1 | ;# Usage: &look(*FILEHANDLE,$key,$dict,$fold)
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2 | #
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3 | # This library is no longer being maintained, and is included for backward
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4 | # compatibility with Perl 4 programs which may require it.
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5 | #
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6 | # In particular, this should not be used as an example of modern Perl
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7 | # programming techniques.
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8 | #
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9 | ;# Sets file position in FILEHANDLE to be first line greater than or equal
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10 | ;# (stringwise) to $key. Pass flags for dictionary order and case folding.
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11 |
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12 | sub look {
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13 | local(*FH,$key,$dict,$fold) = @_;
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14 | local($max,$min,$mid,$_);
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15 | local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,
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16 | $blksize,$blocks) = stat(FH);
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17 | $blksize = 8192 unless $blksize;
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18 | $key =~ s/[^\w\s]//g if $dict;
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19 | $key = lc $key if $fold;
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20 | $max = int($size / $blksize);
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21 | while ($max - $min > 1) {
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22 | $mid = int(($max + $min) / 2);
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23 | seek(FH,$mid * $blksize,0);
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24 | $_ = <FH> if $mid; # probably a partial line
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25 | $_ = <FH>;
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26 | chop;
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27 | s/[^\w\s]//g if $dict;
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28 | $_ = lc $_ if $fold;
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29 | if ($_ lt $key) {
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30 | $min = $mid;
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31 | }
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32 | else {
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33 | $max = $mid;
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34 | }
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35 | }
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36 | $min *= $blksize;
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37 | seek(FH,$min,0);
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38 | <FH> if $min;
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39 | while (<FH>) {
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40 | chop;
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41 | s/[^\w\s]//g if $dict;
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42 | $_ = lc $_ if $fold;
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43 | last if $_ ge $key;
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44 | $min = tell(FH);
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45 | }
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46 | seek(FH,$min,0);
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47 | $min;
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48 | }
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49 |
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50 | 1;
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