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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc (build 1.5.0_13) on Tue Jul 15 15:48:47 NZST 2008 --><TITLE>lalr_item</TITLE><META NAME="keywords" CONTENT="weka.core.parser.java_cup.lalr_item class"><LINK REL ="stylesheet" TYPE="text/css" HREF="../../../../stylesheet.css" TITLE="Style"><SCRIPT type="text/javascript">function windowTitle(){ parent.document.title="lalr_item";}</SCRIPT><NOSCRIPT></NOSCRIPT></HEAD><BODY BGCOLOR="white" onload="windowTitle();"><!-- ========= START OF TOP NAVBAR ======= --><A NAME="navbar_top"><!-- --></A><A HREF="#skip-navbar_top" title="Skip navigation links"></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0" SUMMARY=""><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3" SUMMARY=""> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../index-all.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="http://www.cs.waikato.ac.nz/ml/weka/" target="_blank"><FONT CLASS="NavBarFont1"><B>Weka's home</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../../weka/core/parser/java_cup/internal_error.html" title="class in weka.core.parser.java_cup"><B>PREV CLASS</B></A> <A HREF="../../../../weka/core/parser/java_cup/lalr_item_set.html" title="class in weka.core.parser.java_cup"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../../index.html?weka/core/parser/java_cup/lalr_item.html" target="_top"><B>FRAMES</B></A> <A HREF="lalr_item.html" target="_top"><B>NO FRAMES</B></A> <SCRIPT type="text/javascript"> <!-- if(window==top) { document.writeln('<A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A>'); } //--></SCRIPT><NOSCRIPT> <A HREF="../../../../allclasses-noframe.html"><B>All Classes</B></A></NOSCRIPT></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: NESTED | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><A NAME="skip-navbar_top"></A><!-- ========= END OF TOP NAVBAR ========= --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">weka.core.parser.java_cup</FONT><BR>Class lalr_item</H2><PRE>java.lang.Object <IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html" title="class in weka.core.parser.java_cup">weka.core.parser.java_cup.lr_item_core</A> <IMG SRC="../../../../resources/inherit.gif" ALT="extended by "><B>weka.core.parser.java_cup.lalr_item</B></PRE><HR><DL><DT><PRE>public class <B>lalr_item</B><DT>extends <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html" title="class in weka.core.parser.java_cup">lr_item_core</A></DL></PRE><P>This class represents an LALR item. Each LALR item consists of a production, a "dot" at a position within that production, and a set of lookahead symbols (terminal). (The first two of these parts are provide by the super class). An item is designed to represent a configuration that the parser may be in. For example, an item of the form: <pre> [A ::= B * C d E , {a,b,c}] </pre> indicates that the parser is in the middle of parsing the production <pre> A ::= B C d E </pre> that B has already been parsed, and that we will expect to see a lookahead of either a, b, or c once the complete RHS of this production has been found.<p> Items may initially be missing some items from their lookahead sets. Links are maintained from each item to the set of items that would need to be updated if symbols are added to its lookahead set. During "lookahead propagation", we add symbols to various lookahead sets and propagate these changes across these dependency links as needed.<P><P><DL><DT><B>Version:</B></DT> <DD>last updated: 11/25/95</DD><DT><B>Author:</B></DT> <DD>Scott Hudson</DD><DT><B>See Also:</B><DD><A HREF="../../../../weka/core/parser/java_cup/lalr_item_set.html" title="class in weka.core.parser.java_cup"><CODE>lalr_item_set</CODE></A>, <A HREF="../../../../weka/core/parser/java_cup/lalr_state.html" title="class in weka.core.parser.java_cup"><CODE>lalr_state</CODE></A></DL><HR><P><!-- ======== CONSTRUCTOR SUMMARY ======== --><A NAME="constructor_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>Constructor Summary</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#lalr_item(weka.core.parser.java_cup.production)">lalr_item</A></B>(<A HREF="../../../../weka/core/parser/java_cup/production.html" title="class in weka.core.parser.java_cup">production</A> prod)</CODE><BR> Constructor with default position and empty lookahead set.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#lalr_item(weka.core.parser.java_cup.production, int, weka.core.parser.java_cup.terminal_set)">lalr_item</A></B>(<A HREF="../../../../weka/core/parser/java_cup/production.html" title="class in weka.core.parser.java_cup">production</A> prod, int pos, <A HREF="../../../../weka/core/parser/java_cup/terminal_set.html" title="class in weka.core.parser.java_cup">terminal_set</A> look)</CODE><BR> Full constructor.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#lalr_item(weka.core.parser.java_cup.production, weka.core.parser.java_cup.terminal_set)">lalr_item</A></B>(<A HREF="../../../../weka/core/parser/java_cup/production.html" title="class in weka.core.parser.java_cup">production</A> prod, <A HREF="../../../../weka/core/parser/java_cup/terminal_set.html" title="class in weka.core.parser.java_cup">terminal_set</A> look)</CODE><BR> Constructor with default position (dot at start).</TD></TR></TABLE> <!-- ========== METHOD SUMMARY =========== --><A NAME="method_summary"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor"><TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2"><B>Method Summary</B></FONT></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#add_propagate(weka.core.parser.java_cup.lalr_item)">add_propagate</A></B>(<A HREF="../../../../weka/core/parser/java_cup/lalr_item.html" title="class in weka.core.parser.java_cup">lalr_item</A> prop_to)</CODE><BR> Add a new item to the set of items we propagate to.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../../../weka/core/parser/java_cup/terminal_set.html" title="class in weka.core.parser.java_cup">terminal_set</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#calc_lookahead(weka.core.parser.java_cup.terminal_set)">calc_lookahead</A></B>(<A HREF="../../../../weka/core/parser/java_cup/terminal_set.html" title="class in weka.core.parser.java_cup">terminal_set</A> lookahead_after)</CODE><BR> Calculate lookahead representing symbols that could appear after the symbol that the dot is currently in front of.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#equals(weka.core.parser.java_cup.lalr_item)">equals</A></B>(<A HREF="../../../../weka/core/parser/java_cup/lalr_item.html" title="class in weka.core.parser.java_cup">lalr_item</A> other)</CODE><BR> Equality comparison -- here we only require the cores to be equal since we need to do sets of items based only on core equality (ignoring lookahead sets).</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#equals(java.lang.Object)">equals</A></B>(java.lang.Object other)</CODE><BR> Generic equality comparison.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> int</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#hashCode()">hashCode</A></B>()</CODE><BR> Return a hash code -- here we only hash the core since we only test core matching in LALR items.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> boolean</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#lookahead_visible()">lookahead_visible</A></B>()</CODE><BR> Determine if everything from the symbol one beyond the dot all the way to the end of the right hand side is nullable.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../../../weka/core/parser/java_cup/terminal_set.html" title="class in weka.core.parser.java_cup">terminal_set</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#lookahead()">lookahead</A></B>()</CODE><BR> The lookahead symbols of the item.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> java.util.Stack</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#propagate_items()">propagate_items</A></B>()</CODE><BR> Links to items that the lookahead needs to be propagated to</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> void</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#propagate_lookaheads(weka.core.parser.java_cup.terminal_set)">propagate_lookaheads</A></B>(<A HREF="../../../../weka/core/parser/java_cup/terminal_set.html" title="class in weka.core.parser.java_cup">terminal_set</A> incoming)</CODE><BR> Propagate incoming lookaheads through this item to others need to be changed.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> <A HREF="../../../../weka/core/parser/java_cup/lalr_item.html" title="class in weka.core.parser.java_cup">lalr_item</A></CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#shift()">shift</A></B>()</CODE><BR> Produce the new lalr_item that results from shifting the dot one position to the right.</TD></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1"><CODE> java.lang.String</CODE></FONT></TD><TD><CODE><B><A HREF="../../../../weka/core/parser/java_cup/lalr_item.html#toString()">toString</A></B>()</CODE><BR> Convert to string.</TD></TR></TABLE> <A NAME="methods_inherited_from_class_weka.core.parser.java_cup.lr_item_core"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"><TH ALIGN="left"><B>Methods inherited from class weka.core.parser.java_cup.<A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html" title="class in weka.core.parser.java_cup">lr_item_core</A></B></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE><A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#core_equals(weka.core.parser.java_cup.lr_item_core)">core_equals</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#core_hashCode()">core_hashCode</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#dot_at_end()">dot_at_end</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#dot_before_nt()">dot_before_nt</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#dot_pos()">dot_pos</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#equals(weka.core.parser.java_cup.lr_item_core)">equals</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#shift_core()">shift_core</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#symbol_after_dot()">symbol_after_dot</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#the_production()">the_production</A>, <A HREF="../../../../weka/core/parser/java_cup/lr_item_core.html#to_simple_string()">to_simple_string</A></CODE></TD></TR></TABLE> <A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor"><TH ALIGN="left"><B>Methods inherited from class java.lang.Object</B></TH></TR><TR BGCOLOR="white" CLASS="TableRowColor"><TD><CODE>getClass, notify, notifyAll, wait, wait, wait</CODE></TD></TR></TABLE> <P><!-- ========= CONSTRUCTOR DETAIL ======== --><A NAME="constructor_detail"><!-- --></A><TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY=""><TR 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