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Annotation of 43BSD/contrib/emacs/src/undo.h, revision 1.1

1.1     ! root        1: /* Definitions of objects used by the GNU Emacs undo facility.
        !             2:    Copyright (C) 1985 Fen Labalme and Richard M. Stallman.
        !             3: 
        !             4: This file is part of GNU Emacs.
        !             5: 
        !             6: GNU Emacs is distributed in the hope that it will be useful,
        !             7: but WITHOUT ANY WARRANTY.  No author or distributor
        !             8: accepts responsibility to anyone for the consequences of using it
        !             9: or for whether it serves any particular purpose or works at all,
        !            10: unless he says so in writing.  Refer to the GNU Emacs General Public
        !            11: License for full details.
        !            12: 
        !            13: Everyone is granted permission to copy, modify and redistribute
        !            14: GNU Emacs, but only under the conditions described in the
        !            15: GNU Emacs General Public License.   A copy of this license is
        !            16: supposed to have been given to you along with GNU Emacs so you
        !            17: can know your rights and responsibilities.  It should be in a
        !            18: file named COPYING.  Among other things, the copyright notice
        !            19: and this notice must be preserved on all copies.  */
        !            20: 
        !            21: 
        !            22: enum Ukinds {                  /* The events that can exist in the undo
        !            23:                                   queue. */
        !            24:     Uboundary,                 /* A boundary between sets of undoable things
        !            25:                                   */
        !            26:     Unundoable,                        /* What's done is done -- some things can't
        !            27:                                   be undone */
        !            28:     Udelete,                   /* Delete characters to perform the undo */
        !            29:     Uinsert,                   /* Insert .... */
        !            30:     Uchange,                   /* Replace characters */
        !            31:     Uunmod,                    /* Clear modification-flag to perform undo */
        !            32: };
        !            33: 
        !            34: struct UndoRec {               /* A record of a single undo action */
        !            35:     enum Ukinds kind;          /* the kind of action to be undone */
        !            36:     int pos;                   /* Where dot is */
        !            37:     int len;                   /* The extent of the undo (characters
        !            38:                                   inserted or deleted) */
        !            39: };
        !            40: 
        !            41: /* The undo history consists of two circular queues, one of characters and
        !            42:    one of UndoRecs.  When Uinsert recs are added to UndoRQ characters get
        !            43:    added to UndoCQ.  The position of the characters can be reconstructed by
        !            44:    subtracting len from the fill pointer. */
        !            45: 
        !            46: #define NUndoR (((1 << 13) - 4) / sizeof (struct UndoRec))
        !            47: #define NUndoC ((1 << 13) - 4)
        !            48: 
        !            49: /* Initially allocate them these sizes;
        !            50:  if these sizes get filled up, make them full size */
        !            51: 
        !            52: #define InitNUndoR 8
        !            53: #define InitNUndoC (512 - 4)
        !            54: 
        !            55: struct UndoData
        !            56:   {
        !            57:     struct UndoRec *undorecs;  /* The undo records, NUndoR of them */
        !            58:     char *undochars;   /* And the characters associated, NUndoC in all */
        !            59:     int nextrec;               /* Indices for storing in above two */
        !            60:     int nextchar;
        !            61:     int num_undorecs;          /* Sizes allocated */
        !            62:     int num_undochars;
        !            63:   };
        !            64: 

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