用替代和可选解析正则表达式 [英] Parsing regex with alternatives and optionals

问题描述

我正在构建 RiveScript 的聊天机器人子集，并尝试使用正则表达式构建模式匹配解析器.哪三个正则表达式与以下三个示例匹配?

I'm building a chatbot subset of RiveScript and trying to build the pattern matching parser with regular expression. Which three regexes match the following three examples?

ex1: I am * years old
valid match:
- "I am 24 years old"
invalid match:
- "I am years old"

ex2: what color is [my|your|his|her] (bright red|blue|green|lemon chiffon) *
valid matches:
- "what color is lemon chiffon car"
- "what color is my some random text till the end of string"

ex3: [*] told me to say *
valid matches:
- "Bob and Alice told me to say hallelujah"
- "told me to say by nobody"

通配符表示可以接受任何不为空的文本.

The wildcards mean any text that is not empty is acceptable.

在示例2中，[ ]之间的任何内容是可选的，( )之间的任何内容都是替代的，每个选项或替代选项之间都用|分隔.

In example 2, anything between [ ] is optional, anything between ( ) is alternative, each option or alternative is separated by a |.

在示例3中，[*]是可选的通配符，表示可以接受空白文本.

In example 3, the [*] is an optional wildcard, meaning blank text can be accepted.

推荐答案

1. https://regex101.com/r/CuZuMi/4

I am (?:\d+) years old

https://regex101.com/r/CuZuMi/2

what color is.*(?:my|your|his|her).*(?:bright red|blue|green|lemon chiffon)?.*

https://regex101.com/r/CuZuMi/3

.*told me to say.*

---

我主要使用两件事:

---

I am using mostly 2 things:

1. (?:)非捕获组，用于将事物分组在一起，例如在数学上使用括号.
2. .*匹配任意字符0次或更多次.可以替换为{1,3}以匹配1到3次.

1. (?:) non-capture groups, to group things together like the parenthesis use on math.
2. .* match any character 0 or more times. Could be replaced by {1,3} to match between 1 and 3 times.

您可以用+交换*以匹配至少1个字符，而不是0. 非捕获组之后的?使该组成为可选.

You can exchange * by + to match at least 1 character, instead of 0. And the ? after the non-capture group, makes that group optional.

这些是您开始的黄金地点:

These are golden place for you to start:

1. http://www.rexegg.com/regex-quickstart.html
2. https://regexone.com/
3. http://www.regular-expressions.info/quickstart.html
4. 参考-此正则表达式是什么意思?

1. http://www.rexegg.com/regex-quickstart.html
2. https://regexone.com/
3. http://www.regular-expressions.info/quickstart.html
4. Reference - What does this regex mean?

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