我有一个格式的文件:
- foo bar - baz one two three - or four and another line - next job do this - and that
我的语法是
grammar tasks {
regex TOP { \n* + \n* }
regex oneTask { ^^ \- ( )+ }
regex oneSection { \N+ } # this is not quite working
regex endSection { \n+ }
}
在正则表达式oneSection中,我如何编写"我想匹配' - '只有当它不在一行开头时"的事实？
我把文件放入一个字符串并解析这个字符串:
my $content = slurp("taskFile");
my $result = tasks.parse($content);
这不太合适.
<[\N] - [\-]> does not make the match conditional.
谢谢 !!
更容易放下你想要匹配的东西而不是试图排除某些东西.
你要找的是一行不是换行符或短划线的一个字符,后跟任意数量的非换行符.或者您正在寻找至少一个不是新行之后的换行符.
regex oneSection {
|| ^^ # beginning of line
<-[\n-]> # not newline or dash
\N* # any number of not newlines
|| # check the position before this is not the start of a line
\N+
}
(这太复杂了,因为你试图将复杂性放在语法中的错误位置)
您也可以像当前一样进行匹配,如果以a开头,则添加一个失败的测试-.
regex oneSection {
\N+
}
语法是一种类,正则表达式/标记/规则是一种方法.所以你应该通过添加换行符和注释来这样写.
如果您学习如何使用%和%%正则表达式运算符,编写语法会更好.
(差异%%可以匹配尾随分隔符)
%有效地使用可能需要一些时间来适应,所以我将向您展示我将如何使用它来匹配您的文件.
我还将部分的分隔符从仅换行更改为换行符和两个空格.这将从section匹配中删除空格,这将简化任何进一步处理.
在学习的过程中,我建议使用Grammar :: Debugger和Grammar :: Tracer.
grammar Tasks {
# use token for its :ratchet behaviour
# ( more performant than regex because it doesn't backtrack )
token TOP {
\n* # ignore any preceding empty lines
+ # at least one task
% # separated by
\n+ # at least one newline
\n* # ignore trailing empty lines
}
token task {
^^ '- ' # a task starts with ?- ? at the beginning of a line
+ # has at least one section
% # separated by
"\n " # a newline and two spaces
}
token section { \N+ }
}
my $test = q:to/END/;
- foo bar - baz
one two three - or four
and another line
- next job
do this - and that
END
put Tasks.parse( $test, :actions(class {
method TOP ($/) { make @».made.List }
method task ($/) { make @».made.List }
method section ($/) {
make ~$/ # don't do any processing, just make it a Str
}
})).made.perl;
# (("foo bar - baz", "one two three - or four", "and another line"),
# ("next job", "do this - and that"))
如果我放在use Grammar::Tracer;顶部,这就是输出的内容:
TOP
| task
| | section
| | * MATCH "foo bar - baz"
| | section
| | * MATCH "one two three - or four"
| | section
| | * MATCH "and another line"
| * MATCH "- foo bar - baz\n one two three - or four\n and another l"
| task
| | section
| | * MATCH "next job"
| | section
| | * MATCH "do this - and that"
| * MATCH "- next job\n do this - and that"
| task
| * FAIL
* MATCH "- foo bar - baz\n one two three - or four\n and another line"
这FAIL是预期的,因为有一个尾随换行符,并且语法知道后可以跟着一个任务.
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