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diff --git a/libxml2/doc/entities.html b/libxml2/doc/entities.html new file mode 100644 index 0000000..f9bcc4e --- /dev/null +++ b/libxml2/doc/entities.html @@ -0,0 +1,64 @@ +<?xml version="1.0" encoding="UTF-8"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css"> +TD {font-family: Verdana,Arial,Helvetica} +BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em} +H1 {font-family: Verdana,Arial,Helvetica} +H2 {font-family: Verdana,Arial,Helvetica} +H3 {font-family: Verdana,Arial,Helvetica} +A:link, A:visited, A:active { text-decoration: underline } +</style><title>Entities or no entities</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td width="180"><a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo" /></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C Logo" /></a><a href="http://www.redhat.com/"><img src="redhat.gif" alt="Red Hat Logo" /></a><div align="left"><a href="http://xmlsoft.org/"><img src="Libxml2-Logo-180x168.gif" alt="Made with Libxml2 Logo" /></a></div></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>The XML C parser and toolkit of Gnome</h1><h2>Entities or no entities</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Developer Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html" style="font-weight:bold">Main Menu</a></li><li><a href="html/index.html" style="font-weight:bold">Reference Manual</a></li><li><a href="examples/index.html" style="font-weight:bold">Code Examples</a></li><li><a href="guidelines.html">XML Guidelines</a></li><li><a href="tutorial/index.html">Tutorial</a></li><li><a href="xmlreader.html">The Reader 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bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>Entities in principle are similar to simple C macros. An entity defines an +abbreviation for a given string that you can reuse many times throughout the +content of your document. Entities are especially useful when a given string +may occur frequently within a document, or to confine the change needed to a +document to a restricted area in the internal subset of the document (at the +beginning). Example:</p><pre>1 <?xml version="1.0"?> +2 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [ +3 <!ENTITY xml "Extensible Markup Language"> +4 ]> +5 <EXAMPLE> +6 &xml; +7 </EXAMPLE></pre><p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing +its name with '&' and following it by ';' without any spaces added. There +are 5 predefined entities in libxml2 allowing you to escape characters with +predefined meaning in some parts of the xml document content: +<strong>&lt;</strong> for the character '<', <strong>&gt;</strong> +for the character '>', <strong>&apos;</strong> for the character ''', +<strong>&quot;</strong> for the character '"', and +<strong>&amp;</strong> for the character '&'.</p><p>One of the problems related to entities is that you may want the parser to +substitute an entity's content so that you can see the replacement text in +your application. Or you may prefer to keep entity references as such in the +content to be able to save the document back without losing this usually +precious information (if the user went through the pain of explicitly +defining entities, he may have a a rather negative attitude if you blindly +substitute them as saving time). The <a href="html/libxml-parser.html#xmlSubstituteEntitiesDefault">xmlSubstituteEntitiesDefault()</a> +function allows you to check and change the behaviour, which is to not +substitute entities by default.</p><p>Here is the DOM tree built by libxml2 for the previous document in the +default case:</p><pre>/gnome/src/gnome-xml -> ./xmllint --debug test/ent1 +DOCUMENT +version=1.0 + ELEMENT EXAMPLE + TEXT + content= + ENTITY_REF + INTERNAL_GENERAL_ENTITY xml + content=Extensible Markup Language + TEXT + content=</pre><p>And here is the result when substituting entities:</p><pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1 +DOCUMENT +version=1.0 + ELEMENT EXAMPLE + TEXT + content= Extensible Markup Language</pre><p>So, entities or no entities? Basically, it depends on your use case. I +suggest that you keep the non-substituting default behaviour and avoid using +entities in your XML document or data if you are not willing to handle the +entity references elements in the DOM tree.</p><p>Note that at save time libxml2 enforces the conversion of the predefined +entities where necessary to prevent well-formedness problems, and will also +transparently replace those with chars (i.e. it will not generate entity +reference elements in the DOM tree or call the reference() SAX callback when +finding them in the input).</p><p><span style="background-color: #FF0000">WARNING</span>: handling entities +on top of the libxml2 SAX interface is difficult!!! If you plan to use +non-predefined entities in your documents, then the learning curve to handle +then using the SAX API may be long. If you plan to use complex documents, I +strongly suggest you consider using the DOM interface instead and let libxml +deal with the complexity rather than trying to do it yourself.</p><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html> |