sort.c

THOMSON-DAVIS用C语言开发的编缉器,简单,易懂.

/*
 * These functions sort lines according to keys in a marked BOX block.
 *
 * Being that the data structure was changed from a big text buffer to a
 * linked list, we can replace the simple insertion sort algorithm with a
 * much faster sort algorithm.  The classic search and sort reference is by
 * Donald E. Knuth, _The Art of Computer Programming; Volume 3:  Sorting and
 * Searching_.  One of the fastest and most widely used general purpose
 * sorting algorithms is the "Quicksort" algorithm.
 *
 * For implementation hints and guidelines on the Quicksort algorithm, one
 * might read the original Quicksort paper by C. A. R. Hoare or anything
 * by Robert Sedgewick.  Although Dr. Sedgewick includes a chapter on
 * Quicksort in his intro computer science textbooks, _Algorithms in X_,
 * I prefer the detailed hints and guidelines in his 1978 CACM paper.
 * Incidentally, Dr. Sedgewick's Ph.D. dissertation was on the modification
 * and mathematical analysis of the Quicksort algorithm.
 *
 *
 * See:
 *
 *   Charles Antony Richard Hoare, "Algorithm 63: Partition."  _Communications
 *      of the ACM_, 4 (No. 7): 321, 1961.
 *
 *   Charles Antony Richard Hoare, "Algorithm 64: Quicksort."  _Communications
 *      of the ACM_, 4 (No. 7): 321, 1961.
 *
 *   Charles Antony Richard Hoare, "Quicksort."  _The Computer Journal_,
 *      5 (April 1962 - January 1963): 10-15, 1962.
 *
 * See also:
 *
 *   Donald Ervin Knuth, _The Art of Computer Programming; Volume 3:  Sorting
 *     and Searching_, Addison-Wesley, Reading, Mass., 1973, Chapter 5,
 *     Sorting, pp 114-123.  ISBN 0-201-03803-X.
 *
 *   Robert Sedgewick, "Implementing Quicksort Programs."  _Communications
 *      of the ACM_, 21 (No. 10): 847-857, 1978.
 *
 *
 *                           Quicksort in TDE
 *
 * Quicksort in TDE is a stable, non-recursive implementation based on
 * Program 2, page 851, CACM, 21 (No. 10), 1978, by Robert Sedgewick.  My
 * partition algorithm finds the median-of-three.  Then, it walks from the
 * head of the list, comparing nodes, and uses the first occurrence of the
 * key of the median-of-three as the partition node.  Mostly by accident
 * and partly by design, my partition routine uses a "fat pivot" to keep
 * equal nodes in the same relative order as they appear in the file (the
 * definition of a stable sort).  By using the first median-of-three node
 * as the partitioning node, 1) sorting a sorted list is fairly fast and
 * 2) encountering a worst case is very unlikely.  TDE will sort, fairly
 * fast, multiple keys ascending or descending, ignore or match case, and
 * preserve order in the file, while using a custom sort sequence for your
 * favorite domestic or foreign language.
 *
 *
 * New editor name:  TDE, the Thomson-Davis Editor.
 * Author:           Frank Davis
 * Date:             June 5, 1991, version 1.0
 * Date:             July 29, 1991, version 1.1
 * Date:             October 5, 1991, version 1.2
 * Date:             January 20, 1992, version 1.3
 * Date:             February 17, 1992, version 1.4
 * Date:             April 1, 1992, version 1.5
 * Date:             June 5, 1992, version 2.0
 * Date:             October 31, 1992, version 2.1
 * Date:             April 1, 1993, version 2.2
 * Date:             June 5, 1993, version 3.0
 *
 * This code is released into the public domain, Frank Davis.
 * You may use and distribute it freely.
 */

#include "tdestr.h"
#include "common.h"
#include "tdefunc.h"
#include "define.h"


/*
 * Name:    sort_box_block
 * Purpose: sort lines according to text in marked BOX block
 * Date:    June 5, 1992
 * Passed:  window:  pointer to current window
 * Notes:   quick sort and insertion sort the lines in the BOX buff according
 *           to stuff in a box block.
 */
int  sort_box_block( WINDOW *window )
{
int  prompt_line;
int  block_type;
line_list_ptr ll;
register file_infos *file;
WINDOW *sw;
int  rc;
char line_buff[(MAX_COLS+1)*2]; /* buffer for char and attribute  */

   /*
    * make sure block is marked OK
    */
   rc = OK;
   prompt_line = window->bottom_line;
   entab_linebuff( );
   if (un_copy_line( window->ll, window, TRUE ) == ERROR)
      return( ERROR );
   check_block( );
   if (g_status.marked == TRUE) {
      file  = g_status.marked_file;
      block_type = file->block_type;
      if (block_type == BOX) {
         /*
          * sort ascending or descending?
          */
         rc = get_sort_order( window );
         if (rc != ERROR) {
            file->modified = TRUE;
            if (mode.do_backups == TRUE) {
               sw = g_status.window_list;
               for (; ptoul( sw->file_info ) != ptoul( file );)
                  sw = sw->next;
               backup_file( sw );
            }

            /*
             * figure the width of the block.
             */
            sort.block_len = file->block_ec + 1 - file->block_bc;

            /*
             * save the prompt line and print the quicksort message.
             */
            save_screen_line( 0, prompt_line, line_buff );
            eol_clear( 0, prompt_line, g_display.text_color );
            set_prompt( block22a, prompt_line );

            /*
             * set up the sort structure.
             */
            sort.bc  = g_status.marked_file->block_bc;
            sort.ec  = g_status.marked_file->block_ec;
            sort.order_array = (mode.search_case == IGNORE) ?
                                    sort_order.ignore : sort_order.match;

            /*
             * save the previous node for use with insertion sort.
             */
            ll = file->block_start->prev;
            quick_sort_block( file->block_br, file->block_er,
                              file->block_start, file->block_end );

            /*
             * get back previous node and clean up list with insertion
             *   sort.
             */
            if (ll == NULL)
               ll = file->line_list;
            else
               ll = ll->next;
            set_prompt( block22b, prompt_line );
            insertion_sort_block( file->block_br, file->block_er, ll );

            /*
             * housekeeping.  mark the file as dirty and restore the
             *   cursors, which are scrambled during the sort.
             */
            file->dirty = GLOBAL;
            restore_cursors( file );
            restore_screen_line( 0, prompt_line, line_buff );
         }
      } else {
         /*
          * can only sort box blocks
          */
         error( WARNING, prompt_line, block23 );
         rc = ERROR;
      }
   } else {
      /*
       * box not marked
       */
      error( WARNING, prompt_line, block24 );
      rc = ERROR;
   }
   return( rc );
}


/*
 * Name:    quick_sort_block
 * Purpose: sort lines according to text in marked BOX block
 * Date:    Jaunary 10, 1993
 * Passed:  low:        starting line in box block
 *          high:       ending line in a box block
 *          low_node:   starting node in box block
 *          high_node:  ending node in box block
 * Notes:   Quicksort lines in the BOX block according to keys in
 *           a box block.
 *          because the median of three method is used to find the partion
 *           node,  high - low  should be greater than or equal to 2.
 *          with end recursion removal and sorting the smallest sublist
 *           first, our stack only needs room for log2 (N+1)/(M+2) nodes.
 *           a stack size of 24 can reliably handle almost 500 million lines.
 */
void quick_sort_block( long low, long high, line_list_ptr low_node,
                       line_list_ptr high_node )
{
long low_rline_stack[24];
long high_rline_stack[24];
line_list_ptr low_node_stack[24];
line_list_ptr high_node_stack[24];
long low_count;
long high_count;
long count;
line_list_ptr low_start;
line_list_ptr low_head;
line_list_ptr low_tail;
line_list_ptr high_end;
line_list_ptr high_head;
line_list_ptr high_tail;
line_list_ptr equal_head;
line_list_ptr equal_tail;
line_list_ptr walk_node;
line_list_ptr median_node;
int  i;
int  stack_pointer;

   assert( low_node->len != EOF);
   assert( high_node->len != EOF);

   stack_pointer = 0;
   while (TRUE) {

      /*
       * being that a median-of-three is used as the partition algorithm,
       *  we probably need to have at least 2 nodes in each sublist.  I
       *  chose a minimum of 25 nodes as a SWAG (scientific wild ass guess).
       *  a simple insertion sort mops the list after quicksort finishes.
       */
      while (high - low > 25) {

         assert( high >= 1 );
         assert( low  >= 1 );
         assert( low  <= high );

         /*
          * start the walk node at the head of the list and walk to the
          *  middle of the sublist.
          */
         walk_node  = low_node;
         count = (high - low) / 2;
         for (; count > 0; count--)
            walk_node = walk_node->next;

         /*
          * now, find the median of the low, middle, and high node.
          *
          * being that I am subject to error, let's assert that we really
          *  did find the median-of-three.
          */
         load_pivot( low_node );
         if (compare_pivot( walk_node ) < 0) {
            low_head   = walk_node;
            median_node = low_node;
         } else {
            low_head   = low_node;
            median_node = walk_node;
         }
         high_head = high_node;
         load_pivot( median_node );
         if (compare_pivot( high_node ) < 0) {
            high_head   = median_node;
            median_node = high_node;
         }
         load_pivot( median_node );
         if (compare_pivot( low_head ) > 0) {
            low_tail    = median_node;
            median_node = low_head;
            low_head    = low_tail;
         }

         load_pivot( median_node );

         assert( compare_pivot( low_head ) <= 0 );
         assert( compare_pivot( high_head ) >= 0 );

         /*
          * now, walk again from the head of the list comparing nodes and
          *  use the first occurrence of the median node as the partition.
          */
         walk_node = low_node;
         for (i = 0; ; walk_node = walk_node->next) {
            if (compare_pivot( walk_node ) == 0)
               break;
            i = 1;
         }

         /*
          * initialize pointers and counters for this partition.
          */
         low_start  = low_node->prev;
         high_end   = high_node->next;
         low_head   = low_tail  = NULL;
         high_head  = high_tail = NULL;
         low_count  = high_count = 0;

         /*
          * setup the first occurrence of the median node as a "fat pivot"
          *  sublist.  there are two cases to consider 1) the first
          *  occurrence of the median node is the first element in the
          *  sublist, i == 0, or 2) the first occurrence of the median node
          *  is somewhere in the sublist.
          */
         if (i == 0)
            walk_node = equal_head = equal_tail = low_node;
         else {
            equal_head = equal_tail = walk_node;
            equal_head->next->prev = equal_head->prev;
            equal_head->prev->next = equal_head->next;
            equal_head->next = low_node;
            walk_node = equal_head;
         }
         load_pivot( equal_head );

         /*
          * PARTITION:
          *  put all nodes less than the pivot on the end of the low list.
          *  put all nodes equal to the pivot on the end of the equal list.
          *  put all nodes greater than the pivot on the end of the high list.
          */
         for (count=low+1; count <= high; count++) {
            walk_node = walk_node->next;
            i = compare_pivot( walk_node );
            if (i > 0) {
               if (high_head == NULL)
                  high_head = high_tail = walk_node;
               else {
                  high_tail->next = walk_node;
                  walk_node->prev = high_tail;
                  high_tail = walk_node;
               }

               /*
                * keep a count of the number of nodes in the high list.
                */
               ++high_count;
            } else if (i < 0) {
               if (low_head == NULL)
                  low_head = low_tail = walk_node;
               else {
                  low_tail->next = walk_node;
                  walk_node->prev = low_tail;
                  low_tail = walk_node;
               }

               /*
                * keep a count of the number of nodes in the low list
                */
               ++low_count;
            } else {
               equal_tail->next = walk_node;
               walk_node->prev = equal_tail;
               equal_tail = walk_node;