qdapRegex (version 0.7.8)

explain: Visualize Regular Expressions

Description

Visualize regular expressions using https://regexper.com/

Usage

explain(
  pattern,
  open = FALSE,
  print = TRUE,
  dictionary = getOption("regex.library")
)

Value

Prints https://regexper.com/ to the console, attempts to open the url to the visual representation provided by https://regexper.com/, and invisibly returns a list with the URLs.

Arguments

pattern

A character string containing a regular expression or a character string starting with "@" that is a regular expression from a qdapRegex dictionary.

open

logical. If TRUE the default browser will attempt to open https://regexper.com/ page. Setting open = 2 will utilize an unstable visualization via https://www.debuggex.com. This approach utilizes a non-api scrape that is subject to change and not guaranteed to be stable. The regex is set to Python flavor which handles lookbehinds that the Java based https://regexper.com/ does not. This functionality was developed by Matthew Flickinger (see https://stackoverflow.com/a/27574103/1000343 for details). Note that the user must have httr installed or will be prompted if the package cannot be required.

print

logical. Should explain print output to the console?

dictionary

A dictionary of canned regular expressions to search within.

Author

Ananda Mahto, Matthew Flickinger, and Tyler Rinker <[e-mail]>.

Details

Note that https://regexper.com/ is a Java based regular expression viewer. Lookbehind and negative lookbehinds are not respected.

References

https://stackoverflow.com/a/27489977/1000343
https://regexper.com/
https://stackoverflow.com/a/27574103/1000343

See Also

https://regexper.com/

Examples

explain("\\s*foo[A-Z]\\d{2,3}")
explain("@rm_time")
if (FALSE) {
explain("\\s*foo[A-Z]\\d{2,3}", open = TRUE)
explain("@rm_time", open = TRUE)
}