c# - 以下正则表达式在做什么 (?-mix :{0})

Question

我正在查看这段代码，它正在使用此函数格式化所有正则表达式:

string.Format("(?-mix:{0})", regex);

(?-mix:{0}) 到底是什么意思？ (我知道 {0} 是占位符)。

代码如下:

https://github.com/formosatek/dotliquid/blob/master/src/DotLiquid/Liquid.cs#L36https://github.com/formosatek/dotliquid/blob/master/src/DotLiquid/Util/R.cs#L12

public static string Q(string regex)
        {
            return string.Format("(?-mix:{0})", regex);
        }


public static class Liquid
    {
        internal static readonly ResourceManager ResourceManager = new ResourceManager(typeof(DotLiquid.Properties.Resources));

        public static readonly string FilterSeparator = R.Q(@"\|");
        public static readonly string ArgumentSeparator = R.Q(@",");
        public static readonly string FilterArgumentSeparator = R.Q(@":");
        public static readonly string VariableAttributeSeparator = R.Q(@".");
        public static readonly string TagStart = R.Q(@"\{\%");
        public static readonly string TagEnd = R.Q(@"\%\}");
        public static readonly string VariableSignature = R.Q(@"\(?[\w\-\.\[\]]\)?");
        public static readonly string VariableSegment = R.Q(@"[\w\-]");
        public static readonly string VariableStart = R.Q(@"\{\{");
        public static readonly string VariableEnd = R.Q(@"\}\}");
        public static readonly string VariableIncompleteEnd = R.Q(@"\}\}?");
        public static readonly string QuotedString = R.Q(@"""[^""]*""|'[^']*'");
        public static readonly string QuotedFragment = string.Format(R.Q(@"{0}|(?:[^\s,\|'""]|{0})+"), QuotedString);
        public static readonly string QuotedAssignFragment = string.Format(R.Q(@"{0}|(?:[^\s\|'""]|{0})+"), QuotedString);
        public static readonly string StrictQuotedFragment = R.Q(@"""[^""]+""|'[^']+'|[^\s\|\:\,]+");
        public static readonly string FirstFilterArgument = string.Format(R.Q(@"{0}(?:{1})"), FilterArgumentSeparator, StrictQuotedFragment);
        public static readonly string OtherFilterArgument = string.Format(R.Q(@"{0}(?:{1})"), ArgumentSeparator, StrictQuotedFragment);
        public static readonly string SpacelessFilter = string.Format(R.Q(@"^(?:'[^']+'|""[^""]+""|[^'""])*{0}(?:{1})(?:{2}(?:{3})*)?"), FilterSeparator, StrictQuotedFragment, FirstFilterArgument, OtherFilterArgument);
        public static readonly string Expression = string.Format(R.Q(@"(?:{0}(?:{1})*)"), QuotedFragment, SpacelessFilter);
        public static readonly string TagAttributes = string.Format(R.Q(@"(\w+)\s*\:\s*({0})"), QuotedFragment);
        public static readonly string AnyStartingTag = R.Q(@"\{\{|\{\%");
        public static readonly string PartialTemplateParser = string.Format(R.Q(@"{0}.*?{1}|{2}.*?{3}"), TagStart, TagEnd, VariableStart, VariableIncompleteEnd);
        public static readonly string TemplateParser = string.Format(R.Q(@"({0}|{1})"), PartialTemplateParser, AnyStartingTag);
        public static readonly string VariableParser = string.Format(R.Q(@"\[[^\]]+\]|{0}+\??"), VariableSegment);
        public static readonly string LiteralShorthand = R.Q(@"^(?:\{\{\{\s?)(.*?)(?:\s*\}\}\})$");
        public static readonly string CommentShorthand = R.Q(@"^(?:\{\s?\#\s?)(.*?)(?:\s*\#\s?\})$");

Answer 1

这不是正则表达式 - 它是格式字符串，因为这是对 string.Format 的调用.

这只是格式化字符串并放置 regex 的值变量(或者更确切地说是调用 ToString() 的结果)代替 {0} .

结果是字符串"(?-mix:<whatever regex.ToString() is>)" .

这个字符串看起来可能是一个正则表达式，并且会关闭一些修饰符(因此这将区分大小写，^ 和 $ 仅匹配行的开始和结束以及自由间距模式已关闭)。参见 Regular Expression Advanced Syntax Reference在 www.regular-expressions.info .

所以上面会匹配 regex关闭这些选项。