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<!DOCTYPE html>
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<head>
<title>LuaExpat: XML Expat parsing for the Lua programming language</title>
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<div id="product_name"><big><strong>LuaExpat</strong></big></div>
<div id="product_description">XML Expat parsing for the Lua programming language</div>
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<h2><a name="introduction"></a>Introduction</h2>
<p>Lua Object Model (LOM) is a representation of XML elements
through Lua data types. Currently it is not supposed to be 100%
complete, but simple. LuaExpat provides an implementation of LOM that
gets an XML document and transforms it to a Lua table.
</p>
<h2><a name="characteristics"></a>Characteristics</h2>
<p>The model represents each XML element as a Lua table. A LOM
table has three special characteristics:</p>
<ul>
<li>a special field called <strong><code>tag</code></strong> that holds the
element's name;</li>
<li>an optional field called <strong><code>attr</code></strong> that stores
the element's attributes; and</li>
<li>the element's children are stored at the <em>array-part</em> of
the table. A child could be an ordinary string or another XML
element that will be represented by a Lua table following these
same rules.</li>
</ul>
<p>The special field <strong><code>attr</code></strong> is a Lua table that
stores the XML element's attributes as pairs
<em><key>=<value></em>. To assure an order (if
necessary), the sequence of <em>key</em>s could be placed at the
<em>array-part</em> of this same table.</p>
<h3>Functions</h3>
<dl class="reference">
<dt><strong>lom.parse(string|function|table|file[, opts])</strong></dt>
<dd>Parses the input into the LOM table format and returns it. The input can be;
<ul>
<li><em>string</em>: the entire XML document as a string</li>
<li><em>function</em>: an iterator that returns the next chunk of the
XML document on each call, and returns <em>nil</em> when finished</li>
<li><em>table</em>: an array like table that contains the chunks
that combined make up the XML document</li>
<li><em>file</em>: an open file handle from which the XML document will
be read line-by-line, using <code>read()</code>. <strong>Note</strong>:
the file will not be closed when done.</li>
</ul>
The second parameter <em>opts</em> is an options table that supports the
following options;
<ul>
<li><em>separator (string)</em>: the namespace separator character to use, setting
this will enable namespace aware parsing.</li>
<li><em>threat (table)</em>: a <a href="threat.html#options">threat
protection options</a> table. If provided the threat protection parser
will be used instead of the regular <em>lxp</em> parser.</li>
</ul>
Upon parsing errors it will return <code>nil, err, line, col, pos</code>.
</dd>
<dt><strong>lom.find_elem(node, tag)</strong></dt>
<dd>Traverses the tree recursively, and returns the first element that matches
the <em>tag</em>. Parameter <em>tag</em> (string) is the tag name to look for.
The <em>node</em> table can be the result from the <em>parse</em> function, or
any of its children.</dd>
<dt><strong>lom.list_children(node[, tag])</strong></dt>
<dd>Iterator returning all child tags of a node (non-recursive). It will only
children that are tags, and will skip text-nodes.
The <em>node</em> table can be the result from the <em>parse</em> function, or
any of its children.
If the optional parameter <em>tag</em> (string) is given, then the iterator
will only return tags that match the tag name.
</dd>
</dl>
<h2><a name="examples"></a>Examples</h2>
<p>For a simple string like</p>
<pre class="example">
s = [[<abc a1="A1" a2="A2">inside tag `abc'</abc>]]
</pre>
<p>A call like</p>
<pre class="example">
tab = lxp.lom.parse (s))
</pre>
<p>Would result in a table equivalent to</p>
<pre class="example">
tab = {
["attr"] = {
[1] = "a1",
[2] = "a2",
["a2"] = "A2",
["a1"] = "A1",
},
[1] = "inside tag `abc'",
["tag"] = "abc",
}
</pre>
<p>Now an example with an element nested inside another element</p>
<pre class="example">
tab = lxp.lom.parse(
[[<qwerty q1="q1" q2="q2">
<asdf>some text</asdf>
</qwerty>]]
)
</pre>
<p>The result would have been a table equivalent to</p>
<pre class="example">
tab = {
[1] = "\
",
[2] = {
["attr"] = {
},
[1] = "some text",
["tag"] = "asdf",
},
["attr"] = {
[1] = "q1",
[2] = "q2",
["q2"] = "q2",
["q1"] = "q1",
},
[3] = "\
",
["tag"] = "qwerty",
}
</pre>
<p>Note that even the <em>new-line</em> and <em>tab</em> characters are stored
on the table.</p>
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