From e4a8251749cf1fbf005b045e26e25f3ef7cccb8b Mon Sep 17 00:00:00 2001
From: Yong He <yonghe@outlook.com>
Date: Thu, 10 Dec 2020 09:43:09 -0800
Subject: Move ShaderObject to be under renderer interface. (#1633)

* Move ShaderObject to be under renderer interface.

* Make `create*PipelineState` take `const PipelineStateDesc&`.

* Move ShaderCursor implementation to a cpp file
---
 tools/gfx/shader-cursor.h | 123 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 tools/gfx/shader-cursor.h

(limited to 'tools/gfx/shader-cursor.h')

diff --git a/tools/gfx/shader-cursor.h b/tools/gfx/shader-cursor.h
new file mode 100644
index 000000000..8f48f3581
--- /dev/null
+++ b/tools/gfx/shader-cursor.h
@@ -0,0 +1,123 @@
+#pragma once
+
+#include "tools/gfx/render.h"
+#include "core/slang-basic.h"
+
+namespace gfx
+{
+
+/// Represents a "pointer" to the storage for a shader parameter of a (dynamically) known type.
+///
+/// A `ShaderCursor` serves as a pointer-like type for things stored inside a `ShaderObject`.
+///
+/// A cursor that points to the entire content of a shader object can be formed as
+/// `ShaderCursor(someObject)`. A cursor pointing to a structure field or array element can be
+/// formed from another cursor using `getField` or `getElement` respectively.
+///
+/// Given a cursor pointing to a value of some "primitive" type, we can set or get the value
+/// using operations like `setResource`, `getResource`, etc.
+///
+/// Because type information for shader parameters is being reflected dynamically, all type
+/// checking for shader cursors occurs at runtime, and errors may occur when attempting to
+/// set a parameter using a value of an inappropriate type. As much as possible, `ShaderCursor`
+/// attempts to protect against these cases and return an error `Result` or an invalid
+/// cursor, rather than allowing operations to proceed with incorrect types.
+///
+struct ShaderCursor
+{
+    ShaderObject* m_baseObject = nullptr;
+    slang::TypeLayoutReflection* m_typeLayout = nullptr;
+    ShaderOffset m_offset;
+
+    /// Get the type (layout) of the value being pointed at by the cursor
+    slang::TypeLayoutReflection* getTypeLayout() const { return m_typeLayout; }
+
+    /// Is this cursor valid (that is, does it seem to point to an actual location)?
+    ///
+    /// This check is equivalent to checking whether a pointer is null, so it is
+    /// a very weak sense of "valid." In particular, it is possible to form a
+    /// `ShaderCursor` for which `isValid()` is true, but attempting to get or
+    /// set the value would be an error (like dereferencing a garbage pointer).
+    ///
+    bool isValid() const { return m_baseObject != nullptr; }
+
+    Result getDereferenced(ShaderCursor& outCursor) const;
+
+    ShaderCursor getDereferenced()
+    {
+        ShaderCursor result;
+        getDereferenced(result);
+        return result;
+    }
+
+    /// Form a cursor pointing to the field with the given `name` within the value this cursor
+    /// points at.
+    ///
+    /// If the operation succeeds, then the field cursor is written to `outCursor`.
+    Result getField(Slang::UnownedStringSlice const& name, ShaderCursor& outCursor);
+
+    ShaderCursor getField(Slang::UnownedStringSlice const& name)
+    {
+        ShaderCursor cursor;
+        getField(name, cursor);
+        return cursor;
+    }
+
+    ShaderCursor getField(Slang::String const& name) { return getField(name.getUnownedSlice()); }
+
+    ShaderCursor getElement(Slang::Index index);
+
+    static Result followPath(Slang::UnownedStringSlice const& path, ShaderCursor& ioCursor);
+
+    static Result followPath(Slang::String const& path, ShaderCursor& ioCursor)
+    {
+        return followPath(path.getUnownedSlice(), ioCursor);
+    }
+
+    ShaderCursor getPath(Slang::UnownedStringSlice const& path)
+    {
+        ShaderCursor result(*this);
+        followPath(path, result);
+        return result;
+    }
+
+    ShaderCursor getPath(Slang::String const& path)
+    {
+        ShaderCursor result(*this);
+        followPath(path, result);
+        return result;
+    }
+
+    ShaderCursor() {}
+
+    ShaderCursor(ShaderObject* object)
+        : m_baseObject(object)
+        , m_typeLayout(object->getElementTypeLayout())
+    {}
+
+    SlangResult setData(void const* data, size_t size)
+    {
+        return m_baseObject->setData(m_offset, data, size);
+    }
+
+    SlangResult setObject(ShaderObject* object)
+    {
+        return m_baseObject->setObject(m_offset, object);
+    }
+
+    SlangResult setResource(ResourceView* resourceView)
+    {
+        return m_baseObject->setResource(m_offset, resourceView);
+    }
+
+    SlangResult setSampler(SamplerState* sampler)
+    {
+        return m_baseObject->setSampler(m_offset, sampler);
+    }
+
+    SlangResult setCombinedTextureSampler(ResourceView* textureView, SamplerState* sampler)
+    {
+        return m_baseObject->setCombinedTextureSampler(m_offset, textureView, sampler);
+    }
+};
+}
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