Comparing revisions for LinkRewriting
- [2742] 2004-12-02 09:48:59 by DarTar (unregistered user) [Help needed on regex!]
- [17997] 2008-01-27 02:34:53 by JavaWoman (unregistered user) [Migrated to doc server]
Additions:
===== Regex and Link Rewriting =====
{{lastedit}}
I open this page for discussing a regex issue met during the development of a [[IncludeRemote FetchRemote]] action.
Basically, the aim of this action is to fetch raw page content from a remote Wikka server and rewrite it before printing it on screen.
=== 1. What is //raw content// ===
//Raw content// is the source code of Wikka pages, containing [[FormattingRules WikkaSyntax]] tags. For example, the raw content of a page like WikiEngine is:
%%[[HelpInfo Wikka Documentation]]
----
===== What is a Wiki? =====
A **wiki** (pronounced "wicky" or "weeky" or "viki") is a website (or other hypertext document
collection) that allows any user to add content, but also allows that content to be edited by any
other user while keeping track of the different versions.
In short, a Wiki is one of the most powerful tools for **web-based collaborative editing**.
A WikiEngine is the software used to create and run such websites. For instance, this wiki runs on
the [[HomePage WikkaWiki]] engine.
<<More information on Wikis is available on: [[http://en.wikipedia.org/wiki/Wiki Wikipedia]]<<
----
CategoryDocumentation - CategoryWiki
%%
The new [[Mod042fShowPageCodeHandler showpagecode]] handler allows you to display the raw content of any page by appending ##/showpagecode## to its name in the URL:
http://wikka.jsnx.com/WikiEngine/showpagecode
=== 2. Link rewriting in ##[[IncludeRemote FetchRemote]]## ===
The [[IncludeRemote FetchRemote]] action requires parsing a fetched page's raw content and rewriting internal links in a specific way.
Basically there are two kinds of links that have to be rewritten: //forced internal links// and //""CamelCase"" links//.
For the action to work properly, forced internal links and camelcase links in the fetched page should be respectively rewritten as follows:
~-**Forced links:**
%%[[HelpInfo A good link]] => <a href="FetchRemote?page=HelpInfo">A good link</a>%%
~-**""CamelCase"" links:**
%%HelpInfo => <a href="FetchRemote?page=HelpInfo">HelpInfo</a>%%
=== 3. Link rewriting through ##preg_replace()## ===
To do so, I use the PHP ##preg_replace()## function. I've //almost// managed to have both of the above cases correctly parsed using the following patterns:
%%$forced = "/\[\[([^ \/]+) ([^\]]+)\]\]/";
$camel = "/[^a-z=>\"\[\/\{]([A-Z]+[a-z]+[A-Z][A-Za-z0-9]+)+/";%%
and rewrite the raw page content (##$content##) by applying twice the ##preg_replace()## function:
%%
// rewrite forced links
$content = preg_replace($forced, "\"\"<a href='".$this->Href("","","page=\\1")."'>\\2</a>\"\"", $content);
// rewrite camelcase links
$content = preg_replace($camel, "\"\" <a href='".$this->Href("","","page=\\1")."'>\\1</a>\"\"", $content);
%%
=== 4. Tricky cases ===
The link rewriting rules above will work fine in //most// cases. What they still //cannot// capture is a number of cases in which a ""WikiWord"" appears in the context of a forced internal link, like for example: %%[[HelpInfo This is the homepage of the WikkaWiki Documentation Project]]%%.
It's clear in this case that ""WikkaWiki"" should NOT be rewritten (it's not a link, but part of the //anchor text// of a link).
If you take for example the rawcontent of WikiEngine displayed above, the ##preg_replace()## patterns I'm using won't handle a link like ""[[HomePage WikkaWiki]]"" properly.
After the first ##preg_replace()## application (//forced link rewriting//) this code is correctly rendered as:
%%""<a href='FetchRemote?page=HomePage'>WikkaWiki</a>""%%
But after the second ##preg_replace()## application (camelcase links rewriting), this will be rendered as:
%%""<a href='FetchRemote?page=HomePage'>""<a href='FetchRemote?page=WikkaWiki'>WikkaWiki</a>""</a>""%%
=== 5. Million-dollar question ===
Now, here comes the **big question**.
How can I have the camelcase rewriting rule parse and rewrite any camelcase-formatted strings **except** those that appear in the anchor text of an already rewritten link?
The question is tricky, because whereas in the above example cases like ""FetchRemote"" or ""HomePage"" that appear in the //URI// are easily dealt with by excluding camelcase words that are adjacent to characters like **"**, **=**, **'** etc., a camelcase word within the //anchor text// can be preceded and followed by other text, like:
%%""<a href='FetchRemote?page=HomePage'>Here's some text preceding WikkaWiki, which is in turn followed by other text</a>""%%
How do I exclude ##""WikkaWiki""## from being rewritten?
Thanks if you had the patience to read this long and boring page.
-- DarTar
----
CategoryRegex CategoryDevelopment
{{lastedit}}
I open this page for discussing a regex issue met during the development of a [[IncludeRemote FetchRemote]] action.
Basically, the aim of this action is to fetch raw page content from a remote Wikka server and rewrite it before printing it on screen.
=== 1. What is //raw content// ===
//Raw content// is the source code of Wikka pages, containing [[FormattingRules WikkaSyntax]] tags. For example, the raw content of a page like WikiEngine is:
%%[[HelpInfo Wikka Documentation]]
----
===== What is a Wiki? =====
A **wiki** (pronounced "wicky" or "weeky" or "viki") is a website (or other hypertext document
collection) that allows any user to add content, but also allows that content to be edited by any
other user while keeping track of the different versions.
In short, a Wiki is one of the most powerful tools for **web-based collaborative editing**.
A WikiEngine is the software used to create and run such websites. For instance, this wiki runs on
the [[HomePage WikkaWiki]] engine.
<<More information on Wikis is available on: [[http://en.wikipedia.org/wiki/Wiki Wikipedia]]<<
----
CategoryDocumentation - CategoryWiki
%%
The new [[Mod042fShowPageCodeHandler showpagecode]] handler allows you to display the raw content of any page by appending ##/showpagecode## to its name in the URL:
http://wikka.jsnx.com/WikiEngine/showpagecode
=== 2. Link rewriting in ##[[IncludeRemote FetchRemote]]## ===
The [[IncludeRemote FetchRemote]] action requires parsing a fetched page's raw content and rewriting internal links in a specific way.
Basically there are two kinds of links that have to be rewritten: //forced internal links// and //""CamelCase"" links//.
For the action to work properly, forced internal links and camelcase links in the fetched page should be respectively rewritten as follows:
~-**Forced links:**
%%[[HelpInfo A good link]] => <a href="FetchRemote?page=HelpInfo">A good link</a>%%
~-**""CamelCase"" links:**
%%HelpInfo => <a href="FetchRemote?page=HelpInfo">HelpInfo</a>%%
=== 3. Link rewriting through ##preg_replace()## ===
To do so, I use the PHP ##preg_replace()## function. I've //almost// managed to have both of the above cases correctly parsed using the following patterns:
%%$forced = "/\[\[([^ \/]+) ([^\]]+)\]\]/";
$camel = "/[^a-z=>\"\[\/\{]([A-Z]+[a-z]+[A-Z][A-Za-z0-9]+)+/";%%
and rewrite the raw page content (##$content##) by applying twice the ##preg_replace()## function:
%%
// rewrite forced links
$content = preg_replace($forced, "\"\"<a href='".$this->Href("","","page=\\1")."'>\\2</a>\"\"", $content);
// rewrite camelcase links
$content = preg_replace($camel, "\"\" <a href='".$this->Href("","","page=\\1")."'>\\1</a>\"\"", $content);
%%
=== 4. Tricky cases ===
The link rewriting rules above will work fine in //most// cases. What they still //cannot// capture is a number of cases in which a ""WikiWord"" appears in the context of a forced internal link, like for example: %%[[HelpInfo This is the homepage of the WikkaWiki Documentation Project]]%%.
It's clear in this case that ""WikkaWiki"" should NOT be rewritten (it's not a link, but part of the //anchor text// of a link).
If you take for example the rawcontent of WikiEngine displayed above, the ##preg_replace()## patterns I'm using won't handle a link like ""[[HomePage WikkaWiki]]"" properly.
After the first ##preg_replace()## application (//forced link rewriting//) this code is correctly rendered as:
%%""<a href='FetchRemote?page=HomePage'>WikkaWiki</a>""%%
But after the second ##preg_replace()## application (camelcase links rewriting), this will be rendered as:
%%""<a href='FetchRemote?page=HomePage'>""<a href='FetchRemote?page=WikkaWiki'>WikkaWiki</a>""</a>""%%
=== 5. Million-dollar question ===
Now, here comes the **big question**.
How can I have the camelcase rewriting rule parse and rewrite any camelcase-formatted strings **except** those that appear in the anchor text of an already rewritten link?
The question is tricky, because whereas in the above example cases like ""FetchRemote"" or ""HomePage"" that appear in the //URI// are easily dealt with by excluding camelcase words that are adjacent to characters like **"**, **=**, **'** etc., a camelcase word within the //anchor text// can be preceded and followed by other text, like:
%%""<a href='FetchRemote?page=HomePage'>Here's some text preceding WikkaWiki, which is in turn followed by other text</a>""%%
How do I exclude ##""WikkaWiki""## from being rewritten?
Thanks if you had the patience to read this long and boring page.
-- DarTar
----
CategoryRegex CategoryDevelopment
Deletions:
This page can now be found on the [[Docs:LinkRewriting Wikka Documentation Server]].
Thanks for updating your bookmarks!
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An archive of [[http://wikkawiki.org/LinkRewriting/revisions
old revisions of this page]] is still available for reference.<<
::c::
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CategoryMigratedDocs
