initial checkin of SkSL compiler

src/sksl/ir/SkSLFunctionReference.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+ 
+#ifndef SKSL_FUNCTIONREFERENCE
+#define SKSL_FUNCTIONREFERENCE
+
+#include "SkSLExpression.h"
+
+namespace SkSL {
+
+/**
+ * An identifier referring to a function name. This is an intermediate value: FunctionReferences are 
+ * always eventually replaced by FunctionCalls in valid programs.
+ */
+struct FunctionReference : public Expression {
+    FunctionReference(Position position, std::vector<std::shared_ptr<FunctionDeclaration>> function)
+    : INHERITED(position, kFunctionReference_Kind, kInvalid_Type)
+    , fFunctions(function) {}
+
+    virtual std::string description() const override {
+        ASSERT(false);
+        return "<function>";
+    }
+
+    const std::vector<std::shared_ptr<FunctionDeclaration>> fFunctions;
+
+    typedef Expression INHERITED;
+};
+
+} // namespace
+
+#endif