initial checkin of SkSL compiler

src/sksl/ir/SkSLField.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_FIELD
+#define SKSL_FIELD
+
+#include "SkSLModifiers.h"
+#include "SkSLPosition.h"
+#include "SkSLSymbol.h"
+#include "SkSLType.h"
+
+namespace SkSL {
+
+/** 
+ * A symbol which should be interpreted as a field access. Fields are added to the symboltable 
+ * whenever a bare reference to an identifier should refer to a struct field; in GLSL, this is the 
+ * result of declaring anonymous interface blocks.
+ */
+struct Field : public Symbol {
+    Field(Position position, std::shared_ptr<Variable> owner, int fieldIndex)
+    : INHERITED(position, kField_Kind, owner->fType->fields()[fieldIndex].fName)
+    , fOwner(owner)
+    , fFieldIndex(fieldIndex) {}
+
+    virtual std::string description() const override {
+        return fOwner->description() + "." + fOwner->fType->fields()[fFieldIndex].fName;
+    }
+
+    const std::shared_ptr<Variable> fOwner;
+    const int fFieldIndex;
+
+    typedef Symbol INHERITED;
+};
+
+} // namespace SkSL
+
+#endif