initial checkin of SkSL compiler

src/sksl/ast/SkSLASTModifiers.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_ASTMODIFIERS
+#define SKSL_ASTMODIFIERS
+
+#include "SkSLASTLayout.h"
+#include "SkSLASTNode.h"
+
+namespace SkSL {
+
+/**
+ * A set of modifier keywords (in, out, uniform, etc.) appearing before a declaration. 
+ */
+struct ASTModifiers : public ASTNode {
+    enum Flag {
+        kNo_Flag      =  0,
+        kConst_Flag   =  1,
+        kIn_Flag      =  2,
+        kOut_Flag     =  4,
+        kLowp_Flag    =  8,
+        kMediump_Flag = 16,
+        kHighp_Flag   = 32,
+        kUniform_Flag = 64
+    };
+
+    ASTModifiers(ASTLayout layout, int flags)
+    : fLayout(layout)
+    , fFlags(flags) {}
+
+    std::string description() const override {
+        std::string result = fLayout.description();
+        if (fFlags & kUniform_Flag) {
+            result += "uniform ";
+        }
+        if (fFlags & kConst_Flag) {
+            result += "const ";
+        }
+        if (fFlags & kLowp_Flag) {
+            result += "lowp ";
+        }
+        if (fFlags & kMediump_Flag) {
+            result += "mediump ";
+        }
+        if (fFlags & kHighp_Flag) {
+            result += "highp ";
+        }
+
+        if ((fFlags & kIn_Flag) && (fFlags & kOut_Flag)) {
+            result += "inout ";
+        } else if (fFlags & kIn_Flag) {
+            result += "in ";
+        } else if (fFlags & kOut_Flag) {
+            result += "out ";
+        }
+
+        return result;
+    }
+
+    const ASTLayout fLayout;
+    const int fFlags;
+};
+
+} // namespace
+
+#endif