initial checkin of SkSL compiler

src/sksl/ir/SkSLInterfaceBlock.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_INTERFACEBLOCK
+#define SKSL_INTERFACEBLOCK
+
+#include "SkSLProgramElement.h"
+#include "SkSLVarDeclaration.h"
+
+namespace SkSL {
+
+/**
+ * An interface block, as in:
+ *
+ * out gl_PerVertex {
+ *   layout(builtin=0) vec4 gl_Position;
+ *   layout(builtin=1) float gl_PointSize;
+ * };
+ *
+ * At the IR level, this is represented by a single variable of struct type.
+ */
+struct InterfaceBlock : public ProgramElement {
+    InterfaceBlock(Position position, std::shared_ptr<Variable> var)
+    : INHERITED(position, kInterfaceBlock_Kind) 
+    , fVariable(std::move(var)) {
+        ASSERT(fVariable->fType->kind() == Type::kStruct_Kind);
+    }
+
+    std::string description() const override {
+        std::string result = fVariable->fModifiers.description() + fVariable->fName + " {\n";
+        for (size_t i = 0; i < fVariable->fType->fields().size(); i++) {
+            result += fVariable->fType->fields()[i].description() + "\n";
+        }
+        result += "};";
+        return result;
+    }
+
+    const std::shared_ptr<Variable> fVariable;
+
+    typedef ProgramElement INHERITED;
+};
+
+} // namespace
+
+#endif