initial checkin of SkSL compiler

src/sksl/ast/SkSLASTReturnStatement.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_ASTRETURNSTATEMENT
+#define SKSL_ASTRETURNSTATEMENT
+
+#include "SkSLASTStatement.h"
+
+namespace SkSL {
+
+/**
+ * A 'return' statement.
+ */
+struct ASTReturnStatement : public ASTStatement {
+    // expression may be null
+    ASTReturnStatement(Position position, std::unique_ptr<ASTExpression> expression)
+    : INHERITED(position, kReturn_Kind)
+    , fExpression(std::move(expression)) {}
+
+    std::string description() const override {
+        std::string result("return");
+        if (fExpression) {
+            result += " " + fExpression->description();
+        }
+        return result + ";";        
+    }
+
+    const std::unique_ptr<ASTExpression> fExpression;
+
+    typedef ASTStatement INHERITED;
+};
+
+} // namespace
+
+#endif