From 2a0f9e035f673f1ee387924501a31990de37f18d Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 24 Apr 2015 12:29:20 +0200
Subject: Implement lib/liba/libso{} target group, shared/static library build

---
 build/config/utility.cxx | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 build/config/utility.cxx

(limited to 'build/config/utility.cxx')

diff --git a/build/config/utility.cxx b/build/config/utility.cxx
new file mode 100644
index 0000000..8b26239
--- /dev/null
+++ b/build/config/utility.cxx
@@ -0,0 +1,41 @@
+// file      : build/config/utility.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2015 Code Synthesis Tools CC
+// license   : MIT; see accompanying LICENSE file
+
+#include <build/config/utility>
+
+using namespace std;
+
+namespace build
+{
+  namespace config
+  {
+    // The same as the template except it is a bit more efficient
+    // when it comes to not creating the default value string
+    // unnecessarily.
+    //
+    pair<const string&, bool>
+    required (scope& root, const char* name, const char* def_value)
+    {
+      string r;
+      const variable& var (variable_pool.find (name));
+
+      if (auto v = root[var])
+      {
+        const string& s (v.as<const string&> ());
+
+        if (!v.belongs (*global_scope)) // A value from (some) config.build.
+          return pair<const string&, bool> (s, false);
+
+        r = s;
+      }
+      else
+        r = def_value;
+
+      auto v (root.assign (var));
+      v = move (r);
+
+      return pair<const string&, bool> (v.as<const string&> (), true);
+    }
+  }
+}
-- 
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