[英]perl regex for variable substitution
I want to substitute variables marked by a "#" and terminated by a dot or a non-alphanumeric character. 我想替换以“#”标记并以点或非字母数字字符结尾的变量。 Example: Variable #name should be substituted be "Peter"
示例:应将变量#name替换为“ Peter”
abc#name.def => abcPeterdef abc#namedef => abc#namedef abc#name-def => abcPeter-def
So if the variable is terminated with a dot, it is replaced and the dot removed. 因此,如果变量以点结尾,则将其替换并删除点。 Is it terminated by any non-alphanum character, it is replaced also.
它是否以任何非字母字符终止,也将被替换。
I use the following: 我使用以下内容:
s/#name\./Peter/i
s/#name(\W)/Peter$1/i
This works but is it possible to merge it into one expression? 这可行,但是可以将其合并为一个表达式吗?
There are several possible approaches. 有几种可能的方法。
s/#name(\W)/"Peter" . ($1 eq "." ? "" : $1)/e
Here we use /e
to turn the replacement part into an expression, so we can inspect $1
and choose the replacement string dynamically. 在这里,我们使用
/e
将替换部分转换为表达式,因此我们可以检查$1
并动态选择替换字符串。
s/#name(?|\.()|([^.\w]))/Peter$1/
Here we use (?|
)
to reset the numbering of capture groups between branches, so both \\.()
and ([^.\\w])
set $1
. 在这里,我们使用
(?|
)
重置分支之间捕获组的编号,因此\\.()
和([^.\\w])
设置$1
。 If a .
如果一个
.
is matched, $1
becomes the empty string; 匹配后,
$1
变为空字符串; otherwise it contains the matched character. 否则包含匹配的字符。
You may use 您可以使用
s/#name(?|\.()|(\W))/Peter$1/i
Details 细节
#name
- matches the literal substring #name
匹配文字子串 (?|\\.()|(\\W))
- a branch reset group matching either of the two alternatives: (?|\\.()|(\\W))
-与两个选项之一匹配的分支重置组 :
\\.()
- a dot and then captures an empty string into $1
\\.()
-一个点,然后将一个空字符串捕获到$1
|
- or (\\W)
- any non-word char captured into $1
. (\\W)
-捕获到$1
任何非单词char。 So, upon a match, $1
placeholder is either empty or contains any non-word char other than a dot. 因此,在匹配时,
$1
占位符为空或包含除点以外的任何非单词char。
You can do this by using either a literal dot or a word boundary for the terminator 您可以通过使用文字点或单词边界作为终止符来执行此操作
Like this 像这样
s/#name(?:\.|\b)/Peter/i
Here's a complete program that reproduces the required output shown in your question 这是一个完整的程序,可以再现问题中显示的所需输出
use strict;
use warnings 'all';
for my $s ( 'abc#name.def', 'abc#namedef', 'abc#name-def' ) {
( my $s2 = $s ) =~ s/#name(?:\.|\b)/Peter/i;
printf "%-12s => %-s\n", $s, $s2;
}
abc#name.def => abcPeterdef
abc#namedef => abc#namedef
abc#name-def => abcPeter-def
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