From c9e9432018b57b7f532480415059ff62d7f96a40 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 23 Oct 2023 10:25:58 +0200
Subject: WIP: add rematch_*() functions

---
 libbuild2/algorithm.hxx | 24 +++++++++++++++++++++++-
 libbuild2/algorithm.ixx | 28 ++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/libbuild2/algorithm.hxx b/libbuild2/algorithm.hxx
index e01fbb8..829c5be 100644
--- a/libbuild2/algorithm.hxx
+++ b/libbuild2/algorithm.hxx
@@ -363,7 +363,9 @@ namespace build2
   // to be unchanged after match. If it is unmatch::safe, then unmatch the
   // target if it is safe (this includes unchanged or if we know that someone
   // else will execute this target). Return true in first half of the pair if
-  // unmatch succeeded. Always throw if failed.
+  // unmatch succeeded. Always throw if failed. Note that unmatching doesn't
+  // play well with options -- if unmatch succeeds, the options that have been
+  // passed to match will not be cleared.
   //
   enum class unmatch {none, unchanged, safe};
 
@@ -483,6 +485,26 @@ namespace build2
                unmatch,
                uint64_t options = match_extra::all_options);
 
+  // Re-match with new options a target that has already been matched with one
+  // of the match_*() functions. Note that natually you cannot rematch a
+  // target that you have unmatched.
+  //
+  target_state
+  rematch_sync (action, const target&,
+                uint64_t options,
+                bool fail = true);
+
+  target_state
+  rematch_async (action, const target&,
+                 uint64_t options,
+                 size_t start_count, atomic_count& task_count,
+                 bool fail = true);
+
+  target_state
+  rematch_complete (action, const target&,
+                    uint64_t options,
+                    bool fail = true);
+
   // The standard prerequisite search and match implementations. They call
   // search() (unless a custom is provided) and then match() (unless custom
   // returned NULL) for each prerequisite in a loop omitting out of project
diff --git a/libbuild2/algorithm.ixx b/libbuild2/algorithm.ixx
index 813c685..f9992c9 100644
--- a/libbuild2/algorithm.ixx
+++ b/libbuild2/algorithm.ixx
@@ -675,6 +675,34 @@ namespace build2
     return match_sync (a.inner_action (), t, um, options);
   }
 
+  // Note: rematch is basically normal match but without the counts increment,
+  // so we just delegate to match_direct_*().
+  //
+  inline target_state
+  rematch_sync (action a, const target& t,
+                uint64_t options,
+                bool fail)
+  {
+    return match_direct_sync (a, t, fail, options);
+  }
+
+  inline target_state
+  rematch_async (action a, const target& t,
+                 uint64_t options,
+                 size_t start_count, atomic_count& task_count,
+                 bool fail)
+  {
+    return match_async (a, t, start_count, task_count, fail, options);
+  }
+
+  inline target_state
+  rematch_complete (action a, const target& t,
+                    uint64_t options,
+                    bool fail)
+  {
+    return match_direct_complete (a, t, fail, options);
+  }
+
   LIBBUILD2_SYMEXPORT void
   resolve_group_impl (target_lock&&);
 
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