collectContents: Tools to gather the contents of one or more elements of an...

In omegahat/Rcompression: In-memory decompression for GNU zip and bzip2 formats

Tools to gather the contents of one or more elements of an archive

Description

This function creates an object which contains functions that are used in collecting the contents of elements in an archive file. We typically call this function with the names of the elements in the archive in which we are interested. This amounts to a filter. Then, as we iterate over the contents of the archive in a function such as tarExtract, at the start of each element the callback/handler function is invoked and in the case of collectContents, it either ignores the element if the name is not in this collection of “target” entries, or else it stores the contents of that entry in a list using the entry name as the key. The results can be retrieved from the internal state of these functions using the .ans element of the list. By default, this returns the list of entry contents. Optionally, this function can be given a converter function which is applied element-wise to the entry content list. And if a list of converter functions is passed, then the function is applied to the to the corresponding element of the entry contents list and the list returned.

Usage

collectContents(entries)

Arguments

entries

character vector giving the (full) names of the entries in which we are interested. If the names do not match,

Value

This returns an S3 object of class TarExtractCallback and TarCallback. This identifies that the store element can be used within the tar iterator function tarExtract. The second element .ans is a function that can be used to retrieve the results that are gathered during the different invocations to the store function.

Author(s)

Duncan Temple Lang

See Also

tarExtract

omegahat/Rcompression documentation built on Nov. 29, 2023, 12:45 a.m.