nc (version 2025.3.24)

var_args_list: var args list

Description

Parse the variable-length argument list used in capture_first_vec, capture_first_df, and capture_all_str. This function is mostly intended for internal use, but is useful if you want to see the regex pattern generated by the variable argument syntax.

Usage

var_args_list(..., type.convert = getOption("nc.type.convert", 
    FALSE))

Value

a list with two named elements

fun.list

list of conversion functions with names corresponding to capture group(s)

pattern

regular expression string with capture group(s)

Arguments

...

character vectors (for regex patterns) or functions (which specify how to convert extracted character vectors to other types). All patterns must be character vectors of length 1. If the pattern is a named argument in R, it becomes a capture group in the regex pattern. All patterns are pasted together to obtain the final pattern used for matching. Each named pattern may be followed by at most one function which is used to convert the previous named pattern. Patterns may also be lists, which are parsed recursively for convenience.

type.convert

Default conversion function, which will be used on each capture group, unless a specific conversion is specified for that group. If TRUE, use type.convert; if FALSE, use identity; otherwise must be a function of at least one argument (character), returning an atomic vector of the same length.

Author

Toby Hocking <[e-mail]> [aut, cre]

Examples

pos.pattern <- list("[0-9]+", as.integer)
nc::var_args_list(
  chrom="chr.*?",
  ":",
  chromStart=pos.pattern,
  list(
    "-",
    chromEnd=pos.pattern
  ), "?")