FExpression

Represents an HLSL expression. This is a piece of code that evaluates to a value, but has no side effects. Unlike statements, expressions are not expected to execute in any particular order. They may be cached (or not) in generated code, without the underlying implementation needing to care. Expressions track the outer-most scope in which they're accessed. The generated HLSL code will ensure they are defined in that scope. Examples include constant literals, variable accessors, and various types of math operations This is an abstract base class, with derived classes representing various types of expression