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union: Detect collisions, and delete duplicate leaves.

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* guix/build/union.scm (delete-duplicate-leaves): New procedure.
  (union-build)[leaf=?, resolve-collision]: New procedures.
  Use `delete-duplicate-leaves' on the result of `tree-union'.
* tests/union.scm ("delete-duplicate-leaves, default",
  "delete-duplicate-leaves, file names"): New tests.
This commit is contained in:
Ludovic Courtès 2013-01-09 22:09:58 +01:00
parent b9e5c0a949
commit b2d58cd80a
2 changed files with 83 additions and 4 deletions
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66
guix/build/union.scm
View file

@ -1,5 +1,5 @@
;;; Guix --- Nix package management from Guile. -*- coding: utf-8 -*-
;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
;;; Copyright (C) 2012, 2013 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of Guix.
;;;
@ -19,9 +19,11 @@
(define-module (guix build union)
#:use-module (ice-9 ftw)
#:use-module (ice-9 match)
#:use-module (ice-9 format)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-26)
#:export (tree-union
delete-duplicate-leaves
union-build))
;;; Commentary:
@ -56,6 +58,48 @@ itself a tree. "
'()
(delete-duplicates (map car dirs)))))))))
(define* (delete-duplicate-leaves tree
#:optional
(leaf=? equal?)
(delete-duplicates (match-lambda
((head _ ...) head))))
"Delete duplicate leaves from TREE. Two leaves are considered equal
when LEAF=? applied to them returns #t. Each collision (list of leaves
that are LEAF=?) is passed to DELETE-DUPLICATES, which must return a
single leaf."
(let loop ((tree tree))
(match tree
((dir children ...)
(let ((dirs (filter pair? children))
(leaves (remove pair? children)))
(define collisions
(fold (lambda (leaf result)
(define same?
(cut leaf=? leaf <>))
(if (any (cut find same? <>) result)
result
(match (filter same? leaves)
((_)
result)
((collision ...)
(cons collision result)))))
'()
leaves))
(define non-collisions
(filter (lambda (leaf)
(match (filter (cut leaf=? leaf <>) leaves)
((_) #t)
((_ _ ..1) #f)))
leaves))
`(,dir
,@non-collisions
,@(map delete-duplicates collisions)
,@(map loop dirs))))
(leaf leaf))))
(define* (union-build output directories)
"Build in the OUTPUT directory a symlink tree that is the union of all
the DIRECTORIES."
@ -88,12 +132,28 @@ the DIRECTORIES."
(((? string?) leaves ...)
leaves)))
(define (leaf=? a b)
(equal? (basename a) (basename b)))
(define (resolve-collision leaves)
;; LEAVES all have the same basename, so choose one of them.
(format (current-error-port) "warning: collision encountered: ~{~a ~}~%"
leaves)
;; TODO: Implement smarter strategies.
(format (current-error-port) "warning: arbitrarily choosing ~a~%"
(car leaves))
(car leaves))
(setvbuf (current-output-port) _IOLBF)
(setvbuf (current-error-port) _IOLBF)
(mkdir output)
(let loop ((tree (tree-union (append-map (compose tree-leaves file-tree)
directories)))
(let loop ((tree (delete-duplicate-leaves
(tree-union (append-map (compose tree-leaves file-tree)
directories))
leaf=?
resolve-collision))
(dir '()))
(match tree
((? string?)

21
tests/union.scm
View file

@ -1,5 +1,5 @@
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2012, 2013 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
@ -64,6 +64,25 @@
(bin make)
(share (doc (make README))))))
(test-equal "delete-duplicate-leaves, default"
'(bin make touch ls)
(delete-duplicate-leaves '(bin ls make touch ls)))
(test-equal "delete-duplicate-leaves, file names"
'("doc" ("info"
"/binutils/ld.info"
"/gcc/gcc.info"
"/binutils/standards.info"))
(let ((leaf=? (lambda (a b)
(string=? (basename a) (basename b)))))
(delete-duplicate-leaves '("doc"
("info"
"/binutils/ld.info"
"/binutils/standards.info"
"/gcc/gcc.info"
"/gcc/standards.info"))
leaf=?)))
(test-skip (if (and %store
(false-if-exception
(getaddrinfo "www.gnu.org" "80" AI_NUMERICSERV)))