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104 lines
3.8 KiB
HTML
104 lines
3.8 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
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<HTML>
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<HEAD>
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<TITLE>Mini-XML Programmers Manual, Version 2.2.1</TITLE>
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<META NAME="author" CONTENT="Michael Sweet">
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<META NAME="copyright" CONTENT="Copyright 2003-2005">
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html; CHARSET=iso-iso-8859-1">
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<LINK REL="Start" HREF="index.html">
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<LINK REL="Contents" HREF="toc.html">
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<LINK REL="Prev" HREF="3MoreMiniXMLProgrammingTechniques.html">
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<LINK REL="Next" HREF="SaveCallbacks.html">
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<STYLE TYPE="text/css"><!--
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BODY { font-family: serif }
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H1 { font-family: sans-serif }
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H2 { font-family: sans-serif }
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H3 { font-family: sans-serif }
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H4 { font-family: sans-serif }
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H5 { font-family: sans-serif }
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H6 { font-family: sans-serif }
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SUB { font-size: smaller }
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SUP { font-size: smaller }
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PRE { font-family: monospace }
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--></STYLE>
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</HEAD>
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<BODY>
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<A HREF="toc.html">Contents</A>
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<A HREF="3MoreMiniXMLProgrammingTechniques.html">Previous</A>
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<A HREF="SaveCallbacks.html">Next</A>
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<HR NOSHADE>
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<H2><A name="LOAD_CALLBACKS">Load Callbacks</A></H2>
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<P><A href="#LOAD_XML">Chapter 2</A> introduced the <A href="mxmlLoadFile.html#mxmlLoadFile">
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<TT>mxmlLoadFile()</TT></A> and <A href="mxmlLoadString.html#mxmlLoadString">
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<TT>mxmlLoadString()</TT></A> functions. The last argument to these
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functions is a callback function which is used to determine the value
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type of each data node in an XML document.</P>
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<P>Mini-XML defines several standard callbacks for simple XML data
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files:</P>
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<UL>
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<LI><TT>MXML_INTEGER_CALLBACK</TT> - All data nodes contain
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whitespace-separated integers.</LI>
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<LI><TT>MXML_OPAQUE_CALLBACK</TT> - All data nodes contain opaque
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strings ("CDATA").</LI>
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<LI><TT>MXML_REAL_CALLBACK</TT> - All data nodes contain
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whitespace-separated floating-point numbers.</LI>
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<LI><TT>MXML_TEXT_CALLBACK</TT> - All data nodes contain
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whitespace-separated strings.</LI>
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</UL>
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<P>You can provide your own callback functions for more complex XML
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documents. Your callback function will receive a pointer to the current
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element node and must return the value type of the immediate children
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for that element node: <TT>MXML_INTEGER</TT>, <TT>MXML_OPAQUE</TT>, <TT>
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MXML_REAL</TT>, or <TT>MXML_TEXT</TT>. The function is called<I> after</I>
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the element and its attributes have been read, so you can look at the
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element name, attributes, and attribute values to determine the proper
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value type to return.</P>
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<!-- NEED 2in -->
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<P>The following callback function looks for an attribute named "type"
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or the element name to determine the value type for its child nodes:</P>
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<PRE>
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/*
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* 'type_cb()' - XML data type callback for mxmlLoadFile()...
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*/
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mxml_type_t /* O - Data type */
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type_cb(mxml_node_t *node) /* I - Element node */
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{
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const char *type; /* Type string */
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/*
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* You can lookup attributes and/or use the element name, hierarchy, etc...
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*/
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if ((type = mxmlElementGetAttr(node, "type")) == NULL)
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type = node->value.element.name;
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if (!strcmp(type, "integer"))
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return (MXML_INTEGER);
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else if (!strcmp(type, "opaque"))
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return (MXML_OPAQUE);
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else if (!strcmp(type, "real"))
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return (MXML_REAL);
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else
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return (MXML_TEXT);
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}
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</PRE>
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<P>To use this callback function, simply use the name when you call any
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of the load functions:</P>
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<PRE>
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FILE *fp;
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<A href="mxmlnodet.html#mxml_node_t">mxml_node_t</A> *tree;
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fp = fopen("filename.xml", "r");
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tree = <A href="mxmlLoadFile.html#mxmlLoadFile">mxmlLoadFile</A>(NULL, fp, <B>type_cb</B>);
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fclose(fp);
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</PRE>
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<HR NOSHADE>
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<A HREF="toc.html">Contents</A>
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<A HREF="3MoreMiniXMLProgrammingTechniques.html">Previous</A>
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<A HREF="SaveCallbacks.html">Next</A>
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</BODY>
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</HTML>
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