mxml/doc/docset.intro

<h2 class="title"><a id="INTRODUCTION">Introduction</a></h2>

<p>Mini-XML is a small XML parsing library that you can use to read XML data files or strings in your application without requiring large non-standard libraries.  Mini-XML provides the following functionality:</p>

<ul>
  <li>Reading of UTF-8 and UTF-16 and writing of UTF-8 encoded XML files and strings.</li>
  <li>Data is stored in a linked-list tree structure, preserving the XML data hierarchy.</li>
  <li>SAX (streamed) reading of XML files and strings to minimize memory usage.</li>
  <li>Supports arbitrary element names, attributes, and attribute values with no preset limits, just available memory.</li>
  <li>Supports integer, real, opaque ("cdata"), and text data types in "leaf" nodes.</li>
  <li>Functions for creating and managing trees of data.</li>
  <li>"Find" and "walk" functions for easily locating and navigating trees of data.</li>
</ul>

<p>Mini-XML doesn't do validation or other types of processing on the data based upon schema files or other sources of definition information.</p>


<h2 class="title"><a id="USING">Using Mini-XML</a></h2>

<p>Mini-XML provides a single header file which you include:</p>

<pre class="example">
#include &lt;mxml.h&gt;
</pre>

<p>Nodes are defined by the "<a href="#mxml_node_t">mxml_node_t</a>" structure;
the "type" member defines the node type (element, integer, opaque, real, or
text) which determines which value you want to look at in the "value" union.
New nodes can be created using the
"<a href="#mxmlNewElement">mxmlNewElement()</a>",
"<a href="#mxmlNewInteger">mxmlNewInteger()</a>",
"<a href="#mxmlNewOpaque">mxmlNewOpaque()</a>",
"<a href="#mxmlNewReal">mxmlNewReal()</a>", and
"<a href="#mxmlNewText">mxmlNewText()</a>" functions. Only elements can have
child nodes, and the top node must be an element, usually "?xml".</p>

<p>You load an XML file using the "mxmlLoadFile()" function:</p>

<pre class="example">
FILE *fp;
mxml_node_t *tree;

fp = fopen("filename.xml", "r");
tree = mxmlLoadFile(NULL, fp, MXML_NO_CALLBACK);
fclose(fp);
</pre>

<p>Similarly, you save an XML file using the
"<a href="#mxmlSaveFile">mxmlSaveFile()</a>" function:</p>

<pre class="example">
FILE *fp;
mxml_node_t *tree;

fp = fopen("filename.xml", "w");
mxmlSaveFile(tree, fp, MXML_NO_CALLBACK);
fclose(fp);
</pre>

<p>The "<a href="#mxmlLoadString">mxmlLoadString()</a>",
"<a href="#mxmlSaveAllocString">mxmlSaveAllocString()</a>", and
"<a href="#mxmlSaveString">mxmlSaveString()</a>" functions load XML node trees
from and save XML node trees to strings:</p>

<pre class="example">
char buffer[8192];
char *ptr;
mxml_node_t *tree;

...
tree = mxmlLoadString(NULL, buffer, MXML_NO_CALLBACK);

...
mxmlSaveString(tree, buffer, sizeof(buffer),
	       MXML_NO_CALLBACK);

...
ptr = mxmlSaveAllocString(tree, MXML_NO_CALLBACK);
</pre>

<p>You can find a named element/node using the
"<a href="#mxmlFindElement">mxmlFindElement()</a>" function:</p>

<pre class="example">
mxml_node_t *node = mxmlFindElement(tree, tree, "name",
				    "attr", "value",
				    MXML_DESCEND);
</pre>

<p>The "name", "attr", and "value" arguments can be passed as
<code>NULL</code> to act as wildcards, e.g.:</p>

<pre class="example">
/* Find the first "a" element */
node = mxmlFindElement(tree, tree, "a", NULL, NULL,
		       MXML_DESCEND);

/* Find the first "a" element with "href" attribute */
node = mxmlFindElement(tree, tree, "a", "href", NULL,
		       MXML_DESCEND);

/* Find the first "a" element with "href" to a URL */
node = mxmlFindElement(tree, tree, "a", "href",
		       "http://www.easysw.com/~mike/mxml/",
		       MXML_DESCEND);

/* Find the first element with a "src" attribute*/
node = mxmlFindElement(tree, tree, NULL, "src", NULL,
		       MXML_DESCEND);

/* Find the first element with a "src" = "foo.jpg" */
node = mxmlFindElement(tree, tree, NULL, "src",
		       "foo.jpg", MXML_DESCEND);
</pre>

<p>You can also iterate with the same function:</p>

<pre class="example">
mxml_node_t *node;

for (node = mxmlFindElement(tree, tree, "name", NULL,
			    NULL, MXML_DESCEND);
     node != NULL;
     node = mxmlFindElement(node, tree, "name", NULL,
			    NULL, MXML_DESCEND))
{
  ... do something ...
}
</pre>

<p>The "mxmlFindPath()" function finds the (first) value node under a specific
element using a "path":</p>

<pre class="example">
mxml_node_t *value = mxmlFindPath(tree, "path/to/*/foo/bar");
</pre>

<p>The "mxmlGetInteger()", "mxmlGetOpaque()", "mxmlGetReal()", and
"mxmlGetText()" functions retrieve the value from a node:</p>

<pre class="example">
mxml_node_t *node;

int intvalue = mxmlGetInteger(node);

const char *opaquevalue = mxmlGetOpaque(node);

double realvalue = mxmlGetReal(node);

int whitespacevalue;
const char *textvalue = mxmlGetText(node, &amp;whitespacevalue);
</pre>

<p>Finally, once you are done with the XML data, use the
"<a href="#mxmlDelete">mxmlDelete()</a>" function to recursively free the
memory that is used for a particular node or the entire tree:</p>

<pre class="example">
mxmlDelete(tree);
</pre>