javascript - 正则表达式从字符串中提取一组单词

Question

问题陈述 -

我们需要从字符串中提取一组连续出现的单词。

最简单的示例如下所示，具有预期的输入和输出。

set of words => "word1|word2|word3";

Input string => "i m word1 word2 and this is word3 word2 word1+ i am having this word2 word3.";"

Output => word1 word2
          word3 word2 word1
          word2 word3

注意 -- 请注意“word1+”和“word3”中没有空格。

请将此视为最简单的输入。复杂性可以达到任何程度。意味着可以有多个单词集(比如 500 个单词)，我们需要从输入字符串中找到同时出现的那些单词集。

我在 javascript 中执行此操作，因此我尝试的如下。

var pattern = "word1|word2|word3";
var regobj = new RegExp('((('+pattern+')\\s?)+)', "g");

我的解决方案有什么问题？

For Input string => "i m word1word2 and this is word3word2 word1+ i am having this word2 word3.";"

it will give output as 
word1word2        -- wrong
word3word2 word1  -- wrong 
word2 word3

我为什么要这个？或实时用例..!

我想从一个复杂的表达式中提取单词编号。比如说

"one thousand two+three hundred four+1.3456+log(twenty)"

所以这里我需要提取

one thousand two
three hundred four
twenty

并且需要替换它各自的等效数值。

Answer 1

使用单词边界:

\b(?:word1|word2|word3)\b

Perl 中完整的正则表达式:

my $str = 'i m word1word2 and this is word3 word2 word1+ i am having this word2 word3.';
my @l = ($str =~ /((?:\b(?:word1|word2|word3)\b(?:\s|\.))+)/g);
dump@l;

输出:

("word3 word2 ", "word2 word3.")

最后一个表达式:

my $str = 'one thousand two+three hundred four+1.3456+log(twenty)';
my @l = ($str =~ /((?:\b(?:one|two|three|four|twenty|hundred|thousand)\b\s*)+)/g);
dump@l;

输出:

("one thousand two", "three hundred four", "twenty")