1 files changed, 128 insertions, 0 deletions
diff --git a/libbutl/path-map.hxx b/libbutl/path-map.hxx
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+++ b/libbutl/path-map.hxx
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+// file      : libbutl/path-map.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#pragma once
+
+#include <algorithm> // min()
+
+#include <libbutl/path.hxx>
+#include <libbutl/prefix-map.hxx>
+
+#include <libbutl/export.hxx>
+
+namespace butl
+{
+  // prefix_map for filesystem paths
+  //
+  // Important: the paths should be normalized but can use different directory
+  // separators and different case on case-insensitive platforms.
+  //
+  // Note that the path's representation of POSIX root ('/') is inconsistent
+  // in that we have a trailing delimiter at the end of the path (its "proper"
+  // representation would have been an empty string but that would have
+  // clashed with empty paths). To work around this snag, this implementation,
+  // during key comparison, detects '/' and treats it as empty. Note that the
+  // map will still store the key as you have first inserted it. So if you
+  // want a particular representation (i.e., empty or '/'), pre- populate the
+  // map with it.
+  //
+  template <typename C, typename K>
+  struct compare_prefix<basic_path<C, K>>
+  {
+    typedef basic_path<C, K> key_type;
+
+    typedef C delimiter_type;
+    typedef typename key_type::string_type string_type;
+    typedef typename key_type::size_type size_type;
+    typedef typename key_type::traits_type traits_type;
+
+    explicit
+    compare_prefix (delimiter_type) {}
+
+    bool
+    operator() (const key_type& x, const key_type& y) const
+    {
+      const string_type& xs (x.string ());
+      const string_type& ys (y.string ());
+
+      return compare (xs.c_str (),
+                      root (xs) ? 0 : xs.size (),
+                      ys.c_str (),
+                      root (ys) ? 0 : ys.size ()) < 0;
+    }
+
+    bool
+    prefix (const key_type& p, const key_type& k) const
+    {
+      const string_type& ps (p.string ());
+      const string_type& ks (k.string ());
+
+      return prefix (root (ps) ? string_type () : ps,
+                     root (ks) ? string_type () : ks);
+    }
+
+    bool
+    prefix (key_type& k) const
+    {
+      if (k.empty ())
+        return false;
+
+      k.make_directory ();
+      return true;
+    }
+
+  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)
+    {
+      return p.size () == 1 && key_type::traits_type::is_separator (p[0]);
+    }
+  };
+
+  // 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_type::directory_separator>;
+
+  template <typename T>
+  using dir_path_map =
+    prefix_map<dir_path, T, dir_path::traits_type::directory_separator>;
+}