CodeTransformation

Note: This package is currently not under active development. You might want to have a look at IRTools instead.

This is an experimental package for working with the CodeInfo objects that are containded in the vectors that Julia's code_lowered and code_typed functions return.

These objects can be modified and then turned back into functions (technically methods), making it possible to apply code transformations to functions defined in other packages, or in Julia itself.

Copy a method from one function to another via a CodeInfo object.

using CodeTransformation
g(x) = x + 13
ci = code_lowered(g)[1] # get the CodeInfo from g's first (and only) method
function f end # create an empty function that we can add a method to
addmethod!(Tuple{typeof(f), Any}, ci)
f(1) # returns 14

Search-and-replace in the function g from the previous example. (Applies to all methods, but g only has one.)

function e end
codetransform!(g => e) do ci
    for ex in ci.code
        if ex isa Expr
            map!(x -> x === 13 ? 7 : x, ex.args, ex.args)
        end
    end
    ci
end
e(1) # returns 8
g(1) # still returns 14

Note: The syntax may change in the next minor release of this package.