Le 2015-07-30 13:55, Amirouche Boubekki a écrit :
Héllo,
I've been lurking around skribillo and artanis. I don't really like
the rails-like syntax
of artanis, even if it has its use-cases and I wanted to hack on
something "small", so
I've put together sfx.
The code of skribe reader is included in sfx.scm. So the only
dependency is guile (2.0.11) and
guile-reader that you can install using `guix package -i guile-reader`.
This bare template language has the following features:
- wanna be simpler sxml syntax
- templates with custom environment
- external libraries loading inside the template
# Wanna be simpler sxml syntax
Skribe reader (implemented with guile-reader) provide a handy syntax to
both define keywords and quasiquote. In an sxml context those features
are used to implemented attributes and text nodes.
## attributes
Attributes in sxml are defined as follow:
(div (@ (id "shell")) "This the main area")
Instead of requiring the nesting of `(attribute-name attribute-value)`
sfx use
the simpler keyword syntax `:keyword`. The above snippet becomes:
(div (@ :id "shell") "This the main area")
I'm not sure it's worth the trouble of diverting from sxml standard.
That said, it looks
more like plain xml.
## text nodes
Text nodes can be defined as
(p [héllo hacker])
This is looks the same as the default reader. It becomes handy when
you include an
inline element inside the text node:
(p [héllo ,(b [hacker])
`,()` is a special syntax of skribe reader which provides `(unquote)`
inside [bracket] `quasiquote`.
With the default guile reader, this must be written as:
(p "héllo " (b "hacker"))
This is looks verbose and prone to error. One must not forget the space
in the
string before the `(b)` element.
# templates with custom environment
Right now this part of the template language is not really
userfriendly. But you can pass custom
variables to the template but those must be parameters. In the example
sfx.scm (which includes
example use of the procedures) the environment in which the template
is evaled is defined as follow:
(define value (make-parameter 42))
(define amirouche (make-person "amirouche" 30))
(define env (let ((value value)
(amirouche amirouche))
(the-environment)))
Then `value` can be echo'ed inside the template using the unquote
syntax `,()`, e.g.
(p [Here is a lucky number for you «,(value)»])
As you can see the previous snippet, there is also a `<record>` record
inside the environment.
One can (maybe) provide in the environment the required procedures to
echo the correct
fields but this is verbose. Instead sfx use `(use-modules)` inside the
template definition
file. This is presented in the following and last part.
# external libraries loading inside the template
Currently it's (only) possible to do `(use-modules)` inside the
template file. The template
file looks like the following:
```
(use-modules (person))
`(html
(body
(p [My name is ,(person-name amirouche)])))
```
I could not make procedure definition work inside the template, this
my be linked to the way
I eval the template. It's shame because for quick and dirty hacks it
can be handy like defining
mini-templates inside the big template.
This is my second try at this and having a look at the code of haunt
[1] was helpful.
Hope this helps!
[1] https://git.dthompson.us/haunt.git
Sorry for the double posting. This mail is not a duplicate.
I though that the implementation `extend` would be more involving.
`extend` is the dual of `include`. Given a base template `base.sfx` you
define placeholders
say `,(main)` and `,(sidebar)` and the rest is the "shell" of the
application ie. the part of
GUI that is always the same over the application.
If `index.sfx` inherit `base.sfx` the context in which `base.sfx` is
rendered is the same as the context
used to render `ìndex.sfx` plus the variables defined/passed in
`ìndex.sfx` to `base.sfx`.
In the following example, `title` and `intro` are evaled and then added
to `(current-module)` environment
with which `base.sfx` is rendered.
(extend "base.sfx"
(current-module)
`((title `(h1 [Héllo again hacker!!]))
(intro "This is a little presentation of sfx template
language")))
I don't how to make `(current-module)` disappear but it's also more
explicit. I'm not sure.
`extend` implement a pattern similar to inheritance in OOP.
I attach complete code with an example. There is small doc in the header
of the file.;;; Copyright © 2015 Amirouche Boubekki <[email protected]>
;;; Copyright © 2005, 2006 Ludovic Courtès <[email protected]>
;;;
;;; 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, see
;;; <http://www.gnu.org/licenses/>.
;; sfx.scm
;;
;; sxml and skribe based mini html template engine
;;
;; takes as input a quasiquoted pseudo sxml e.g.:
;;
;; `(html
;; (head
;; (meta (@ :charset "utf-8"))
;; (title [This is a page generated from scheme])
;; (meta (@ :name "author" :content "Amirouche BOUBEKKI
<[email protected]>"))
;; (meta (@ :name "viewport" :content "width=device-width, initial-scale=1"))
;; (link (@ :rel "stylesheet" :href "static/css/bootstrap.min.css"))
;; (link (@ :rel "stylesheet" :href "static/css/bootstrap-theme.min.css"))
;; (link (@ :rel "stylesheet" :href "static/css/main.css")))
;; (body (@ :class "index")
;; (div (@ :class container)
;; (div (@ :class "header clearfix")
;; (nav
;; (ul (@ :class "nav nav-pills pull-right")
;; (li (@ :role "presentation" :class "active")
;; (a (@ :href "#") [Home]))
;; (li (@ :role "presentation" )
;; (a (@ :href "#") [About]))
;; (li (@ :role "presentation" )
;; (a (@ :href "#") [Contact]))))
;; (h3 (@ :class "text-muted") [hypermove.net])))))
;;
;; It's similar to sxml except the syntax to declare attributes is less verbose
;; *and* you can use some scheme code but they are limitations. You can
(use-modules)
;; and variable must wrapped with `(make-parameter)`. The sxml must appear last
in the file.
;; It's possible to pass variables to the template but right now it's hardcoded
cf. `flyeval`.
;;
;; Use of `map` inside a template:
;;
;; (div (@ :class "row")
;; (ul ,(map (lambda (person) `(li ,(person-name person)))
;; persons)))
;;
;; Use of `extend` inside a template:
;;
;;
;; (extend "base.sfx"
;; (current-module)
;; `((title `(h1 [Héllo again hacker!!]))
;; (intro "This is a little presentation of sfx template
language")))
;;
;; Mind the fact that there is no quasiquote at the beginning
;; of this template, since it's a procedure call and not skribe
;; sxml.
;;
;; Then you can use in `base.sfx` template `title` and `intro`
;; like variables using the unquote syntax e.g. `,(title)`
;;
(use-modules (srfi srfi-1))
(use-modules ((srfi srfi-26) #:select (cut)))
(use-modules (ice-9 r5rs)) ;; scheme-report-environment
(use-modules (ice-9 match))
(use-modules (ice-9 format))
(use-modules (ice-9 hash-table))
(use-modules (ice-9 optargs))
(use-modules (ice-9 local-eval))
(use-modules (sxml simple))
;; the Scheme reader composition framework (guile-reader)
(use-modules ((system reader) #:renamer (symbol-prefix-proc 'r:)))
;;;
;;; skribe reader (borrowed from skribilo)
;;;
(define (make-colon-free-token-reader tr)
;; Stolen from `guile-reader' 0.3.
"If token reader @var{tr} handles the @code{:} (colon) character, remove it
from its specification and return the new token reader."
(let* ((spec (r:token-reader-specification tr))
(proc (r:token-reader-procedure tr)))
(r:make-token-reader (filter (lambda (chr)
(not (char=? chr #\:)))
spec)
proc)))
(define &sharp-reader
;; The reader for what comes after a `#' character.
(let* ((dsssl-keyword-reader ;; keywords à la `#!key'
(r:make-token-reader #\!
(r:token-reader-procedure
(r:standard-token-reader 'keyword)))))
(r:make-reader (cons dsssl-keyword-reader
(map r:standard-token-reader
'(character srfi-4 vector
number+radix boolean
srfi30-block-comment
srfi62-sexp-comment)))
#f ;; use default fault handler
'reader/record-positions)))
(define (make-skribe-reader)
(let ((colon-keywords ;; keywords à la `:key' fashion
(r:make-token-reader #\:
(r:token-reader-procedure
(r:standard-token-reader 'keyword))))
(symbol-misc-chars-tr
;; Make sure `:' is handled only by the keyword token reader.
(make-colon-free-token-reader
(r:standard-token-reader 'r6rs-symbol-misc-chars))))
;; Note: we use the `r6rs-symbol-*' and `r6rs-number' token readers since
;; they consider square brackets as delimiters.
(r:make-reader (cons* (r:make-token-reader #\# &sharp-reader)
colon-keywords
symbol-misc-chars-tr
(map r:standard-token-reader
`(whitespace
sexp string r6rs-number
r6rs-symbol-lower-case
r6rs-symbol-upper-case
quote-quasiquote-unquote
semicolon-comment
skribe-exp)))
#f ;; use the default fault handler
'reader/record-positions
)))
(define skribe (make-skribe-reader))
;;;
;;; sfx template specifics
;;;
(define (keywords->attributes keywords)
"Convert (list :one \"key\" :two \"word\") to sxml attributes (list ('one
\"key\") ('two \"word\"))"
(match keywords
((keyword value rest ...) (cons (list (keyword->symbol keyword) value)
(keywords->attributes rest)))
(_ '())))
(define (sfx->sxml sfx)
"Turn sfx template into sxml"
(match sfx
(('quasiquote value) (map sfx->sxml value))
(('unquote value) (list 'unquote value))
((tag ('@ keywords ...)) (list tag (append '(@) (keywords->attributes
keywords))))
((tag ('@ keywords ...) children ...) (append (list tag (append '(@)
(keywords->attributes keywords))) (map sfx->sxml children)))
((tag children ...) (append (list tag) (map sfx->sxml children)))
((value ...) (map sfx->sxml value))
(_ sfx)))
;;
;; Environment definition
;;
;; FIXME: the environment is hardcoded inside flyeval
;;
(use-modules (person))
(define value (make-parameter 42))
(define amirouche (make-person "amirouche" 30))
(define julien (make-person "julien" 30))
(define mez (make-person "mez" 27))
(define example-env (scheme-report-environment 5))
(module-add! example-env
'title
(make-variable (make-parameter '(h1 "Héllo hacker"))))
(define (extend base env context)
(map (lambda (pair)
(match pair
((name value)
(module-add! env
name
(make-variable
(make-parameter (flyeval value env)))))))
context)
(call-with-output-string
(lambda (port)
(with-input-from-file base
(lambda ()
(template->xml env port))))))
(module-add! example-env 'extend (make-variable extend))
(module-add! example-env 'current-module (make-variable current-module))
;; (define persons (list amirouche julien mez))
(define (flyeval sexpr env)
((local-eval `(lambda () ,sexpr) env)))
(define* (read-eval-template env #:optional out)
(let ((sexp (skribe)))
(if (eof-object? sexp)
out
(read-eval-template env (flyeval sexp env)))))
(define (template->xml env port)
(sxml->xml (flyeval (list 'quasiquote (sfx->sxml (read-eval-template env)))
env)) port)
(define (output)
(call-with-output-string
(lambda (port)
(with-input-from-file "index.sfx"
(lambda ()
(display "<!DOCTYPE html>")
(template->xml example-env port))))))
;; (output) ;; display html to stdout
(with-output-to-file "index.html"
(lambda () (output)))
`(html
(head
(meta (@ :charset "utf-8"))
(title [This is a page generated from scheme])
(meta (@ :name "author" :content "Amirouche BOUBEKKI
<[email protected]>"))
(meta (@ :name "viewport" :content "width=device-width, initial-scale=1"))
(link (@ :rel "stylesheet" :href "static/css/bootstrap.min.css"))
(link (@ :rel "stylesheet" :href "static/css/bootstrap-theme.min.css"))
(link (@ :rel "stylesheet" :href "static/css/main.css")))
(body (@ :class "index")
(div (@ :class container)
(div (@ :class "header clearfix")
(nav
(ul (@ :class "nav nav-pills pull-right")
(li (@ :role "presentation" :class "active")
(a (@ :href "#") [Home]))
(li (@ :role "presentation" )
(a (@ :href "mailto:[email protected]";)
[Contact]))))
(h3 (@ :class "text-muted") [hyperdev.fr]))
(h1 [,(title)])
,(intro))))
(extend "base.sfx"
(current-module)
`((title `(h1 [Héllo again hacker!!]))
(intro "This is a little presentation of sfx template language")))
