src/TortoiseMerge/libsvn_diff/token.c

   1 /*
   2  * token.c :  routines for doing diffs
   3  *
   4  * ====================================================================
   5  * Copyright (c) 2000-2004 CollabNet.  All rights reserved.
   6  *
   7  * This software is licensed as described in the file COPYING, which
   8  * you should have received as part of this distribution.  The terms
   9  * are also available at http://subversion.tigris.org/license-1.html.
  10  * If newer versions of this license are posted there, you may use a
  11  * newer version instead, at your option.
  12  *
  13  * This software consists of voluntary contributions made by many
  14  * individuals.  For exact contribution history, see the revision
  15  * history and logs, available at http://subversion.tigris.org/.
  16  * ====================================================================
  17  */
  18
  19
  20 #include <apr.h>
  21 #include <apr_pools.h>
  22 #include <apr_general.h>
  23 #include "svn_error.h"
  24 #include "svn_version.h"
  25 #include "svn_io.h"
  26
  27 #include "diff.h"
  28
  29
  30 /*
  31  * Prime number to use as the size of the hash table.  This number was
  32  * not selected by testing of any kind and may need tweaking.
  33  */
  34 #define SVN_DIFF__HASH_SIZE 127
  35
  36 struct svn_diff__node_t
  37 {
  38   svn_diff__node_t     *parent;
  39   svn_diff__node_t     *left;
  40   svn_diff__node_t     *right;
  41
  42   apr_uint32_t          hash;
  43   void                 *token;
  44 };
  45
  46 struct svn_diff__tree_t
  47 {
  48   svn_diff__node_t     *root[SVN_DIFF__HASH_SIZE];
  49   apr_pool_t           *pool;
  50 };
  51
  52
  53 /*
  54  * Support functions to build a tree of token positions
  55  */
  56
  57 void
  58 svn_diff__tree_create(svn_diff__tree_t **tree, apr_pool_t *pool)
  59 {
  60   *tree = apr_pcalloc(pool, sizeof(**tree));
  61   (*tree)->pool = pool;
  62 }
  63
  64
  65 static svn_error_t *
  66 svn_diff__tree_insert_token(svn_diff__node_t **node, svn_diff__tree_t *tree,
  67                             void *diff_baton,
  68                             const svn_diff_fns_t *vtable,
  69                             apr_uint32_t hash, void *token)
  70 {
  71   svn_diff__node_t *new_node;
  72   svn_diff__node_t **node_ref;
  73   svn_diff__node_t *parent;
  74   int rv;
  75
  76   SVN_ERR_ASSERT(token);
  77
  78   parent = NULL;
  79   node_ref = &tree->root[hash % SVN_DIFF__HASH_SIZE];
  80
  81   while (*node_ref != NULL)
  82     {
  83       parent = *node_ref;
  84
  85       rv = hash - parent->hash;
  86       if (!rv)
  87         SVN_ERR(vtable->token_compare(diff_baton, parent->token, token, &rv));
  88
  89       if (rv == 0)
  90         {
  91           /* Discard the previous token.  This helps in cases where
  92            * only recently read tokens are still in memory.
  93            */
  94           if (vtable->token_discard != NULL)
  95             vtable->token_discard(diff_baton, parent->token);
  96
  97           parent->token = token;
  98           *node = parent;
  99
 100           return SVN_NO_ERROR;
 101         }
 102       else if (rv > 0)
 103         {
 104           node_ref = &parent->left;
 105         }
 106       else
 107         {
 108           node_ref = &parent->right;
 109         }
 110     }
 111
 112   /* Create a new node */
 113   new_node = apr_palloc(tree->pool, sizeof(*new_node));
 114   new_node->parent = parent;
 115   new_node->left = NULL;
 116   new_node->right = NULL;
 117   new_node->hash = hash;
 118   new_node->token = token;
 119
 120   *node = *node_ref = new_node;
 121
 122   return SVN_NO_ERROR;
 123 }
 124
 125
 126 /*
 127  * Get all tokens from a datasource.  Return the
 128  * last item in the (circular) list.
 129  */
 130 svn_error_t *
 131 svn_diff__get_tokens(svn_diff__position_t **position_list,
 132                      svn_diff__tree_t *tree,
 133                      void *diff_baton,
 134                      const svn_diff_fns_t *vtable,
 135                      svn_diff_datasource_e datasource,
 136                      apr_pool_t *pool)
 137 {
 138   svn_diff__position_t *start_position;
 139   svn_diff__position_t *position = NULL;
 140   svn_diff__position_t **position_ref;
 141   svn_diff__node_t *node;
 142   void *token;
 143   apr_off_t offset;
 144   apr_uint32_t hash;
 145
 146   *position_list = NULL;
 147
 148
 149   SVN_ERR(vtable->datasource_open(diff_baton, datasource));
 150
 151   position_ref = &start_position;
 152   offset = 0;
 153   hash = 0; /* The callback fn doesn't need to touch it per se */
 154   while (1)
 155     {
 156       SVN_ERR(vtable->datasource_get_next_token(&hash, &token,
 157                                                 diff_baton, datasource));
 158       if (token == NULL)
 159         break;
 160
 161       offset++;
 162       SVN_ERR(svn_diff__tree_insert_token(&node, tree,
 163                                           diff_baton, vtable,
 164                                           hash, token));
 165
 166       /* Create a new position */
 167       position = apr_palloc(pool, sizeof(*position));
 168       position->next = NULL;
 169       position->node = node;
 170       position->offset = offset;
 171
 172       *position_ref = position;
 173       position_ref = &position->next;
 174     }
 175
 176   *position_ref = start_position;
 177
 178   SVN_ERR(vtable->datasource_close(diff_baton, datasource));
 179
 180   *position_list = position;
 181
 182   return SVN_NO_ERROR;
 183 }