29 lines
691 B
C
29 lines
691 B
C
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/*
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* Copyright (c) 1992 by the University of Southern California
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*
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* For copying and distribution information, please see the file <usc-copyr.h>
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*/
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/* Author: Steven Augart, swa@isi.edu */
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#include <usc-copyr.h>
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#include <stdio.h>
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#include <pfs.h>
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extern int pfs_debug;
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/* Return the NTH element of a sequence S. Indexing starts at zero. Works
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just like the Common LISP ELT function. */
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char *
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elt(TOKEN s, int nth)
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{
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if (nth < 0) {
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if (pfs_debug)
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fprintf(stderr, "elt() called with illegal negative index %d\n",
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nth);
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return NULL;
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}
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for (; s && nth > 0; s = s->next, --nth)
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;
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return s ? s->token : NULL;
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}
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