I was recently tasked with making CSV files from a list of tab delimited files.

I slurped the file as they are about 10 Megs and I do my substitutions, but they are slow.

Sample input file looks like:
Foo\tBar\t ... FieldX\n
etc...

I do not need to check for row consistency within the file
# Read File from $INPUT
local $/ = undef;
my $file = <$INPUT>;

# Replace for ", in the file as converting to , " delimiters would cau
+se ", to potentially cause parsing problems in the output files
$file =~ s/\",/,/g;

# Replace tab with "," hard coded for now
$file =~ s/\t/\",\"/g;

# Inserting " at beginning and end of everyline
$file =~ s/\n/\"\n\"/g;

# Remove dangling " at eof if $INPUT ends with \n
$file =~ s/\"\z//;

# Prepend " for first line
$file = '"'.$file;

[download]


I looked at Text::CSV_XS and may end up using that, though I still have a few things to figure out with how to do everything I listed.

However I'm mainly concerned about why these regexs are so expensive. Any insights would be greatly appreciated.

I ran DProf and my report has 98% of run time is tied to these regexs.

In reply to Making CSV Files from Tab Delimited Files by MajingaZ

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