mdw@git.distorted.org.uk Git - mLib/blob - struct/dstr.c

   1 /* -*-c-*-
   2  *
   3  * Handle dynamically growing strings
   4  *
   5  * (c) 1998 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the mLib utilities library.
  11  *
  12  * mLib is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU Library General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * mLib is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with mLib; if not, write to the Free
  24  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25  * MA 02111-1307, USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33
  34 #include "alloc.h"
  35 #include "dstr.h"
  36
  37 /*----- Tunable constants -------------------------------------------------*/
  38
  39 /*
  40  * If the buffer is empty, it is set to @DSTR_INITSZ@ bytes in size.
  41  * Otherwise, it's set to the next power of two that's large enough.  This is
  42  * memory-hungry, but efficient.
  43  */
  44
  45 #define DSTR_INITSZ 64                  /* Initial buffer size */
  46
  47 /*----- Main code ---------------------------------------------------------*/
  48
  49 /* --- @dstr_create@ --- *
  50  *
  51  * Arguments:   @dstr *d@ = pointer to a dynamic string block
  52  *
  53  * Returns:     ---
  54  *
  55  * Use:         Initializes a dynamic string.
  56  */
  57
  58 void dstr_create(dstr *d) { DCREATE(d); }
  59
  60 /* --- @dstr_destroy@ --- *
  61  *
  62  * Arguments:   @dstr *d@ = pointer to a dynamic string block
  63  *
  64  * Returns:     ---
  65  *
  66  * Use:         Reclaims the space used by a dynamic string.
  67  */
  68
  69 void dstr_destroy(dstr *d) { DDESTROY(d); }
  70
  71 /* --- @dstr_reset@ --- *
  72  *
  73  * Arguments:   @dstr *d@ = pointer to a dynamic string block
  74  *
  75  * Returns:     ---
  76  *
  77  * Use:         Resets a string so that new data gets put at the beginning.
  78  */
  79
  80 void dstr_reset(dstr *d) { DRESET(d); }
  81
  82 /* --- @dstr_ensure@ --- *
  83  *
  84  * Arguments:   @dstr *d@ = pointer to a dynamic string block
  85  *              @size_t sz@ = amount of free space to ensure
  86  *
  87  * Returns:     ---
  88  *
  89  * Use:         Ensures that at least @sz@ bytes are available in the
  90  *              given string.
  91  */
  92
  93 void dstr_ensure(dstr *d, size_t sz)
  94 {
  95   size_t rq = d->len + sz;
  96   size_t nsz;
  97
  98   /* --- If we have enough space, just leave it --- */
  99
 100   if (rq <= d->sz)
 101     return;
 102
 103   /* --- Grow the buffer --- */
 104
 105   nsz = d->sz;
 106
 107   if (nsz == 0)
 108     nsz = (DSTR_INITSZ >> 1);
 109   do nsz <<= 1; while (nsz < rq);
 110
 111   if (d->buf)
 112     d->buf = x_realloc(d->a, d->buf, nsz, d->sz);
 113   else
 114     d->buf = x_alloc(d->a, nsz);
 115   d->sz = nsz;
 116 }
 117
 118 /* --- @dstr_putc@ --- *
 119  *
 120  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 121  *              @int ch@ = character to append
 122  *
 123  * Returns:     ---
 124  *
 125  * Use:         Appends a character to a string.
 126  */
 127
 128 void dstr_putc(dstr *d, int ch) { DPUTC(d, ch); }
 129
 130 /* --- @dstr_putz@ --- *
 131  *
 132  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 133  *
 134  * Returns:     ---
 135  *
 136  * Use:         Appends a null byte to a string.  The null byte does not
 137  *              contribute to the string's length, and will be overwritten
 138  *              by subsequent `put' operations.
 139  */
 140
 141 void dstr_putz(dstr *d) { DPUTZ(d); }
 142
 143 /* --- @dstr_puts@ --- *
 144  *
 145  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 146  *              @const char *s@ = pointer to string to append
 147  *
 148  * Returns:     ---
 149  *
 150  * Use:         Appends a character string to a string.  A trailing null
 151  *              byte is added, as for @dstr_putz@.
 152  */
 153
 154 void dstr_puts(dstr *d, const char *s) { DPUTS(d, s); }
 155
 156 /* --- @dstr_putd@ --- *
 157  *
 158  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 159  *              @const dstr *s@ = pointer to a dynamic string to append
 160  *
 161  * Returns:     ---
 162  *
 163  * Use:         Appends a dynamic string to a string.  A trailing null
 164  *              byte is added, as for @dstr_putz@.
 165  */
 166
 167 void dstr_putd(dstr *d, const dstr *s) { DPUTD(d, s); }
 168
 169 /* --- @dstr_putm@ --- *
 170  *
 171  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 172  *              @const void *p@ = pointer to a block to append
 173  *              @size_t sz@ = size of the block
 174  *
 175  * Returns:     Appends an arbitrary data block to a string.  No trailing
 176  *              null is appended.
 177  */
 178
 179 void dstr_putm(dstr *d, const void *p, size_t sz) { DPUTM(d, p, sz); }
 180
 181 /* --- @dstr_tidy@ --- *
 182  *
 183  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 184  *
 185  * Returns:     ---
 186  *
 187  * Use:         Reduces the amount of memory used by a string.  A trailing
 188  *              null byte is added, as for @dstr_putz@.
 189  */
 190
 191 void dstr_tidy(dstr *d)
 192 {
 193   d->buf = x_realloc(d->a, d->buf, d->len + 1, d->sz);
 194   d->buf[d->len] = 0;
 195   d->sz = d->len + 1;
 196 }
 197
 198 /* --- @dstr_putline@ --- *
 199  *
 200  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 201  *              @FILE *fp@ = a stream to read from
 202  *
 203  * Returns:     The number of characters read into the buffer, or @EOF@ if
 204  *              end-of-file was reached before any characters were read.
 205  *
 206  * Use:         Appends the next line from the given input stream to the
 207  *              string.  A trailing newline is not added; a trailing null
 208  *              byte is appended, as for @dstr_putz@.
 209  */
 210
 211 int dstr_putline(dstr *d, FILE *fp)
 212 {
 213   size_t left = d->sz - d->len;
 214   size_t off = d->len;
 215   int rd = 0;
 216   int ch;
 217
 218   for (;;) {
 219
 220     /* --- Read the next byte --- */
 221
 222     ch = getc(fp);
 223
 224     /* --- End-of-file when no characters read is special --- */
 225
 226     if (ch == EOF && !rd)
 227       return (EOF);
 228
 229     /* --- Make sure there's some buffer space --- */
 230
 231     if (!left) {
 232       d->len = off;
 233       dstr_ensure(d, 1);
 234       left = d->sz - off;
 235     }
 236
 237     /* --- End-of-file or newline ends the loop --- */
 238
 239     if (ch == EOF || ch == '\n') {
 240       d->buf[off] = 0;
 241       d->len = off;
 242       return rd;
 243     }
 244
 245     /* --- Append the character and continue --- */
 246
 247     d->buf[off++] = ch;
 248     left--; rd++;
 249   }
 250 }
 251
 252 /* --- @dstr_write@ --- *
 253  *
 254  * Arguments:   @dstr *d@ = pointer to a dynamic string block
 255  *              @FILE *fp@ = a stream to write on
 256  *
 257  * Returns:     The number of bytes written (as for @fwrite@).
 258  *
 259  * Use:         Writes a dynamic string to a file.
 260  */
 261
 262 size_t dstr_write(const dstr *d, FILE *fp) { return (DWRITE(d, fp)); }
 263
 264 /*----- That's all, folks -------------------------------------------------*/