用于匹配perl BLOCK的Perl正则表达式

Question

如果块不相互嵌套或自身嵌套,我如何在以下语句中匹配多行块:

       if (EXPR) BLOCK
       if (EXPR) BLOCK else BLOCK
       if (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK
       unless (EXPR) BLOCK
       unless (EXPR) BLOCK else BLOCK
       unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK
       LABEL while (EXPR) BLOCK
       LABEL while (EXPR) BLOCK continue BLOCK
       LABEL until (EXPR) BLOCK
       LABEL until (EXPR) BLOCK continue BLOCK
       LABEL for (EXPR; EXPR; EXPR) BLOCK
       LABEL foreach VAR (LIST) BLOCK
       LABEL foreach VAR (LIST) BLOCK continue BLOCK
       LABEL BLOCK continue BLOCK

如果使用正则表达式无法做到这一点,是否有一个状态机能够这样做？

Answer 1

不要试图自己解析perl.如果你真的需要,使用PPI,这是一个不错的工作.

use PPI;
my $source = 'LABEL: { print "block" } continue { print "cont block" }';
my $doc = PPI::Document->new(\$source);
my $blocks = $doc->find("PPI::Structure::Block");
print ":$_:\n" for @$blocks;