From aec6628e8c1f0ebdb87767cbf804b01504d82459 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Wed, 20 Nov 2024 09:25:50 +0200
Subject: Generalize config::specified_config()

---
 libbuild2/config/utility.cxx | 40 +++++++++++++++++++++++++---------------
 libbuild2/config/utility.hxx | 18 ++++++++++++------
 libbuild2/dist/init.cxx      |  2 +-
 libbuild2/install/init.cxx   |  2 +-
 4 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/libbuild2/config/utility.cxx b/libbuild2/config/utility.cxx
index aa0d5af..35ff3ff 100644
--- a/libbuild2/config/utility.cxx
+++ b/libbuild2/config/utility.cxx
@@ -87,10 +87,13 @@ namespace build2
     }
 
     bool
-    specified_config (scope& rs,
-                      const string& n,
-                      initializer_list<const char*> ig)
+    specified_config (const scope& rs,
+                      const string& ns,
+                      initializer_list<const char*> ig,
+                      bool exact)
     {
+      assert (!exact || ig.size () == 0);
+
       // Note: go straight for the public variable pool.
       //
       auto& vp (rs.ctx.var_pool);
@@ -103,8 +106,7 @@ namespace build2
       // any original values, they will be "visible"; see find_override() for
       // details.
       //
-      const string ns ("config." + n);
-      for (scope* s (&rs); s != nullptr; s = s->parent_scope ())
+      for (const scope* s (&rs); s != nullptr; s = s->parent_scope ())
       {
         for (auto p (s->vars.lookup_namespace (ns));
              p.first != p.second;
@@ -117,17 +119,25 @@ namespace build2
           if (size_t n = v->override ())
             v = vp.find (string (v->name, 0, n));
 
-          auto match_tail = [&ns, v] (const char* t)
+          if (exact)
           {
-            return v->name.compare (ns.size () + 1, string::npos, t) == 0;
-          };
-
-          // Ignore config.*.configured and user-supplied names.
-          //
-          if (v->name.size () <= ns.size () ||
-              (!match_tail ("configured") &&
-               find_if (ig.begin (), ig.end (), match_tail) == ig.end ()))
-            return true;
+            if (v->name.size () == ns.size ())
+              return true;
+          }
+          else
+          {
+            auto match_tail = [&ns, v] (const char* t)
+            {
+              return v->name.compare (ns.size () + 1, string::npos, t) == 0;
+            };
+
+            // Ignore config.*.configured and user-supplied names.
+            //
+            if (v->name.size () <= ns.size () || // @@ Hm, when can it be < ?
+                (!match_tail ("configured") &&
+                 find_if (ig.begin (), ig.end (), match_tail) == ig.end ()))
+              return true;
+          }
         }
       }
 
diff --git a/libbuild2/config/utility.hxx b/libbuild2/config/utility.hxx
index 3b67c6c..57f253f 100644
--- a/libbuild2/config/utility.hxx
+++ b/libbuild2/config/utility.hxx
@@ -506,17 +506,23 @@ namespace build2
     // that it is unconfigured (e.g., in order to avoid re-running the tests,
     // etc; see below). Additional variables (e.g., unsaved) can be ignored
     // with the third argument. If specified, it should contain the part(s)
-    // after config.<name>.
+    // after the namespace (config.<name>).
+    //
+    // Note that <name> may include several components (separated with `.`).
+    // And you can request the exact match rather than the prefix.
+    //
+    // Note: unlike the above functions, can be called from any phase.
     //
     LIBBUILD2_SYMEXPORT bool
-    specified_config (scope& rs,
-                      const string& var,
-                      initializer_list<const char*> ignore);
+    specified_config (const scope& rs,
+                      const string& ns,
+                      initializer_list<const char*> ignore,
+                      bool exact = false);
 
     inline bool
-    specified_config (scope& rs, const string& var)
+    specified_config (const scope& rs, const string& ns, bool exact = false)
     {
-      return specified_config (rs, var, {});
+      return specified_config (rs, ns, {}, exact);
     }
 
     // Check if there is a false config.*.configured value. This mechanism can
diff --git a/libbuild2/dist/init.cxx b/libbuild2/dist/init.cxx
index 48a3e15..32cbff2 100644
--- a/libbuild2/dist/init.cxx
+++ b/libbuild2/dist/init.cxx
@@ -132,7 +132,7 @@ namespace build2
 
       // Note: ignore config.dist.bootstrap.
       //
-      bool s (specified_config (rs, "dist", {"bootstrap"}));
+      bool s (specified_config (rs, "config.dist", {"bootstrap"}));
 
       // config.dist.root
       //
diff --git a/libbuild2/install/init.cxx b/libbuild2/install/init.cxx
index 3df912f..19c57d4 100644
--- a/libbuild2/install/init.cxx
+++ b/libbuild2/install/init.cxx
@@ -427,7 +427,7 @@ namespace build2
 
         // Note: ignore config.install.{scope,manifest} (see below).
         //
-        bool s (specified_config (rs, "install", {"scope", "manifest"}));
+        bool s (specified_config (rs, "config.install", {"scope", "manifest"}));
 
         // Adjust module priority so that the (numerous) config.install.*
         // values are saved at the end of config.build.
-- 
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