# 
# patch "ChangeLog"
#  from [304f4c134fbf6ec5457ffc731c82a7e031bc7bbc]
#    to [cc5ee96bf067ff3952cc6bac909501eb17f66ec2]
# 
# patch "change_set.cc"
#  from [f680797285e20aa2ff83233d95e7d2ac111443bb]
#    to [bd5f0a03f8512b1319cb9c2323a3aa81f8d67b1c]
# 
--- ChangeLog
+++ ChangeLog
@@ -1,3 +1,11 @@
+2005-04-21  Nathaniel Smith  <address@hidden>
+
+	* change_set.cc (apply_path_rearrangement_can_fastpath) 
+	(apply_path_rearrangement_fastpath) 
+	(apply_path_rearrangement_slowpath, apply_path_rearrangement):
+	Refactor into pieces, so all versions of apply_path_rearrangement
+	can take a fast-path when possible.
+
 2005-04-20  Nathaniel Smith  <address@hidden>
 
 	* Makefile.am (EXTRA_DIST): Put $(wildcard) around "debian/*", so
--- change_set.cc
+++ change_set.cc
@@ -2464,18 +2464,6 @@
 // application stuff
 
 void
-apply_path_rearrangement(path_set const & old_ps,
-                         change_set::path_rearrangement const & pr,
-                         path_set & new_ps)
-{
-  pr.check_sane();
-  change_set::path_rearrangement a, b, c;
-  a.added_files = old_ps;
-  concatenate_rearrangements(a, pr, c);
-  new_ps = c.added_files;
-}
-
-void
 build_pure_addition_change_set(manifest_map const & man,
                                change_set & cs)
 {
@@ -2568,30 +2556,70 @@
     }
 }
 
-// quick, optimistic and destructive version
+static inline bool
+apply_path_rearrangement_can_fastpath(change_set::path_rearrangement const & pr)
+{
+  return pr.added_files.empty()
+    && pr.renamed_files.empty()
+    && pr.renamed_dirs.empty()
+    && pr.deleted_dirs.empty();
+}
+
+static inline void
+apply_path_rearrangement_fastpath(change_set::path_rearrangement const & pr,
+                                  path_set & ps)
+{
+  pr.check_sane();
+  // fast path for simple drop-or-nothing file operations
+  for (std::set<file_path>::const_iterator i = pr.deleted_files.begin();
+       i != pr.deleted_files.end(); ++i)
+    {
+      I(ps.find(*i) != ps.end());
+      ps.erase(*i);
+    }
+}
+
+static inline void
+apply_path_rearrangement_slowpath(path_set const & old_ps,
+                                  change_set::path_rearrangement const & pr,
+                                  path_set & new_ps)
+{
+  pr.check_sane();
+  change_set::path_rearrangement a, b;
+  a.added_files = old_ps;
+  concatenate_rearrangements(a, pr, b);
+  new_ps = b.added_files;
+}
+
 void
+apply_path_rearrangement(path_set const & old_ps,
+                         change_set::path_rearrangement const & pr,
+                         path_set & new_ps)
+{
+  if (apply_path_rearrangement_can_fastpath(pr))
+    {
+      new_ps = old_ps;
+      apply_path_rearrangement_fastpath(pr, new_ps);
+    }
+  else
+    {
+      apply_path_rearrangement_slowpath(old_ps, pr, new_ps);
+    }
+}
+
+// destructive version
+void
 apply_path_rearrangement(change_set::path_rearrangement const & pr,
                          path_set & ps)
 {
-  pr.check_sane();
-  if (pr.added_files.empty()
-      && pr.renamed_files.empty() 
-      && pr.renamed_dirs.empty()
-      && pr.deleted_dirs.empty())
+  if (apply_path_rearrangement_can_fastpath(pr))
     {
-      // fast path for simple drop-or-nothing file operations
-      for (std::set<file_path>::const_iterator i = pr.deleted_files.begin();
-           i != pr.deleted_files.end(); ++i)
-        {
-          I(ps.find(*i) != ps.end());
-          ps.erase(*i);
-        }
+      apply_path_rearrangement_fastpath(pr, ps);
     }
   else
     {
-      // fall back to the slow way
-      path_set tmp;
-      apply_path_rearrangement(ps, pr, tmp);
+      path_set tmp = ps;
+      apply_path_rearrangement_slowpath(ps, pr, tmp);
       ps = tmp;
     }
 }