Make Identifier usable from associative containers

Author: kunitoki

modules/juce_core/text/juce_Identifier.h

@@ -147,3 +147,19 @@ class JUCE_API Identifier final
 };
 
 } // namespace juce
+
+#ifndef DOXYGEN
+namespace std
+{
+
+template <>
+struct hash<juce::Identifier>
+{
+    size_t operator() (const juce::Identifier& identifier) const noexcept
+    {
+        return static_cast<size_t> (*reinterpret_cast<uintptr_t*> (identifier.getCharPointer().getAddress()));
+    }
+};
+
+} // namespace std
+#endif

tests/juce_core/juce_Identifier.cpp

@@ -23,6 +23,8 @@
 
 #include <juce_core/juce_core.h>
 
+#include <unordered_map>
+
 using namespace juce;
 
 TEST (Identifier, DefaultConstructorCreatesNullIdentifier)
@@ -110,3 +112,13 @@ TEST (Identifier, ConversionToCharPointer)
     auto ptr = id.getCharPointer();
     EXPECT_STREQ (ptr.getAddress(), "pointer");
 }
+
+TEST (Identifier, UseInAssociativeContainers)
+{
+    std::unordered_map<Identifier, Identifier> ids;
+    ids[Identifier("test1")] = Identifier("test2");
+
+    ASSERT_TRUE(ids.find(Identifier("test1")) != ids.end());
+    EXPECT_EQ(ids.find(Identifier("test1"))->first, Identifier("test1"));
+    EXPECT_EQ(ids.find(Identifier("test1"))->second, Identifier("test2"));
+}