RE: html tree question. clumsy ?
Thanks for your info Rob. But look at what you wrote: I'm pretty sure,
I understand it to mean, I believe...
My comments and solutions are based on my _actually_writing_code_ to try
to do the things you muse about, and _it_did_not_work_.
Don't take this the wrong way Rob, I just want to make things clear for
other people reading this who might run into the same problem and/or be
inclined to try it out.
- - Martin
-Original Message-
From: Rob Dixon [mailto:[EMAIL PROTECTED]
Sent: Tuesday, September 23, 2003 5:27 PM
To: [EMAIL PROTECTED]
Subject: Re: html tree question. clumsy ?
Martin Thurn wrote:
I ran into similar problems for my module WWW::Search.
No, out-of-the-box you can not re-use an
HTML::TreeBuilder object to parse
a new file.
I'm pretty sure you're wrong about that. HTML::TreeBuilder subclasses
HTML::Parser, which provides the 'new', 'parse',
'parse_file', and 'eof'
methods. The documentation says:
After $p-eof has been called, the parse() and
parse_file() methods
can be invoked to feed new documents with the parser object.
which is poor English, but I understand it to mean that, once
the 'eof'
method has been called, any further calls to 'parse' or 'parse_file'
will create a new HTML tree from scratch.
BUT you can use the following code as a reset. I.e. call
parse, muck with the tree, do the following four lines, and
call parse
again. This does the same as new() but without changing
the store_comments,
store_pis settings, etc:
$self-{'_head'} = $self-insert_element('head',1);
$self-{'_pos'} = undef; # pull it back up
$self-{'_body'} = $self-insert_element('body',1);
$self-{'_pos'} = undef; # pull it back up again
HTML::Parser will itself insert any implicit html, head and body
tags when further input is parsed.
The reason you can't re-use your HTML::Element is because it's a
reference, and when the tree gets deleted, your Element
gets deleted right
along with it.
Once you have called $tree-delete the object no longer exists, but I
believe $tree-delete_content or $tree-eof will allow you to reuse
the same object for parsing a new document.
Rob
Re: html tree question. clumsy ?
Martin Thurn wrote:
I ran into similar problems for my module WWW::Search.
No, out-of-the-box you can not re-use an HTML::TreeBuilder object to parse
a new file.
I'm pretty sure you're wrong about that. HTML::TreeBuilder subclasses
HTML::Parser, which provides the 'new', 'parse', 'parse_file', and 'eof'
methods. The documentation says:
After $p-eof has been called, the parse() and parse_file() methods
can be invoked to feed new documents with the parser object.
which is poor English, but I understand it to mean that, once the 'eof'
method has been called, any further calls to 'parse' or 'parse_file'
will create a new HTML tree from scratch.
BUT you can use the following code as a reset. I.e. call
parse, muck with the tree, do the following four lines, and call parse
again. This does the same as new() but without changing the store_comments,
store_pis settings, etc:
$self-{'_head'} = $self-insert_element('head',1);
$self-{'_pos'} = undef; # pull it back up
$self-{'_body'} = $self-insert_element('body',1);
$self-{'_pos'} = undef; # pull it back up again
HTML::Parser will itself insert any implicit html, head and body
tags when further input is parsed.
The reason you can't re-use your HTML::Element is because it's a
reference, and when the tree gets deleted, your Element gets deleted right
along with it.
Once you have called $tree-delete the object no longer exists, but I
believe $tree-delete_content or $tree-eof will allow you to reuse
the same object for parsing a new document.
Rob
Re: html tree question. clumsy ?
James.Q.L wrote:
Thurn, Martin wrote:
I ran into similar problems for my module WWW::Search.
No, out-of-the-box you can not re-use an HTML::TreeBuilder object to parse
a new file. BUT you can use the following code as a reset. I.e. call
parse, muck with the tree, do the following four lines, and call parse
again. This does the same as new() but without changing the store_comments,
store_pis settings, etc:
$self-{'_head'} = $self-insert_element('head',1);
$self-{'_pos'} = undef; # pull it back up
$self-{'_body'} = $self-insert_element('body',1);
$self-{'_pos'} = undef; # pull it back up again
i will look into how that can be added to $tree later.
but a reset method from HTML::TreeBuilder would be nice.
As per my previous post, I think $tree-eof or $tree-delete_content will
do the trick.
The reason you can't re-use your HTML::Element is because it's a
reference, and when the tree gets deleted, your Element gets deleted right
along with it.
- - Martin Thurn
just found that $h-clone can get around this. too bad i can't do the same to a tree
before it
parses the file.
from HTML::Element,
You are free to clone HTML::TreeBuilder trees, just as long as: 1) they're done
being parsed, or
2) you don't expect to resume parsing into the clone. (You can continue parsing into
the original;
it is never affected.)
just to make sure, (english isn't my first language) does it say that i can't clone
a tree if it
doesn't parse something?
No. What this is saying is that you can't do:
my $tree = new HTML::TreeBuilder;
$tree-parse($string1);
$tree-parse($string2);
my $tree2 = $tree-clone;
$tree2-parse($string3);
But, here, you could write
$tree-parse($string4);
In other words, you can't carry on parsing HTML text into a cloned
tree, but the original tree is unaffected.
HTH,
Rob
Re: html tree question. clumsy ?
At 09:42 AM 2003-09-23, James.Q.L wrote:
1. will $tree-parse_file(parse a new file) will overwrite the old parsed
$tree content?
No, don't try that. You can call parse_file on a $tree only once. As far
as I remember, there's no re-using it.
so that i dont have to delete the tree in the sub?
Why not just delete the tree?
As to your question here:
## why can't keep it outside ?/
my $literal = HTML::Element-new('~literal','text' = $insert);
I think because once you insert the $literal object into a tree, then when
you later destroy the tree, that deletes that $literal object, too.
(Deleting a tree basically means deleting every attribute in every node in
the tree.)
--
Sean M. Burkehttp://search.cpan.org/~sburke/
RE: html tree question. clumsy ?
I ran into similar problems for my module WWW::Search.
No, out-of-the-box you can not re-use an HTML::TreeBuilder object to parse
a new file. BUT you can use the following code as a reset. I.e. call
parse, muck with the tree, do the following four lines, and call parse
again. This does the same as new() but without changing the store_comments,
store_pis settings, etc:
$self-{'_head'} = $self-insert_element('head',1);
$self-{'_pos'} = undef; # pull it back up
$self-{'_body'} = $self-insert_element('body',1);
$self-{'_pos'} = undef; # pull it back up again
The reason you can't re-use your HTML::Element is because it's a
reference, and when the tree gets deleted, your Element gets deleted right
along with it.
- - Martin Thurn
RE: html tree question. clumsy ?
--- Thurn, Martin [EMAIL PROTECTED] wrote:
I ran into similar problems for my module WWW::Search.
No, out-of-the-box you can not re-use an HTML::TreeBuilder object to parse
a new file. BUT you can use the following code as a reset. I.e. call
parse, muck with the tree, do the following four lines, and call parse
again. This does the same as new() but without changing the store_comments,
store_pis settings, etc:
$self-{'_head'} = $self-insert_element('head',1);
$self-{'_pos'} = undef; # pull it back up
$self-{'_body'} = $self-insert_element('body',1);
$self-{'_pos'} = undef; # pull it back up again
i will look into how that can be added to $tree later.
but a reset method from HTML::TreeBuilder would be nice.
The reason you can't re-use your HTML::Element is because it's a
reference, and when the tree gets deleted, your Element gets deleted right
along with it.
- - Martin Thurn
just found that $h-clone can get around this. too bad i can't do the same to a tree
before it
parses the file.
from HTML::Element,
You are free to clone HTML::TreeBuilder trees, just as long as: 1) they're done being
parsed, or
2) you don't expect to resume parsing into the clone. (You can continue parsing into
the original;
it is never affected.)
just to make sure, (english isn't my first language) does it say that i can't clone a
tree if it
doesn't parse something?
Qiang
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