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<title>Accessing Node (GNU Emacs Lisp Reference Manual)</title>
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<div class="section" id="Accessing-Node">
<div class="header">
<p>
Next: <a href="Pattern-Matching.html" accesskey="n" rel="next">Pattern Matching Tree-sitter Nodes</a>, Previous: <a href="Retrieving-Node.html" accesskey="p" rel="prev">Retrieving Node</a>, Up: <a href="Parsing-Program-Source.html" accesskey="u" rel="up">Parsing Program Source</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<span id="Accessing-Node-Information"></span><h3 class="section">37.4 Accessing Node Information</h3>
<p>Before going further, make sure you have read the basic conventions
about tree-sitter nodes in the previous node.
</p>
<span id="Basic-information"></span><h3 class="heading">Basic information</h3>
<p>Every node is associated with a parser, and that parser is associated
with a buffer. The following functions let you retrieve them.
</p>
<dl class="def">
<dt id="index-treesit_002dnode_002dparser"><span class="category">Function: </span><span><strong>treesit-node-parser</strong> <em>node</em><a href='#index-treesit_002dnode_002dparser' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function returns <var>node</var>’s associated parser.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dbuffer"><span class="category">Function: </span><span><strong>treesit-node-buffer</strong> <em>node</em><a href='#index-treesit_002dnode_002dbuffer' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function returns <var>node</var>’s parser’s associated buffer.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dlanguage"><span class="category">Function: </span><span><strong>treesit-node-language</strong> <em>node</em><a href='#index-treesit_002dnode_002dlanguage' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function returns <var>node</var>’s parser’s associated language.
</p></dd></dl>
<p>Each node represents a piece of text in the buffer. Functions below
finds relevant information about that text.
</p>
<dl class="def">
<dt id="index-treesit_002dnode_002dstart"><span class="category">Function: </span><span><strong>treesit-node-start</strong> <em>node</em><a href='#index-treesit_002dnode_002dstart' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Return the start position of <var>node</var>.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dend"><span class="category">Function: </span><span><strong>treesit-node-end</strong> <em>node</em><a href='#index-treesit_002dnode_002dend' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Return the end position of <var>node</var>.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dtext"><span class="category">Function: </span><span><strong>treesit-node-text</strong> <em>node &optional object</em><a href='#index-treesit_002dnode_002dtext' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Returns the buffer text that <var>node</var> represents. (If <var>node</var> is
retrieved from parsing a string, it will be text from that string.)
</p></dd></dl>
<p>Here are some basic checks on tree-sitter nodes.
</p>
<dl class="def">
<dt id="index-treesit_002dnode_002dp"><span class="category">Function: </span><span><strong>treesit-node-p</strong> <em>object</em><a href='#index-treesit_002dnode_002dp' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Checks if <var>object</var> is a tree-sitter syntax node.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002deq"><span class="category">Function: </span><span><strong>treesit-node-eq</strong> <em>node1 node2</em><a href='#index-treesit_002dnode_002deq' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Checks if <var>node1</var> and <var>node2</var> are the same node in a syntax
tree.
</p></dd></dl>
<span id="Property-information"></span><h3 class="heading">Property information</h3>
<p>In general, nodes in a concrete syntax tree fall into two categories:
<em>named nodes</em> and <em>anonymous nodes</em>. Whether a node is named
or anonymous is determined by the language definition
(see <a href="Language-Definitions.html#tree_002dsitter-named-node">named node</a>).
</p>
<span id="index-tree_002dsitter-missing-node"></span>
<p>Apart from being named/anonymous, a node can have other properties. A
node can be “missing”: missing nodes are inserted by the parser in
order to recover from certain kinds of syntax errors, i.e., something
should probably be there according to the grammar, but not there.
</p>
<span id="index-tree_002dsitter-extra-node"></span>
<p>A node can be “extra”: extra nodes represent things like comments,
which can appear anywhere in the text.
</p>
<span id="index-tree_002dsitter-node-that-has-changes"></span>
<p>A node “has changes” if the buffer changed since when the node is
retrieved, i.e., outdated.
</p>
<span id="index-tree_002dsitter-node-that-has-error"></span>
<p>A node “has error” if the text it spans contains a syntax error. It
can be the node itself has an error, or one of its
children/grandchildren... has an error.
</p>
<dl class="def">
<dt id="index-treesit_002dnode_002dcheck"><span class="category">Function: </span><span><strong>treesit-node-check</strong> <em>node property</em><a href='#index-treesit_002dnode_002dcheck' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function checks if <var>node</var> has <var>property</var>. <var>property</var>
can be <code>'named</code>, <code>'missing</code>, <code>'extra</code>,
<code>'has-changes</code>, or <code>'has-error</code>.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dtype"><span class="category">Function: </span><span><strong>treesit-node-type</strong> <em>node</em><a href='#index-treesit_002dnode_002dtype' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>Named nodes have “types” (see <a href="Language-Definitions.html#tree_002dsitter-node-type">node type</a>).
For example, a named node can be a <code>string_literal</code> node, where
<code>string_literal</code> is its type.
</p>
<p>This function returns <var>node</var>’s type as a string.
</p></dd></dl>
<span id="Information-as-a-child-or-parent"></span><h3 class="heading">Information as a child or parent</h3>
<dl class="def">
<dt id="index-treesit_002dnode_002dindex"><span class="category">Function: </span><span><strong>treesit-node-index</strong> <em>node &optional named</em><a href='#index-treesit_002dnode_002dindex' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function returns the index of <var>node</var> as a child node of its
parent. If <var>named</var> is non-nil, it only count named nodes
(see <a href="Language-Definitions.html#tree_002dsitter-named-node">named node</a>).
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dfield_002dname"><span class="category">Function: </span><span><strong>treesit-node-field-name</strong> <em>node</em><a href='#index-treesit_002dnode_002dfield_002dname' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>A child of a parent node could have a field name (see <a href="Language-Definitions.html#tree_002dsitter-node-field-name">field name</a>). This function returns the field name
of <var>node</var> as a child of its parent.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dnode_002dfield_002dname_002dfor_002dchild"><span class="category">Function: </span><span><strong>treesit-node-field-name-for-child</strong> <em>node n</em><a href='#index-treesit_002dnode_002dfield_002dname_002dfor_002dchild' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function returns the field name of the <var>n</var>’th child of
<var>node</var>.
</p></dd></dl>
<dl class="def">
<dt id="index-treesit_002dchild_002dcount"><span class="category">Function: </span><span><strong>treesit-child-count</strong> <em>node &optional named</em><a href='#index-treesit_002dchild_002dcount' class='copiable-anchor'> ¶</a></span></dt>
<dd><p>This function finds the number of children of <var>node</var>. If
<var>named</var> is non-nil, it only counts named child (see <a href="Language-Definitions.html#tree_002dsitter-named-node">named node</a>).
</p></dd></dl>
</div>
<hr>
<div class="header">
<p>
Next: <a href="Pattern-Matching.html">Pattern Matching Tree-sitter Nodes</a>, Previous: <a href="Retrieving-Node.html">Retrieving Node</a>, Up: <a href="Parsing-Program-Source.html">Parsing Program Source</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
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