item.length + delim.length;

                 curpos.ptr += processed;

                 curpos.length -= processed;

             } else {

                 // limit reached, copy the _full_ remaining string

                 output[n - 1] = curpos;

                 break;

             }

         } else {

             // no more matches, copy last string

             output[n - 1] = curpos;

             break;

         }

     }

     return n;

 }

 size_t cx_strsplit_a(

         CxAllocator *allocator,

         cxstring string,

         cxstring delim,

         size_t limit,

         cxstring **output

 ) {

     // find out how many splits we're going to make and allocate memory

     size_t n = 0;

     cxstring curpos = string;

     while (1) {

         ++n;

         cxstring match = cx_strstr(curpos, delim);

         if (match.length > 0) {

             // is the limit reached?

             if (n < limit) {

                 size_t processed = match.ptr - curpos.ptr + delim.length;

                 curpos.ptr += processed;

                 curpos.length -= processed;

             } else {

                 // limit reached

                 break;

             }

         } else {

             // no more matches

             break;

         }

     }

     *output = cxCalloc(allocator, n, sizeof(cxstring));

     return cx_strsplit(string, delim, n, *output);

 }

 size_t cx_strsplit_m(

         cxmutstr string,

         cxstring delim,

         size_t limit,

         cxmutstr *output

 ) {

     return cx_strsplit(cx_strcast(string),

                        delim, limit, (cxstring *) output);

 }

 size_t cx_strsplit_ma(

         CxAllocator *allocator,

         cxmutstr string,

         cxstring delim,

         size_t limit,

         cxmutstr **output

 ) {

     return cx_strsplit_a(allocator, cx_strcast(string),

                          delim, limit, (cxstring **) output);

 }

 int cx_strcmp(

         cxstring s1,

         cxstring s2

 ) {

     if (s1.length == s2.length) {

         return memcmp(s1.ptr, s2.ptr, s1.length);

     } else if (s1.length > s2.length) {

         return 1;

     } else {

         return -1;

     }

 }

 int cx_strcasecmp(

         cxstring s1,

         cxstring s2

 ) {

     if (s1.length == s2.length) {

 #ifdef _WIN32

         return _strnicmp(s1.ptr, s2.ptr, s1.length);

 #else

         return strncasecmp(s1.ptr, s2.ptr, s1.length);

 #endif

     } else if (s1.length > s2.length) {

         return 1;

     } else {

         return -1;

     }

 }

 cxmutstr cx_strdup_a(

         CxAllocator *allocator,

         cxstring string

 ) {

     cxmutstr result = {

             cxMalloc(allocator, string.length + 1),

             string.length

     };

     if (result.ptr == NULL) {

         result.length = 0;

         return result;

     }

     memcpy(result.ptr, string.ptr, string.length);

     result.ptr[string.length] = '\0';

     return result;

 }

 cxstring cx_strtrim(cxstring string) {

     cxstring result = string;

     // TODO: optimize by comparing multiple bytes at once

     while (result.length > 0 && isspace(*result.ptr)) {

         result.ptr++;

         result.length--;

     }

     while (result.length > 0 && isspace(result.ptr[result.length - 1])) {

         result.length--;

     }

     return result;

 }

 cxmutstr cx_strtrim_m(cxmutstr string) {

     cxstring result = cx_strtrim(cx_strcast(string));

     return (cxmutstr) {(char *) result.ptr, result.length};

 }

 bool cx_strprefix(

         cxstring string,

         cxstring prefix

 ) {

     if (string.length < prefix.length) return false;

     return memcmp(string.ptr, prefix.ptr, prefix.length) == 0;

 }

 bool cx_strsuffix(

         cxstring string,

         cxstring suffix

 ) {

     if (string.length < suffix.length) return false;

     return memcmp(string.ptr + string.length - suffix.length,

                   suffix.ptr, suffix.length) == 0;

 }

 bool cx_strcaseprefix(

         cxstring string,

         cxstring prefix

 ) {

     if (string.length < prefix.length) return false;

 #ifdef _WIN32

     return _strnicmp(string.ptr, prefix.ptr, prefix.length) == 0;

 #else

     return strncasecmp(string.ptr, prefix.ptr, prefix.length) == 0;

 #endif

 }

 bool cx_strcasesuffix(

         cxstring string,

         cxstring suffix

 ) {

     if (string.length < suffix.length) return false;

 #ifdef _WIN32

     return _strnicmp(string.ptr+string.length-suffix.length,

                   suffix.ptr, suffix.length) == 0;

 #else

     return strncasecmp(string.ptr + string.length - suffix.length,

                        suffix.ptr, suffix.length) == 0;

 #endif

 }

 void cx_strlower(cxmutstr string) {

     cx_for_n(i, string.length) {

         string.ptr[i] = (char) tolower(string.ptr[i]);

     }

 }

 void cx_strupper(cxmutstr string) {

     cx_for_n(i, string.length) {

         string.ptr[i] = (char) toupper(string.ptr[i]);

     }

 }

 #define REPLACE_INDEX_BUFFER_MAX 100

 struct cx_strreplace_ibuf {

     size_t *buf;

     struct cx_strreplace_ibuf *next;

     unsigned int len;

 };

 static void cx_strrepl_free_ibuf(struct cx_strreplace_ibuf *buf) {

     while (buf) {

         struct cx_strreplace_ibuf *next = buf->next;

         free(buf->buf);

         free(buf);

         buf = next;

     }

 }

 cxmutstr cx_strreplacen_a(

         CxAllocator *allocator,

         cxstring str,

         cxstring pattern,

         cxstring replacement,

         size_t replmax

 ) {

     if (pattern.length == 0 || pattern.length > str.length || replmax == 0)

         return cx_strdup_a(allocator, str);

     // Compute expected buffer length

     size_t ibufmax = str.length / pattern.length;

     size_t ibuflen = replmax < ibufmax ? replmax : ibufmax;

     if (ibuflen > REPLACE_INDEX_BUFFER_MAX) {

         ibuflen = REPLACE_INDEX_BUFFER_MAX;

     }

     // Allocate first index buffer

     struct cx_strreplace_ibuf *firstbuf, *curbuf;

     firstbuf = curbuf = calloc(1, sizeof(struct cx_strreplace_ibuf));

     if (!firstbuf) return cx_mutstrn(NULL, 0);

     firstbuf->buf = calloc(ibuflen, sizeof(size_t));

     if (!firstbuf->buf) {

         free(firstbuf);

         return cx_mutstrn(NULL, 0);

     }

     // Search occurrences

     cxstring searchstr = str;

     size_t found = 0;

     do {

         cxstring match = cx_strstr(searchstr, pattern);

         if (match.length > 0) {

             // Allocate next buffer in chain, if required

             if (curbuf->len == ibuflen) {

                 struct cx_strreplace_ibuf *nextbuf =

                         calloc(1, sizeof(struct cx_strreplace_ibuf));

                 if (!nextbuf) {

                     cx_strrepl_free_ibuf(firstbuf);

                     return cx_mutstrn(NULL, 0);

                 }

                 nextbuf->buf = calloc(ibuflen, sizeof(size_t));

                 if (!nextbuf->buf) {

                     free(nextbuf);

                     cx_strrepl_free_ibuf(firstbuf);

                     return cx_mutstrn(NULL, 0);

                 }

                 curbuf->next = nextbuf;

                 curbuf = nextbuf;

             }

             // Record match index

             found++;

             size_t idx = match.ptr - str.ptr;

             curbuf->buf[curbuf->len++] = idx;

             searchstr.ptr = match.ptr + pattern.length;

             searchstr.length = str.length - idx - pattern.length;

         } else {

             break;

         }

     } while (searchstr.length > 0 && found < replmax);

     // Allocate result string

     cxmutstr result;

     {

         ssize_t adjlen = (ssize_t) replacement.length - (ssize_t) pattern.length;

         size_t rcount = 0;

         curbuf = firstbuf;

         do {

             rcount += curbuf->len;

             curbuf = curbuf->next;

         } while (curbuf);

         result.length = str.length + rcount * adjlen;

         result.ptr = cxMalloc(allocator, result.length + 1);

         if (!result.ptr) {

             cx_strrepl_free_ibuf(firstbuf);

             return cx_mutstrn(NULL, 0);

         }

     }

     // Build result string

     curbuf = firstbuf;

     size_t srcidx = 0;

     char *destptr = result.ptr;

     do {

         for (size_t i = 0; i < curbuf->len; i++) {

             // Copy source part up to next match

             size_t idx = curbuf->buf[i];

             size_t srclen = idx - srcidx;

             if (srclen > 0) {

                 memcpy(destptr, str.ptr + srcidx, srclen);

                 destptr += srclen;

                 srcidx += srclen;

             }

             // Copy the replacement and skip the source pattern

             srcidx += pattern.length;

             memcpy(destptr, replacement.ptr, replacement.length);

             destptr += replacement.length;

         }

         curbuf = curbuf->next;

     } while (curbuf);

     memcpy(destptr, str.ptr + srcidx, str.length - srcidx);

     // Result is guaranteed to be zero-terminated

     result.ptr[result.length] = '\0';

     // Free index buffer

     cx_strrepl_free_ibuf(firstbuf);

     return result;

 }