[core] move OpenGL extension loading to their own headers

9 files changed, 129 insertions, 54 deletions

diff --git a/src/mbgl/geometry/vao.cpp b/src/mbgl/geometry/vao.cpp
index 214ed7a88d..2c5e1677ff 100644
--- a/src/mbgl/geometry/vao.cpp
+++ b/src/mbgl/geometry/vao.cpp
@@ -1,4 +1,5 @@
 #include <mbgl/geometry/vao.hpp>
+#include <mbgl/gl/vertex_array.hpp>
 #include <mbgl/platform/log.hpp>
 #include <mbgl/util/string.hpp>
 #include <mbgl/gl/gl.hpp>
diff --git a/src/mbgl/gl/context.cpp b/src/mbgl/gl/context.cpp
index 3c1b5e45ae..ae50e64cbc 100644
--- a/src/mbgl/gl/context.cpp
+++ b/src/mbgl/gl/context.cpp
@@ -1,5 +1,6 @@
 #include <mbgl/gl/context.hpp>
 #include <mbgl/gl/gl.hpp>
+#include <mbgl/gl/vertex_array.hpp>
 #include <mbgl/util/traits.hpp>
 
 namespace mbgl {
diff --git a/src/mbgl/gl/debugging.cpp b/src/mbgl/gl/debugging.cpp
index e61de42bc3..943710ab7f 100644
--- a/src/mbgl/gl/debugging.cpp
+++ b/src/mbgl/gl/debugging.cpp
@@ -1,5 +1,6 @@
 #include <mbgl/gl/debugging.hpp>
 #include <mbgl/gl/gl.hpp>
+#include <mbgl/gl/extension.hpp>
 #include <mbgl/platform/event.hpp>
 #include <mbgl/platform/log.hpp>
 
diff --git a/src/mbgl/gl/extension.cpp b/src/mbgl/gl/extension.cpp
new file mode 100644
index 0000000000..ee94e8ecfd
--- /dev/null
+++ b/src/mbgl/gl/extension.cpp
@@ -0,0 +1,48 @@
+#include <mbgl/gl/extension.hpp>
+#include <mbgl/gl/gl.hpp>
+
+#include <mutex>
+#include <string>
+#include <vector>
+
+namespace mbgl {
+namespace gl {
+namespace detail {
+
+using Probes = std::vector<ExtensionFunctionBase::Probe>;
+using ExtensionFunctions = std::vector<std::pair<glProc*, Probes>>;
+ExtensionFunctions& extensionFunctions() {
+    static ExtensionFunctions functions;
+    return functions;
+}
+
+ExtensionFunctionBase::ExtensionFunctionBase(std::initializer_list<Probe> probes) {
+    extensionFunctions().emplace_back(&ptr, probes);
+}
+
+} // namespace detail
+
+static std::once_flag initializeExtensionsOnce;
+
+void InitializeExtensions(glProc (*getProcAddress)(const char*)) {
+    std::call_once(initializeExtensionsOnce, [getProcAddress] {
+        const char* extensionsPtr =
+            reinterpret_cast<const char*>(MBGL_CHECK_ERROR(glGetString(GL_EXTENSIONS)));
+
+        if (!extensionsPtr)
+            return;
+
+        const std::string extensions = extensionsPtr;
+        for (auto fn : detail::extensionFunctions()) {
+            for (auto probe : fn.second) {
+                if (extensions.find(probe.first) != std::string::npos) {
+                    *fn.first = getProcAddress(probe.second);
+                    break;
+                }
+            }
+        }
+    });
+}
+
+} // namespace gl
+} // namespace mbgl
diff --git a/src/mbgl/gl/extension.hpp b/src/mbgl/gl/extension.hpp
new file mode 100644
index 0000000000..ea5a1ae5f5
--- /dev/null
+++ b/src/mbgl/gl/extension.hpp
@@ -0,0 +1,41 @@
+#pragma once
+
+#include <initializer_list>
+#include <utility>
+
+namespace mbgl {
+namespace gl {
+
+using glProc = void (*)();
+void InitializeExtensions(glProc (*getProcAddress)(const char*));
+
+namespace detail {
+
+class ExtensionFunctionBase {
+public:
+    using Probe = std::pair<const char*, const char*>;
+    ExtensionFunctionBase(std::initializer_list<Probe>);
+    glProc ptr;
+};
+
+} // namespace detail
+
+template <class>
+class ExtensionFunction;
+
+template <class R, class... Args>
+class ExtensionFunction<R(Args...)> : protected detail::ExtensionFunctionBase {
+public:
+    using detail::ExtensionFunctionBase::ExtensionFunctionBase;
+
+    explicit operator bool() const {
+        return ptr;
+    }
+
+    R operator()(Args... args) const {
+        return (*reinterpret_cast<R (*)(Args...)>(ptr))(std::forward<Args>(args)...);
+    }
+};
+
+} // namespace gl
+} // namespace mbgl
diff --git a/src/mbgl/gl/gl.cpp b/src/mbgl/gl/gl.cpp
index 2040ff0573..5cef254160 100644
--- a/src/mbgl/gl/gl.cpp
+++ b/src/mbgl/gl/gl.cpp
@@ -1,63 +1,9 @@
 #include <mbgl/gl/gl.hpp>
 #include <mbgl/util/string.hpp>
-#include <mbgl/platform/log.hpp>
-
-#include <cassert>
-#include <iostream>
-#include <unordered_map>
-#include <mutex>
 
 namespace mbgl {
 namespace gl {
 
-ExtensionFunction<void (GLuint array)>
-    BindVertexArray({
-        {"GL_ARB_vertex_array_object", "glBindVertexArray"},
-        {"GL_OES_vertex_array_object", "glBindVertexArrayOES"},
-        {"GL_APPLE_vertex_array_object", "glBindVertexArrayAPPLE"}
-    });
-
-ExtensionFunction<void (GLsizei n, const GLuint* arrays)>
-    DeleteVertexArrays({
-        {"GL_ARB_vertex_array_object", "glDeleteVertexArrays"},
-        {"GL_OES_vertex_array_object", "glDeleteVertexArraysOES"},
-        {"GL_APPLE_vertex_array_object", "glDeleteVertexArraysAPPLE"}
-    });
-
-ExtensionFunction<void (GLsizei n, GLuint* arrays)>
-    GenVertexArrays({
-        {"GL_ARB_vertex_array_object", "glGenVertexArrays"},
-        {"GL_OES_vertex_array_object", "glGenVertexArraysOES"},
-        {"GL_APPLE_vertex_array_object", "glGenVertexArraysAPPLE"}
-    });
-
-std::vector<ExtensionFunctionBase*>& ExtensionFunctionBase::functions() {
-    static std::vector<ExtensionFunctionBase*> functions;
-    return functions;
-}
-
-static std::once_flag initializeExtensionsOnce;
-
-void InitializeExtensions(glProc (*getProcAddress)(const char *)) {
-    std::call_once(initializeExtensionsOnce, [getProcAddress] {
-        const char * extensionsPtr = reinterpret_cast<const char *>(
-            MBGL_CHECK_ERROR(glGetString(GL_EXTENSIONS)));
-
-        if (!extensionsPtr)
-            return;
-
-        const std::string extensions = extensionsPtr;
-        for (auto fn : ExtensionFunctionBase::functions()) {
-            for (auto probe : fn->probes) {
-                if (extensions.find(probe.first) != std::string::npos) {
-                    fn->ptr = getProcAddress(probe.second);
-                    break;
-                }
-            }
-        }
-    });
-}
-
 namespace {
 
 constexpr const char* stringFromError(GLenum err) {
diff --git a/src/mbgl/gl/value.cpp b/src/mbgl/gl/value.cpp
index ae7d648a45..e78b97ef2e 100644
--- a/src/mbgl/gl/value.cpp
+++ b/src/mbgl/gl/value.cpp
@@ -1,5 +1,6 @@
 #include <mbgl/gl/value.hpp>
 #include <mbgl/gl/gl.hpp>
+#include <mbgl/gl/vertex_array.hpp>
 
 namespace mbgl {
 namespace gl {
diff --git a/src/mbgl/gl/vertex_array.cpp b/src/mbgl/gl/vertex_array.cpp
new file mode 100644
index 0000000000..df63bbc4b7
--- /dev/null
+++ b/src/mbgl/gl/vertex_array.cpp
@@ -0,0 +1,22 @@
+#include <mbgl/gl/vertex_array.hpp>
+
+namespace mbgl {
+namespace gl {
+
+ExtensionFunction<void(GLuint array)>
+    BindVertexArray({ { "GL_ARB_vertex_array_object", "glBindVertexArray" },
+                      { "GL_OES_vertex_array_object", "glBindVertexArrayOES" },
+                      { "GL_APPLE_vertex_array_object", "glBindVertexArrayAPPLE" } });
+
+ExtensionFunction<void(GLsizei n, const GLuint* arrays)>
+    DeleteVertexArrays({ { "GL_ARB_vertex_array_object", "glDeleteVertexArrays" },
+                         { "GL_OES_vertex_array_object", "glDeleteVertexArraysOES" },
+                         { "GL_APPLE_vertex_array_object", "glDeleteVertexArraysAPPLE" } });
+
+ExtensionFunction<void(GLsizei n, GLuint* arrays)>
+    GenVertexArrays({ { "GL_ARB_vertex_array_object", "glGenVertexArrays" },
+                      { "GL_OES_vertex_array_object", "glGenVertexArraysOES" },
+                      { "GL_APPLE_vertex_array_object", "glGenVertexArraysAPPLE" } });
+
+} // namespace gl
+} // namespace mbgl
diff --git a/src/mbgl/gl/vertex_array.hpp b/src/mbgl/gl/vertex_array.hpp
new file mode 100644
index 0000000000..6215e56f21
--- /dev/null
+++ b/src/mbgl/gl/vertex_array.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include <mbgl/gl/extension.hpp>
+#include <mbgl/gl/gl.hpp>
+
+namespace mbgl {
+namespace gl {
+
+extern ExtensionFunction<void(GLuint array)> BindVertexArray;
+extern ExtensionFunction<void(GLsizei n, const GLuint* arrays)> DeleteVertexArrays;
+extern ExtensionFunction<void(GLsizei n, GLuint* arrays)> GenVertexArrays;
+
+} // namespace gl
+} // namespace mbgl
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