added c2hal

This is a transpiler which converts C headers to .hal files. Its design
is intended to mirror hidl-gen in order to make it easier for team
members familiar with one to be familiar with the other.

After making c2hal, commands from ~/android/master/:

Build the test.h header:
c2hal -r android.hardware:hardware/interfaces -p android.hardware.baz@1.0 system/tools/hidl/c2hal/test/test.h

Build the simple.h header:
c2hal -r android.hardware:hardware/interfaces -p android.hardware.simple@1.0 system/tools/hidl/c2hal/test/simple.h

Build all headers from libhardware:
python3 system/tools/hidl/c2hal/test/build_all.py ~/android/master/hardware/libhardware/include/hardware/

Build various OpenGl versions:
python3 system/tools/hidl/c2hal/test/build_all.py -g ~/android/master/frameworks/native/opengl/include/EGL/
python3 system/tools/hidl/c2hal/test/build_all.py -g ~/android/master/frameworks/native/opengl/include/ETC1/
python3 system/tools/hidl/c2hal/test/build_all.py -g ~/android/master/frameworks/native/opengl/include/GLES/
python3 system/tools/hidl/c2hal/test/build_all.py -g ~/android/master/frameworks/native/opengl/include/GLES2/
python3 system/tools/hidl/c2hal/test/build_all.py -g ~/android/master/frameworks/native/opengl/include/GLES3/
python3 system/tools/hidl/c2hal/test/build_all.py -g ~/android/master/frameworks/native/opengl/include/KHR/

Change-Id: I5a3b1d6d2350dd7e1ff825deeec212314b49d083
diff --git a/c2hal/Scope.h b/c2hal/Scope.h
new file mode 100644
index 0000000..7ff77ef
--- /dev/null
+++ b/c2hal/Scope.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SCOPE_H_
+#define SCOPE_H_
+
+#include <android-base/macros.h>
+#include <android-base/logging.h>
+#include <string>
+#include <vector>
+#include <map>
+
+namespace android {
+
+/* This class is used to represent declarations or notes
+ * which are otherwise not included in a HIDL HAL
+ */
+template<typename T>
+struct Scope {
+    Scope() {}
+    ~Scope() {}
+
+    void enter(std::string name, T item);
+    void leave(std::string name);
+
+    T lookup(std::string name) const;
+
+private:
+    std::map<std::string, T> mScopeContents;
+
+    DISALLOW_COPY_AND_ASSIGN(Scope);
+};
+
+template<typename T>
+void Scope<T>::enter(std::string name, T item) {
+    auto it = mScopeContents.find(name);
+
+    if (it != mScopeContents.end()) {
+        LOG(WARNING) << "Redeclaring variable in scope: " << name;
+        return;
+    }
+
+    mScopeContents[name] = item;
+}
+
+template<typename T>
+void Scope<T>::leave(std::string name) {
+    auto it = mScopeContents.find(name);
+
+    if (it == mScopeContents.end()) {
+        LOG(WARNING) << "Tried to undefined already undefined value in scope: " << name;
+        return;
+    }
+
+    mScopeContents.erase(it);
+}
+
+template<typename T>
+T Scope<T>::lookup(std::string name) const {
+    auto it = mScopeContents.find(name);
+
+    if (it == mScopeContents.end()) {
+        return NULL;
+    }
+
+    return (*it).second;
+}
+
+}  // namespace android
+
+#endif  // SCOPE_H_
\ No newline at end of file