src/hci/editstring.c

   1 /*
   2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <assert.h>
  22 #include <string.h>
  23 #include <gpxe/keys.h>
  24 #include <gpxe/editstring.h>
  25
  26 /** @file
  27  *
  28  * Editable strings
  29  *
  30  */
  31
  32 static void insert_delete ( struct edit_string *string, size_t delete_len,
  33                             const char *insert_text )
  34                             __attribute__ (( nonnull (1) ));
  35 static void insert_character ( struct edit_string *string,
  36                                unsigned int character ) __nonnull;
  37 static void delete_character ( struct edit_string *string ) __nonnull;
  38 static void backspace ( struct edit_string *string ) __nonnull;
  39 static void kill_eol ( struct edit_string *string ) __nonnull;
  40
  41 /**
  42  * Insert and/or delete text within an editable string
  43  *
  44  * @v string            Editable string
  45  * @v delete_len        Length of text to delete from current cursor position
  46  * @v insert_text       Text to insert at current cursor position, or NULL
  47  */
  48 static void insert_delete ( struct edit_string *string, size_t delete_len,
  49                             const char *insert_text ) {
  50         size_t old_len, max_delete_len, insert_len, max_insert_len, new_len;
  51
  52         /* Calculate lengths */
  53         old_len = strlen ( string->buf );
  54         assert ( string->cursor <= old_len );
  55         max_delete_len = ( old_len - string->cursor );
  56         if ( delete_len > max_delete_len )
  57                 delete_len = max_delete_len;
  58         insert_len = ( insert_text ? strlen ( insert_text ) : 0 );
  59         max_insert_len = ( ( string->len - 1 ) - ( old_len - delete_len ) );
  60         if ( insert_len > max_insert_len )
  61                 insert_len = max_insert_len;
  62         new_len = ( old_len - delete_len + insert_len );
  63
  64         /* Fill in edit history */
  65         string->mod_start = string->cursor;
  66         string->mod_end = ( ( new_len > old_len ) ? new_len : old_len );
  67
  68         /* Move data following the cursor */
  69         memmove ( ( string->buf + string->cursor + insert_len ),
  70                   ( string->buf + string->cursor + delete_len ),
  71                   ( max_delete_len + 1 - delete_len ) );
  72
  73         /* Copy inserted text to cursor position */
  74         memcpy ( ( string->buf + string->cursor ), insert_text, insert_len );
  75         string->cursor += insert_len;
  76 }
  77
  78 /**
  79  * Insert character at current cursor position
  80  *
  81  * @v string            Editable string
  82  * @v character         Character to insert
  83  */
  84 static void insert_character ( struct edit_string *string,
  85                               unsigned int character ) {
  86         char insert_text[2] = { character, '\0' };
  87         insert_delete ( string, 0, insert_text );
  88 }
  89
  90 /**
  91  * Delete character at current cursor position
  92  *
  93  * @v string            Editable string
  94  */
  95 static void delete_character ( struct edit_string *string ) {
  96         insert_delete ( string, 1, NULL );
  97 }
  98
  99 /**
 100  * Delete character to left of current cursor position
 101  *
 102  * @v string            Editable string
 103  */
 104 static void backspace ( struct edit_string *string ) {
 105         if ( string->cursor > 0 ) {
 106                 string->cursor--;
 107                 delete_character ( string );
 108         }
 109 }
 110
 111 /**
 112  * Delete to end of line
 113  *
 114  * @v string            Editable string
 115  */
 116 static void kill_eol ( struct edit_string *string ) {
 117         insert_delete ( string, ~( ( size_t ) 0 ), NULL );
 118 }
 119
 120 /**
 121  * Edit editable string
 122  *
 123  * @v string            Editable string
 124  * @v key               Key pressed by user
 125  * @ret key             Key returned to application, or zero
 126  *
 127  * Handles keypresses and updates the content of the editable string.
 128  * Basic line editing facilities (delete/insert/cursor) are supported.
 129  * If edit_string() understands and uses the keypress it will return
 130  * zero, otherwise it will return the original key.
 131  *
 132  * This function does not update the display in any way.
 133  *
 134  * The string's edit history will be updated to allow the caller to
 135  * efficiently bring the display into sync with the string content.
 136  */
 137 int edit_string ( struct edit_string *string, int key ) {
 138         int retval = 0;
 139         size_t len = strlen ( string->buf );
 140
 141         /* Prepare edit history */
 142         string->last_cursor = string->cursor;
 143         string->mod_start = string->cursor;
 144         string->mod_end = string->cursor;
 145
 146         /* Interpret key */
 147         if ( ( key >= 0x20 ) && ( key <= 0x7e ) ) {
 148                 /* Printable character; insert at current position */
 149                 insert_character ( string, key );
 150         } else switch ( key ) {
 151         case KEY_BACKSPACE:
 152                 /* Backspace */
 153                 backspace ( string );
 154                 break;
 155         case KEY_DC:
 156         case CTRL_D:
 157                 /* Delete character */
 158                 delete_character ( string );
 159                 break;
 160         case CTRL_K:
 161                 /* Delete to end of line */
 162                 kill_eol ( string );
 163                 break;
 164         case KEY_HOME:
 165         case CTRL_A:
 166                 /* Start of line */
 167                 string->cursor = 0;
 168                 break;
 169         case KEY_END:
 170         case CTRL_E:
 171                 /* End of line */
 172                 string->cursor = len;
 173                 break;
 174         case KEY_LEFT:
 175         case CTRL_B:
 176                 /* Cursor left */
 177                 if ( string->cursor > 0 )
 178                         string->cursor--;
 179                 break;
 180         case KEY_RIGHT:
 181         case CTRL_F:
 182                 /* Cursor right */
 183                 if ( string->cursor < len )
 184                         string->cursor++;
 185                 break;
 186         default:
 187                 retval = key;
 188                 break;
 189         }
 190
 191         return retval;
 192 }