libio/editbuf.h

   1 /* This is part of libio/iostream, providing -*- C++ -*- input/output.
   2 Copyright (C) 1993 Free Software Foundation
   3
   4 This file is part of the GNU IO Library.  This library is free
   5 software; you can redistribute it and/or modify it under the
   6 terms of the GNU General Public License as published by the
   7 Free Software Foundation; either version 2, or (at your option)
   8 any later version.
   9
  10 This library is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this library; see the file COPYING.  If not, write to the Free
  17 Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  18
  19 As a special exception, if you link this library with files
  20 compiled with a GNU compiler to produce an executable, this does not cause
  21 the resulting executable to be covered by the GNU General Public License.
  22 This exception does not however invalidate any other reasons why
  23 the executable file might be covered by the GNU General Public License.
  24
  25 Written by Per Bothner (bothner@cygnus.com). */
  26
  27 #ifndef _EDITBUF_H
  28 #define _EDITBUF_H
  29 #ifdef __GNUG__
  30 #pragma interface
  31 #endif
  32 #include <stdio.h>
  33 #include <fstream.h>
  34
  35 extern "C++" {
  36 typedef unsigned long mark_pointer;
  37 // At some point, it might be nice to parameterize this code
  38 // in terms of buf_char.
  39 typedef /*unsigned*/ char buf_char;
  40
  41 // Logical pos from start of buffer (does not count gap).
  42 typedef long buf_index;
  43
  44 // Pos from start of buffer, possibly including gap_size.
  45 typedef long buf_offset;
  46
  47 #if 0
  48 struct buf_cookie {
  49     FILE *file;
  50     struct edit_string *str;
  51     struct buf_cookie *next;
  52     buf_index tell();
  53 };
  54 #endif
  55
  56 struct edit_buffer;
  57 struct edit_mark;
  58
  59 // A edit_string is defined as the region between the 'start' and 'end' marks.
  60 // Normally (always?) 'start->insert_before()' should be false,
  61 // and 'end->insert_before()' should be true.
  62
  63 struct edit_string {
  64     struct edit_buffer *buffer; // buffer that 'start' and 'end' belong to
  65     struct edit_mark *start, *end;
  66     int length() const; // count of buf_chars currently in string
  67     edit_string(struct edit_buffer *b,
  68                       struct edit_mark *ms, struct edit_mark *me)
  69         { buffer = b; start = ms; end = me; }
  70 /* Make a fresh, contiguous copy of the data in STR.
  71    Assign length of STR to *LENP.
  72    (Output has extra NUL at out[*LENP].) */
  73     buf_char *copy_bytes(int *lenp) const;
  74 //    FILE *open_file(char *mode);
  75     void assign(struct edit_string *src); // copy bytes from src to this
  76 };
  77
  78 struct edit_streambuf : public streambuf {
  79     friend edit_buffer;
  80     edit_string *str;
  81     edit_streambuf* next; // Chain of edit_streambuf's for a edit_buffer.
  82     short _mode;
  83     edit_streambuf(edit_string* bstr, int mode);
  84     ~edit_streambuf();
  85     virtual int underflow();
  86     virtual int overflow(int c = EOF);
  87     virtual streampos seekoff(streamoff, _seek_dir, int mode=ios::in|ios::out);
  88     void flush_to_buffer();
  89     void flush_to_buffer(edit_buffer* buffer);
  90     int _inserting;
  91     int inserting() { return _inserting; }
  92     void inserting(int i) { _inserting = i; }
  93 //    int delete_chars(int count, char* cut_buf); Not implemented.
  94     int truncate();
  95     int is_reading() { return gptr() != NULL; }
  96     buf_char* current() { return is_reading() ? gptr() : pptr(); }
  97     void set_current(char *p, int is_reading);
  98   protected:
  99     void disconnect_gap_from_file(edit_buffer* buffer);
 100 };
 101
 102 // A 'edit_mark' indicates a position in a buffer.
 103 // It is "attached" the text (rather than the offset).
 104 // There are two kinds of mark, which have different behavior
 105 // when text is inserted at the mark:
 106 // If 'insert_before()' is true the mark will be adjusted to be
 107 // *after* the new text.
 108
 109 struct edit_mark {
 110     struct edit_mark *chain;
 111     mark_pointer _pos;
 112     inline int insert_before() { return _pos & 1; }
 113     inline unsigned long index_in_buffer(struct edit_buffer *)
 114         { return _pos >> 1; }
 115     inline buf_char *ptr(struct edit_buffer *buf);
 116     buf_index tell();
 117     edit_mark() { }
 118     edit_mark(struct edit_string *str, long delta);
 119     edit_buffer *buffer();
 120     ~edit_mark();
 121 };
 122
 123 // A 'edit_buffer' consists of a sequence of buf_chars (the data),
 124 // a list of edit_marks pointing into the data, and a list of FILEs
 125 // also pointing into the data.
 126 // A 'edit_buffer' coerced to a edit_string is the string of
 127 // all the buf_chars in the buffer.
 128
 129 // This implementation uses a conventional buffer gap (as in Emacs).
 130 // The gap start is defined by de-referencing a (buf_char**).
 131 // This is because sometimes a FILE is inserting into the buffer,
 132 // so rather than having each putc adjust the gap, we use indirection
 133 // to have the gap be defined as the write pointer of the FILE.
 134 // (This assumes that putc adjusts a pointer (as in GNU's libc), not an index.)
 135
 136 struct edit_buffer {
 137     buf_char *data; /* == emacs buffer_text.p1+1 */
 138     buf_char *_gap_start;
 139     edit_streambuf* _writer; // If non-NULL, currently writing stream
 140     inline buf_char *gap_start()
 141         { return _writer ? _writer->pptr() : _gap_start; }
 142     buf_offset __gap_end_pos; // size of part 1 + size of gap
 143     /* int gap; implicit: buf_size - size1 - size2 */
 144     int buf_size;
 145     struct edit_streambuf *files;
 146     struct edit_mark start_mark;
 147     struct edit_mark end_mark;
 148     edit_buffer();
 149     inline buf_offset gap_end_pos() { return __gap_end_pos; }
 150     inline struct edit_mark *start_marker() { return &start_mark; }
 151     inline struct edit_mark *end_marker() { return &end_mark; }
 152 /* these should be protected, ultimately */
 153     buf_index tell(edit_mark*);
 154     buf_index tell(buf_char*);
 155     inline buf_char *gap_end() { return data + gap_end_pos(); }
 156     inline int gap_size() { return gap_end() - gap_start(); }
 157     inline int size1() { return gap_start() - data; }
 158     inline int size2() { return buf_size - gap_end_pos(); }
 159     inline struct edit_mark * mark_list() { return &start_mark; }
 160     void make_gap (buf_offset);
 161     void move_gap (buf_offset pos);
 162     void move_gap (buf_char *pos) { move_gap(pos - data); }
 163     void gap_left (int pos);
 164     void gap_right (int pos);
 165     void adjust_markers(mark_pointer low, mark_pointer high,
 166                         int amount, buf_char *old_data);
 167     void delete_range(buf_index from, buf_index to);
 168     void delete_range(struct edit_mark *start, struct edit_mark *end);
 169 };
 170
 171 extern buf_char * bstr_copy(struct edit_string *str, int *lenp);
 172
 173 // Convert a edit_mark to a (buf_char*)
 174
 175 inline buf_char *edit_mark::ptr(struct edit_buffer *buf)
 176         { return buf->data + index_in_buffer(buf); }
 177
 178 inline void edit_streambuf::flush_to_buffer()
 179 {
 180     edit_buffer* buffer = str->buffer;
 181     if (buffer->_writer == this) flush_to_buffer(buffer);
 182 }
 183 } // extern "C++"
 184 #endif /* !_EDITBUF_H*/
 185