如何匹配scala正则表达式中括号的内容 [英] How do I match the contents of parenthesis in a scala regular expression

问题描述

我正在尝试使用 Scala 正则表达式获取像这样 (2.2,3.4) 这样的字符串的内容，以获得像下面这样的字符串 2.2,3.4

I'm trying to get at the contents of a string like this (2.2,3.4) with a scala regular expression to obtain a string like the following 2.2,3.4

这将使我得到带有括号的字符串以及来自一行其他文本的所有内容:

This will get me the string with parenthesis and all from a line of other text:

"""\(.*?\)"""

但我似乎无法找到只获取括号内容的方法.

But I can't seem to find a way to get just the contents of the parenthesis.

我试过: """\((.*?)\)""" """((.*?))""" 和其他一些组合，但没有运气.

I've tried: """\((.*?)\)""" """((.*?))""" and some other combinations, without luck.

我过去在其他 Java 应用程序中使用过这个:\\((.*?)\\)，这就是为什么我认为 """\((.*?)\)""" 会起作用.

I've used this one in the past in other Java apps: \\((.*?)\\), which is why I thought the first attempt in the line above """\((.*?)\)""" would work.

就我而言，这看起来像:

For my purposes, this looks something like:

var points = "pointA: (2.12, -3.48), pointB: (2.12, -3.48)"
var parenth_contents = """\((.*?)\)""".r;
val center = parenth_contents.findAllIn(points(0));
var cxy = center.next();   
val cx = cxy.split(",")(0).toDouble;

推荐答案

使用 Lookahead 和 Lookbehind

您可以使用此正则表达式:

You can use this regex:

(?<=\()\d+\.\d+,\d+\.\d+(?=\))

或者，如果您不需要括号内的精度:

Or, if you don't need precision inside the parentheses:

(?<=\()[^)]+(?=\))

请参阅演示 1 和 演示 2

说明

• 后视 (?<=\() 断言 (
• \d+\.\d+,\d+\.\d+ 匹配字符串
• 或者，在选项 2 中，[^)]+ 匹配任何不是右括号的字符
• 前瞻(?=\)) 断言接下来是)

• The lookbehind (?<=\() asserts that what precedes is a (
• \d+\.\d+,\d+\.\d+ matches the string
• or, in Option 2, [^)]+ matches any chars that are not a closing parenthesis
• The lookahead (?=\)) asserts that what follows is a )

参考

• 前瞻和后视零长度断言
• 掌握前瞻和后视

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