1 files changed, 44 insertions, 0 deletions
diff --git a/contrib/perl5/lib/look.pl b/contrib/perl5/lib/look.pl
new file mode 100644
index 000000000000..e8dc8aacb6a2
--- /dev/null
+++ b/contrib/perl5/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 = lc $key 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;
+	$_ = lc $_ 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;
+	$_ = lc $_ if $fold;
+	last if $_ ge $key;
+	$min = tell(FH);
+    }
+    seek(FH,$min,0);
+    $min;
+}
+
+1;