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 + ")";

[dogben, 2016/06/22 17:43:57]

nit: just return?

[ethannicholas, 2016/06/24 21:23:10]

It's a stylistic point for me -- I'm certainly willing to do early returns if it
simplifies the flow, but if it doesn't make things more readable or performant
I'd prefer to just let the return that's only one statement farther down handle
it.

+        }
+        return result;
+    }
+
+    const int fLocation;
+    const int fBinding;
+    const int fIndex;
+    const int fSet;
+    const int fBuiltin;
+};
+
+} // namespace
+
+#endif