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kkaeferkkaefer
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test even higher level bindings
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5 files changed

+250
-2
lines changed

5 files changed

+250
-2
lines changed

‎Makefile

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -40,6 +40,11 @@ libpeer.$(dylib)_SOURCES = examples/native_peer.cpp
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CXXFLAGS__examples/native_peer.cpp = -Wno-shadow
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libpeer.$(dylib)_LDFLAGS = $(LDFLAGS_shared)
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TARGETS += libbinding.$(dylib)
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libbinding.$(dylib)_SOURCES = examples/binding.cpp
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CXXFLAGS__examples/binding.cpp = -Wno-shadow
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libbinding.$(dylib)_LDFLAGS = $(LDFLAGS_shared)
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.PHONY: all
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all: $(TARGETS)
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@@ -49,9 +54,15 @@ test: low_level high_level
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$(BUILD)/high_level
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.PHONY: examples
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examples: libhello.$(dylib) examples/Hello.class libpeer.$(dylib) examples/NativePeer.class
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examples: libhello.$(dylib) examples/Hello.class
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examples: libpeer.$(dylib) examples/NativePeer.class
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examples: libbinding.$(dylib) examples/Binding.class
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java -Djava.library.path=$(BUILD) -Xcheck:jni -cp examples Hello $(shell whoami)
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java -Djava.library.path=$(BUILD) -Xcheck:jni -cp examples NativePeer
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java -Djava.library.path=$(BUILD) -Xcheck:jni -cp examples Binding
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example-binding: libbinding.$(dylib) examples/Binding.class
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java -Djava.library.path=$(BUILD) -Xcheck:jni -cp examples Binding
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# --------------------------------------------------------------------------------------------------
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‎examples/Binding.java

Lines changed: 17 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
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class HighLevelBinding {
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public native void greet(String args);
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public native void greet(int args);
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public static native void greet(double args);
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public int quadruple(int num) {
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return num * 4;
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}
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}
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public class Binding {
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public static void main(String[] args) {
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System.loadLibrary("binding");
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new HighLevelBinding().greet("test");
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new HighLevelBinding().greet(4);
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HighLevelBinding.greet(3.14);
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}
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}

‎examples/binding.cpp

Lines changed: 103 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,103 @@
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#include "binding.hpp"
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namespace java { namespace lang { struct Object; } }
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namespace java { namespace lang { struct String; } }
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namespace jni {
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template <> struct Name<java::lang::Object> {
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using Tag = ObjectTag;
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};
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template <> struct Name<java::lang::String> {
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using Tag = StringTag;
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};
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} // namespace jni
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namespace java {
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namespace lang {
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struct Object : jni::Binding<Object> {
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using Binding::Binding;
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};
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struct String : jni::Binding<String> {
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using Binding::Binding;
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// Java methods
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jni::jint length(jni::JNIEnv& env) {
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static const auto method = jni_GetMethod<jni::jint()>(env, "length");
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return self.Call(env, method);
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}
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};
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} // namespace lang
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} // namespace java
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struct HighLevelBinding;
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namespace jni {
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template <> struct Name<HighLevelBinding>::Tag {
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static constexpr auto Name() { return "HighLevelBinding"; }
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};
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} // namespace jni
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struct HighLevelBinding : jni::Binding<HighLevelBinding> {
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using Binding::Binding;
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HighLevelBinding(jni::JNIEnv& env) : Binding(jni_New<>(env)) {}
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// Java methods
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jni::jint quadruple(jni::JNIEnv& env, jni::jint num) {
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// Call Java method
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static const auto method = jni_GetMethod<jni::jint(jni::jint)>(env, "quadruple");
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return self.Call(env, method, num);
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}
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// Native methods
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void greet(jni::JNIEnv&, java::lang::String args);
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void greet(jni::JNIEnv&, jni::jint args);
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static void greet(jni::JNIEnv&, jni::jdouble args);
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static void jni_Register(jni::JNIEnv& env) {
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jni::RegisterNatives(env, jni_Class(env),
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jni_Bind<void(java::lang::String)>::Method<&HighLevelBinding::greet>("greet"),
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jni_Bind<void(jni::jint)>::Method<&HighLevelBinding::greet>("greet"),
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jni_Bind<void(jni::jdouble)>::StaticMethod<&HighLevelBinding::greet>("greet")
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);
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}
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};
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void HighLevelBinding::greet(jni::JNIEnv& env, java::lang::String args) {
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const auto test = jni::Make<std::string>(env, args);
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fprintf(stderr, "greet '%s' (length %d)\n", test.c_str(), args.length(env));
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}
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void HighLevelBinding::greet(jni::JNIEnv& env, jni::jint args) {
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fprintf(stderr, "greet %d\n", quadruple(env, args));
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}
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void HighLevelBinding::greet(jni::JNIEnv&, jni::jdouble args) {
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fprintf(stderr, "greet static %f\n", args);
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}
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extern "C" JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void*) {
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jni::JNIEnv& env{ jni::GetEnv(*vm) };
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try {
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java::lang::Object::jni_Register(env);
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java::lang::String::jni_Register(env);
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HighLevelBinding::jni_Register(env);
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} catch (const jni::PendingJavaException&) {
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jni::ExceptionDescribe(env);
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}
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return jni::Unwrap(jni::jni_version_1_2);
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}

‎examples/binding.hpp

Lines changed: 117 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,117 @@
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#pragma once
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#include <jni/jni.hpp>
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namespace jni
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{
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template < class T >
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struct Name
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{
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struct Tag {};
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};
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template < class T >
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class Binding
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{
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using Tag = typename Name<T>::Tag;
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public:
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// Constructs from jobject* pointers directly.
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explicit Binding(UntaggedType<Object<Tag>> self_) : self(self_) {}
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Binding(Object<Tag> self_) : self(self_) {}
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static void jni_Register(jni::JNIEnv&) {}
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operator Object<Tag>() const { return self; }
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protected:
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static auto jni_Class(JNIEnv& env)
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{
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static auto javaClass = Class<Tag>::Find(env).NewGlobalRef(env).release();
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return *javaClass;
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}
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template < class... Args >
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static auto jni_New(JNIEnv& env, Args&&... args)
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{
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static const auto constructor = jni_Class(env).template GetConstructor<Args...>(env);
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return jni_Class(env).New(env, constructor, std::forward<Args>(args)...);
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}
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template < class Signature >
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static auto jni_GetMethod(JNIEnv& env, const char* name)
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{
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return jni_Class(env).template GetMethod<Signature>(env, name);
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}
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template < class M >
50+
struct jni_Bind;
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template < class R, class... Args >
53+
struct jni_Bind< R (Args...) > {
54+
template <R (*method)(JNIEnv&, Args...)>
55+
static auto StaticMethod(const char* name)
56+
{
57+
auto wrapper = [](JNIEnv* env, UntaggedType<Class<Tag>>, UntaggedType<Args>... args) -> UntaggedType<R>
58+
{
59+
try
60+
{
61+
return method(*env, AddTag<Args>(args)...);
62+
}
63+
catch (...)
64+
{
65+
ThrowJavaError(*env, std::current_exception());
66+
return UntaggedType<R>();
67+
}
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};
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using FunctionType = typename NativeMethodTraits<decltype(wrapper)>::Type;
71+
return JNINativeMethod<FunctionType>{ name, TypeSignature<R (Args...)>()(), wrapper };
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}
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template <R (T::*method)(JNIEnv&, Args...)>
75+
static auto Method(const char* name)
76+
{
77+
using Subject = Object<Tag>;
78+
auto wrapper = [](JNIEnv* env, UntaggedType<Subject> subject, UntaggedType<Args>... args) -> UntaggedType<R>
79+
{
80+
try
81+
{
82+
return (T(AddTag<Subject>(*subject)).*method)(*env, AddTag<Args>(args)...);
83+
}
84+
catch (...)
85+
{
86+
ThrowJavaError(*env, std::current_exception());
87+
return UntaggedType<R>();
88+
}
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};
90+
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using FunctionType = typename NativeMethodTraits<decltype(wrapper)>::Type;
92+
return JNINativeMethod<FunctionType>{ name, TypeSignature<R(Args...)>()(), wrapper };
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}
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};
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protected:
97+
Object<Tag> self;
98+
};
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template < class T >
103+
auto RemoveTag(const Binding<T>& t)
104+
{
105+
return Object<typename Name<T>::Tag>(t).Get();
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}
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template < class T >
110+
struct TypeSignature< T, std::enable_if_t<std::is_base_of<Binding<T>, T>::value> > {
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const char * operator()() const
112+
{
113+
return TypeSignature<Object<typename Name<T>::Tag>>()();
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}
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};
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} // jni

‎include/jni/type_signature.hpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
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1010
namespace jni
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{
12-
template < class > struct TypeSignature;
12+
template < class, class = void > struct TypeSignature;
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1414
template <> struct TypeSignature< jboolean > { const char * operator()() const { return "Z"; } };
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template <> struct TypeSignature< jbyte > { const char * operator()() const { return "B"; } };

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