Remove canonicalization requirement from path_map

1 files changed, 54 insertions, 11 deletions

diff --git a/butl/path-map b/butl/path-map
index fc66002..3852723 100644
--- a/butl/path-map
+++ b/butl/path-map
@@ -5,6 +5,8 @@
 #ifndef BUTL_PATH_MAP
 #define BUTL_PATH_MAP
 
+#include <algorithm> // min()
+
 #include <butl/path>
 #include <butl/prefix-map>
 
@@ -12,7 +14,8 @@ namespace butl
 {
   // prefix_map for filesystem paths
   //
-  // Important: the paths should be normalized and canonicalized.
+  // Important: the paths should be normalized but don't have to be
+  // canonicalized.
   //
   // Note that the path's representation of POSIX root ('/') is
   // inconsistent in that we have a trailing delimiter at the end of
@@ -25,16 +28,17 @@ namespace butl
   // populate the map with it.
   //
   template <typename C, typename K>
-  struct compare_prefix<basic_path<C, K>>: compare_prefix<std::basic_string<C>>
+  struct compare_prefix<basic_path<C, K>>
   {
     typedef basic_path<C, K> key_type;
 
     typedef C delimiter_type;
-    typedef std::basic_string<C> string_type;
-    typedef compare_prefix<std::basic_string<C>> base;
+    typedef typename key_type::string_type string_type;
+    typedef typename key_type::size_type size_type;
+    typedef typename key_type::traits traits_type;
 
     explicit
-    compare_prefix (delimiter_type d): base (d) {}
+    compare_prefix (delimiter_type) {}
 
     bool
     operator() (const key_type& x, const key_type& y) const
@@ -42,10 +46,10 @@ namespace butl
       const string_type& xs (x.string ());
       const string_type& ys (y.string ());
 
-      return base::compare (xs.c_str (),
-                            root (xs) ? 0 : xs.size (),
-                            ys.c_str (),
-                            root (ys) ? 0 : ys.size ()) < 0;
+      return compare (xs.c_str (),
+                      root (xs) ? 0 : xs.size (),
+                      ys.c_str (),
+                      root (ys) ? 0 : ys.size ()) < 0;
     }
 
     bool
@@ -54,11 +58,47 @@ namespace butl
       const string_type& ps (p.string ());
       const string_type& ks (k.string ());
 
-      return base::prefix (root (ps) ? string_type () : ps,
-                           root (ks) ? string_type () : ks);
+      return prefix (root (ps) ? string_type () : ps,
+                     root (ks) ? string_type () : ks);
     }
 
   protected:
+    bool
+    prefix (const string_type& p, const string_type& k) const
+    {
+      // The same code as in prefix_map but using our compare().
+      //
+      size_type pn (p.size ()), kn (k.size ());
+      return pn == 0 || // Empty key is always a prefix.
+        (pn <= kn &&
+         compare (p.c_str (), pn, k.c_str (), pn == kn ? pn : pn + 1) == 0);
+    }
+
+    int
+    compare (const C* x, size_type xn,
+             const C* y, size_type yn) const
+    {
+      size_type n (std::min (xn, yn));
+      int r (traits_type::compare (x, n, y, n));
+
+      if (r == 0)
+      {
+        // Pretend there is a delimiter characters at the end of the
+        // shorter string.
+        //
+        char xc (xn > n ? x[n] : (xn++, traits_type::directory_separator));
+        char yc (yn > n ? y[n] : (yn++, traits_type::directory_separator));
+        r = traits_type::compare (&xc, 1, &yc, 1);
+
+        // If we are still equal, then compare the lengths.
+        //
+        if (r == 0)
+          r = (xn == yn ? 0 : (xn < yn ? -1 : 1));
+      }
+
+      return r;
+    }
+
     static bool
     root (const string_type& p)
     {
@@ -66,6 +106,9 @@ namespace butl
     }
   };
 
+  // Note that the delimiter character is not used (is_delimiter() from
+  // path_traits is used instead).
+  //
   template <typename T>
   using path_map = prefix_map<path, T, path::traits::directory_separator>;