subversion/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
  24 #include "svn_error.h"
  25 #include "svn_diff.h"
  26 #include "svn_types.h"
  27
  28 #include "diff.h"
  29
  30
  31 /*
  32  * Prime number to use as the size of the hash table.  This number was
  33  * not selected by testing of any kind and may need tweaking.
  34  */
  35 #define SVN_DIFF__HASH_SIZE 127
  36
  37 struct svn_diff__node_t
  38 {
  39   svn_diff__node_t     *parent;
  40   svn_diff__node_t     *left;
  41   svn_diff__node_t     *right;
  42
  43   apr_uint32_t          hash;
  44   void                 *token;
  45 };
  46
  47 struct svn_diff__tree_t
  48 {
  49   svn_diff__node_t     *root[SVN_DIFF__HASH_SIZE];
  50   apr_pool_t           *pool;
  51 };
  52
  53
  54 /*
  55  * Support functions to build a tree of token positions
  56  */
  57
  58 void
  59 svn_diff__tree_create(svn_diff__tree_t **tree, apr_pool_t *pool)
  60 {
  61   *tree = apr_pcalloc(pool, sizeof(**tree));
  62   (*tree)->pool = pool;
  63 }
  64
  65
  66 static svn_error_t *
  67 svn_diff__tree_insert_token(svn_diff__node_t **node, svn_diff__tree_t *tree,
  68                             void *diff_baton,
  69                             const svn_diff_fns_t *vtable,
  70                             apr_uint32_t hash, void *token)
  71 {
  72   svn_diff__node_t *new_node;
  73   svn_diff__node_t **node_ref;
  74   svn_diff__node_t *parent;
  75   int rv;
  76
  77   if (!token)
  78     abort();
  79
  80   parent = NULL;
  81   node_ref = &tree->root[hash % SVN_DIFF__HASH_SIZE];
  82
  83   while (*node_ref != NULL)
  84     {
  85       parent = *node_ref;
  86
  87       rv = hash - parent->hash;
  88       if (!rv)
  89         SVN_ERR(vtable->token_compare(diff_baton, parent->token, token, &rv));
  90
  91       if (rv == 0)
  92         {
  93           /* Discard the previous token.  This helps in cases where
  94            * only recently read tokens are still in memory.
  95            */
  96           if (vtable->token_discard != NULL)
  97             vtable->token_discard(diff_baton, parent->token);
  98
  99           parent->token = token;
 100           *node = parent;
 101
 102           return SVN_NO_ERROR;
 103         }
 104       else if (rv > 0)
 105         {
 106           node_ref = &parent->left;
 107         }
 108       else
 109         {
 110           node_ref = &parent->right;
 111         }
 112     }
 113
 114   /* Create a new node */
 115   new_node = apr_palloc(tree->pool, sizeof(*new_node));
 116   new_node->parent = parent;
 117   new_node->left = NULL;
 118   new_node->right = NULL;
 119   new_node->hash = hash;
 120   new_node->token = token;
 121
 122   *node = *node_ref = new_node;
 123
 124   return SVN_NO_ERROR;
 125 }
 126
 127
 128 /*
 129  * Get all tokens from a datasource.  Return the
 130  * last item in the (circular) list.
 131  */
 132 svn_error_t *
 133 svn_diff__get_tokens(svn_diff__position_t **position_list,
 134                      svn_diff__tree_t *tree,
 135                      void *diff_baton,
 136                      const svn_diff_fns_t *vtable,
 137                      svn_diff_datasource_e datasource,
 138                      apr_pool_t *pool)
 139 {
 140   svn_diff__position_t *start_position;
 141   svn_diff__position_t *position = NULL;
 142   svn_diff__position_t **position_ref;
 143   svn_diff__node_t *node;
 144   void *token;
 145   apr_off_t offset;
 146   apr_uint32_t hash;
 147
 148   *position_list = NULL;
 149
 150
 151   SVN_ERR(vtable->datasource_open(diff_baton, datasource));
 152
 153   position_ref = &start_position;
 154   offset = 0;
 155   hash = 0; /* The callback fn doesn't need to touch it per se */
 156   while (1)
 157     {
 158       SVN_ERR(vtable->datasource_get_next_token(&hash, &token,
 159                                                 diff_baton, datasource));
 160       if (token == NULL)
 161         break;
 162
 163       offset++;
 164       SVN_ERR(svn_diff__tree_insert_token(&node, tree,
 165                                           diff_baton, vtable,
 166                                           hash, token));
 167
 168       /* Create a new position */
 169       position = apr_palloc(pool, sizeof(*position));
 170       position->next = NULL;
 171       position->node = node;
 172       position->offset = offset;
 173
 174       *position_ref = position;
 175       position_ref = &position->next;
 176     }
 177
 178   *position_ref = start_position;
 179
 180   SVN_ERR(vtable->datasource_close(diff_baton, datasource));
 181
 182   *position_list = position;
 183
 184   return SVN_NO_ERROR;
 185 }