From 0baeb5209d3a111a53070c032d7cdb1e609e3516 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 31 May 2021 16:32:40 +0200
Subject: Implement ad hoc regex pattern rule support

An ad hoc pattern rule consists of a pattern that mimics a dependency
declaration followed by one or more recipes. For example:

exe{~'/(.*)/'}: cxx{~'/\1/'}
{{
  $cxx.path -o $path($>) $path($<[0])
}}

If a pattern matches a dependency declaration of a target, then the recipe is
used to perform the corresponding operation on this target. For example, the
following dependency declaration matches the above pattern which means the
rule's recipe will be used to update this target:

exe{hello}: cxx{hello}

While the following declarations do not match the above pattern:

exe{hello}:   c{hello}  # Type mismatch.
exe{hello}: cxx{howdy}  # Name mismatch.

On the left hand side of `:` in the pattern we can have a single target or an
ad hoc target group. The single target or the first (primary) ad hoc group
member must be a regex pattern (~). The rest of the ad hoc group members can
be patterns or substitutions (^). For example:

<exe{~'/(.*)/'} file{^'/\1.map/'}>: cxx{~'/\1/'}
{{
  $cxx.path -o $path($>[0]) "-Wl,-Map=$path($>[1])" $path($<[0])
}}

On the left hand side of `:` in the pattern we have prerequisites which can
be patterns, substitutions, or non-patterns. For example:

<exe{~'/(.*)/'} file{^'/\1.map/'}>: cxx{~'/\1/'} hxx{^'/\1/'} hxx{common}
{{
  $cxx.path -o $path($>[0]) "-Wl,-Map=$path($>[1])" $path($<[0])
}}

Substitutions on the left hand side of `:` and substitutions and non-patterns
on the right hand side are added to the dependency declaration. For example,
given the above rule and dependency declaration, the effective dependency is
going to be:

<exe{hello} file{hello.map>: cxx{hello} hxx{hello} hxx{common}
---
 libbuild2/rule-map.hxx | 49 +++++++++++++++++++++++++++++++++++++------------
 1 file changed, 37 insertions(+), 12 deletions(-)

(limited to 'libbuild2/rule-map.hxx')

diff --git a/libbuild2/rule-map.hxx b/libbuild2/rule-map.hxx
index 8014d02..c4cdb9f 100644
--- a/libbuild2/rule-map.hxx
+++ b/libbuild2/rule-map.hxx
@@ -28,16 +28,20 @@ namespace build2
   class operation_rule_map
   {
   public:
-    template <typename T>
-    void
-    insert (operation_id oid, const char* hint, const rule& r)
+    // Return false in case of a duplicate.
+    //
+    bool
+    insert (operation_id oid,
+            const target_type& tt,
+            string hint,
+            const rule& r)
     {
       // 3 is the number of builtin operations.
       //
       if (oid >= map_.size ())
         map_.resize ((oid < 3 ? 3 : oid) + 1);
 
-      map_[oid][&T::static_type].emplace (hint, r);
+      return map_[oid][&tt].emplace (move (hint), r).second;
     }
 
     // Return NULL if not found.
@@ -69,33 +73,54 @@ namespace build2
   class rule_map
   {
   public:
+    // Return false in case of a duplicate.
+    //
+    bool
+    insert (action_id a,
+            const target_type& tt,
+            string hint,
+            const rule& r)
+    {
+      return insert (a >> 4, a & 0x0F, tt, move (hint), r);
+    }
+
     template <typename T>
-    void
-    insert (action_id a, const char* hint, const rule& r)
+    bool
+    insert (action_id a, string hint, const rule& r)
     {
-      insert<T> (a >> 4, a & 0x0F, hint, r);
+      return insert (a, T::static_type, move (hint), r);
     }
 
     // 0 oid is a wildcard.
     //
-    template <typename T>
-    void
+    bool
     insert (meta_operation_id mid,
             operation_id oid,
-            const char* hint,
+            const target_type& tt,
+            string hint,
             const rule& r)
     {
       if (mid_ == mid)
-        map_.insert<T> (oid, hint, r);
+        return map_.insert (oid, tt, move (hint), r);
       else
       {
         if (next_ == nullptr)
           next_.reset (new rule_map (mid));
 
-        next_->insert<T> (mid, oid, hint, r);
+        return next_->insert (mid, oid, tt, move (hint), r);
       }
     }
 
+    template <typename T>
+    bool
+    insert (meta_operation_id mid,
+            operation_id oid,
+            string hint,
+            const rule& r)
+    {
+      return insert (mid, oid, T::static_type, move (hint), r);
+    }
+
     // Return NULL if not found.
     //
     const operation_rule_map*
-- 
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