117 lines
4.4 KiB
Scheme
117 lines
4.4 KiB
Scheme
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;;; Guix --- Nix package management from Guile. -*- coding: utf-8 -*-
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;;; Copyright (C) 2012 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of Guix.
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;;;
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;;; Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix build union)
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#:use-module (ice-9 ftw)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-26)
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#:export (tree-union
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union-build))
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;;; Commentary:
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;;;
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;;; Build a directory that is the union of a set of directories, using
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;;; symbolic links.
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;;;
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;;; Code:
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(define (tree-union trees)
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"Return a tree that is the union of the trees listed in TREES. Each
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tree has the form (PARENT LEAVES ...) or just LEAF, where each leaf is
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itself a tree. "
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(let loop ((trees trees))
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(match trees
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(() ; nothing left
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'())
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(_
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(let ((dirs (filter pair? trees))
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(leaves (remove pair? trees)))
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`(,@leaves
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,@(fold (lambda (dir result)
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(cons `(,dir
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,@(loop
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(concatenate
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(filter-map (match-lambda
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((head children ...)
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(and (equal? head dir)
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children)))
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dirs))))
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result))
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'()
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(delete-duplicates (map car dirs)))))))))
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(define* (union-build output directories)
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"Build in the OUTPUT directory a symlink tree that is the union of all
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the DIRECTORIES."
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(define (file-tree dir)
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;; Return the contents of DIR as a tree.
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(match (file-system-fold (const #t)
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(lambda (file stat result) ; leaf
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(match result
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(((siblings ...) rest ...)
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`((,file ,@siblings) ,@rest))))
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(lambda (dir stat result) ; down
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`(() ,@result))
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(lambda (dir stat result) ; up
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(match result
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(((leaves ...) (siblings ...) rest ...)
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`(((,(basename dir) ,@leaves) ,@siblings)
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,@rest))))
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(const #f) ; skip
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(lambda (file stat errno result)
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(format (current-error-port) "union-build: ~a: ~a~%"
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file (strerror errno)))
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'(())
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dir)
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(((tree)) tree)
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(() #f)))
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(define tree-leaves
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;; Return the leaves of the given tree.
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(match-lambda
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(((? string?) leaves ...)
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leaves)))
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(setvbuf (current-output-port) _IOLBF)
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(setvbuf (current-error-port) _IOLBF)
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(mkdir output)
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(let loop ((tree (tree-union (append-map (compose tree-leaves file-tree)
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directories)))
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(dir '()))
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(match tree
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((? string?)
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;; A leaf: create a symlink.
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(let* ((dir (string-join dir "/"))
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(target (string-append output "/" dir "/" (basename tree))))
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(format (current-error-port) "`~a' ~~> `~a'~%"
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tree target)
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(symlink tree target)))
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(((? string? subdir) leaves ...)
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;; A sub-directory: create it in OUTPUT, and iterate over LEAVES.
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(let ((dir (string-join dir "/")))
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(mkdir (string-append output "/" dir "/" subdir)))
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(for-each (cute loop <> `(,@dir ,subdir))
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leaves))
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((leaves ...)
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;; A series of leaves: iterate over them.
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(for-each (cut loop <> dir) leaves)))))
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;;; union.scm ends here
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