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Diffstat (limited to 'gnu/usr.bin/perl/lib/look.pl')
-rw-r--r-- | gnu/usr.bin/perl/lib/look.pl | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/gnu/usr.bin/perl/lib/look.pl b/gnu/usr.bin/perl/lib/look.pl new file mode 100644 index 0000000..4c14e64 --- /dev/null +++ b/gnu/usr.bin/perl/lib/look.pl @@ -0,0 +1,44 @@ +;# Usage: &look(*FILEHANDLE,$key,$dict,$fold) + +;# Sets file position in FILEHANDLE to be first line greater than or equal +;# (stringwise) to $key. Pass flags for dictionary order and case folding. + +sub look { + local(*FH,$key,$dict,$fold) = @_; + local($max,$min,$mid,$_); + local($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime, + $blksize,$blocks) = stat(FH); + $blksize = 8192 unless $blksize; + $key =~ s/[^\w\s]//g if $dict; + $key =~ y/A-Z/a-z/ if $fold; + $max = int($size / $blksize); + while ($max - $min > 1) { + $mid = int(($max + $min) / 2); + seek(FH,$mid * $blksize,0); + $_ = <FH> if $mid; # probably a partial line + $_ = <FH>; + chop; + s/[^\w\s]//g if $dict; + y/A-Z/a-z/ if $fold; + if ($_ lt $key) { + $min = $mid; + } + else { + $max = $mid; + } + } + $min *= $blksize; + seek(FH,$min,0); + <FH> if $min; + while (<FH>) { + chop; + s/[^\w\s]//g if $dict; + y/A-Z/a-z/ if $fold; + last if $_ ge $key; + $min = tell(FH); + } + seek(FH,$min,0); + $min; +} + +1; |