From d20d2a641351b7f9e8c9bd9b841d8de4d824aa82 Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Sat, 10 Aug 2019 17:14:37 +0300
Subject: Add default options loading and merging API

---
 libbutl/default-options.txx | 166 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)
 create mode 100644 libbutl/default-options.txx

(limited to 'libbutl/default-options.txx')

diff --git a/libbutl/default-options.txx b/libbutl/default-options.txx
new file mode 100644
index 0000000..42dd585
--- /dev/null
+++ b/libbutl/default-options.txx
@@ -0,0 +1,166 @@
+// file      : libbutl/default-options.txx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
+{
+  // Search for and parse the options files in the specified directory and
+  // its local/ subdirectory, if exists, and append the options to the
+  // resulting list.
+  //
+  // Note that we check for the local/ subdirectory even if we don't think it
+  // belongs to the remote directory; the user may move things around or it
+  // could be a VCS we don't yet recognize and there doesn't seem to be any
+  // harm in doing so.
+  //
+  // Also note that if the directory is remote, then for now the options files
+  // in both the directory itself and its local/ subdirectory are considered
+  // remote (see load_default_options() for details).
+  //
+  template <typename O, typename S, typename U>
+  void
+  load_default_options_files (const dir_path& d,
+                              bool remote,
+                              const small_vector<path, 2>& fs,
+                              default_options<O>& r)
+  {
+    auto load = [&fs, &r] (const dir_path& d, bool remote)
+    {
+      using namespace std;
+
+      for (const path& f: fs)
+      {
+        path p (d / f);
+
+        if (file_exists (p)) // Follows symlinks.
+        {
+          S s (p.string ());
+
+          // @@ Note that the potentially thrown exceptions (unknown option,
+          //    unexpected argument, etc) will not contain any location
+          //    information. Intercepting exception handling to add the file
+          //    attribution feels too hairy for now. Maybe we should support
+          //    this in CLI.
+          //
+          O o;
+          o.parse (s, U::fail, U::fail);
+
+          r.push_back (default_options_entry<O> {move (p), move (o), remote});
+        }
+      }
+    };
+
+    load (d, remote);
+
+    dir_path ld (d / dir_path ("local"));
+
+    if (dir_exists (ld))
+      load (ld, remote);
+  }
+
+  // Search for and parse the options files in the specified and outer
+  // directories until root/home directory (excluding) and append the options
+  // to the resulting list. Return true if the directory is "remote" (i.e.,
+  // belongs to a VCS repository).
+  //
+  template <typename O, typename S, typename U>
+  bool
+  load_default_options_files (const dir_path& start_dir,
+                              const optional<dir_path>& home_dir,
+                              const small_vector<path, 2>& fs,
+                              default_options<O>& r)
+  {
+    if (start_dir.root () || (home_dir && start_dir == *home_dir))
+      return false;
+
+    bool remote (load_default_options_files<O, S, U> (start_dir.directory (),
+                                                     home_dir,
+                                                     fs,
+                                                     r) ||
+                 git_repository (start_dir));
+
+    dir_path d (start_dir / dir_path (".build2"));
+
+    if (dir_exists (d))
+      load_default_options_files<O, S, U> (d, remote, fs, r);
+
+    return remote;
+  }
+
+  template <typename O, typename S, typename U>
+  default_options<O>
+  load_default_options (const optional<dir_path>& sys_dir,
+                        const optional<dir_path>& home_dir,
+                        const default_options_files& ofs)
+  {
+    default_options<O> r;
+
+    if (sys_dir)
+    {
+      assert (sys_dir->absolute () && sys_dir->normalized ());
+
+      if (dir_exists (*sys_dir))
+        load_default_options_files<O, S, U> (*sys_dir,
+                                             false /* remote */,
+                                             ofs.files,
+                                             r);
+    }
+
+    if (home_dir)
+    {
+      assert (home_dir->absolute () && home_dir->normalized ());
+
+      dir_path d (*home_dir / dir_path (".build2"));
+
+      if (dir_exists (d))
+        load_default_options_files<O, S, U> (d,
+                                             false /* remote */,
+                                             ofs.files,
+                                             r);
+    }
+
+    if (ofs.start_dir)
+    {
+      assert (ofs.start_dir->absolute () && ofs.start_dir->normalized ());
+
+      load_default_options_files<O, S, U> (*ofs.start_dir,
+                                           home_dir,
+                                           ofs.files,
+                                           r);
+    }
+
+    return r;
+  }
+
+  template <typename O, typename F>
+  O
+  merge_default_options (const default_options<O>& def_ops,
+                         const O& cmd_ops,
+                         F&& f)
+  {
+    // Optimize for the common case.
+    //
+    if (def_ops.empty ())
+      return cmd_ops;
+
+    O r;
+    for (const default_options_entry<O>& e: def_ops)
+    {
+      f (e, cmd_ops);
+      r.merge (e.options);
+    }
+
+    r.merge (cmd_ops);
+    return r;
+  }
+
+  template <typename O>
+  inline O
+  merge_default_options (const default_options<O>& def_ops, const O& cmd_ops)
+  {
+    return merge_default_options (
+      def_ops,
+      cmd_ops,
+      [] (const default_options_entry<O>&, const O&) {});
+  }
+}
-- 
cgit v1.1