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   6 <TITLE>The SUIF Version 1 Library - Lexicon</TITLE>
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  17 <H2><A NAME="SEC102" HREF="suif1_toc.html#TOC102">Lexicon</A></H2>
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  26 Almost all character strings in SUIF are entered in a hash table called
  27 the <CODE>lexicon</CODE>.  This table removes duplicate strings so that string
  28 comparisons can be reduced to simple pointer comparisons.  The
  29 <CODE>lexicon</CODE> is an object of the <CODE>string_table</CODE> class defined in
  30 the <TT>`stringtable.h'</TT> and <TT>`stringtable.cc'</TT> files.
  31
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  36 A <CODE>string_table</CODE> is an open hash table; each bucket is a linked
  37 list of string entries represented by objects of the <CODE>string_e</CODE>
  38 class.  The only public method in the <CODE>string_table</CODE> class is
  39 called <CODE>enter</CODE>.  This method searches the table for a specified
  40 string.  If the string is found, <CODE>enter</CODE> returns a pointer to the
  41 existing <CODE>string_e</CODE> entry.  Otherwise, it creates a new entry and
  42 adds it to the table.  In either case, the actual character string
  43 pointer can be retrieved directly from the <CODE>sp</CODE> field of the
  44 resulting <CODE>string_e</CODE> entry.
  45
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  47 <P>
  48 None of the strings in the <CODE>lexicon</CODE> are deallocated until a SUIF
  49 program terminates.  Consequently, when adding a new string to the
  50 table, it is copied to the heap in case the original string is stored on
  51 the stack.  If the string is known to be allocated on the heap and will
  52 never be modified or deallocated, this string copy can be avoided by
  53 setting the optional <CODE>fixed</CODE> flag when calling <CODE>enter</CODE>.
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