1 files changed, 44 insertions, 0 deletions
diff --git a/libbuild2/prerequisite-key.hxx b/libbuild2/prerequisite-key.hxx
new file mode 100644
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+++ b/libbuild2/prerequisite-key.hxx
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+// file      : libbuild2/prerequisite-key.hxx -*- C++ -*-
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_PREREQUISITE_KEY_HXX
+#define LIBBUILD2_PREREQUISITE_KEY_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/forward.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/target-key.hxx>
+#include <libbuild2/target-type.hxx>
+
+#include <libbuild2/export.hxx>
+
+namespace build2
+{
+  // Light-weight (by being shallow-pointing) prerequisite key, similar
+  // to (and based on) target key.
+  //
+  // Note that unlike prerequisite, the key is not (necessarily) owned by a
+  // target. So for the key we instead have the base scope of the target that
+  // (would) own it. Note that we assume keys to be ephemeral enough for the
+  // base scope to remain unchanged.
+  //
+  class prerequisite_key
+  {
+  public:
+    using scope_type = build2::scope;
+
+    const optional<project_name>& proj;
+    target_key tk;                // The .dir and .out members can be relative.
+    const scope_type* scope;      // Can be NULL if tk.dir is absolute.
+
+    template <typename T>
+    bool is_a () const {return tk.is_a<T> ();}
+    bool is_a (const target_type& tt) const {return tk.is_a (tt);}
+  };
+
+  LIBBUILD2_SYMEXPORT ostream&
+  operator<< (ostream&, const prerequisite_key&);
+}
+
+#endif // LIBBUILD2_PREREQUISITE_KEY_HXX