Perl flow charts

Supported languages

Visustin generates flow charts from code written in Perl. The support is current up to Perl 5.12.2. Visustin has been tested with Perl 4.0 and it also works well with other Perl versions.

Supported Perl statements

if..elsif..else
unless..elsif..else
while, until
for, foreach
do
eval
switch..case..else
given..when..default
for|foreach..when..default
modifiers if, unless, while, until, for, foreach, when
next, last, redo
break, continue
goto
return
die, exit, dump
loop and block labels
sub
BEGIN, END
comments

Other statements are supported but have no specific visualization.

Limitations in Perl visualization

Perl is a complicated language to parse and visualize, partially because of its complex use of the punctuation characters. Visustin well is aware of regular expressions, comments, string literals, the qq{} syntax, special variables such as $; and $", the <<EOF syntax and various other peculiarities that make the Perl language such a great but complex tool.

If you encounter a piece of code that doesn't visualize well, try removing any non-code elements such as regular expressions, strings and comments and possibly rewriting the logic with clear statements. Pay attention to the use of punctuation and complicated expressions. Even if it works well, it might not read and visualize so well.

Code inside string literals (for the eval function, for example) is not analyzed.
The structure of expressions is not visualized. For example, the following expressions are not split: conditional expression :?, short-circuited logic such as && or ||, comma-separated expressions. This means that the following idioms are not visualized: chdir $foo || die;
eval {} and do {} are visualized only when used as a standalone statement. For example, in the syntax $value = eval { ... }, none of the eval block contents are visualized as eval used as a part of the assignment statement. Standalone use is visualized well.
Anonymous run-time subprocedures are not supported: $subref = sub {}
Literals and regexes covering multiple lines are not parsed correctly. You may see effects near them. If this happens, remove the line breaks within the literals and try again.
Perl4: The old literal quotation syntax for q{abc} where the delimiter is a space (such as q abc ) is not taken as a literal but as normal code. This only has an effect if the literal contains punctuation.

Notes

switch statement of Switch.pm is supported. By default, there is an implicit last; at the end of each case. If use Switch 'fallthrough'; exists in the code, there is an implicit next; instead. If you use use Switch 'fallthrough'; make sure it is in the input fed to Visustin.
<<HEREDOC is displayed as a comment. The name used in the <<HEREDOC syntax must be in one of the following formats: <<HEREDOC, <<"HEREDOC", <<`HEREDOC` or <<'HEREDOC'. Although legal in Perl, the name HEREDOC cannot be empty.