diff options
Diffstat (limited to 'guix/build/union.scm')
| -rw-r--r-- | guix/build/union.scm | 66 |
1 files changed, 63 insertions, 3 deletions
diff --git a/guix/build/union.scm b/guix/build/union.scm index ffd367917a..d1578a6ef5 100644 --- a/guix/build/union.scm +++ b/guix/build/union.scm @@ -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?) |