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 {
+    static const int kNo_Bit      =  0;
+    static const int kConst_Bit   =  1;
+    static const int kIn_Bit      =  2;
+    static const int kOut_Bit     =  4;
+    static const int kLowp_Bit    =  8;
+    static const int kMediump_Bit = 16;
+    static const int kHighp_Bit   = 32;
+    static const int kUniform_Bit = 64;
+
+    ASTModifiers(ASTLayout layout, int bits)
+    : fLayout(layout)
+    , fBits(bits) {}
+
+    std::string description() const override {
+        std::string result = fLayout.description();
+        if (fBits & kUniform_Bit) {
+            result += "uniform ";
+        }
+        if (fBits & kConst_Bit) {
+            result += "const ";
+        }
+        if (fBits & kLowp_Bit) {
+            result += "lowp ";
+        }
+        if (fBits & kMediump_Bit) {
+            result += "mediump ";
+        }
+        if (fBits & kHighp_Bit) {
+            result += "highp ";
+        }
+
+        if ((fBits & kIn_Bit) && (fBits & kOut_Bit)) {
+            result += "inout ";
+        } else if (fBits & kIn_Bit) {
+            result += "in ";
+        } else if (fBits & kOut_Bit) {
+            result += "out ";
+        }
+
+        return result;
+    }
+
+    const ASTLayout fLayout;
+    const int fBits;
+};
+
+} // namespace
+
+#endif