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<div class="sub-title"><span class="module-label-in-type">Module</span>&nbsp;<a href="../../../../../../../module-summary.html">openj9.dtfj</a></div>
<div class="sub-title"><span class="package-label-in-type">Package</span>&nbsp;<a href="package-summary.html">com.ibm.dtfj.javacore.parser.framework.parser</a></div>
<h1 title="Interface ILookAheadBuffer" class="title">Interface ILookAheadBuffer</h1>
</div>
<section class="description">
<dl class="notes">
<dt>All Known Implementing Classes:</dt>
<dd><code><a href="../scanner/LookAheadBuffer.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">LookAheadBuffer</a></code></dd>
</dl>
<hr>
<div class="type-signature"><span class="modifiers">public interface </span><span class="element-name type-name-label">ILookAheadBuffer</span></div>
<div class="block">Prediction buffer that holds a certain number of tokens. Tokens are consumed when the are matched, and the buffer
is kept filled all the time until end of token stream is reached.</div>
</section>
<section class="summary">
<ul class="summary-list">
<!-- ========== METHOD SUMMARY =========== -->
<li>
<section class="method-summary" id="method.summary">
<h2>Method Summary</h2>
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<div class="table-tabs" role="tablist" aria-orientation="horizontal"><button id="method-summary-table-tab0" role="tab" aria-selected="true" aria-controls="method-summary-table.tabpanel" tabindex="0" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table', 3)" class="active-table-tab">All Methods</button><button id="method-summary-table-tab2" role="tab" aria-selected="false" aria-controls="method-summary-table.tabpanel" tabindex="-1" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table-tab2', 3)" class="table-tab">Instance Methods</button><button id="method-summary-table-tab3" role="tab" aria-selected="false" aria-controls="method-summary-table.tabpanel" tabindex="-1" onkeydown="switchTab(event)" onclick="show('method-summary-table', 'method-summary-table-tab3', 3)" class="table-tab">Abstract Methods</button></div>
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<div class="table-header col-first">Modifier and Type</div>
<div class="table-header col-second">Method</div>
<div class="table-header col-last">Description</div>
<div class="col-first even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>boolean</code></div>
<div class="col-second even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#allConsumed()">allConsumed</a></span>()</code></div>
<div class="col-last even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">&nbsp;</div>
<div class="col-first odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>void</code></div>
<div class="col-second odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#consume()">consume</a></span>()</code></div>
<div class="col-last odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">
<div class="block">Consumes the first element of the buffer.</div>
</div>
<div class="col-first even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>void</code></div>
<div class="col-second even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#init()">init</a></span>()</code></div>
<div class="col-last even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">&nbsp;</div>
<div class="col-first odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>int</code></div>
<div class="col-second odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#length()">length</a></span>()</code></div>
<div class="col-last odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">&nbsp;</div>
<div class="col-first even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><a href="../scanner/IParserToken.html" title="interface in com.ibm.dtfj.javacore.parser.framework.scanner">IParserToken</a></code></div>
<div class="col-second even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#lookAhead(int)">lookAhead</a></span>&#8203;(int&nbsp;depth)</code></div>
<div class="col-last even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">
<div class="block">Looks ahead by a depth amount.</div>
</div>
<div class="col-first odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>boolean</code></div>
<div class="col-second odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#match(java.lang.String)">match</a></span>&#8203;(<a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link" target="_blank">String</a>&nbsp;type)</code></div>
<div class="col-last odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">
<div class="block">Matches a given type to the token type found at the first element of the buffer.</div>
</div>
<div class="col-first even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>int</code></div>
<div class="col-second even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#maxDepth()">maxDepth</a></span>()</code></div>
<div class="col-last even-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">&nbsp;</div>
<div class="col-first odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code>void</code></div>
<div class="col-second odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3"><code><span class="member-name-link"><a href="#setLookAheadDepth(int)">setLookAheadDepth</a></span>&#8203;(int&nbsp;depth)</code></div>
<div class="col-last odd-row-color method-summary-table-tab2 method-summary-table method-summary-table-tab3">
<div class="block">Depth of the lookahead can be changed after creation.</div>
</div>
</div>
</div>
</div>
</section>
</li>
</ul>
</section>
<section class="details">
<ul class="details-list">
<!-- ============ METHOD DETAIL ========== -->
<li>
<section class="method-details" id="method.detail">
<h2>Method Details</h2>
<ul class="member-list">
<li>
<section class="detail" id="match(java.lang.String)">
<h3>match</h3>
<div class="member-signature"><span class="return-type">boolean</span>&nbsp;<span class="element-name">match</span>&#8203;<span class="parameters">(<a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/String.html" title="class or interface in java.lang" class="external-link" target="_blank">String</a>&nbsp;type)</span></div>
<div class="block">Matches a given type to the token type found at the first element of the buffer.</div>
<dl class="notes">
<dt>Parameters:</dt>
<dd><code>type</code> - to match against first element in buffer</dd>
<dt>Returns:</dt>
<dd>true if match is successful</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="consume()">
<h3>consume</h3>
<div class="member-signature"><span class="return-type">void</span>&nbsp;<span class="element-name">consume</span>()
throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a>,
<a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></span></div>
<div class="block">Consumes the first element of the buffer.</div>
<dl class="notes">
<dt>Throws:</dt>
<dd><code><a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></code></dd>
<dd><code><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a></code></dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="allConsumed()">
<h3>allConsumed</h3>
<div class="member-signature"><span class="return-type">boolean</span>&nbsp;<span class="element-name">allConsumed</span>()</div>
<dl class="notes">
<dt>Returns:</dt>
<dd>true if all tokens from both the input stream and the lookahead buffer have been consumed</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="lookAhead(int)">
<h3>lookAhead</h3>
<div class="member-signature"><span class="return-type"><a href="../scanner/IParserToken.html" title="interface in com.ibm.dtfj.javacore.parser.framework.scanner">IParserToken</a></span>&nbsp;<span class="element-name">lookAhead</span>&#8203;<span class="parameters">(int&nbsp;depth)</span>
throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a>,
<a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a>,
<a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/IndexOutOfBoundsException.html" title="class or interface in java.lang" class="external-link" target="_blank">IndexOutOfBoundsException</a></span></div>
<div class="block">Looks ahead by a depth amount. The lowest depth to look ahead is 1. Note that in some cases,
a lookahead may be attempted on an earlier error condition that lead to an empty buffer (e.g.,
an exception was thrown during a fill process, and although more tokens may remain in the
input source, the lookahead value may itself be null. Consequently, the lookahead buffer refills first
before attempting the lookahead.</div>
<dl class="notes">
<dt>Parameters:</dt>
<dd><code>depth</code> - to lookahead</dd>
<dt>Returns:</dt>
<dd>token at specified lookahead depth or <a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/IndexOutOfBoundsException.html" title="class or interface in java.lang" class="external-link" target="_blank"><code>IndexOutOfBoundsException</code></a>.</dd>
<dt>Throws:</dt>
<dd><code><a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></code></dd>
<dd><code><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a></code></dd>
<dd><code><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/lang/IndexOutOfBoundsException.html" title="class or interface in java.lang" class="external-link" target="_blank">IndexOutOfBoundsException</a></code> - if depth is outside the depth range of the buffer. Minimum depth is always 1.</dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="length()">
<h3>length</h3>
<div class="member-signature"><span class="return-type">int</span>&nbsp;<span class="element-name">length</span>()</div>
</section>
</li>
<li>
<section class="detail" id="maxDepth()">
<h3>maxDepth</h3>
<div class="member-signature"><span class="return-type">int</span>&nbsp;<span class="element-name">maxDepth</span>()</div>
</section>
</li>
<li>
<section class="detail" id="init()">
<h3>init</h3>
<div class="member-signature"><span class="return-type">void</span>&nbsp;<span class="element-name">init</span>()
throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a>,
<a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></span></div>
<dl class="notes">
<dt>Throws:</dt>
<dd><code><a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></code></dd>
<dd><code><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a></code></dd>
</dl>
</section>
</li>
<li>
<section class="detail" id="setLookAheadDepth(int)">
<h3>setLookAheadDepth</h3>
<div class="member-signature"><span class="return-type">void</span>&nbsp;<span class="element-name">setLookAheadDepth</span>&#8203;<span class="parameters">(int&nbsp;depth)</span>
throws <span class="exceptions"><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a>,
<a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></span></div>
<div class="block">Depth of the lookahead can be changed after creation.
<br>
If the new depth is less that the current depth,
no new tokens will be read until the outstanding tokens (current depth - new depth)
are first consumed.
<br>
If the new depth is greater than the current depth,
the lookahead will read new tokens to fill the delta.
<br></div>
<dl class="notes">
<dt>Parameters:</dt>
<dd><code>depth</code> - to change</dd>
<dt>Throws:</dt>
<dd><code><a href="../scanner/ScannerException.html" title="class in com.ibm.dtfj.javacore.parser.framework.scanner">ScannerException</a></code> - as increasing the current depth of the buffer requires to fill the buffer to the new length</dd>
<dd><code><a href="https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/io/IOException.html" title="class or interface in java.io" class="external-link" target="_blank">IOException</a></code></dd>
</dl>
</section>
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