我正在尝试从看起来像使用.Net Core 2.1标记的字符串中解析键/值对。
考虑下面的示例Program.cs文件...
如何编写模式kvp来表现为“键和值（如果存在）”而不是当前的键或值？
例如，在测试用例2的输出中，代替：
=============================
input = <tag KEY1="vAl1">
--------------------
kvp[0] = KEY1
key = KEY1
value =
--------------------
kvp[1] = vAl1
key =
value = vAl1
=============================
我想看：
=============================
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 =
=============================
如何编写模式value以在与名为“ 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>将由运行时匹配的值（设计时定义的模式不是不是）替换为(?<quotes>[""'`])。
例如，在测试用例5的输出中，代替：
--------------------
kvp[4] = key3='hello,
key =
value = key3='hello,
--------------------
kvp[5] = experts
key =
value = experts
=============================
我想看看（尽管解决了问题1）：
--------------------
kvp[4] = key3
key = key3
value =
--------------------
kvp[5] = hello, "experts"
key =
value = hello, "experts"
=============================
如何编写模式value以在/>之前停止匹配？在测试用例7中，key2的值应为thing-1。我不记得自己尝试过的所有内容，但是我没有找到一种在不破坏测试用例6的情况下有效的模式，其中/ 是值的一部分。 / p>
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"]}");
}
}
}
}
答案 0 :(得分：2)
您可以使用
\s(?<key>[a-z_:][a-z0-9_:.-]*)(?:\s*=\s*(?:(?<q>[`'"])(?<value>.*?)\k<q>|(?<value>(?:(?!/>)[^\s`'"<>])+)))?
请参见regex demo，其中包含高亮组和.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
}
详细信息
\s-空格(?<key>[a-z_:][a-z0-9_:.-]*)-组“键”：一个字母_或:，然后是0+个字母，数字，_，:，{{ 1}}或. --出现一次或零次（因此该值是可选的）：
(?:\s*=\s*(?:(?['"])(?<value>.*?)\k<q>|(?<value>(?:(?!/>)[^\s'"<>])+)))?-一个'"])(?<value>.*?)\k<q>|(?<value>(?:(?!/>)[^\s包含0+空格\s*=\s*-一个非捕获组的开始：
=-分隔符(?:，(?[`'"])或` '-分组“值”，使其与除换行符以外的任何0+个字符尽可能少地匹配"-反向引用组“ q”，相同的值必须匹配(?<value>.*?)-或
\k<q>-组“值”：除空格，|，(?<value>(?:(?!/>)[^\s`'"<>])+)(?<value>，`和'以外的一个字符， 1次或多次出现，没有开始"字符序列<-非捕获组的结尾。