;;; High-level compiler interface

;; Copyright (C) 2001, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.

;;; This library is free software; you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public
;;; License as published by the Free Software Foundation; either
;;; version 3 of the License, or (at your option) any later version.
;;;
;;; This library 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
;;; Lesser General Public License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

;;; Code:

(define-module (system base compile)
  #:use-module (system base syntax)
  #:use-module (system base language)
  #:use-module (system base message)
  #:use-module (system vm vm) ;; FIXME: there's a reason for this, can't remember why tho
  #:use-module (ice-9 regex)
  #:use-module (ice-9 optargs)
  #:use-module (ice-9 receive)
  #:export (compiled-file-name
            compile-file
            compile-and-load
            read-and-compile
            compile
            decompile))


;;;
;;; Compiler
;;;

(define (call-once thunk)
  (let ((entered #f))
    (dynamic-wind
        (lambda ()
          (if entered
              (error "thunk may only be entered once: ~a" thunk))
          (set! entered #t))
        thunk
        (lambda () #t))))

;; emacs: (put 'call-with-output-file/atomic 'scheme-indent-function 1)
(define* (call-with-output-file/atomic filename proc #:optional reference)
  (let* ((template (string-append filename ".XXXXXX"))
         (tmp (mkstemp! template "wb")))
    (call-once
     (lambda ()
       (with-throw-handler #t
         (lambda ()
           (proc tmp)
           ;; Chmodding by name instead of by port allows this chmod to
           ;; work on systems without fchmod, like MinGW.
           (let ((perms (or (false-if-exception (stat:perms (stat reference)))
                            (lognot (umask)))))
             (chmod template (logand #o0666 perms)))
           (close-port tmp)
           (rename-file template filename))
         (lambda args
           (close-port tmp)
           (delete-file template)))))))

(define (ensure-language x)
  (if (language? x)
      x
      (lookup-language x)))

;; Throws an exception if `dir' is not writable.  The mkdir occurs
;; before the check, so that we avoid races (possibly due to parallel
;; compilation).
;;
(define (ensure-directory dir)
  (catch 'system-error
    (lambda ()
      (mkdir dir))
    (lambda (k subr fmt args rest)
      (let ((errno (and (pair? rest) (car rest))))
        (cond
         ((eqv? errno EEXIST)
          ;; Assume it's a writable directory, to avoid TOCTOU errors,
          ;; as well as UID/EUID mismatches that occur with access(2).
          #t)
         ((eqv? errno ENOENT)
          (ensure-directory (dirname dir))
          (ensure-directory dir))
         (else
          (throw k subr fmt args rest)))))))

;;; This function is among the trickiest I've ever written. I tried many
;;; variants. In the end, simple is best, of course.
;;;
;;; After turning this around a number of times, it seems that the
;;; desired behavior is that .go files should exist in a path, for
;;; searching. That is orthogonal to this function. For writing .go
;;; files, either you know where they should go, in which case you tell
;;; compile-file explicitly, as in the srcdir != builddir case; or you
;;; don't know, in which case this function is called, and we just put
;;; them in your own ccache dir in ~/.cache/guile/ccache.
;;;
;;; See also boot-9.scm:load.
(define (compiled-file-name file)
  ;; FIXME: would probably be better just to append SHA1(canon-path)
  ;; to the %compile-fallback-path, to avoid deep directory stats.
  (define (canonical->suffix canon)
    (cond
     ((string-prefix? "/" canon) canon)
     ((and (> (string-length canon) 2)
           (eqv? (string-ref canon 1) #\:))
      ;; Paths like C:... transform to /C...
      (string-append "/" (substring canon 0 1) (substring canon 2)))
     (else canon)))
  (define (compiled-extension)
    (cond ((or (null? %load-compiled-extensions)
               (string-null? (car %load-compiled-extensions)))
           (warn "invalid %load-compiled-extensions"
                 %load-compiled-extensions)
           ".go")
          (else (car %load-compiled-extensions))))
  (and %compile-fallback-path
       (let ((f (string-append
                 %compile-fallback-path
                 (canonical->suffix (canonicalize-path file))
                 (compiled-extension))))
         (and (false-if-exception (ensure-directory (dirname f)))
              f))))

(define* (compile-file file #:key
                       (output-file #f)
                       (from (current-language))
                       (to 'bytecode)
                       (env (default-environment from))
                       (opts '())
                       (canonicalization 'relative))
  (with-fluids ((%file-port-name-canonicalization canonicalization))
    (let* ((comp (or output-file (compiled-file-name file)
                     (error "failed to create path for auto-compiled file"
                            file)))
           (in (open-input-file file))
           (enc (file-encoding in)))
      ;; Choose the input encoding deterministically.
      (set-port-encoding! in (or enc "UTF-8"))

      (ensure-directory (dirname comp))
      (call-with-output-file/atomic comp
        (lambda (port)
          ((language-printer (ensure-language to))
           (read-and-compile in #:env env #:from from #:to to #:opts
                             (cons* #:to-file? #t opts))
           port))
        file)
      comp)))

(define* (compile-and-load file #:key (from (current-language)) (to 'value)
                           (env (current-module)) (opts '())
                           (canonicalization 'relative))
  (with-fluids ((%file-port-name-canonicalization canonicalization))
    (read-and-compile (open-input-file file)
                      #:from from #:to to #:opts opts
                      #:env env)))

