initial checkin of SkSL compiler

src/sksl/ir/SkSLLayout.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_LAYOUT
+#define SKSL_LAYOUT
+
+namespace SkSL {
+
+/**
+ * Represents a layout block appearing before a variable declaration, as in:
+ *
+ * layout (location = 0) int x;
+ */
+struct Layout {
+    Layout(const ASTLayout& layout)
+    : fLocation(layout.fLocation)
+    , fBinding(layout.fBinding)
+    , fIndex(layout.fIndex)
+    , fSet(layout.fSet)
+    , fBuiltin(layout.fBuiltin) {}
+
+    Layout(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;
+    }
+
+    bool operator==(const Layout& other) const {
+        return fLocation == other.fLocation &&
+               fBinding  == other.fBinding &&
+               fIndex    == other.fIndex &&
+               fSet      == other.fSet &&
+               fBuiltin  == other.fBuiltin;
+    }
+
+    bool operator!=(const Layout& other) const {
+        return !(*this == other);
+    }
+
+    const int fLocation;
+    const int fBinding;
+    const int fIndex;
+    const int fSet;
+    const int fBuiltin;
+};
+
+} // namespace
+
+#endif