mkModifyCodeWalker: Low-level Modifying Code Walker and Function Generators to...

In duncantl/CodeAnalysis: Tools for Static Analysis of R code

Low-level Modifying Code Walker and Function Generators to Rewrite Code

Description

mkModifyCodeWalker generates a code-walker object that can be passed to walkCode. Rather than analyzing code, this actively rewrites code and assembles the results to create a modified version of the code passed to walkCode.

The other functions are simple generator-functions that take information and return a function that does any rewriting of each code element it is passed. The result of these are passed as the rewrite argument of mkModifyCodeWalker. These are closure generators and helper functions.

Usage

mkModifyCodeWalker(rewrite = function(x, ...) x, skipIfFalse = TRUE, mkLiteralMap = FALSE, ..., verbose = FALSE)
genAddArgsToCalls(funArgs)
genRemoveCode(pred)
genRewriteVars(names)

Arguments

rewrite	a function that is called with the current language element (and the code walker object) and can return that object or a modified version of it to be inserted into the updated code. Alternatively, it can return NULL and this element of the code will be removed.
skipIfFalse	a scalar logical indicating whether to skip or descend into if(FALSE) blocks of code.
mkLiteralMap	a scalar logical. This is likely to be moved. For now it helps avoid any errors in less-tested code.
...	additional arguments
verbose	a scalar logical controlling whether verbose messages about the processing are displayed on the console. Useful only for debugging/understanding.
funArgs	a list of character vectors, one for each of the functions to whose calls need to be updated in the original function(s). Ideally these should be named character mapping the names of the new parameters to arguments.
pred	a function that identifies which language objects (typically calls to remove.
names	a named-character vector. The names identify the names of current/existing variables and the corresponding values give the new names to which these should be mapped.

Value

An object which is list of functions that can be passed to walkCode.

Author(s)

Duncan Temple Lang

References

codetools

See Also

There are several higher level functions that use this low-level mechanism, e.g., extractFunctions, mkGlobalsLocal.

duncantl/CodeAnalysis documentation built on June 12, 2025, 6:44 a.m.