initial checkin of SkSL compiler

src/sksl/ast/SkSLASTDeclaration.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_ASTDECLARATION
+#define SKSL_ASTDECLARATION
+
+#include "SkSLASTPositionNode.h"
+
+namespace SkSL {
+
+/**
+ * Abstract supertype of declarations such as variables and functions. 
+ */
+struct ASTDeclaration : public ASTPositionNode {
+    enum Kind {

[dogben, 2016/06/20 16:23:17]

nit: In the context of a compiler, "Kind" seems like a loaded word, i.e.:
https://en.wikipedia.org/wiki/Kind_(type_theory)

OTOH, maybe it's the least loaded of the loaded words?

[ethannicholas, 2016/06/20 17:45:49]

"Type" is even more overloaded :-). Is there a better word to represent "What
kind of declaration is this?"

[dogben, 2016/06/20 18:26:26]

Where you use "Kind" to enumerate subclasses, I would probably just use "Enum,"
but I can understand if you don't like that option. My next choice would be
"Sort," but I'm not sure that's better than "Kind."

[ethannicholas, 2016/06/20 20:17:10]

Unless you've got a major objection, I'd prefer to just stick with Kind. While
I'm aware of the type theory meaning of the word, "enum Enum" and "enum Sort"
both seem to me to have bigger problems :-).

+        kVar_Kind,
+        kFunction_Kind,
+        kInterfaceBlock_Kind,
+        kExtension_Kind
+    };
+
+    ASTDeclaration(Position position, Kind kind)
+    : INHERITED(position)
+    , fKind(kind) {}
+
+    Kind fKind;
+
+    typedef ASTPositionNode INHERITED;
+};
+
+} // namespace
+
+#endif