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-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
- "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
- <head>
- <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
- <meta name="description" content="Describes config schema framework in HTML Purifier." />
- <link rel="stylesheet" type="text/css" href="./style.css" />
- <title>Config Schema - HTML Purifier</title>
- </head>
- <body>
-
- <h1>Config Schema</h1>
-
- <div id="filing">Filed under Development</div>
- <div id="index">Return to the <a href="index.html">index</a>.</div>
- <div id="home"><a href="http://htmlpurifier.org/">HTML Purifier</a> End-User Documentation</div>
-
- <p>
- HTML Purifier has a fairly complex system for configuration. Users
- interact with a <code>HTMLPurifier_Config</code> object to
- set configuration directives. The values they set are validated according
- to a configuration schema, <code>HTMLPurifier_ConfigSchema</code>.
- </p>
-
- <p>
- The schema is mostly transparent to end-users, but if you're doing development
- work for HTML Purifier and need to define a new configuration directive,
- you'll need to interact with it. We'll also talk about how to define
- userspace configuration directives at the very end.
- </p>
-
- <h2>Write a directive file</h2>
-
- <p>
- Directive files define configuration directives to be used by
- HTML Purifier. They are placed in <code>library/HTMLPurifier/ConfigSchema/schema/</code>
- in the form <code><em>Namespace</em>.<em>Directive</em>.txt</code> (I
- couldn't think of a more descriptive file extension.)
- Directive files are actually what we call <code>StringHash</code>es,
- i.e. associative arrays represented in a string form reminiscent of
- <a href="http://qa.php.net/write-test.php">PHPT</a> tests. Here's a
- sample directive file, <code>Test.Sample.txt</code>:
- </p>
-
- <pre>Test.Sample
-TYPE: string/null
-DEFAULT: NULL
-ALLOWED: 'foo', 'bar'
-VALUE-ALIASES: 'baz' => 'bar'
-VERSION: 3.1.0
---DESCRIPTION--
-This is a sample configuration directive for the purposes of the
-&lt;code&gt;dev-config-schema.html&lt;code&gt; documentation.
---ALIASES--
-Test.Example</pre>
-
- <p>
- Each of these segments has a specific meaning:
- </p>
-
- <table class="table">
- <thead>
- <tr>
- <th>Key</th>
- <th>Example</th>
- <th>Description</th>
- </tr>
- </thead>
- <tbody>
- <tr>
- <td>ID</td>
- <td>Test.Sample</td>
- <td>The name of the directive, in the form Namespace.Directive
- (implicitly the first line)</td>
- </tr>
- <tr>
- <td>TYPE</td>
- <td>string/null</td>
- <td>The type of variable this directive accepts. See below for
- details. You can also add <code>/null</code> to the end of
- any basic type to allow null values too.</td>
- </tr>
- <tr>
- <td>DEFAULT</td>
- <td>NULL</td>
- <td>A parseable PHP expression of the default value.</td>
- </tr>
- <tr>
- <td>DESCRIPTION</td>
- <td>This is a...</td>
- <td>An HTML description of what this directive does.</td>
- </tr>
- <tr>
- <td>VERSION</td>
- <td>3.1.0</td>
- <td><em>Recommended</em>. The version of HTML Purifier this directive was added.
- Directives that have been around since 1.0.0 don't have this,
- but any new ones should.</td>
- </tr>
- <tr>
- <td>ALIASES</td>
- <td>Test.Example</td>
- <td><em>Optional</em>. A comma separated list of aliases for this directive.
- This is most useful for backwards compatibility and should
- not be used otherwise.</td>
- </tr>
- <tr>
- <td>ALLOWED</td>
- <td>'foo', 'bar'</td>
- <td><em>Optional</em>. Set of allowed value for a directive,
- a comma separated list of parseable PHP expressions. This
- is only allowed string, istring, text and itext TYPEs.</td>
- </tr>
- <tr>
- <td>VALUE-ALIASES</td>
- <td>'baz' =&gt; 'bar'</td>
- <td><em>Optional</em>. Mapping of one value to another, and
- should be a comma separated list of keypair duples. This
- is only allowed string, istring, text and itext TYPEs.</td>
- </tr>
- <tr>
- <td>DEPRECATED-VERSION</td>
- <td>3.1.0</td>
- <td><em>Not shown</em>. Indicates that the directive was
- deprecated this version.</td>
- </tr>
- <tr>
- <td>DEPRECATED-USE</td>
- <td>Test.NewDirective</td>
- <td><em>Not shown</em>. Indicates what new directive should be
- used instead. Note that the directives will functionally be
- different, although they should offer the same functionality.
- If they are identical, use an alias instead.</td>
- </tr>
- <tr>
- <td>EXTERNAL</td>
- <td>CSSTidy</td>
- <td><em>Not shown</em>. Indicates if there is an external library
- the user will need to download and install to use this configuration
- directive. As of right now, this is merely a Google-able name; future
- versions may also provide links and instructions.</td>
- </tr>
- </tbody>
- </table>
-
- <p>
- Some notes on format and style:
- </p>
-
- <ul>
- <li>
- Each of these keys can be expressed in the short format
- (<code>KEY: Value</code>) or the long format
- (<code>--KEY--</code> with value beneath). You must use the
- long format if multiple lines are needed, or if a long format
- has been used already (that's why <code>ALIASES</code> in our
- example is in the long format); otherwise, it's user preference.
- </li>
- <li>
- The HTML descriptions should be wrapped at about 80 columns; do
- not rely on editor word-wrapping.
- </li>
- </ul>
-
- <p>
- Also, as promised, here is the set of possible types:
- </p>
-
- <table class="table">
- <thead>
- <tr>
- <th>Type</th>
- <th>Example</th>
- <th>Description</th>
- </tr>
- </thead>
- <tbody>
- <tr>
- <td>string</td>
- <td>'Foo'</td>
- <td><a href="http://docs.php.net/manual/en/language.types.string.php">String</a> without newlines</td>
- </tr>
- <tr>
- <td>istring</td>
- <td>'foo'</td>
- <td>Case insensitive ASCII string without newlines</td>
- </tr>
- <tr>
- <td>text</td>
- <td>"A<em>\n</em>b"</td>
- <td>String with newlines</td>
- </tr>
- <tr>
- <td>itext</td>
- <td>"a<em>\n</em>b"</td>
- <td>Case insensitive ASCII string without newlines</td>
- </tr>
- <tr>
- <td>int</td>
- <td>23</td>
- <td>Integer</td>
- </tr>
- <tr>
- <td>float</td>
- <td>3.0</td>
- <td>Floating point number</td>
- </tr>
- <tr>
- <td>bool</td>
- <td>true</td>
- <td>Boolean</td>
- </tr>
- <tr>
- <td>lookup</td>
- <td>array('key' =&gt; true)</td>
- <td>Lookup array, used with <code>isset($var[$key])</code></td>
- </tr>
- <tr>
- <td>list</td>
- <td>array('f', 'b')</td>
- <td>List array, with ordered numerical indexes</td>
- </tr>
- <tr>
- <td>hash</td>
- <td>array('key' =&gt; 'val')</td>
- <td>Associative array of keys to values</td>
- </tr>
- <tr>
- <td>mixed</td>
- <td>new stdclass</td>
- <td>Any PHP variable is fine</td>
- </tr>
- </tbody>
- </table>
-
- <p>
- The examples represent what will be returned out of the configuration
- object; users have a little bit of leeway when setting configuration
- values (for example, a lookup value can be specified as a list;
- HTML Purifier will flip it as necessary.) These types are defined
- in <a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/VarParser.php">
- library/HTMLPurifier/VarParser.php</a>.
- </p>
-
- <p>
- For more information on what values are allowed, and how they are parsed,
- consult <a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php">
- library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php</a>, as well
- as <a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/ConfigSchema/Interchange/Directive.php">
- library/HTMLPurifier/ConfigSchema/Interchange/Directive.php</a> for
- the semantics of the parsed values.
- </p>
-
- <h2>Refreshing the cache</h2>
-
- <p>
- You may have noticed that your directive file isn't doing anything
- yet. That's because it hasn't been added to the runtime
- <code>HTMLPurifier_ConfigSchema</code> instance. Run
- <code>maintenance/generate-schema-cache.php</code> to fix this.
- If there were no errors, you're good to go! Don't forget to add
- some unit tests for your functionality!
- </p>
-
- <p>
- If you ever make changes to your configuration directives, you
- will need to run this script again.
- </p>
- <h2>Adding in-house schema definitions</h2>
-
- <p>
- Placing stuff directly in HTML Purifier's source tree is generally not a
- good idea, so HTML Purifier 4.0.0+ has some facilities in place to make your
- life easier.
- </p>
-
- <p>
- The first is to pass an extra parameter to <code>maintenance/generate-schema-cache.php</code>
- with the location of your directory (relative or absolute path will do). For example,
- if I'm storing my custom definitions in <em>/var/htmlpurifier/myschema</em>, run:
- <code>php maintenance/generate-schema-cache.php /var/htmlpurifier/myschema</code>.
- </p>
-
- <p>
- Alternatively, you can create a small loader PHP file in the HTML Purifier base
- directory named <code>config-schema.php</code> (this is the same directory
- you would place a <code>test-settings.php</code> file). In this file, add
- the following line for each directory you want to load:
- </p>
-
-<pre>$builder-&gt;buildDir($interchange, '/var/htmlpurifier/myschema');</pre>
-
- <p>You can even load a single file using:</p>
-
-<pre>$builder-&gt;buildFile($interchange, '/var/htmlpurifier/myschema/MyApp.Directive.txt');</pre>
-
- <p>Storing custom definitions that you don't plan on sending back upstream in
- a separate directory is <em>definitely</em> a good idea! Additionally, picking
- a good namespace can go a long way to saving you grief if you want to use
- someone else's change, but they picked the same name, or if HTML Purifier
- decides to add support for a configuration directive that has the same name.</p>
-
- <!-- TODO: how to name directives that rely on naming conventions -->
-
- <h2>Errors</h2>
-
- <p>
- All directive files go through a rigorous validation process
- through <a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/ConfigSchema/Validator.php">
- library/HTMLPurifier/ConfigSchema/Validator.php</a>, as well
- as some basic checks during building. While
- listing every error out here is out-of-scope for this document, we
- can give some general tips for interpreting error messages.
- There are two types of errors: builder errors and validation errors.
- </p>
-
- <h3>Builder errors</h3>
-
- <blockquote>
- <p>
- <strong>Exception:</strong> Expected type string, got
- integer in DEFAULT in directive hash 'Ns.Dir'
- </p>
- </blockquote>
-
- <p>
- You can identify a builder error by the keyword "directive hash."
- These are the easiest to deal with, because they directly correspond
- with your directive file. Find the offending directive file (which
- is the directive hash plus the .txt extension), find the
- offending index ("in DEFAULT" means the DEFAULT key) and fix the error.
- This particular error would occur if your default value is not the same
- type as TYPE.
- </p>
-
- <h3>Validation errors</h3>
-
- <blockquote>
- <p>
- <strong>Exception:</strong> Alias 3 in valueAliases in directive
- 'Ns.Dir' must be a string
- </p>
- </blockquote>
-
- <p>
- These are a little trickier, because we're not actually validating
- your directive file, or even the direct string hash representation.
- We're validating an Interchange object, and the error messages do
- not mention any string hash keys.
- </p>
-
- <p>
- Nevertheless, it's not difficult to figure out what went wrong.
- Read the "context" statements in reverse:
- </p>
-
- <dl>
- <dt>in directive 'Ns.Dir'</dt>
- <dd>This means we need to look at the directive file <code>Ns.Dir.txt</code></dd>
- <dt>in valueAliases</dt>
- <dd>There's no key actually called this, but there's one that's close:
- VALUE-ALIASES. Indeed, that's where to look.</dd>
- <dt>Alias 3</dt>
- <dd>The value alias that is equal to 3 is the culprit.</dd>
- </dl>
-
- <p>
- In this particular case, you're not allowed to alias integers values to
- strings values.
- </p>
-
- <p>
- The most difficult part is translating the Interchange member variable (valueAliases)
- into a directive file key (VALUE-ALIASES), but there's a one-to-one
- correspondence currently. If the two formats diverge, any discrepancies
- will be described in <a href="http://repo.or.cz/w/htmlpurifier.git?a=blob;hb=HEAD;f=library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php">
- library/HTMLPurifier/ConfigSchema/InterchangeBuilder.php</a>.
- </p>
-
- <h2>Internals</h2>
-
- <p>
- Much of the configuration schema framework's codebase deals with
- shuffling data from one format to another, and doing validation on this
- data.
- The keystone of all of this is the <code>HTMLPurifier_ConfigSchema_Interchange</code>
- class, which represents the purest, parsed representation of the schema.
- </p>
-
- <p>
- Hand-writing this data is unwieldy, however, so we write directive files.
- These directive files are parsed by <code>HTMLPurifier_StringHashParser</code>
- into <code>HTMLPurifier_StringHash</code>es, which then
- are run through <code>HTMLPurifier_ConfigSchema_InterchangeBuilder</code>
- to construct the interchange object.
- </p>
-
- <p>
- From the interchange object, the data can be siphoned into other forms
- using <code>HTMLPurifier_ConfigSchema_Builder</code> subclasses.
- For example, <code>HTMLPurifier_ConfigSchema_Builder_ConfigSchema</code>
- generates a runtime <code>HTMLPurifier_ConfigSchema</code> object,
- which <code>HTMLPurifier_Config</code> uses to validate its incoming
- data. There is also an XML serializer, which is used to build documentation.
- </p>
-
- </body>
-</html>
-
-<!-- vim: et sw=4 sts=4
--->