Before we had:
ClangFunction
ClangUtilityFunction
ClangUserExpression
and code all over in lldb that explicitly made Clang-based expressions. This patch adds an Expression
base class, and three pure virtual implementations for the Expression kinds:
FunctionCaller
UtilityFunction
UserExpression
You can request one of these expression types from the Target using the Get<ExpressionType>ForLanguage.
The Target will then consult all the registered TypeSystem plugins, and if the type system that matches
the language can make an expression of that kind, it will do so and return it.
Because all of the real expression types need to communicate with their ExpressionParser in a uniform way,
I also added a ExpressionTypeSystemHelper class that expressions generically can vend, and a ClangExpressionHelper
that encapsulates the operations that the ClangExpressionParser needs to perform on the ClangExpression types.
Then each of the Clang* expression kinds constructs the appropriate helper to do what it needs.
The patch also fixes a wart in the UtilityFunction that to use it you had to create a parallel FunctionCaller
to actually call the function made by the UtilityFunction. Now the UtilityFunction can be asked to vend a
FunctionCaller that will run its function. This cleaned up a lot of boiler plate code using UtilityFunctions.
Note, in this patch all the expression types explicitly depend on the LLVM JIT and IR, and all the common
JIT running code is in the FunctionCaller etc base classes. At some point we could also abstract that dependency
but I don't see us adding another back end in the near term, so I'll leave that exercise till it is actually necessary.
llvm-svn: 247720
Jim Ingham