我正在尝试使用 .Net Core 2.1 从看起来像标记的字符串中解析键值对。
考虑下面的示例 Program.cs 文件...
我的问题是:
1.
我怎样才能写出模式 kvp
充当“键和值(如果存在)”而不是当前行为的“键或值”?
例如,在测试用例2的输出中,而不是:
=============================
input = <tag KEY1="vAl1">
--------------------
kvp[0] = KEY1
key = KEY1
value =
--------------------
kvp[1] = vAl1
key =
value = vAl1
=============================
我想看看:
=============================
input = <tag KEY1="vAl1">
--------------------
kvp[0] = KEY1="vAl1"
key = KEY1
value = vAl1
=============================
不破坏测试用例 9:
=============================
input = <tag noValue1 noValue2>
--------------------
kvp[0] = noValue1
key = noValue1
value =
--------------------
kvp[1] = noValue2
key = noValue2
value =
=============================
2.
我怎样才能写出模式 value
在名为“quotes”的组匹配的下一个字符处停止匹配?换句话说,下一个平衡报价。我显然误解了反向引用的工作原理,我的理解是 \k<quotes>
将替换为运行时匹配的值(不是设计时定义的模式)由 (?<quotes>[""'`])
.
例如,在测试用例5的输出中,而不是:
--------------------
kvp[4] = key3='hello,
key =
value = key3='hello,
--------------------
kvp[5] = experts
key =
value = experts
=============================
我想看看(尽管有问题 1 的解决方案):
--------------------
kvp[4] = key3
key = key3
value =
--------------------
kvp[5] = hello, "experts"
key =
value = hello, "experts"
=============================
3.
我怎样才能写出模式 value
在 />
之前停止匹配?在测试用例 7 中,key2
的值应该是 thing-1
.我不记得我尝试过的所有内容,但我还没有找到一种在不破坏测试用例 6 的情况下工作的模式,其中 /
是值的一部分。
程序.cs
using System;
using System.Reflection;
using System.Text.RegularExpressions;
namespace ConsoleApp1
{
class Program
{
static void Main(string[] args)
{
RegExTest();
Console.ReadLine();
}
static void RegExTest()
{
// Test Cases
var case1 = @"<tag>";
var case2 = @"<tag KEY1=""vAl1"">";
var case3 = @"<tag kEy2='val2'>";
var case4 = @"<tag key3=`VAL3`>";
var case5 = @"<tag key1='val1'
key2=""http://www.w3.org"" key3='hello, ""experts""'>";
var case6 = @"<tag :key1 =some/thing>";
var case7 = @"<tag key2=thing-1/>";
var case8 = @"<tag key3 = thing-2>";
var case9 = @"<tag noValue1 noValue2>";
var case10 = @"<tag/>";
var case11 = @"<tag />";
// A key may begin with a letter, underscore or colon, follow by
// zero or more of those, or numbers, periods, or dashs.
string key = @"(?<key>(?<=\s+)[a-z_:][a-z0-9_:\.-]*?(?=[\s=>]+))";
// A value may contain any character, and must be wrapped in balanced quotes (double, single,
// or back) if the value contains any quote, whitespace, equal, or greater- or less- than
// character.
string value = @"(?<value>((?<=(?<quotes>[""'`])).*?(?=\k<quotes>)|(?<=[=][\s]*)[^""'`\s=<>]+))";
// A key-value pair must contain a key,
// a value is optional
string kvp = $"(?<kvp>{key}|{value})"; // Without the | (pipe), it doesn't match any test case...
// ...value needs to be optional (case9), tried:
//kvp = $"(?<kvp>{key}{value}?)";
//kvp = $"(?<kvp>{key}({value}?))";
//kvp = $"(?<kvp>{key}({value})?)";
// ...each only matches key, but also matches value in case8 as key
Regex getKvps = new Regex(kvp, RegexOptions.IgnoreCase);
FormatMatches(getKvps.Matches(case1)); // OK
FormatMatches(getKvps.Matches(case2)); // OK
FormatMatches(getKvps.Matches(case3)); // OK
FormatMatches(getKvps.Matches(case4)); // OK
FormatMatches(getKvps.Matches(case5)); // Backreference and/or lazy qualifier doesn't work.
FormatMatches(getKvps.Matches(case6)); // OK
FormatMatches(getKvps.Matches(case7)); // The / is not part of the value.
FormatMatches(getKvps.Matches(case8)); // OK
FormatMatches(getKvps.Matches(case9)); // OK
FormatMatches(getKvps.Matches(case10)); // OK
FormatMatches(getKvps.Matches(case11)); // OK
}
static void FormatMatches(MatchCollection matches)
{
Console.WriteLine(new string('=', 78));
var _input = matches.GetType().GetField("_input",
BindingFlags.NonPublic |
BindingFlags.Instance)
.GetValue(matches);
Console.WriteLine($"input = {_input}");
Console.WriteLine();
if (matches.Count < 1)
{
Console.WriteLine("[kvp not matched]");
return;
}
for (int i = 0; i < matches.Count; i++)
{
Console.WriteLine(new string('-', 20));
Console.WriteLine($"kvp[{i}] = {matches[i].Groups["kvp"]}");
Console.WriteLine($"\t key\t=\t{matches[i].Groups["key"]}");
Console.WriteLine($"\tvalue\t=\t{matches[i].Groups["value"]}");
}
}
}
}
最佳答案
你可以使用
\s(?<key>[a-z_:][a-z0-9_:.-]*)(?:\s*=\s*(?:(?<q>[`'"])(?<value>.*?)\k<q>|(?<value>(?:(?!/>)[^\s`'"<>])+)))?
参见 regex demo突出显示组和 .NET regex demo (证明)。
C# 用法:
var pattern = @"\s(?<key>[a-z_:][a-z0-9_:.-]*)(?:\s*=\s*(?:(?<q>[`'""])(?<value>.*?)\k<q>|(?<value>(?:(?!/>)[^\s`'""<>])+)))?";
var matches = Regex.Matches(case, pattern, RegexOptions.IgnoreCase);
foreach (Match m in matches)
{
Console.WriteLine(m.Value); // The whole match
Console.WriteLine(m.Groups["key"].Value); // Group "key" value
Console.WriteLine(m.Groups["value"].Value); // Group "value" value
}
详情
-
\s
- 一个空格 -
(?<key>[a-z_:][a-z0-9_:.-]*)
- 组“键”:一封信,_
或:
然后是 0+ 个字母、数字、_
,:
,.
或-
-
(?:\s*=\s*(?:(?[<code>'"])(?<value>.*?)\k<q>|(?<value>(?:(?!/>)[^\s</code>'"<>])+)))?
- 一次或零次出现(因此该值是可选的):-
\s*=\s*
- 一个=
用 0+ 个空格括起来 -
(?:
- 非捕获组的开始:-
(?[`'"])
- 分隔符,`
,'
或"
-
(?<value>.*?)
- 将匹配除换行字符以外的任何 0+ 个字符的“值”分组尽可能少 -
\k<q>
- 对组“q”的反向引用,相同的值必须匹配
-
-
|
- 或者-
<code>(?<value></code>(?:(?!/>)[^\s`'"<>])+)
- 组“值”:空格以外的字符,`
,'
,"
,<
和>
,出现 1 次或多次,不会启动/>
字符序列
-
-
-
)
- 非捕获组结束。
关于c# - .Net Core 正则表达式、命名组、嵌套组、反向引用和惰性限定符,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53365251/