1 files changed, 106 insertions, 0 deletions
diff --git a/libbuild2/target-key.hxx b/libbuild2/target-key.hxx
new file mode 100644
index 0000000..e23991d
--- /dev/null
+++ b/libbuild2/target-key.hxx
@@ -0,0 +1,106 @@
+// file      : libbuild2/target-key.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_TARGET_KEY_HXX
+#define LIBBUILD2_TARGET_KEY_HXX
+
+#include <map>
+#include <cstring> // strcmp()
+
+#include <libbutl/utility.mxx> // compare_c_string
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/target-type.hxx>
+
+#include <libbuild2/export.hxx>
+
+namespace build2
+{
+  // Light-weight (by being shallow-pointing) target key.
+  //
+  class target_key
+  {
+  public:
+    const target_type* const type;
+    const dir_path* const dir; // Can be relative if part of prerequisite_key.
+    const dir_path* const out; // Can be relative if part of prerequisite_key.
+    const string* const name;
+    mutable optional<string> ext; // Absent - unspecified, empty - none.
+
+    template <typename T>
+    bool is_a () const {return type->is_a<T> ();}
+    bool is_a (const target_type& tt) const {return type->is_a (tt);}
+  };
+
+  inline bool
+  operator== (const target_key& x, const target_key& y)
+  {
+    if (x.type  != y.type ||
+        *x.dir  != *y.dir ||
+        *x.out  != *y.out ||
+        *x.name != *y.name)
+      return false;
+
+    // Unless fixed, unspecified and specified extensions are assumed equal.
+    //
+    const target_type& tt (*x.type);
+
+    if (tt.fixed_extension == nullptr)
+      return !x.ext || !y.ext || *x.ext == *y.ext;
+    else
+    {
+      // Note that for performance reasons here we use the specified extension
+      // without calling fixed_extension().
+      //
+      const char* xe (x.ext
+                      ? x.ext->c_str ()
+                      : tt.fixed_extension (x, nullptr /* root scope */));
+
+      const char* ye (y.ext
+                      ? y.ext->c_str ()
+                      : tt.fixed_extension (y, nullptr /* root scope */));
+
+      return strcmp (xe, ye) == 0;
+    }
+  }
+
+  inline bool
+  operator!= (const target_key& x, const target_key& y) {return !(x == y);}
+
+  // If the target type has a custom print function, call that. Otherwise,
+  // call to_stream(). Both are defined in target.cxx.
+  //
+  LIBBUILD2_SYMEXPORT ostream&
+  operator<< (ostream&, const target_key&);
+
+  LIBBUILD2_SYMEXPORT ostream&
+  to_stream (ostream&, const target_key&, optional<stream_verbosity> = nullopt);
+}
+
+namespace std
+{
+  // Note that we ignore the extension when calculating the hash because of
+  // its special "unspecified" logic (see operator== above).
+  //
+  template <>
+  struct hash<build2::target_key>
+  {
+    using argument_type = build2::target_key;
+    using result_type = size_t;
+
+    size_t
+    operator() (const build2::target_key& k) const noexcept
+    {
+      return build2::combine_hash (
+        hash<const build2::target_type*> () (k.type),
+        hash<build2::dir_path> () (*k.dir),
+        hash<build2::dir_path> () (*k.out),
+        hash<string> () (*k.name));
+    }
+  };
+}
+
+#endif // LIBBUILD2_TARGET_KEY_HXX