initial checkin of SkSL compiler

src/sksl/ast/SkSLASTLayout.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_ASTLAYOUT
+#define SKSL_ASTLAYOUT
+
+#include "SkSLASTNode.h"
+#include "SkSLUtil.h"
+
+namespace SkSL {
+
+/**
+ * Represents a layout block appearing before a variable declaration, as in:
+ *
+ * layout (location = 0) int x;
+ */
+struct ASTLayout : public ASTNode {
+    // For all parameters, a -1 means no value
+    ASTLayout(int location, int binding, int index, int set, int builtin)
+    : fLocation(location)
+    , fBinding(binding)
+    , fIndex(index)
+    , fSet(set)
+    , fBuiltin(builtin) {}
+
+    std::string description() const {
+        std::string result;
+        std::string separator;
+        if (fLocation >= 0) {
+            result += separator + "location = " + to_string(fLocation);
+            separator = ", ";
+        }
+        if (fBinding >= 0) {
+            result += separator + "binding = " + to_string(fBinding);
+            separator = ", ";
+        }
+        if (fIndex >= 0) {
+            result += separator + "index = " + to_string(fIndex);
+            separator = ", ";
+        }
+        if (fSet >= 0) {
+            result += separator + "set = " + to_string(fSet);
+            separator = ", ";
+        }
+        if (fBuiltin >= 0) {
+            result += separator + "builtin = " + to_string(fBuiltin);
+            separator = ", ";
+        }
+        if (result.length() > 0) {
+            result = "layout (" + result + ")";
+        }
+        return result;
+    }
+
+    const int fLocation;
+    const int fBinding;
+    const int fIndex;
+    const int fSet;
+    const int fBuiltin;
+};
+
+} // namespace
+
+#endif