lib/stringbuilder.c

   1 /*
   2     libpsh/stringbuilder.c - string builder
   3     Copyright 2020 Zhang Maiyun
   4
   5     This file is part of Psh, P shell.
   6
   7     Psh is free software: you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation, either version 3 of the License, or
  10     (at your option) any later version.
  11
  12     Psh is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with this program.  If not, see <https://www.gnu.org/licenses/>.
  19 */
  20
  21 #ifdef HAVE_CONFIG_H
  22 #include "config.h"
  23 #endif
  24
  25 #include <stddef.h>
  26 #include <string.h>
  27 #ifdef DEBUG
  28 #include <stdio.h>
  29 #endif
  30
  31 #include "libpsh/stringbuilder.h"
  32 #include "libpsh/xmalloc.h"
  33
  34 /* Create a new builder */
  35 psh_stringbuilder *psh_stringbuilder_create()
  36 {
  37     psh_stringbuilder *builder = xmalloc(sizeof(psh_stringbuilder));
  38     builder->total_length = 0;
  39     builder->current = builder->first = NULL;
  40     return builder;
  41 }
  42
  43 /* Append a string starting at *STRING with a length of LENGTH to the builder.
  44    STRING gets free()d if IF_FREE is 1 */
  45 const char *psh_stringbuilder_add_length(psh_stringbuilder *builder,
  46                                          const char *string, size_t length,
  47                                          int if_free)
  48 {
  49     struct _psh_sb_item *previous;
  50     /* Don't waste memory here */
  51     if (length == 0)
  52         return string;
  53     builder->total_length += length;
  54     if (builder->current)
  55     {
  56         /* Not empty */
  57 #ifdef DEBUG
  58         printf("[psh_stringbuilder_add_length]\n");
  59         printf("orig this: %p\n", builder->current->next);
  60 #endif
  61         builder->current->next = xmalloc(sizeof(struct _psh_sb_item));
  62 #ifdef DEBUG
  63         printf("this: %p\n", builder->current->next);
  64         printf("last: %p\n", builder->current);
  65         printf("orig string: %p\n", builder->current->next->string);
  66         printf("string: %s\n", string);
  67 #endif
  68         previous = builder->current;
  69         builder->current = builder->current->next;
  70     }
  71     else
  72     {
  73         /* Empty */
  74         builder->first = xmalloc(sizeof(struct _psh_sb_item));
  75         builder->current = builder->first;
  76         previous = NULL;
  77     }
  78     /* Now current is to be filled */
  79     builder->current->previous = previous;
  80     builder->current->length = length;
  81     builder->current->string = string;
  82     builder->current->if_free = if_free;
  83     builder->current->next = NULL;
  84     /* Now current is filled */
  85     return string;
  86 }
  87
  88 /* Append STRING to the builder */
  89 const char *psh_stringbuilder_add(psh_stringbuilder *builder,
  90                                   const char *string, int if_free)
  91 {
  92     size_t length = strlen(string);
  93     return psh_stringbuilder_add_length(builder, string, length, if_free);
  94 }
  95
  96 /* Remove the last member of the builder */
  97 void psh_stringbuilder_pop(psh_stringbuilder *builder)
  98 {
  99     builder->total_length -= builder->current->length;
 100     if (builder->current->if_free)
 101         xfree(builder->current->string);
 102     builder->current = builder->current->previous;
 103     xfree(builder->current->next);
 104     builder->current->next = NULL;
 105 }
 106
 107 /* Generate a string from the builder */
 108 char *psh_stringbuilder_yield(psh_stringbuilder *builder)
 109 {
 110     struct _psh_sb_item *cur_from = builder->first;
 111     char *result = xmalloc(P_CS * builder->total_length + 1);
 112     char *cur_to = result;
 113     while (cur_from)
 114     {
 115         /* Copy the string without trailing NUL */
 116         memmove(cur_to, cur_from->string, cur_from->length);
 117         /* Increase result pointer */
 118         cur_to += cur_from->length;
 119         /* Get next string */
 120         cur_from = cur_from->next;
 121     }
 122     /* NUL-terminate */
 123     result[builder->total_length] = 0;
 124     return result;
 125 }
 126
 127 /* Free resources used by the builder */
 128 void psh_stringbuilder_free(psh_stringbuilder *builder)
 129 {
 130     struct _psh_sb_item *cur = builder->first;
 131     while (1)
 132     {
 133         if (cur->if_free)
 134             xfree(cur->string);
 135         xfree(cur->previous);
 136         if (!cur->next)
 137         {
 138             xfree(cur);
 139             break;
 140         }
 141         cur = cur->next;
 142     }
 143     xfree(builder);
 144 }