1 files changed, 48 insertions, 0 deletions
diff --git a/libbuild2/in/target.hxx b/libbuild2/in/target.hxx
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+++ b/libbuild2/in/target.hxx
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+// file      : libbuild2/in/target.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_IN_TARGET_HXX
+#define LIBBUILD2_IN_TARGET_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/target.hxx>
+
+#include <libbuild2/in/export.hxx>
+
+namespace build2
+{
+  namespace in
+  {
+    // This is the venerable .in ("input") file that needs some kind of
+    // preprocessing.
+    //
+    // One interesting aspect of this target type is that the prerequisite
+    // search is target-dependent. Consider:
+    //
+    // hxx{version}: in{version.hxx} // version.hxx.in -> version.hxx
+    //
+    // Having to specify the header extension explicitly is inelegant. Instead
+    // what we really want to write is this:
+    //
+    // hxx{version}: in{version}
+    //
+    // But how do we know that in{version} means version.hxx.in? That's where
+    // the target-dependent search comes in: we take into account the target
+    // we are a prerequisite of.
+    //
+    class LIBBUILD2_IN_SYMEXPORT in: public file
+    {
+    public:
+      using file::file;
+
+    public:
+      static const target_type static_type;
+      virtual const target_type& dynamic_type () const {return static_type;}
+    };
+  }
+}
+
+#endif // LIBBUILD2_IN_TARGET_HXX