From akamaus at gmail.com  Mon Nov 23 16:37:04 2009
From: akamaus at gmail.com (Dmitry V'yal)
Date: Mon, 23 Nov 2009 19:37:04 +0300
Subject: [cl-who-devel] Generating html tree with dynamic structure
Message-ID: <4B0ABA30.3000206@gmail.com>

Hello anyone,

I have a simple problem, but I can't find an elegant solution.

Basically I have a message and two flags, the first one signals message 
should be rendered in <strong> tag and the second - in <italic>. So 
there are four possibilities.

Here is the actual code:

(defmethod p-render-html ((s-tree tree) (p text-piece) s)
   (with-html-output (s nil :prologue nil)
     (let ((style (style-of p))
           (txt (text-of p)))
       (if style
           (if (tree-find-prop s-tree style #'bold)
               (htm (:strong (if (tree-find-prop s-tree style #'italic)
                                 (htm (:italic (str txt)))
                                 (str txt))))
               (if (tree-find-prop s-tree style #'italic)
                   (htm (:italic (str txt)))
                   (str txt)))
           (str txt)))))

I had to test for each case and it resulted in code duplication. Can it 
be avoided? What if I had 5 flags or so?



From kengruven at gmail.com  Mon Nov 23 18:49:01 2009
From: kengruven at gmail.com (Ken Harris)
Date: Mon, 23 Nov 2009 10:49:01 -0800
Subject: [cl-who-devel] Generating html tree with dynamic structure
In-Reply-To: <4B0ABA30.3000206@gmail.com>
References: <4B0ABA30.3000206@gmail.com>
Message-ID: <d97bec7a0911231049x1ffc4d2ega5c1b67438b39cb7@mail.gmail.com>

Hi Dmitry,

I had the same problem about a year ago.  After looking at cl-who, my
conclusion was that it's really designed for efficiently writing fixed
structure with variable content, not variable structure.

My first attempt was simply string concatenation on the result of
multiple with-html-output-to-string calls.  It worked fine, but with
bigger inputs it became unusably slow due to all the consing.

A second option I considered was to slap a big ol' EVAL (or
MACROEXPAND? I can't remember, offhand) in there.  This is a little
weird, since cl-who transforms the input sexp into code to efficiently
write it, but then I'm only using it once.  Also, due to the weird
call structure (to-macro-and-back), I recall it being somewhat hard to
debug.

The thing I finally settled on was writing my own function that took
as input something that looked like cl-who's input, and wrote it out
to a stream.  It was surprisingly simple to write (I think it was
10-15 lines, but I don't have it in front of me right now), though it
obviously doesn't handle every case cl-who does.  It wouldn't handle
htm/str/txt or prologues or inline code or whatever -- I just pass in
a complete sexp, and it walks the tree and writes to a stream.

In your case, you'd just need to generate a value like (:strong
(:italic "text")) to pass in -- and Lisp tends to be pretty good at
letting you build lists.  :-)

(I hooked it up to write to my web server's response stream directly,
and it screamed.  Well, at least compared to the old "cons a few
gigabytes every request" method.)

I can dig up that function tonight if it sounds useful to you.


- Ken



From amalawi at gmail.com  Mon Nov 23 19:26:06 2009
From: amalawi at gmail.com (Ala'a (cmo-0))
Date: Mon, 23 Nov 2009 23:26:06 +0400
Subject: [cl-who-devel] Generating html tree with dynamic structure
In-Reply-To: <4B0ABA30.3000206@gmail.com>
References: <4B0ABA30.3000206@gmail.com>
Message-ID: <af6a3d2d0911231126k7c2cdc7as588adfd5a0aad806@mail.gmail.com>

this is a my first shot. I do not know what is an s-tree, thus the
implementation of 'text-style'

(defmethod p-render-html ((s-tree tree) (p text-piece) stream)
  (with-html-output (stream nil :prologue nil)
    (let ((text (text-of p)))
      (if (styled-p text-piece)
          (styled-str text )
          (str text)))))

(defun styled-p (text-piece)
  (if (style-of text-piece) t nil))

(defun styled-str (text)
  (dolist (style (text-styles text))
    (setf text (apply-style style text)))
  text) ;; or you can use recursive style

;; this is only for light testing
(defun text-styles (text)
  (list 'italic 'bold))

;; you may change the internals to a macro (aka defstyle ) based for
example on a hastable of lambdas
;; rather than using and maintaining/updating ecase form manually
(defun apply-style (style text)
  (with-output-to-string (out)
    (with-html-output (out nil :prologue nil)
      (ecase style
        ('italic (htm (:italic (str text))))
        ('bold (htm (:strong (str text))))))))

Regards,

Ala'a (cmo-0)

On Mon, Nov 23, 2009 at 8:37 PM, Dmitry V'yal <akamaus at gmail.com> wrote:
> Hello anyone,
>
> I have a simple problem, but I can't find an elegant solution.
>
> Basically I have a message and two flags, the first one signals message
> should be rendered in <strong> tag and the second - in <italic>. So
> there are four possibilities.
>
> Here is the actual code:
>
> (defmethod p-render-html ((s-tree tree) (p text-piece) s)
> ? (with-html-output (s nil :prologue nil)
> ? ? (let ((style (style-of p))
> ? ? ? ? ? (txt (text-of p)))
> ? ? ? (if style
> ? ? ? ? ? (if (tree-find-prop s-tree style #'bold)
> ? ? ? ? ? ? ? (htm (:strong (if (tree-find-prop s-tree style #'italic)
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? (htm (:italic (str txt)))
> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? (str txt))))
> ? ? ? ? ? ? ? (if (tree-find-prop s-tree style #'italic)
> ? ? ? ? ? ? ? ? ? (htm (:italic (str txt)))
> ? ? ? ? ? ? ? ? ? (str txt)))
> ? ? ? ? ? (str txt)))))
>
> I had to test for each case and it resulted in code duplication. Can it
> be avoided? What if I had 5 flags or so?
>
> _______________________________________________
> cl-who-devel site list
> cl-who-devel at common-lisp.net
> http://common-lisp.net/mailman/listinfo/cl-who-devel
>



-- 
It does not matter how fast your code is, if it does not work!



From akamaus at gmail.com  Tue Nov 24 08:47:22 2009
From: akamaus at gmail.com (Dmitry V'yal)
Date: Tue, 24 Nov 2009 11:47:22 +0300
Subject: [cl-who-devel] Generating html tree with dynamic structure
In-Reply-To: <d97bec7a0911231049x1ffc4d2ega5c1b67438b39cb7@mail.gmail.com>
References: <4B0ABA30.3000206@gmail.com>
	<d97bec7a0911231049x1ffc4d2ega5c1b67438b39cb7@mail.gmail.com>
Message-ID: <4B0B9D9A.9090209@gmail.com>

Ken Harris wrote:
> Hi Dmitry,
> 
> I had the same problem about a year ago.  After looking at cl-who, my
> conclusion was that it's really designed for efficiently writing fixed
> structure with variable content, not variable structure.

I have the same feeling now

> 
> My first attempt was simply string concatenation on the result of
> multiple with-html-output-to-string calls.  It worked fine, but with
> bigger inputs it became unusably slow due to all the consing.

> A second option I considered was to slap a big ol' EVAL (or
> MACROEXPAND? I can't remember, offhand) in there.  This is a little
> weird, since cl-who transforms the input sexp into code to efficiently
> write it, but then I'm only using it once.  Also, due to the weird
> call structure (to-macro-and-back), I recall it being somewhat hard to
> debug.
> 
> The thing I finally settled on was writing my own function that took
> as input something that looked like cl-who's input, and wrote it out
> to a stream.  It was surprisingly simple to write (I think it was
> 10-15 lines, but I don't have it in front of me right now), though it
> obviously doesn't handle every case cl-who does.  It wouldn't handle
> htm/str/txt or prologues or inline code or whatever -- I just pass in
> a complete sexp, and it walks the tree and writes to a stream.
> 
> In your case, you'd just need to generate a value like (:strong
> (:italic "text")) to pass in -- and Lisp tends to be pretty good at
> letting you build lists.  :-)
> 
> (I hooked it up to write to my web server's response stream directly,
> and it screamed.  Well, at least compared to the old "cons a few
> gigabytes every request" method.)
> 
> I can dig up that function tonight if it sounds useful to you.

Yes, please, share it. I thought about such approach and was sure 
someone already faced that problem and has a solution.

P.S. After some search I found htmlgen library. It seems to have built 
in functions for generate html from s-expressions. Probably it better 
suited for my use case.