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Diffstat (limited to 'gnu/installer/steps.scm')
| -rw-r--r-- | gnu/installer/steps.scm | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/gnu/installer/steps.scm b/gnu/installer/steps.scm new file mode 100644 index 0000000000..5fd54356dd --- /dev/null +++ b/gnu/installer/steps.scm @@ -0,0 +1,187 @@ +;;; GNU Guix --- Functional package management for GNU +;;; Copyright © 2018 Mathieu Othacehe <m.othacehe@gmail.com> +;;; +;;; This file is part of GNU Guix. +;;; +;;; GNU Guix is free software; you can redistribute it and/or modify it +;;; under the terms of the GNU General Public License as published by +;;; the Free Software Foundation; either version 3 of the License, or (at +;;; your option) any later version. +;;; +;;; GNU Guix is distributed in the hope that it will be useful, but +;;; WITHOUT ANY WARRANTY; without even the implied warranty of +;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +;;; GNU General Public License for more details. +;;; +;;; You should have received a copy of the GNU General Public License +;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>. + +(define-module (gnu installer steps) + #:use-module (guix records) + #:use-module (ice-9 match) + #:use-module (srfi srfi-1) + #:use-module (srfi srfi-34) + #:use-module (srfi srfi-35) + #:export (&installer-step-abort + installer-step-abort? + + &installer-step-break + installer-step-break? + + <installer-step> + installer-step + make-installer-step + installer-step? + installer-step-id + installer-step-description + installer-step-compute + installer-step-configuration-proc + + run-installer-steps + find-step-by-id + result->step-ids + result-step + result-step-done?)) + +;; This condition may be raised to abort the current step. +(define-condition-type &installer-step-abort &condition + installer-step-abort?) + +;; This condition may be raised to break out from the steps execution. +(define-condition-type &installer-step-break &condition + installer-step-break?) + +;; An installer-step record is basically an id associated to a compute +;; procedure. The COMPUTE procedure takes exactly one argument, an association +;; list containing the results of previously executed installer-steps (see +;; RUN-INSTALLER-STEPS description). The value returned by the COMPUTE +;; procedure will be stored in the results list passed to the next +;; installer-step and so on. +(define-record-type* <installer-step> + installer-step make-installer-step + installer-step? + (id installer-step-id) ;symbol + (description installer-step-description ;string + (default #f)) + (compute installer-step-compute) ;procedure + (configuration-format-proc installer-step-configuration-proc ;procedure + (default #f))) + +(define* (run-installer-steps #:key + steps + (rewind-strategy 'previous) + (menu-proc (const #f))) + "Run the COMPUTE procedure of all <installer-step> records in STEPS +sequencially. If the &installer-step-abort condition is raised, fallback to a +previous install-step, accordingly to the specified REWIND-STRATEGY. + +REWIND-STRATEGY possible values are 'previous, 'menu and 'start. If 'previous +is selected, the execution will resume at the previous installer-step. If +'menu is selected, the MENU-PROC procedure will be called. Its return value +has to be an installer-step ID to jump to. The ID has to be the one of a +previously executed step. It is impossible to jump forward. Finally if 'start +is selected, the execution will resume at the first installer-step. + +The result of every COMPUTE procedures is stored in an association list, under +the form: + + '((STEP-ID . COMPUTE-RESULT) ...) + +where STEP-ID is the ID field of the installer-step and COMPUTE-RESULT the +result of the associated COMPUTE procedure. This result association list is +passed as argument of every COMPUTE procedure. It is finally returned when the +computation is over. + +If the &installer-step-break condition is raised, stop the computation and +return the accumalated result so far." + (define (pop-result list) + (cdr list)) + + (define (first-step? steps step) + (match steps + ((first-step . rest-steps) + (equal? first-step step)))) + + (define* (skip-to-step step result + #:key todo-steps done-steps) + (match (list todo-steps done-steps) + (((todo . rest-todo) (prev-done ... last-done)) + (if (eq? (installer-step-id todo) + (installer-step-id step)) + (run result + #:todo-steps todo-steps + #:done-steps done-steps) + (skip-to-step step (pop-result result) + #:todo-steps (cons last-done todo-steps) + #:done-steps prev-done))))) + + (define* (run result #:key todo-steps done-steps) + (match todo-steps + (() (reverse result)) + ((step . rest-steps) + (guard (c ((installer-step-abort? c) + (case rewind-strategy + ((previous) + (match done-steps + (() + ;; We cannot go previous the first step. So re-raise + ;; the exception. It might be useful in the case of + ;; nested run-installer-steps. Abort to 'raise-above + ;; prompt to prevent the condition from being catched + ;; by one of the previously installed guard. + (abort-to-prompt 'raise-above c)) + ((prev-done ... last-done) + (run (pop-result result) + #:todo-steps (cons last-done todo-steps) + #:done-steps prev-done)))) + ((menu) + (let ((goto-step (menu-proc + (append done-steps (list step))))) + (if (eq? goto-step step) + (run result + #:todo-steps todo-steps + #:done-steps done-steps) + (skip-to-step goto-step result + #:todo-steps todo-steps + #:done-steps done-steps)))) + ((start) + (if (null? done-steps) + ;; Same as above, it makes no sense to jump to start + ;; when we are at the first installer-step. Abort to + ;; 'raise-above prompt to re-raise the condition. + (abort-to-prompt 'raise-above c) + (run '() + #:todo-steps steps + #:done-steps '()))))) + ((installer-step-break? c) + (reverse result))) + (let* ((id (installer-step-id step)) + (compute (installer-step-compute step)) + (res (compute result))) + (run (alist-cons id res result) + #:todo-steps rest-steps + #:done-steps (append done-steps (list step)))))))) + + (call-with-prompt 'raise-above + (lambda () + (run '() + #:todo-steps steps + #:done-steps '())) + (lambda (k condition) + (raise condition)))) + +(define (find-step-by-id steps id) + "Find and return the step in STEPS whose id is equal to ID." + (find (lambda (step) + (eq? (installer-step-id step) id)) + steps)) + +(define (result-step results step-id) + "Return the result of the installer-step specified by STEP-ID in +RESULTS." + (assoc-ref results step-id)) + +(define (result-step-done? results step-id) + "Return #t if the installer-step specified by STEP-ID has a COMPUTE value +stored in RESULTS. Return #f otherwise." + (and (assoc step-id results) #t)) |