From e872913956c05c6fe1826ff3f2a3e67953e31064 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 23 Jun 2022 06:36:20 +0200
Subject: Minor enhancements to algorithms

---
 libbuild2/algorithm.cxx | 59 ++++++++++++++++++++++++++++++++++++++++---------
 libbuild2/algorithm.hxx | 28 ++++++++++++++---------
 libbuild2/algorithm.ixx | 15 +++++++++++++
 3 files changed, 82 insertions(+), 20 deletions(-)

diff --git a/libbuild2/algorithm.cxx b/libbuild2/algorithm.cxx
index 564105c..843808d 100644
--- a/libbuild2/algorithm.cxx
+++ b/libbuild2/algorithm.cxx
@@ -1217,9 +1217,8 @@ namespace build2
     match_prerequisite_range (a, t, group_prerequisite_members (a, t), msm, s);
   }
 
-  template <typename T>
   void
-  match_members (action a, target& t, T const* ts, size_t n)
+  match_members (action a, target& t, const target* const* ts, size_t n)
   {
     // Pretty much identical to match_prerequisite_range() except we don't
     // search.
@@ -1251,15 +1250,45 @@ namespace build2
     }
   }
 
-  // Instantiate only for what we need.
-  //
-  template LIBBUILD2_SYMEXPORT void
-  match_members<const target*> (action, target&,
-                                const target* const*, size_t);
+  void
+  match_members (action a,
+                 target& t,
+                 prerequisite_targets& ts,
+                 size_t s,
+                 pair<uintptr_t, uintptr_t> imv)
+  {
+    size_t n (ts.size ());
+
+    wait_guard wg (t.ctx, t.ctx.count_busy (), t[a].task_count, true);
 
-  template LIBBUILD2_SYMEXPORT void
-  match_members<prerequisite_target> (action, target&,
-                                      prerequisite_target const*, size_t);
+    for (size_t i (s); i != n; ++i)
+    {
+      const prerequisite_target& pt (ts[i]);
+      const target* m (pt.target);
+
+      if (m == nullptr ||
+          marked (m)   ||
+          (imv.first != 0 && (pt.include & imv.first) != imv.second))
+        continue;
+
+      match_async (a, *m, t.ctx.count_busy (), t[a].task_count);
+    }
+
+    wg.wait ();
+
+    for (size_t i (s); i != n; ++i)
+    {
+      const prerequisite_target& pt (ts[i]);
+      const target* m (pt.target);
+
+      if (m == nullptr ||
+          marked (m)   ||
+          (imv.first != 0 && (pt.include & imv.first) != imv.second))
+        continue;
+
+      match_complete (a, *m);
+    }
+  }
 
   const fsdir*
   inject_fsdir (action a, target& t, bool parent)
@@ -2313,6 +2342,16 @@ namespace build2
     if (n == 0)
       return false;
 
+    // Provide additional information on what's going on.
+    //
+    auto df = make_diag_frame (
+      [&t](const diag_record& dr)
+      {
+        if (verb != 0)
+          dr << info << "while updating during match prerequisites of "
+             << "target " << t;
+      });
+
     context& ctx (t.ctx);
 
     phase_switch ps (ctx, run_phase::execute);
diff --git a/libbuild2/algorithm.hxx b/libbuild2/algorithm.hxx
index 75976bf..db3e93d 100644
--- a/libbuild2/algorithm.hxx
+++ b/libbuild2/algorithm.hxx
@@ -145,6 +145,15 @@ namespace build2
           const string* ext = nullptr,
           const scope* = nullptr);
 
+  template <typename T>
+  const T*
+  search_existing (context&,
+                   const dir_path& dir,
+                   const dir_path& out,
+                   const string& name,
+                   const string* ext = nullptr,
+                   const scope* = nullptr);
+
   // Search for a target identified by the name. The semantics is "as if" we
   // first created a prerequisite based on this name in exactly the same way
   // as the parser would and then searched based on this prerequisite. If the
@@ -471,11 +480,8 @@ namespace build2
   // dependencies. Similar in semantics to match_prerequisites(). Any marked
   // target pointers are skipped.
   //
-  // T can only be const target* or prerequisite_target.
-  //
-  template <typename T>
-  void
-  match_members (action, target&, T const*, size_t);
+  LIBBUILD2_SYMEXPORT void
+  match_members (action, target&, const target* const*, size_t);
 
   template <size_t N>
   inline void
@@ -484,14 +490,16 @@ namespace build2
     match_members (a, t, ts, N);
   }
 
-  inline void
+  // As above plus if the include mask (first) and value (second) are
+  // specified, then only match prerequisites that satisfy the
+  // ((prerequisite_target::include & mask) == value) condition.
+  //
+  LIBBUILD2_SYMEXPORT void
   match_members (action a,
                  target& t,
                  prerequisite_targets& ts,
-                 size_t start = 0)
-  {
-    match_members (a, t, ts.data () + start, ts.size () - start);
-  }
+                 size_t start = 0,
+                 pair<uintptr_t, uintptr_t> include = {0, 0});
 
   // Unless already known, match, and, if necessary, execute the group in
   // order to resolve its members list. Note that even after that the member's
diff --git a/libbuild2/algorithm.ixx b/libbuild2/algorithm.ixx
index 10ed754..ea4241e 100644
--- a/libbuild2/algorithm.ixx
+++ b/libbuild2/algorithm.ixx
@@ -187,6 +187,21 @@ namespace build2
       t, T::static_type, dir, out, name, ext, scope).template as<T> ();
   }
 
+  template <typename T>
+  inline const T*
+  search_existing (context& ctx,
+                   const dir_path& dir,
+                   const dir_path& out,
+                   const string& name,
+                   const string* ext,
+                   const scope* scope)
+  {
+    const target* r (
+      search_existing (
+        ctx, T::static_type, dir, out, name, ext, scope));
+    return r != nullptr ? &r->template as<T> () : nullptr;
+  }
+
   LIBBUILD2_SYMEXPORT target_lock
   lock_impl (action, const target&, optional<scheduler::work_queue>);
 
-- 
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