From 3cc5e3bd441fc9d18fece3d9e99fae75c78438e7 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 28 Jun 2018 09:44:15 +0200
Subject: Implement support for excluded and ad hoc prerequisites

The inclusion/exclusion is controlled via the 'include' prerequisite-specific
variable. Valid values are:

false  - exclude
true   - include
adhoc  - include but treat as an ad hoc input

For example:

lib{foo}: cxx{win32-utility}: include = ($cxx.targe.class == 'windows')
exe{bar}: libs{plugin}: include = adhoc
---
 build2/prerequisite.cxx | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

(limited to 'build2/prerequisite.cxx')

diff --git a/build2/prerequisite.cxx b/build2/prerequisite.cxx
index 8edcc74..5900589 100644
--- a/build2/prerequisite.cxx
+++ b/build2/prerequisite.cxx
@@ -94,4 +94,29 @@ namespace build2
 
     return r;
   }
+
+  // include()
+  //
+  include_type
+  include_impl (action a,
+                const target& t,
+                const string& v,
+                const prerequisite& p,
+                const target* m)
+  {
+    include_type r (false);
+
+    if      (v == "false") r = include_type::excluded;
+    else if (v == "adhoc") r = include_type::adhoc;
+    else if (v == "true")  r = include_type::normal;
+    else
+      fail << "invalid " << var_include->name << " variable value "
+           << "'" << v << "' specified for prerequisite " << p;
+
+    // Call the meta-operation override, if any (currently used by dist).
+    //
+    return current_mif->include == nullptr
+      ? r
+      : current_mif->include (a, t, prerequisite_member {p, m}, r);
+  }
 }
-- 
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