lib/sf-istream.c

   1 /* A string or file based input stream.
   2    Copyright (C) 2024 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation, either version 3 of the
   7    License, or (at your option) any later version.
   8
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2024.  */
  18
  19 #include <config.h>
  20
  21 /* Specification.  */
  22 #include "sf-istream.h"
  23
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27 void
  28 sf_istream_init_from_file (sf_istream_t *stream, FILE *fp)
  29 {
  30   stream->fp = fp;
  31   stream->input = NULL;
  32   stream->input_end = NULL;
  33 }
  34
  35 void
  36 sf_istream_init_from_string (sf_istream_t *stream,
  37                              const char *input)
  38 {
  39   stream->fp = NULL;
  40   stream->input = input;
  41   stream->input_end = input + strlen (input);
  42 }
  43
  44 void
  45 sf_istream_init_from_string_desc (sf_istream_t *stream,
  46                                   string_desc_t input)
  47 {
  48   stream->fp = NULL;
  49   stream->input = string_desc_data (input);
  50   stream->input_end = stream->input + string_desc_length (input);
  51 }
  52
  53 int
  54 sf_getc (sf_istream_t *stream)
  55 {
  56   int c;
  57
  58   if (stream->fp != NULL)
  59     c = getc (stream->fp);
  60   else
  61     {
  62       if (stream->input == stream->input_end)
  63         return EOF;
  64       c = (unsigned char) *(stream->input++);
  65     }
  66
  67   return c;
  68 }
  69
  70 int
  71 sf_ferror (sf_istream_t *stream)
  72 {
  73   return (stream->fp != NULL && ferror (stream->fp));
  74 }
  75
  76 void
  77 sf_ungetc (sf_istream_t *stream, int c)
  78 {
  79   if (c != EOF)
  80     {
  81       if (stream->fp != NULL)
  82         ungetc (c, stream->fp);
  83       else
  84         {
  85           stream->input--;
  86           if (!(c == (unsigned char) *stream->input))
  87             /* C was incorrect.  */
  88             abort ();
  89         }
  90     }
  91 }
  92
  93 void
  94 sf_free (sf_istream_t *stream)
  95 {
  96 }