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git: Factorize 'resolve-reference'. 

* guix/git.scm (resolve-reference): New procedure.
(switch-to-ref): Use it.
This commit is contained in:
Ludovic Courtès 2020-07-15 23:58:29 +02:00
parent 9e0d896bf3
commit 1c058c382a
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1 changed files with 42 additions and 37 deletions
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@ -150,47 +150,52 @@ of SHA1 string."
(last (string-split url #\/)) ".git" "")
"-" (string-take sha1 7)))
(define (resolve-reference repository ref)
"Resolve the branch, commit or tag specified by REF, and return the
corresponding Git object."
(let resolve ((ref ref))
(match ref
(('branch . branch)
(let ((oid (reference-target
(branch-lookup repository branch BRANCH-REMOTE))))
(object-lookup repository oid)))
(('commit . commit)
(let ((len (string-length commit)))
;; 'object-lookup-prefix' appeared in Guile-Git in Mar. 2018, so we
;; can't be sure it's available. Furthermore, 'string->oid' used to
;; read out-of-bounds when passed a string shorter than 40 chars,
;; which is why we delay calls to it below.
(if (< len 40)
(if (module-defined? (resolve-interface '(git object))
'object-lookup-prefix)
(object-lookup-prefix repository (string->oid commit) len)
(raise (condition
(&message
(message "long Git object ID is required")))))
(object-lookup repository (string->oid commit)))))
(('tag-or-commit . str)
(if (or (> (string-length str) 40)
(not (string-every char-set:hex-digit str)))
(resolve `(tag . ,str)) ;definitely a tag
(catch 'git-error
(lambda ()
(resolve `(tag . ,str)))
(lambda _
;; There's no such tag, so it must be a commit ID.
(resolve `(commit . ,str))))))
(('tag . tag)
(let ((oid (reference-name->oid repository
(string-append "refs/tags/" tag))))
;; OID may point to a "tag" object, but it can also point directly
;; to a "commit" object, as surprising as it may seem. Return that
;; object, whatever that is.
(object-lookup repository oid))))))
(define (switch-to-ref repository ref)
"Switch to REPOSITORY's branch, commit or tag specified by REF. Return the
OID (roughly the commit hash) corresponding to REF."
(define obj
(let resolve ((ref ref))
(match ref
(('branch . branch)
(let ((oid (reference-target
(branch-lookup repository branch BRANCH-REMOTE))))
(object-lookup repository oid)))
(('commit . commit)
(let ((len (string-length commit)))
;; 'object-lookup-prefix' appeared in Guile-Git in Mar. 2018, so we
;; can't be sure it's available. Furthermore, 'string->oid' used to
;; read out-of-bounds when passed a string shorter than 40 chars,
;; which is why we delay calls to it below.
(if (< len 40)
(if (module-defined? (resolve-interface '(git object))
'object-lookup-prefix)
(object-lookup-prefix repository (string->oid commit) len)
(raise (condition
(&message
(message "long Git object ID is required")))))
(object-lookup repository (string->oid commit)))))
(('tag-or-commit . str)
(if (or (> (string-length str) 40)
(not (string-every char-set:hex-digit str)))
(resolve `(tag . ,str)) ;definitely a tag
(catch 'git-error
(lambda ()
(resolve `(tag . ,str)))
(lambda _
;; There's no such tag, so it must be a commit ID.
(resolve `(commit . ,str))))))
(('tag . tag)
(let ((oid (reference-name->oid repository
(string-append "refs/tags/" tag))))
;; OID may point to a "tag" object, but it can also point directly
;; to a "commit" object, as surprising as it may seem. Return that
;; object, whatever that is.
(object-lookup repository oid))))))
(resolve-reference repository ref))
(reset repository obj RESET_HARD)
(object-id obj))