From 8ee02c5d40006d52d0048a748a695d589b3627cb Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 11 Apr 2016 17:37:29 +0200
Subject: Simplify unconfigured module interface

---
 build2/b.cxx                |  2 +-
 build2/cli/module.cxx       | 22 ++++++++--------------
 build2/config/operation.cxx | 42 +++++++++++++++++++++++++++++++-----------
 build2/config/utility       |  8 +++++++-
 4 files changed, 47 insertions(+), 27 deletions(-)

diff --git a/build2/b.cxx b/build2/b.cxx
index 313fe95..7ebbab1 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -315,7 +315,7 @@ main (int argc, char* argv[])
           os.push_back (targetspec (name ("dir", string ())));
 
         const path p ("<buildspec>");
-        const location l (&p, 1, 0); //@@ TODO
+        const location l (&p, 0, 0); //@@ TODO
 
         operation_id oid (0); // Not yet translated.
         const operation_info* oif (nullptr);
diff --git a/build2/cli/module.cxx b/build2/cli/module.cxx
index 7b98e93..bc6e13f 100644
--- a/build2/cli/module.cxx
+++ b/build2/cli/module.cxx
@@ -87,7 +87,7 @@ namespace build2
       // Don't re-run tests if the configuration says we are unconfigured.
       //
       if (optional && config::unconfigured (root, "config.cli"))
-          return false;
+        return false;
 
       // config.cli
       //
@@ -96,9 +96,9 @@ namespace build2
         // Return version or empty string if unable to execute (e.g.,
         // the cli executable is not found).
         //
-        auto test = [optional] (const char* cli) -> string
+        auto test = [optional] (const path& cli) -> string
         {
-          const char* args[] = {cli, "--version", nullptr};
+          const char* args[] = {cli.string ().c_str (), "--version", nullptr};
 
           if (verb >= 2)
             print_process (args);
@@ -145,7 +145,7 @@ namespace build2
         };
 
         string ver;
-        const char* cli ("cli"); // Default.
+        path cli ("cli"); // Default.
 
         if (optional)
         {
@@ -169,19 +169,19 @@ namespace build2
           }
           else
           {
-            auto p (config::required (root, "config.cli", path (cli)));
-            assert (p.second && cast<string> (p.first) == cli);
+            auto p (config::required (root, "config.cli", cli));
+            assert (p.second && cast<path> (p.first) == cli);
           }
         }
         else
         {
-          auto p (config::required (root, "config.cli", path (cli)));
+          auto p (config::required (root, "config.cli", cli));
 
           // If we actually set a new value, test it by trying to execute.
           //
           if (p.second)
           {
-            cli = cast<string> (p.first).c_str ();
+            cli = cast<path> (p.first);
             ver = test (cli);
 
             if (ver.empty ())
@@ -189,12 +189,6 @@ namespace build2
           }
         }
 
-        // Clear the unconfigured flag, if any.
-        //
-        // @@ Get rid of needing to do this.
-        //
-        config::unconfigured (root, "config.cli", false);
-
         if (!ver.empty () && verb >= 2)
           text << cli << " " << ver;
       }
diff --git a/build2/config/operation.cxx b/build2/config/operation.cxx
index ec92e89..8b0bb3d 100644
--- a/build2/config/operation.cxx
+++ b/build2/config/operation.cxx
@@ -127,8 +127,11 @@ namespace build2
         //
         names storage;
 
-        for (const auto& p: mod.vars)
+        for (auto b (mod.vars.begin ()), i (b), e (mod.vars.end ());
+             i != e;
+             ++i)
         {
+          const auto& p (*i);
           const variable& var (p.first);
 
           pair<lookup, size_t> org (root.find_original (var));
@@ -208,32 +211,49 @@ namespace build2
             }
           }
 
-          const value& val (*l);
+          const string& n (var.name);
+          const value& v (*l);
 
           // We will only write config.*.configured if it is false (true is
-          // implied by its absence).
-          //
-          // @@ Do we still need this?
+          // implied by its absence). We will also ignore false values if
+          // there is any other value for this module (see unconfigured()).
           //
-          const string& n (var.name);
-
           if (n.size () > 11 &&
               n.compare (n.size () - 11, 11, ".configured") == 0)
           {
-            if (val == nullptr || cast<bool> (val))
+            if (cast<bool> (v))
+              continue;
+
+            size_t m (n.size () - 11); // Prefix size.
+            auto same = [&n, m] (const variable& v)
+            {
+              return v.name.size () >= m &&
+                v.name.compare (0, m, n, 0, m) == 0;
+            };
+
+            // Check if this is the first value for this module.
+            //
+            auto j (i);
+            if (j != b && same ((--j)->first))
+              continue;
+
+            // Check if this is the last value for this module.
+            //
+            j = i;
+            if (++j != e && same (j->first))
               continue;
           }
 
           if (next_module (var))
             ofs << endl;
 
-          if (val)
+          if (v)
           {
             storage.clear ();
-            ofs << var.name << " = " << reverse (val, storage) << endl;
+            ofs << n << " = " << reverse (v, storage) << endl;
           }
           else
-            ofs << var.name << " = [null]" << endl;
+            ofs << n << " = [null]" << endl;
         }
       }
       catch (const ofstream::failure&)
diff --git a/build2/config/utility b/build2/config/utility
index 8a93c09..beab758 100644
--- a/build2/config/utility
+++ b/build2/config/utility
@@ -86,11 +86,17 @@ namespace build2
     bool
     specified (scope& root, const string& ns);
 
-    //
+    // Check if there is a false config.*.configured value. This mechanism can
+    // be used to "remember" that the module is left unconfigured in order to
+    // avoid re-running the tests, etc.
     //
     bool
     unconfigured (scope& root, const string& ns);
 
+    // Set the config.*.configured value. Note that you only need to set it to
+    // false. It will be automatically ignored if there are any other config.*
+    // values for this module.
+    //
     void
     unconfigured (scope& root, const string& ns, bool);
 
-- 
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