Re-land sksl fragment processor support

This reverts commit ed50200682e0de72c3abecaa4d5324ebcd1ed9f9.

Bug: skia:
Change-Id: I9caa7454b391450620d6989dc472abb3cf7a2cab
Reviewed-on: https://skia-review.googlesource.com/20965
Reviewed-by: Ben Wagner <benjaminwagner@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/src/sksl/ir/SkSLSetting.h b/src/sksl/ir/SkSLSetting.h
new file mode 100644
index 0000000000..995fcf55bf
--- /dev/null
+++ b/src/sksl/ir/SkSLSetting.h
@@ -0,0 +1,51 @@
+/*
+ * 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_SETTING
+#define SKSL_SETTING
+
+#include "SkSLContext.h"
+#include "SkSLExpression.h"
+
+namespace SkSL {
+
+/**
+ * Represents a compile-time constant setting, such as sk_Caps.fbFetchSupport. These are generally
+ * collapsed down to their constant representations during the compilation process.
+ */
+struct Setting : public Expression {
+    Setting(Position position, String name, std::unique_ptr<Expression> value)
+    : INHERITED(position, kSetting_Kind, value->fType)
+    , fName(std::move(name))
+    , fValue(std::move(value)) {
+        ASSERT(fValue->isConstant());
+    }
+
+    std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
+                                                  const DefinitionMap& definitions) override;
+
+    String description() const override {
+        return fName;
+    }
+
+    bool hasSideEffects() const override {
+        return false;
+    }
+
+    bool isConstant() const override {
+        return true;
+    }
+
+    const String fName;
+    std::unique_ptr<Expression> fValue;
+
+    typedef Expression INHERITED;
+};
+
+} // namespace
+
+#endif