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Initial commit. Adds the main classes and types which will feature in the library.
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‎LICENSE

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MIT License
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Copyright (c) 2016 Mitch
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Copyright (c) 2016 Mitchell Dowd
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal

‎README.md

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# jnipp
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C++ wrapper for the Java Native Interface
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Java Native Interface for C++
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=============================
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## Overview
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JNIPP is just a C++ wrapper for the standard Java Native Interface (JNI). It
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tries to take some of the long-winded annoyance out of integrating your Java
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and C++ code.
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## Requirements
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To compile you will need:
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- A C++11 compatible compiler
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- An installation of the Java Development Kit (JDK)
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To compile in Visual Studio, you will need your `JAVA_HOME` environment variable
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correctly set to the JDK installation directory.
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‎jnipp.cpp

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// External Dependencies
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#include <jni.h>
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// Local Dependencies
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#include "jnipp.h"
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namespace jni
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{
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// Static Variables
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static JavaVM* javaVm = nullptr;
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/**
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Maintains the lifecycle of a JNIEnv.
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*/
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class ScopedEnv final
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{
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public:
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ScopedEnv() : _vm(nullptr), _env(nullptr), _attached(false) {}
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~ScopedEnv();
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void init(JavaVM* vm);
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JNIEnv* get() const { return _env; }
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private:
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// Instance Variables
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JavaVM* _vm;
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JNIEnv* _env;
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bool _attached; ///< Manually attached, as opposed to already attached.
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};
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ScopedEnv::~ScopedEnv()
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{
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if (_vm && _attached)
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_vm->DetachCurrentThread();
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}
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void ScopedEnv::init(JavaVM* vm)
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{
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if (_env != nullptr)
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return;
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if (vm == nullptr)
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throw InitializationException("JNI not initialized");
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if (vm->GetEnv((void**) &_env, JNI_VERSION_1_4) != JNI_OK)
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{
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if (vm->AttachCurrentThread((void**) &_env, nullptr) != 0)
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throw InitializationException("Could not attach JNI to thread");
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_attached = true;
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}
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}
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/*
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Helper Functions
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*/
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static JNIEnv* env()
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{
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static thread_local ScopedEnv env;
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if (env.get() == nullptr)
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env.init(javaVm);
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return env.get();
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}
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/*
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Stand-alone Function Impelementations
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*/
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void init(JNIEnv* env)
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{
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if (javaVm != nullptr)
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return;
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if (env->GetJavaVM(&javaVm) != 0)
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throw InitializationException("Could not acquire Java VM");
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}
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/*
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Object Implementation
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*/
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Object::Object(jobject ref, int scopeFlags) : _handle(ref), _class(nullptr), _isGlobal((scopeFlags & Temporary) == 0)
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{
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if (!_isGlobal)
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return;
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JNIEnv* env = jni::env();
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_handle = env->NewGlobalRef(ref);
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if (scopeFlags & DeleteLocalInput)
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env->DeleteLocalRef(ref);
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}
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Object::~Object()
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{
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JNIEnv* env = jni::env();
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if (_isGlobal)
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env->DeleteGlobalRef(_handle);
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if (_class != nullptr)
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env->DeleteGlobalRef(_class);
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}
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/*
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Class Implementation
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*/
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Class::Class(jclass ref, int scopeFlags) : Object(ref, scopeFlags)
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{
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}
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}
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‎jnipp.h

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#ifndef _JNIPP_H_
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#define _JNIPP_H_ 1
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// Local Dependencies
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#include "types.h"
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namespace jni
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{
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/**
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Initialises the Java Native Interface with the given JNIEnv handle, which
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gets passed into a native function which is called from Java. This only
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needs to be done once per process - further calls are no-ops. Note that
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this does _not_ start a new Java Virtual Machine, it simply attaches to
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an existing one.
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\param env A JNI environment handle.
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*/
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void init(JNIEnv* env);
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/**
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Object corresponds with a `java.lang.Object` instance. With an Object,
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you can then call Java methods, and access fields on the Object. To
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instantiate an Object of a given class, use the `Class` class.
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*/
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class Object
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{
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public:
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/** Flags which can be passed to the Object constructor. */
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enum ScopeFlags
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{
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Temporary = 1, ///< Temporary object. Do not create a global reference.
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DeleteLocalInput = 2 ///< The input reference is temporary and can be deleted.
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};
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/**
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Creates an Object from a local JNI reference.
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\param ref The local JNI reference.
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\param scopeFlags Bitmask of ScopeFlags values.
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*/
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Object(jobject ref, int scopeFlags = 0);
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/**
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Destructor. Releases this reference on the Java Object so it can be
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picked up by the garbage collector.
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*/
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virtual ~Object();
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private:
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// Instance Variables
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jobject _handle;
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mutable jclass _class;
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bool _isGlobal;
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};
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/**
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Class corresponds with `java.lang.Class`, and allows you to instantiate
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Objects and get class members such as methods and fields.
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*/
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class Class final : public Object
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{
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public:
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/**
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Creates a Class object by JNI reference.
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\param ref The JNI class reference.
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\param scopeFlags Bitmask of Object::ScopeFlags.
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*/
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Class(jclass ref, int scopeFlags = 0);
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};
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/**
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A Java method call threw an Exception.
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*/
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class InvokationException : public Exception
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{
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};
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/**
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The Java Native Interface was not properly initialized.
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*/
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class InitializationException : public Exception
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{
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public:
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/**
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Constructor with an error message.
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\param msg Message to pass to the Exception.
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*/
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InitializationException(const char* msg) : Exception(msg) {}
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};
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}
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#endif // _JNIPP_H_
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‎jnipp.sln

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Microsoft Visual Studio Solution File, Format Version 12.00
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# Visual Studio 14
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VisualStudioVersion = 14.0.25420.1
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MinimumVisualStudioVersion = 10.0.40219.1
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Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "jnipp", "jnipp.vcxproj", "{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}"
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EndProject
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Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Files", "Solution Files", "{5A4C5782-6F86-4413-9E19-3F6539DCD835}"
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ProjectSection(SolutionItems) = preProject
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LICENSE = LICENSE
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README.md = README.md
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EndProjectSection
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EndProject
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Global
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GlobalSection(SolutionConfigurationPlatforms) = preSolution
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Debug|x64 = Debug|x64
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Debug|x86 = Debug|x86
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Release|x64 = Release|x64
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Release|x86 = Release|x86
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EndGlobalSection
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GlobalSection(ProjectConfigurationPlatforms) = postSolution
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Debug|x64.ActiveCfg = Debug|x64
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Debug|x64.Build.0 = Debug|x64
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Debug|x86.ActiveCfg = Debug|Win32
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Debug|x86.Build.0 = Debug|Win32
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Release|x64.ActiveCfg = Release|x64
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Release|x64.Build.0 = Release|x64
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Release|x86.ActiveCfg = Release|Win32
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{A32D4B7D-7009-4C87-9DE8-D7DB659F5B58}.Release|x86.Build.0 = Release|Win32
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EndGlobalSection
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GlobalSection(SolutionProperties) = preSolution
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HideSolutionNode = FALSE
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EndGlobalSection
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EndGlobal

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