From fa313152767ae60941987450268f9562e1d59d42 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Fri, 8 Nov 2019 00:17:11 +0300
Subject: Add path_name_value struct

---
 libbutl/path-io.mxx |  4 ++++
 libbutl/path.ixx    | 38 ++++++++++++++++++++++++++++++++++++
 libbutl/path.mxx    | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 94 insertions(+), 3 deletions(-)

diff --git a/libbutl/path-io.mxx b/libbutl/path-io.mxx
index 54d884b..5a91dac 100644
--- a/libbutl/path-io.mxx
+++ b/libbutl/path-io.mxx
@@ -8,6 +8,8 @@
 
 // C includes.
 
+#include <cassert>
+
 #ifndef __cpp_lib_modules_ts
 #include <ostream>
 #endif
@@ -45,6 +47,8 @@ LIBBUTL_MODEXPORT namespace butl
   inline std::basic_ostream<C>&
   operator<< (std::basic_ostream<C>& os, const basic_path_name<P>& pn)
   {
+    assert (!pn.empty ());
+
     return os << (pn.name ? *pn.name : pn.path->string ());
   }
 }
diff --git a/libbutl/path.ixx b/libbutl/path.ixx
index 7786fbc..ae19b58 100644
--- a/libbutl/path.ixx
+++ b/libbutl/path.ixx
@@ -701,4 +701,42 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
     if (!d.path_.empty () && d.tsep_ == 0)
       d.tsep_ = 1; // Canonical separator is always first.
   }
+
+  // basic_path_name_value
+  //
+  template <typename P>
+  inline basic_path_name_value<P>::
+  basic_path_name_value (basic_path_name_value&& p)
+      : basic_path_name_value (std::move (p.path_), std::move (p.name))
+  {
+  }
+
+  template <typename P>
+  inline basic_path_name_value<P>::
+  basic_path_name_value (const basic_path_name_value& p)
+      : basic_path_name_value (p.path_, p.name)
+  {
+  }
+
+  template <typename P>
+  inline basic_path_name_value<P>& basic_path_name_value<P>::
+  operator= (basic_path_name_value&& p)
+  {
+    if (this != &p)
+    {
+      path_ = std::move (p.path_);
+      this->name = std::move (p.name);
+    }
+  }
+
+  template <typename P>
+  inline basic_path_name_value<P>& basic_path_name_value<P>::
+  operator= (const basic_path_name_value& p)
+  {
+    if (this != &p)
+    {
+      path_ = p.path_;
+      this->name = p.name;
+    }
+  }
 }
diff --git a/libbutl/path.mxx b/libbutl/path.mxx
index 1d0ada9..2374fb5 100644
--- a/libbutl/path.mxx
+++ b/libbutl/path.mxx
@@ -536,15 +536,21 @@ LIBBUTL_MODEXPORT namespace butl
   // that this is a view-like type with the original path shallow-referenced
   // rather than copied.
   //
-  // Note: we could also have a copying version that derives from the view
-  // (and thus can be passed down as a view).
-  //
   template <typename P>
   struct basic_path_name;
 
   using path_name = basic_path_name<path>;
   using dir_path_name = basic_path_name<dir_path>;
 
+  // The copying version of the above that derives from the view (and thus can
+  // be passed down as a view).
+  //
+  template <typename P>
+  struct basic_path_name_value;
+
+  using path_name_value = basic_path_name_value<path>;
+  using dir_name_value = basic_path_name_value<dir_path>;
+
   // Low-level path data storage. It is also used by the implementation to
   // pass around initialized/valid paths.
   //
@@ -1359,9 +1365,52 @@ LIBBUTL_MODEXPORT namespace butl
     explicit
     basic_path_name (const path_type* p, optional<string_type> n = nullopt)
         : path (p), name (std::move (n)) {}
+
+    basic_path_name (): path (nullptr) {} // Create empty/NULL path name.
+
+    bool
+    empty () const {return path == nullptr && !name;}
   };
 
   // For operator<< (ostream) see the path-io header.
+
+  template <typename P>
+  struct basic_path_name_value: basic_path_name<P>
+  {
+    using base = basic_path_name<P>;
+
+    using path_type = typename base::path_type;
+    using string_type = typename base::string_type;
+
+    explicit
+    basic_path_name_value (path_type p, optional<string_type> n = nullopt)
+        : base (&path_, std::move (n)), path_ (std::move (p)) {}
+
+    int
+    compare (const basic_path_name_value& x) const
+    {
+      if (int r = path_.compare (x.path_))
+        return r;
+
+      return this->name < x.name ? -1 : this->name > x.name ? 1 : 0;
+    }
+
+    basic_path_name_value (basic_path_name_value&&);
+    basic_path_name_value (const basic_path_name_value&);
+    basic_path_name_value& operator= (basic_path_name_value&&);
+    basic_path_name_value& operator= (const basic_path_name_value&);
+
+  private:
+    P path_;
+  };
+
+  template <typename P>
+  inline bool
+  operator< (const basic_path_name_value<P>& x,
+             const basic_path_name_value<P>& y)
+  {
+    return x.compare (y) < 0;
+  }
 }
 
 LIBBUTL_MODEXPORT namespace std
-- 
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