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|
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Modifying document data</title>
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<table width="100%"><tr>
<td>
<a href="http://pugixml.org/">pugixml 1.4</a> manual |
<a href="../manual.html">Overview</a> |
<a href="install.html">Installation</a> |
Document:
<a href="dom.html">Object model</a> · <a href="loading.html">Loading</a> · <a href="access.html">Accessing</a> · <b>Modifying</b> · <a href="saving.html">Saving</a> |
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<hr>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="manual.modify"></a><a class="link" href="modify.html" title="Modifying document data">Modifying document data</a>
</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="modify.html#manual.modify.nodedata">Setting node data</a></span></dt>
<dt><span class="section"><a href="modify.html#manual.modify.attrdata">Setting attribute data</a></span></dt>
<dt><span class="section"><a href="modify.html#manual.modify.add">Adding nodes/attributes</a></span></dt>
<dt><span class="section"><a href="modify.html#manual.modify.remove">Removing nodes/attributes</a></span></dt>
<dt><span class="section"><a href="modify.html#manual.modify.text">Working with text contents</a></span></dt>
<dt><span class="section"><a href="modify.html#manual.modify.clone">Cloning nodes/attributes</a></span></dt>
<dt><span class="section"><a href="modify.html#manual.modify.fragments">Assembling document from fragments</a></span></dt>
</dl></div>
<p>
The document in pugixml is fully mutable: you can completely change the document
structure and modify the data of nodes/attributes. This section provides documentation
for the relevant functions. All functions take care of memory management and
structural integrity themselves, so they always result in structurally valid
tree - however, it is possible to create an invalid XML tree (for example,
by adding two attributes with the same name or by setting attribute/node name
to empty/invalid string). Tree modification is optimized for performance and
for memory consumption, so if you have enough memory you can create documents
from scratch with pugixml and later save them to file/stream instead of relying
on error-prone manual text writing and without too much overhead.
</p>
<p>
All member functions that change node/attribute data or structure are non-constant
and thus can not be called on constant handles. However, you can easily convert
constant handle to non-constant one by simple assignment: <code class="computeroutput"><span class="keyword">void</span>
<span class="identifier">foo</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">)</span>
<span class="special">{</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">nc</span> <span class="special">=</span> <span class="identifier">n</span><span class="special">;</span> <span class="special">}</span></code>, so const-correctness
here mainly provides additional documentation.
</p>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.nodedata"></a><a class="link" href="modify.html#manual.modify.nodedata" title="Setting node data">Setting node data</a>
</h3></div></div></div>
<p>
<a name="xml_node::set_name"></a><a name="xml_node::set_value"></a>As discussed
before, nodes can have name and value, both of which are strings. Depending
on node type, name or value may be absent. <a class="link" href="dom.html#node_document">node_document</a>
nodes do not have a name or value, <a class="link" href="dom.html#node_element">node_element</a>
and <a class="link" href="dom.html#node_declaration">node_declaration</a> nodes always
have a name but never have a value, <a class="link" href="dom.html#node_pcdata">node_pcdata</a>,
<a class="link" href="dom.html#node_cdata">node_cdata</a>, <a class="link" href="dom.html#node_comment">node_comment</a>
and <a class="link" href="dom.html#node_doctype">node_doctype</a> nodes never have a name
but always have a value (it may be empty though), <a class="link" href="dom.html#node_pi">node_pi</a>
nodes always have a name and a value (again, value may be empty). In order
to set node's name or value, you can use the following functions:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">set_name</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
Both functions try to set the name/value to the specified string, and return
the operation result. The operation fails if the node can not have name or
value (for instance, when trying to call <code class="computeroutput"><span class="identifier">set_name</span></code>
on a <a class="link" href="dom.html#node_pcdata">node_pcdata</a> node), if the node handle
is null, or if there is insufficient memory to handle the request. The provided
string is copied into document managed memory and can be destroyed after
the function returns (for example, you can safely pass stack-allocated buffers
to these functions). The name/value content is not verified, so take care
to use only valid XML names, or the document may become malformed.
</p>
<p>
There is no equivalent of <a class="link" href="access.html#xml_node::child_value">child_value</a>
function for modifying text children of the node.
</p>
<p>
This is an example of setting node name and value (<a href="../samples/modify_base.cpp" target="_top">samples/modify_base.cpp</a>):
</p>
<p>
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"node"</span><span class="special">);</span>
<span class="comment">// change node name</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">set_name</span><span class="special">(</span><span class="string">"notnode"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">", new node name: "</span> <span class="special"><<</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">name</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="comment">// change comment text</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">last_child</span><span class="special">().</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"useless comment"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">", new comment text: "</span> <span class="special"><<</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">last_child</span><span class="special">().</span><span class="identifier">value</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="comment">// we can't change value of the element or name of the comment</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"1"</span><span class="special">)</span> <span class="special"><<</span> <span class="string">", "</span> <span class="special"><<</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">last_child</span><span class="special">().</span><span class="identifier">set_name</span><span class="special">(</span><span class="string">"2"</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.attrdata"></a><a class="link" href="modify.html#manual.modify.attrdata" title="Setting attribute data">Setting attribute data</a>
</h3></div></div></div>
<p>
<a name="xml_attribute::set_name"></a><a name="xml_attribute::set_value"></a>All
attributes have name and value, both of which are strings (value may be empty).
You can set them with the following functions:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_name</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
Both functions try to set the name/value to the specified string, and return
the operation result. The operation fails if the attribute handle is null,
or if there is insufficient memory to handle the request. The provided string
is copied into document managed memory and can be destroyed after the function
returns (for example, you can safely pass stack-allocated buffers to these
functions). The name/value content is not verified, so take care to use only
valid XML names, or the document may become malformed.
</p>
<p>
In addition to string functions, several functions are provided for handling
attributes with numbers and booleans as values:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">double</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">bool</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="identifier">set_value</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
The above functions convert the argument to string and then call the base
<code class="computeroutput"><span class="identifier">set_value</span></code> function. Integers
are converted to a decimal form, floating-point numbers are converted to
either decimal or scientific form, depending on the number magnitude, boolean
values are converted to either <code class="computeroutput"><span class="string">"true"</span></code>
or <code class="computeroutput"><span class="string">"false"</span></code>.
</p>
<div class="caution"><table border="0" summary="Caution">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Caution]" src="../images/caution.png"></td>
<th align="left">Caution</th>
</tr>
<tr><td align="left" valign="top"><p>
Number conversion functions depend on current C locale as set with <code class="computeroutput"><span class="identifier">setlocale</span></code>, so may generate unexpected
results if the locale is different from <code class="computeroutput"><span class="string">"C"</span></code>.
</p></td></tr>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
<code class="computeroutput"><span class="identifier">set_value</span></code> overloads with
<code class="computeroutput"><span class="keyword">long</span> <span class="keyword">long</span></code>
type are only available if your platform has reliable support for the type,
including string conversions.
</p></td></tr>
</table></div>
<p>
<a name="xml_attribute::assign"></a>For convenience, all <code class="computeroutput"><span class="identifier">set_value</span></code>
functions have the corresponding assignment operators:
</p>
<pre class="programlisting"><span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">double</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">bool</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">xml_attribute</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
These operators simply call the right <code class="computeroutput"><span class="identifier">set_value</span></code>
function and return the attribute they're called on; the return value of
<code class="computeroutput"><span class="identifier">set_value</span></code> is ignored, so
errors are ignored.
</p>
<p>
This is an example of setting attribute name and value (<a href="../samples/modify_base.cpp" target="_top">samples/modify_base.cpp</a>):
</p>
<p>
</p>
<pre class="programlisting"><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_attribute</span> <span class="identifier">attr</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"id"</span><span class="special">);</span>
<span class="comment">// change attribute name/value</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">set_name</span><span class="special">(</span><span class="string">"key"</span><span class="special">)</span> <span class="special"><<</span> <span class="string">", "</span> <span class="special"><<</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"345"</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">", new attribute: "</span> <span class="special"><<</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">name</span><span class="special">()</span> <span class="special"><<</span> <span class="string">"="</span> <span class="special"><<</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="comment">// we can use numbers or booleans</span>
<span class="identifier">attr</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="number">1.234</span><span class="special">);</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"new attribute value: "</span> <span class="special"><<</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="comment">// we can also use assignment operators for more concise code</span>
<span class="identifier">attr</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"final attribute value: "</span> <span class="special"><<</span> <span class="identifier">attr</span><span class="special">.</span><span class="identifier">value</span><span class="special">()</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
</pre>
<p>
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.add"></a><a class="link" href="modify.html#manual.modify.add" title="Adding nodes/attributes">Adding nodes/attributes</a>
</h3></div></div></div>
<p>
<a name="xml_node::prepend_attribute"></a><a name="xml_node::append_attribute"></a><a name="xml_node::insert_attribute_after"></a><a name="xml_node::insert_attribute_before"></a><a name="xml_node::prepend_child"></a><a name="xml_node::append_child"></a><a name="xml_node::insert_child_after"></a><a name="xml_node::insert_child_before"></a>Nodes
and attributes do not exist without a document tree, so you can't create
them without adding them to some document. A node or attribute can be created
at the end of node/attribute list or before/after some other node:
</p>
<pre class="programlisting"><span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">append_attribute</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">);</span>
<span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">prepend_attribute</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">);</span>
<span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_attribute_after</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">attr</span><span class="special">);</span>
<span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_attribute_before</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">attr</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">append_child</span><span class="special">(</span><span class="identifier">xml_node_type</span> <span class="identifier">type</span> <span class="special">=</span> <span class="identifier">node_element</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">prepend_child</span><span class="special">(</span><span class="identifier">xml_node_type</span> <span class="identifier">type</span> <span class="special">=</span> <span class="identifier">node_element</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_child_after</span><span class="special">(</span><span class="identifier">xml_node_type</span> <span class="identifier">type</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">node</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_child_before</span><span class="special">(</span><span class="identifier">xml_node_type</span> <span class="identifier">type</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">node</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">append_child</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">prepend_child</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_child_after</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">node</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_child_before</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">node</span><span class="special">);</span>
</pre>
<p>
<code class="computeroutput"><span class="identifier">append_attribute</span></code> and <code class="computeroutput"><span class="identifier">append_child</span></code> create a new node/attribute
at the end of the corresponding list of the node the method is called on;
<code class="computeroutput"><span class="identifier">prepend_attribute</span></code> and <code class="computeroutput"><span class="identifier">prepend_child</span></code> create a new node/attribute
at the beginning of the list; <code class="computeroutput"><span class="identifier">insert_attribute_after</span></code>,
<code class="computeroutput"><span class="identifier">insert_attribute_before</span></code>,
<code class="computeroutput"><span class="identifier">insert_child_after</span></code> and <code class="computeroutput"><span class="identifier">insert_attribute_before</span></code> add the node/attribute
before or after the specified node/attribute.
</p>
<p>
Attribute functions create an attribute with the specified name; you can
specify the empty name and change the name later if you want to. Node functions
with the <code class="computeroutput"><span class="identifier">type</span></code> argument create
the node with the specified type; since node type can't be changed, you have
to know the desired type beforehand. Also note that not all types can be
added as children; see below for clarification. Node functions with the
<code class="computeroutput"><span class="identifier">name</span></code> argument create the
element node (<a class="link" href="dom.html#node_element">node_element</a>) with the
specified name.
</p>
<p>
All functions return the handle to the created object on success, and null
handle on failure. There are several reasons for failure:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
Adding fails if the target node is null;
</li>
<li class="listitem">
Only <a class="link" href="dom.html#node_element">node_element</a> nodes can contain
attributes, so attribute adding fails if node is not an element;
</li>
<li class="listitem">
Only <a class="link" href="dom.html#node_document">node_document</a> and <a class="link" href="dom.html#node_element">node_element</a>
nodes can contain children, so child node adding fails if the target
node is not an element or a document;
</li>
<li class="listitem">
<a class="link" href="dom.html#node_document">node_document</a> and <a class="link" href="dom.html#node_null">node_null</a>
nodes can not be inserted as children, so passing <a class="link" href="dom.html#node_document">node_document</a>
or <a class="link" href="dom.html#node_null">node_null</a> value as <code class="computeroutput"><span class="identifier">type</span></code> results in operation failure;
</li>
<li class="listitem">
<a class="link" href="dom.html#node_declaration">node_declaration</a> nodes can only
be added as children of the document node; attempt to insert declaration
node as a child of an element node fails;
</li>
<li class="listitem">
Adding node/attribute results in memory allocation, which may fail;
</li>
<li class="listitem">
Insertion functions fail if the specified node or attribute is null or
is not in the target node's children/attribute list.
</li>
</ul></div>
<p>
Even if the operation fails, the document remains in consistent state, but
the requested node/attribute is not added.
</p>
<div class="caution"><table border="0" summary="Caution">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Caution]" src="../images/caution.png"></td>
<th align="left">Caution</th>
</tr>
<tr><td align="left" valign="top"><p>
attribute() and child() functions do not add attributes or nodes to the
tree, so code like <code class="computeroutput"><span class="identifier">node</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"id"</span><span class="special">)</span> <span class="special">=</span> <span class="number">123</span><span class="special">;</span></code> will not do anything if <code class="computeroutput"><span class="identifier">node</span></code> does not have an attribute with
name <code class="computeroutput"><span class="string">"id"</span></code>. Make sure
you're operating with existing attributes/nodes by adding them if necessary.
</p></td></tr>
</table></div>
<p>
This is an example of adding new attributes/nodes to the document (<a href="../samples/modify_add.cpp" target="_top">samples/modify_add.cpp</a>):
</p>
<p>
</p>
<pre class="programlisting"><span class="comment">// add node with some name</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="string">"node"</span><span class="special">);</span>
<span class="comment">// add description node with text child</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">descr</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="string">"description"</span><span class="special">);</span>
<span class="identifier">descr</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">node_pcdata</span><span class="special">).</span><span class="identifier">set_value</span><span class="special">(</span><span class="string">"Simple node"</span><span class="special">);</span>
<span class="comment">// add param node before the description</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">param</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">insert_child_before</span><span class="special">(</span><span class="string">"param"</span><span class="special">,</span> <span class="identifier">descr</span><span class="special">);</span>
<span class="comment">// add attributes to param node</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">append_attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">)</span> <span class="special">=</span> <span class="string">"version"</span><span class="special">;</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">append_attribute</span><span class="special">(</span><span class="string">"value"</span><span class="special">)</span> <span class="special">=</span> <span class="number">1.1</span><span class="special">;</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">insert_attribute_after</span><span class="special">(</span><span class="string">"type"</span><span class="special">,</span> <span class="identifier">param</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">))</span> <span class="special">=</span> <span class="string">"float"</span><span class="special">;</span>
</pre>
<p>
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.remove"></a><a class="link" href="modify.html#manual.modify.remove" title="Removing nodes/attributes">Removing nodes/attributes</a>
</h3></div></div></div>
<p>
<a name="xml_node::remove_attribute"></a><a name="xml_node::remove_child"></a>If
you do not want your document to contain some node or attribute, you can
remove it with one of the following functions:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">remove_attribute</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">a</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">remove_child</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">n</span><span class="special">);</span>
</pre>
<p>
<code class="computeroutput"><span class="identifier">remove_attribute</span></code> removes
the attribute from the attribute list of the node, and returns the operation
result. <code class="computeroutput"><span class="identifier">remove_child</span></code> removes
the child node with the entire subtree (including all descendant nodes and
attributes) from the document, and returns the operation result. Removing
fails if one of the following is true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
The node the function is called on is null;
</li>
<li class="listitem">
The attribute/node to be removed is null;
</li>
<li class="listitem">
The attribute/node to be removed is not in the node's attribute/child
list.
</li>
</ul></div>
<p>
Removing the attribute or node invalidates all handles to the same underlying
object, and also invalidates all iterators pointing to the same object. Removing
node also invalidates all past-the-end iterators to its attribute or child
node list. Be careful to ensure that all such handles and iterators either
do not exist or are not used after the attribute/node is removed.
</p>
<p>
If you want to remove the attribute or child node by its name, two additional
helper functions are available:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">remove_attribute</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">remove_child</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">name</span><span class="special">);</span>
</pre>
<p>
These functions look for the first attribute or child with the specified
name, and then remove it, returning the result. If there is no attribute
or child with such name, the function returns <code class="computeroutput"><span class="keyword">false</span></code>;
if there are two nodes with the given name, only the first node is deleted.
If you want to delete all nodes with the specified name, you can use code
like this: <code class="computeroutput"><span class="keyword">while</span> <span class="special">(</span><span class="identifier">node</span><span class="special">.</span><span class="identifier">remove_child</span><span class="special">(</span><span class="string">"tool"</span><span class="special">))</span> <span class="special">;</span></code>.
</p>
<p>
This is an example of removing attributes/nodes from the document (<a href="../samples/modify_remove.cpp" target="_top">samples/modify_remove.cpp</a>):
</p>
<p>
</p>
<pre class="programlisting"><span class="comment">// remove description node with the whole subtree</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"node"</span><span class="special">);</span>
<span class="identifier">node</span><span class="special">.</span><span class="identifier">remove_child</span><span class="special">(</span><span class="string">"description"</span><span class="special">);</span>
<span class="comment">// remove id attribute</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">param</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"param"</span><span class="special">);</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">remove_attribute</span><span class="special">(</span><span class="string">"value"</span><span class="special">);</span>
<span class="comment">// we can also remove nodes/attributes by handles</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_attribute</span> <span class="identifier">id</span> <span class="special">=</span> <span class="identifier">param</span><span class="special">.</span><span class="identifier">attribute</span><span class="special">(</span><span class="string">"name"</span><span class="special">);</span>
<span class="identifier">param</span><span class="special">.</span><span class="identifier">remove_attribute</span><span class="special">(</span><span class="identifier">id</span><span class="special">);</span>
</pre>
<p>
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.text"></a><a class="link" href="modify.html#manual.modify.text" title="Working with text contents">Working with text contents</a>
</h3></div></div></div>
<p>
pugixml provides a special class, <code class="computeroutput"><span class="identifier">xml_text</span></code>,
to work with text contents stored as a value of some node, i.e. <code class="computeroutput"><span class="special"><</span><span class="identifier">node</span><span class="special">><</span><span class="identifier">description</span><span class="special">></span><span class="identifier">This</span> <span class="identifier">is</span> <span class="identifier">a</span> <span class="identifier">node</span><span class="special"></</span><span class="identifier">description</span><span class="special">></</span><span class="identifier">node</span><span class="special">></span></code>.
Working with text objects to retrieve data is described in <a class="link" href="access.html#manual.access.text" title="Working with text contents">the
documentation for accessing document data</a>; this section describes
the modification interface of <code class="computeroutput"><span class="identifier">xml_text</span></code>.
</p>
<p>
<a name="xml_text::set"></a>Once you have an <code class="computeroutput"><span class="identifier">xml_text</span></code>
object, you can set the text contents using the following function:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
This function tries to set the contents to the specified string, and returns
the operation result. The operation fails if the text object was retrieved
from a node that can not have a value and is not an element node (i.e. it
is a <a class="link" href="dom.html#node_declaration">node_declaration</a> node), if the
text object is empty, or if there is insufficient memory to handle the request.
The provided string is copied into document managed memory and can be destroyed
after the function returns (for example, you can safely pass stack-allocated
buffers to this function). Note that if the text object was retrieved from
an element node, this function creates the PCDATA child node if necessary
(i.e. if the element node does not have a PCDATA/CDATA child already).
</p>
<p>
<a name="xml_text::set_value"></a>In addition to a string function, several
functions are provided for handling text with numbers and booleans as contents:
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">double</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">bool</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="identifier">set</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
The above functions convert the argument to string and then call the base
<code class="computeroutput"><span class="identifier">set</span></code> function. These functions
have the same semantics as similar <code class="computeroutput"><span class="identifier">xml_attribute</span></code>
functions. You can <a class="link" href="modify.html#xml_attribute::set_value">refer to documentation
for the attribute functions</a> for details.
</p>
<p>
<a name="xml_text::assign"></a>For convenience, all <code class="computeroutput"><span class="identifier">set</span></code>
functions have the corresponding assignment operators:
</p>
<pre class="programlisting"><span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">const</span> <span class="identifier">char_t</span><span class="special">*</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">double</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">bool</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
<span class="identifier">xml_text</span><span class="special">&</span> <span class="identifier">xml_text</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="keyword">unsigned</span> <span class="keyword">long</span> <span class="keyword">long</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<p>
These operators simply call the right <code class="computeroutput"><span class="identifier">set</span></code>
function and return the attribute they're called on; the return value of
<code class="computeroutput"><span class="identifier">set</span></code> is ignored, so errors
are ignored.
</p>
<p>
This is an example of using <code class="computeroutput"><span class="identifier">xml_text</span></code>
object to modify text contents (<a href="../samples/text.cpp" target="_top">samples/text.cpp</a>):
</p>
<p>
</p>
<pre class="programlisting"><span class="comment">// change project version</span>
<span class="identifier">project</span><span class="special">.</span><span class="identifier">child</span><span class="special">(</span><span class="string">"version"</span><span class="special">).</span><span class="identifier">text</span><span class="special">()</span> <span class="special">=</span> <span class="number">1.2</span><span class="special">;</span>
<span class="comment">// add description element and set the contents</span>
<span class="comment">// note that we do not have to explicitly add the node_pcdata child</span>
<span class="identifier">project</span><span class="special">.</span><span class="identifier">append_child</span><span class="special">(</span><span class="string">"description"</span><span class="special">).</span><span class="identifier">text</span><span class="special">().</span><span class="identifier">set</span><span class="special">(</span><span class="string">"a test project"</span><span class="special">);</span>
</pre>
<p>
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.clone"></a><a class="link" href="modify.html#manual.modify.clone" title="Cloning nodes/attributes">Cloning nodes/attributes</a>
</h3></div></div></div>
<p>
<a name="xml_node::prepend_copy"></a><a name="xml_node::append_copy"></a><a name="xml_node::insert_copy_after"></a><a name="xml_node::insert_copy_before"></a>With
the help of previously described functions, it is possible to create trees
with any contents and structure, including cloning the existing data. However
since this is an often needed operation, pugixml provides built-in node/attribute
cloning facilities. Since nodes and attributes do not exist without a document
tree, you can't create a standalone copy - you have to immediately insert
it somewhere in the tree. For this, you can use one of the following functions:
</p>
<pre class="programlisting"><span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">append_copy</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">);</span>
<span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">prepend_copy</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">);</span>
<span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_copy_after</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">attr</span><span class="special">);</span>
<span class="identifier">xml_attribute</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_copy_before</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_attribute</span><span class="special">&</span> <span class="identifier">attr</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">append_copy</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">prepend_copy</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_copy_after</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">node</span><span class="special">);</span>
<span class="identifier">xml_node</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">insert_copy_before</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">proto</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">xml_node</span><span class="special">&</span> <span class="identifier">node</span><span class="special">);</span>
</pre>
<p>
These functions mirror the structure of <code class="computeroutput"><span class="identifier">append_child</span></code>,
<code class="computeroutput"><span class="identifier">prepend_child</span></code>, <code class="computeroutput"><span class="identifier">insert_child_before</span></code> and related functions
- they take the handle to the prototype object, which is to be cloned, insert
a new attribute/node at the appropriate place, and then copy the attribute
data or the whole node subtree to the new object. The functions return the
handle to the resulting duplicate object, or null handle on failure.
</p>
<p>
The attribute is copied along with the name and value; the node is copied
along with its type, name and value; additionally attribute list and all
children are recursively cloned, resulting in the deep subtree clone. The
prototype object can be a part of the same document, or a part of any other
document.
</p>
<p>
The failure conditions resemble those of <code class="computeroutput"><span class="identifier">append_child</span></code>,
<code class="computeroutput"><span class="identifier">insert_child_before</span></code> and related
functions, <a class="link" href="modify.html#xml_node::append_child">consult their documentation
for more information</a>. There are additional caveats specific to cloning
functions:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
Cloning null handles results in operation failure;
</li>
<li class="listitem">
Node cloning starts with insertion of the node of the same type as that
of the prototype; for this reason, cloning functions can not be directly
used to clone entire documents, since <a class="link" href="dom.html#node_document">node_document</a>
is not a valid insertion type. The example below provides a workaround.
</li>
<li class="listitem">
It is possible to copy a subtree as a child of some node inside this
subtree, i.e. <code class="computeroutput"><span class="identifier">node</span><span class="special">.</span><span class="identifier">append_copy</span><span class="special">(</span><span class="identifier">node</span><span class="special">.</span><span class="identifier">parent</span><span class="special">().</span><span class="identifier">parent</span><span class="special">());</span></code>.
This is a valid operation, and it results in a clone of the subtree in
the state before cloning started, i.e. no infinite recursion takes place.
</li>
</ul></div>
<p>
This is an example with one possible implementation of include tags in XML
(<a href="../samples/include.cpp" target="_top">samples/include.cpp</a>). It illustrates
node cloning and usage of other document modification functions:
</p>
<p>
</p>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">load_preprocess</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span><span class="special">&</span> <span class="identifier">doc</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">path</span><span class="special">);</span>
<span class="keyword">bool</span> <span class="identifier">preprocess</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">node</span><span class="special">)</span>
<span class="special">{</span>
<span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">child</span> <span class="special">=</span> <span class="identifier">node</span><span class="special">.</span><span class="identifier">first_child</span><span class="special">();</span> <span class="identifier">child</span><span class="special">;</span> <span class="special">)</span>
<span class="special">{</span>
<span class="keyword">if</span> <span class="special">(</span><span class="identifier">child</span><span class="special">.</span><span class="identifier">type</span><span class="special">()</span> <span class="special">==</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">node_pi</span> <span class="special">&&</span> <span class="identifier">strcmp</span><span class="special">(</span><span class="identifier">child</span><span class="special">.</span><span class="identifier">name</span><span class="special">(),</span> <span class="string">"include"</span><span class="special">)</span> <span class="special">==</span> <span class="number">0</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">include</span> <span class="special">=</span> <span class="identifier">child</span><span class="special">;</span>
<span class="comment">// load new preprocessed document (note: ideally this should handle relative paths)</span>
<span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">path</span> <span class="special">=</span> <span class="identifier">include</span><span class="special">.</span><span class="identifier">value</span><span class="special">();</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span> <span class="identifier">doc</span><span class="special">;</span>
<span class="keyword">if</span> <span class="special">(!</span><span class="identifier">load_preprocess</span><span class="special">(</span><span class="identifier">doc</span><span class="special">,</span> <span class="identifier">path</span><span class="special">))</span> <span class="keyword">return</span> <span class="keyword">false</span><span class="special">;</span>
<span class="comment">// insert the comment marker above include directive</span>
<span class="identifier">node</span><span class="special">.</span><span class="identifier">insert_child_before</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">node_comment</span><span class="special">,</span> <span class="identifier">include</span><span class="special">).</span><span class="identifier">set_value</span><span class="special">(</span><span class="identifier">path</span><span class="special">);</span>
<span class="comment">// copy the document above the include directive (this retains the original order!)</span>
<span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">ic</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">first_child</span><span class="special">();</span> <span class="identifier">ic</span><span class="special">;</span> <span class="identifier">ic</span> <span class="special">=</span> <span class="identifier">ic</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">())</span>
<span class="special">{</span>
<span class="identifier">node</span><span class="special">.</span><span class="identifier">insert_copy_before</span><span class="special">(</span><span class="identifier">ic</span><span class="special">,</span> <span class="identifier">include</span><span class="special">);</span>
<span class="special">}</span>
<span class="comment">// remove the include node and move to the next child</span>
<span class="identifier">child</span> <span class="special">=</span> <span class="identifier">child</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">();</span>
<span class="identifier">node</span><span class="special">.</span><span class="identifier">remove_child</span><span class="special">(</span><span class="identifier">include</span><span class="special">);</span>
<span class="special">}</span>
<span class="keyword">else</span>
<span class="special">{</span>
<span class="keyword">if</span> <span class="special">(!</span><span class="identifier">preprocess</span><span class="special">(</span><span class="identifier">child</span><span class="special">))</span> <span class="keyword">return</span> <span class="keyword">false</span><span class="special">;</span>
<span class="identifier">child</span> <span class="special">=</span> <span class="identifier">child</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">();</span>
<span class="special">}</span>
<span class="special">}</span>
<span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span>
<span class="special">}</span>
<span class="keyword">bool</span> <span class="identifier">load_preprocess</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span><span class="special">&</span> <span class="identifier">doc</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">path</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_parse_result</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">load_file</span><span class="special">(</span><span class="identifier">path</span><span class="special">,</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">parse_default</span> <span class="special">|</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">parse_pi</span><span class="special">);</span> <span class="comment">// for <?include?></span>
<span class="keyword">return</span> <span class="identifier">result</span> <span class="special">?</span> <span class="identifier">preprocess</span><span class="special">(</span><span class="identifier">doc</span><span class="special">)</span> <span class="special">:</span> <span class="keyword">false</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="manual.modify.fragments"></a><a class="link" href="modify.html#manual.modify.fragments" title="Assembling document from fragments">Assembling document from fragments</a>
</h3></div></div></div>
<p>
<a name="xml_node::append_buffer"></a>pugixml provides several ways to assemble
an XML document from other XML documents. Assuming there is a set of document
fragments, represented as in-memory buffers, the implementation choices are
as follows:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
Use a temporary document to parse the data from a string, then clone
the nodes to a destination node. For example:
</li></ul></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">append_fragment</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">target</span><span class="special">,</span> <span class="keyword">const</span> <span class="keyword">char</span><span class="special">*</span> <span class="identifier">buffer</span><span class="special">,</span> <span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">)</span>
<span class="special">{</span>
<span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span> <span class="identifier">doc</span><span class="special">;</span>
<span class="keyword">if</span> <span class="special">(!</span><span class="identifier">doc</span><span class="special">.</span><span class="identifier">load_buffer</span><span class="special">(</span><span class="identifier">buffer</span><span class="special">,</span> <span class="identifier">size</span><span class="special">))</span> <span class="keyword">return</span> <span class="keyword">false</span><span class="special">;</span>
<span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">child</span> <span class="special">=</span> <span class="identifier">doc</span><span class="special">.</span><span class="identifier">first_child</span><span class="special">();</span> <span class="identifier">child</span><span class="special">;</span> <span class="identifier">child</span> <span class="special">=</span> <span class="identifier">child</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">())</span>
<span class="identifier">target</span><span class="special">.</span><span class="identifier">append_copy</span><span class="special">(</span><span class="identifier">child</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
Cache the parsing step - instead of keeping in-memory buffers, keep document
objects that already contain the parsed fragment:
</li></ul></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">append_fragment</span><span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">target</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_document</span><span class="special">&</span> <span class="identifier">cached_fragment</span><span class="special">)</span>
<span class="special">{</span>
<span class="keyword">for</span> <span class="special">(</span><span class="identifier">pugi</span><span class="special">::</span><span class="identifier">xml_node</span> <span class="identifier">child</span> <span class="special">=</span> <span class="identifier">cached_fragment</span><span class="special">.</span><span class="identifier">first_child</span><span class="special">();</span> <span class="identifier">child</span><span class="special">;</span> <span class="identifier">child</span> <span class="special">=</span> <span class="identifier">child</span><span class="special">.</span><span class="identifier">next_sibling</span><span class="special">())</span>
<span class="identifier">target</span><span class="special">.</span><span class="identifier">append_copy</span><span class="special">(</span><span class="identifier">child</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
Use xml_node::append_buffer directly:
</li></ul></div>
<pre class="programlisting"><span class="identifier">xml_parse_result</span> <span class="identifier">xml_node</span><span class="special">::</span><span class="identifier">append_buffer</span><span class="special">(</span><span class="keyword">const</span> <span class="keyword">void</span><span class="special">*</span> <span class="identifier">contents</span><span class="special">,</span> <span class="identifier">size_t</span> <span class="identifier">size</span><span class="special">,</span> <span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">options</span> <span class="special">=</span> <span class="identifier">parse_default</span><span class="special">,</span> <span class="identifier">xml_encoding</span> <span class="identifier">encoding</span> <span class="special">=</span> <span class="identifier">encoding_auto</span><span class="special">);</span>
</pre>
<p>
The first method is more convenient, but slower than the other two. The relative
performance of <code class="computeroutput"><span class="identifier">append_copy</span></code>
and <code class="computeroutput"><span class="identifier">append_buffer</span></code> depends
on the buffer format - usually <code class="computeroutput"><span class="identifier">append_buffer</span></code>
is faster if the buffer is in native encoding (UTF-8 or wchar_t, depending
on <code class="computeroutput"><span class="identifier">PUGIXML_WCHAR_MODE</span></code>). At
the same time it might be less efficient in terms of memory usage - the implementation
makes a copy of the provided buffer, and the copy has the same lifetime as
the document - the memory used by that copy will be reclaimed after the document
is destroyed, but no sooner. Even deleting all nodes in the document, including
the appended ones, won't reclaim the memory.
</p>
<p>
<code class="computeroutput"><span class="identifier">append_buffer</span></code> behaves in
the same way as <a class="link" href="loading.html#xml_document::load_buffer">xml_document::load_buffer</a>
- the input buffer is a byte buffer, with size in bytes; the buffer is not
modified and can be freed after the function returns.
</p>
<p>
<a name="status_append_invalid_root"></a>Since <code class="computeroutput"><span class="identifier">append_buffer</span></code>
needs to append child nodes to the current node, it only works if the current
node is either document or element node. Calling <code class="computeroutput"><span class="identifier">append_buffer</span></code>
on a node with any other type results in an error with <code class="computeroutput"><span class="identifier">status_append_invalid_root</span></code>
status.
</p>
</div>
</div>
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<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2014 Arseny Kapoulkine<p>
Distributed under the MIT License
</p>
</div></td>
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<td>
<a href="http://pugixml.org/">pugixml 1.4</a> manual |
<a href="../manual.html">Overview</a> |
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Document:
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<a href="apiref.html">API Reference</a> |
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