ls_remote function

Analogous to git ls-remote, returns all references from a remote
repository.

Author: jimhester

NAMESPACE

@@ -9,6 +9,7 @@ export(is_commit)
 export(libgit2_features)
 export(libgit2_sha)
 export(libgit2_version)
+export(ls_remote)
 export(punch_card)
 exportClasses(cred_env)
 exportClasses(cred_ssh_key)
@@ -80,6 +81,7 @@ exportMethods(is_merge)
 exportMethods(is_shallow)
 exportMethods(length)
 exportMethods(lookup)
+exportMethods(ls_remote)
 exportMethods(merge)
 exportMethods(merge_base)
 exportMethods(note_create)

NEWS

@@ -3,6 +3,8 @@ git2r 0.11.0.9000
 
 NEW FEATURES
 
+* Add 'ls_remote' method to list references in a remote repository.
+
 * Add 'remote_set_url' method to set the remote's url in the
   configuration.
 

R/remote.r

@@ -350,3 +350,44 @@ setMethod("remote_url",
               .Call(git2r_remote_url, repo, remote)
           }
 )
+
+
+##' List references in a remote repository
+##'
+##' Displays references available in a remote repository along with the associated commit IDs.
+##' @rdname ls_remote-methods
+##' @docType methods
+##' @param name Character vector with the with "remote" repository URL to query.
+##' @return Character vector for each reference with the associated commit IDs.
+##' @param repo an optional repository object used to store data temporarily.
+##' @keywords methods
+##' @examples
+##' \dontrun{
+##' ls_remote("https://github.com/ropensci/git2r")
+##' }
+##' @export
+setGeneric("ls_remote",
+           signature = c("name", "repo"),
+           function(name, repo)
+           standardGeneric("ls_remote"))
+
+##' @rdname ls_remote-methods
+##' @export
+setMethod("ls_remote",
+          signature(name = "character",
+                    repo = "missing"),
+          function(name)
+          {
+              .Call(git2r_ls_remote, git2r::init(tempdir()), name)
+          }
+)
+##' @rdname ls_remote-methods
+##' @export
+setMethod("ls_remote",
+          signature(name = "character",
+                    repo = "git_repository"),
+          function(name, repo)
+          {
+              .Call(git2r_ls_remote, repo, name)
+          }
+)

man/ls_remote-methods.Rd

@@ -0,0 +1,33 @@
+% Generated by roxygen2 (4.1.1): do not edit by hand
+% Please edit documentation in R/remote.r
+\docType{methods}
+\name{ls_remote}
+\alias{ls_remote}
+\alias{ls_remote,character,git_repository-method}
+\alias{ls_remote,character,missing-method}
+\title{List references in a remote repository}
+\usage{
+ls_remote(name, repo)
+
+\S4method{ls_remote}{character,missing}(name)
+
+\S4method{ls_remote}{character,git_repository}(name, repo)
+}
+\arguments{
+\item{name}{Character vector with the with "remote" repository URL to query.}
+
+\item{repo}{an optional repository object used to store data temporarily.}
+}
+\value{
+Character vector for each reference with the associated commit IDs.
+}
+\description{
+Displays references available in a remote repository along with the associated commit IDs.
+}
+\examples{
+\dontrun{
+ls_remote("https://github.com/ropensci/git2r")
+}
+}
+\keyword{methods}
+

src/git2r.c

@@ -119,6 +119,7 @@ static const R_CallMethodDef callMethods[] =
     {"git2r_remote_rename", (DL_FUNC)&git2r_remote_rename, 3},
     {"git2r_remote_set_url", (DL_FUNC)&git2r_remote_set_url, 3},
     {"git2r_remote_url", (DL_FUNC)&git2r_remote_url, 2},
+    {"git2r_ls_remote", (DL_FUNC)&git2r_ls_remote, 2},
     {"git2r_repository_can_open", (DL_FUNC)&git2r_repository_can_open, 1},
     {"git2r_repository_discover", (DL_FUNC)&git2r_repository_discover, 1},
     {"git2r_repository_fetch_heads", (DL_FUNC)&git2r_repository_fetch_heads, 1},

src/git2r_remote.c

@@ -391,3 +391,71 @@ SEXP git2r_remote_url(SEXP repo, SEXP remote)
 
     return url;
 }
+
+SEXP git2r_ls_remote(SEXP repo, SEXP name)
+{
+    if (git2r_arg_check_string(name))
+        git2r_error(__func__, NULL, "'name'", git2r_err_string_arg);
+
+    const char *name_ = CHAR(STRING_ELT(name, 0));
+    SEXP result = R_NilValue;
+    SEXP names = R_NilValue;
+    git_remote *remote = NULL;
+    int error;
+    const git_remote_head **refs;
+    size_t refs_len, i;
+    git_remote_callbacks callbacks = GIT_REMOTE_CALLBACKS_INIT;
+    git_repository *repo_ = NULL;
+
+    repo_ = git2r_repository_open(repo);
+
+    error = git_remote_lookup(&remote, repo_, name_);
+    if (error < 0) {
+      error = git_remote_create_anonymous(&remote, repo_, name_);
+      if (error < 0) {
+        goto cleanup;
+      }
+    }
+
+    /**
+     * Connect to the remote and call the printing function for
+     * each of the remote references.
+     */
+    callbacks.credentials = git2r_cred_acquire_cb;
+
+    error = git_remote_connect(remote, GIT_DIRECTION_FETCH, &callbacks);
+    if (error < 0) {
+      goto cleanup;
+    }
+
+    /**
+     * Get the list of references on the remote and print out
+     * their name next to what they point to.
+     */
+    if (git_remote_ls(&refs, &refs_len, remote) < 0) {
+      goto cleanup;
+    }
+
+    PROTECT(result = allocVector(STRSXP, refs_len));
+    PROTECT(names = allocVector(STRSXP, refs_len));
+
+    for (i = 0; i < refs_len; i++) {
+      char oid[GIT_OID_HEXSZ + 1] = {0};
+      git_oid_fmt(oid, &refs[i]->oid);
+      SET_STRING_ELT(result, i, mkChar(oid));
+      SET_STRING_ELT(names, i, mkChar(refs[i]->name));
+    }
+    setAttrib(result, R_NamesSymbol, names);
+
+cleanup:
+    if (repo_)
+        git_repository_free(repo_);
+
+    if (result != R_NilValue)
+      UNPROTECT(2);
+
+    if (error)
+        git2r_error(__func__, giterr_last(), NULL, NULL);
+
+    return(result);
+}

src/git2r_remote.h

@@ -33,5 +33,6 @@ SEXP git2r_remote_remove(SEXP repo, SEXP remote);
 SEXP git2r_remote_rename(SEXP repo, SEXP oldname, SEXP newname);
 SEXP git2r_remote_set_url(SEXP repo, SEXP name, SEXP url);
 SEXP git2r_remote_url(SEXP repo, SEXP remote);
+SEXP git2r_ls_remote(SEXP repo, SEXP name);
 
 #endif

tests/remotes.R

@@ -56,5 +56,13 @@ remote_remove(repo, "foobar")
 
 stopifnot(identical(remotes(repo), character(0)))
 
+refs <- ls_remote("https://github.com/ropensci/git2r")
+stopifnot(length(refs) > 0)
+stopifnot(names(refs) > 0)
+stopifnot(any(names(refs) == "HEAD"))
+
+# an invalid URL should throw an error
+tools::assertError(ls_remote("bad"))
+
 ## Cleanup
 unlink(path, recursive=TRUE)