Parse a concise GitHub repo specification

github_rx.txt

^(?:(?:([^/]+)/)?([^/@#]+)(?:/([^@#]*[^@#/]))?(?:(?:@([^*].*))|(?:#([0-9]+))|(?:@([*]release)))?|(.*))$

parse_github_repo_spec.R

## used in hadley/devtools and MangoTheCat/remotes (at least)
## to parse "a concise GitHub repo specification"
username_rx <- "(?:([^/]+)/)?"
repo_rx <- "([^/@#]+)"
subdir_rx <- "(?:/([^@#]*[^@#/]))?"
ref_rx <- "(?:@([^*].*))"
pull_rx <- "(?:#([0-9]+))"
release_rx <- "(?:@([*]release))"
ref_or_pull_or_release_rx <-
  sprintf("(?:%s|%s|%s)?", ref_rx, pull_rx, release_rx)
github_rx <- sprintf("^(?:%s%s%s%s|(.*))$",
                     username_rx, repo_rx, subdir_rx, ref_or_pull_or_release_rx)
param_names <-
  c("username", "repo", "subdir", "ref", "pull", "release", "invalid")
replace <- stats::setNames(sprintf("\\%d", seq_along(param_names)), param_names)

## examples from
## https://github.com/MangoTheCat/remotes/blob/65abf4b2a910edab82a86fad907b8f860d8d4d6b/R/install-github.R#L224-L262
repo <- "metacran/crandb"
repo <- "jeroenooms/[email protected]"
repo <- "jimhester/covr#47"
repo <- "hadley/dplyr@*release"
repo <- "mangothecat/remotes@550a3c7d3f9e1493a2ba"
repo <- "nope I totally do not match" ## hmmm ....

params <- lapply(replace, function(r) gsub(github_rx, r, repo, perl = TRUE))
params

@daattali I deleted your comment with the regex because somehow it had unmatched parentheses? And I've added the regex as a proper little file in this gist. I also know you'll never see this because gist comments don't notify.