From 1cdb233cedd12069a4aa5d761e20b42e842ec58f Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 5 Aug 2021 11:20:30 +0300
Subject: Convert default_options_start() to template function which accepts
 iterators range

---
 libbutl/default-options.cxx      | 73 ----------------------------------------
 libbutl/default-options.mxx      | 23 ++++++++++---
 libbutl/default-options.txx      | 39 +++++++++++++++++++++
 tests/default-options/driver.cxx |  2 +-
 4 files changed, 58 insertions(+), 79 deletions(-)
 delete mode 100644 libbutl/default-options.cxx

diff --git a/libbutl/default-options.cxx b/libbutl/default-options.cxx
deleted file mode 100644
index 28f6fb7..0000000
--- a/libbutl/default-options.cxx
+++ /dev/null
@@ -1,73 +0,0 @@
-// file      : libbutl/default-options.cxx -*- C++ -*-
-// license   : MIT; see accompanying LICENSE file
-
-#ifndef __cpp_modules_ts
-#include <libbutl/default-options.mxx>
-#endif
-
-#include <cassert>
-
-#ifndef __cpp_lib_modules_ts
-#include <vector>
-#endif
-
-// Other includes.
-
-#ifdef __cpp_modules_ts
-module butl.default_options;
-
-// Only imports additional to interface.
-#ifdef __clang__
-#ifdef __cpp_lib_modules_ts
-import std.core;
-#endif
-import butl.path;
-import butl.optional;
-import butl.small_vector;
-#endif
-
-#endif
-
-using namespace std;
-
-namespace butl
-{
-  optional<dir_path>
-  default_options_start (const optional<dir_path>& home,
-                         const vector<dir_path>& dirs)
-  {
-    if (home)
-      assert (home->absolute () && home->normalized ());
-
-    if (dirs.empty ())
-      return nullopt;
-
-    // Use the first directory as a start.
-    //
-    auto i (dirs.begin ());
-    dir_path d (*i);
-
-    // Try to find a common prefix for each subsequent directory.
-    //
-    for (++i; i != dirs.end (); ++i)
-    {
-      bool p (false);
-
-      for (;
-           !(d.root () || (home && d == *home));
-           d = d.directory ())
-      {
-        if (i->sub (d))
-        {
-          p = true;
-          break;
-        }
-      }
-
-      if (!p)
-        return nullopt;
-    }
-
-    return d;
-  }
-}
diff --git a/libbutl/default-options.mxx b/libbutl/default-options.mxx
index 11f7bb2..2d44333 100644
--- a/libbutl/default-options.mxx
+++ b/libbutl/default-options.mxx
@@ -152,12 +152,25 @@ LIBBUTL_MODEXPORT namespace butl
   AS
   merge_default_arguments (const default_options<O>&, const AS&, F&&);
 
-  // Find a common start (parent) directory stopping at home or root
-  // (excluding).
+  // Find a common start (parent) directory for directories specified as an
+  // iterator range, stopping at home or root (excluding). Optionally pass a
+  // function resolving an iterator into a directory in a way other than just
+  // dereferencing it. The function signature is:
   //
-  LIBBUTL_SYMEXPORT optional<dir_path>
-  default_options_start (const optional<dir_path>& home_dir,
-                         const std::vector<dir_path>&);
+  // const dir_path& (I)
+  //
+  template <typename I, typename F>
+  optional<dir_path>
+  default_options_start (const optional<dir_path>& home, I, I, F&&);
+
+  template <typename I>
+  inline optional<dir_path>
+  default_options_start (const optional<dir_path>& home, I b, I e)
+  {
+    return default_options_start (home,
+                                  b, e,
+                                  [] (I i) -> const dir_path& {return *i;});
+  }
 }
 
 #include <libbutl/default-options.ixx>
diff --git a/libbutl/default-options.txx b/libbutl/default-options.txx
index eaf4235..dc809ad 100644
--- a/libbutl/default-options.txx
+++ b/libbutl/default-options.txx
@@ -318,4 +318,43 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
     r.insert (r.end (), cmd_args.begin (), cmd_args.end ());
     return r;
   }
+
+  template <typename I, typename F>
+  optional<dir_path>
+  default_options_start (const optional<dir_path>& home, I b, I e, F&& f)
+  {
+    if (home)
+      assert (home->absolute () && home->normalized ());
+
+    if (b == e)
+      return nullopt;
+
+    // Use the first directory as a start.
+    //
+    I i (b);
+    dir_path d (f (i));
+
+    // Try to find a common prefix for each subsequent directory.
+    //
+    for (++i; i != e; ++i)
+    {
+      bool p (false);
+
+      for (;
+           !(d.root () || (home && d == *home));
+           d = d.directory ())
+      {
+        if (f (i).sub (d))
+        {
+          p = true;
+          break;
+        }
+      }
+
+      if (!p)
+        return nullopt;
+    }
+
+    return d;
+  }
 }
diff --git a/tests/default-options/driver.cxx b/tests/default-options/driver.cxx
index b3f66bf..009cddb 100644
--- a/tests/default-options/driver.cxx
+++ b/tests/default-options/driver.cxx
@@ -250,7 +250,7 @@ main (int argc, const char* argv[])
 
   // Deduce a common start directory.
   //
-  fs.start = default_options_start (home_dir, dirs);
+  fs.start = default_options_start (home_dir, dirs.begin (), dirs.end ());
 
   // Load and print the default options.
   //
-- 
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