正則表達式匹配（貪婪/不真實？）

Question

我正在遇到一些麻煩，「挑選」這些數據「分開」。 Altough幫助函數等是的一個選項，我真的很想解決這個問題，只使用正則表達式（匹配後處理matchgroups）。

這是（部分）我有數據：

Belgium 
Belgium M_Foo 
Belgium A_Bar 
Belgium M_FooBar 
Belgium S_Whooptee Doo 
Belgium Xxx 
Belgium S_Foo Bar 
United Kingdom 
United Kingdom W_Foo-Bar 
United Kingdom M_Yay 
United Kingdom Xxx 
United Kingdom S_Derp 
United Kingdom F_Doh Lorem 
United Kingdom S_Ipsum Dolor 
United States of America L_Foo 
Macedonia F.Y.R. Xxx 
Macedonia F.Y.R. S_Foo Bar 
Cyprus (Greek) M_Foo 
Congo (Democratic Republic of) 
Congo (Democratic Republic of) Q_Yolo 

本質上這是一個「鍵/值」排序字符串數組的。它包含一個國家/地區名稱（未歸一化，因此我不能使用硬編碼的國家/地區名稱或「查找」，它可能是其他字符串，而不是國家/地區名稱），並且optionally後跟關鍵字Xxx或<random_upcase_char>_<random_text>。

我想出了下面的正則表達式：

^(.+?)(?:\s+(Xxx|[A-Z]_.*)?) 

，或者在第一matchgroup的小分歧：

^(.*?)(?:\s+(Xxx|[A-Z]_.*)?) 

這工作正常啓動與Belgium第一個字符串。它返回，對於這些記錄，結果如下：

Group 1  Group 2 
================================ 
Belgium 
Belgium  M_Foo 
Belgium  A_Bar 
Belgium  M_FooBar 
Belgium  S_Whooptee Doo 
Belgium  Xxx 
Belgium  S_Foo Bar 

但是，下面的線造成麻煩：

Group 1  Group 2 
================================ 
United 
United 
United 
United 
United 
United 
United 
United 
Macedonia 
Macedonia 
Cyprus 
Congo 
Congo 

我想什麼正則表達式做的是以下幾點：

Group 1       Group 2 
================================================ 
United Kingdom 
United Kingdom     W_Foo-Bar 
United Kingdom     M_Yay 
United Kingdom     Xxx 
United Kingdom     S_Derp 
United Kingdom     F_Doh Lorem 
United Kingdom     S_Ipsum Dolor 
United States of America  L_Foo 
Macedonia F.Y.R.    Xxx 
Macedonia F.Y.R.    S_Foo Bar 
Cyprus (Greek)     M_Foo 
Congo (Democratic Republic of) 
Congo (Democratic Republic of) Q_Yolo 

但我不能得到第一部分匹配。我很確定它與第一個匹配組的greedy/ungreedy選項有關，但在經過一段時間的擺弄之後，我無法完成它的工作......

我不在乎額外/其他/更多的匹配組被返回。正則表達式旨在用於.Net C#應用程序中（如果您想知道這是哪種「方言」）。

任何幫助將非常感激。

Answer 1

有時，在非貪婪的匹配中，錨定非常重要。在這種情況下，錨定到線路末端解決了問題。你的正則表達式應該是：

^(.+?)(?:\s+(Xxx|[A-Z]_.*))?$ 

請注意，我也動了一個多分組級別外的可選（?）量詞，所以空間是可選的。

Answer 2

我管理你想要的東西與此正則表達式（與多跑）：

^((?:.+?|)+?)(?:\s+(Xxx|[A-Z]_.*)|\s)?$ 

使用輸入給了我這樣的結果：

1: Belgium     2: 
1: Belgium     2: M_Foo 
1: Belgium     2: A_Bar 
1: Belgium     2: M_FooBar 
1: Belgium     2: S_Whooptee Doo 
1: Belgium     2: Xxx 
1: Belgium     2: S_Foo Bar 
1: United Kingdom   2: 
1: United Kingdom   2: W_Foo-Bar 
1: United Kingdom   2: M_Yay 
1: United Kingdom   2: Xxx 
1: United Kingdom   2: S_Derp 
1: United Kingdom   2: F_Doh Lorem 
1: United Kingdom   2: S_Ipsum Dolor 
1: United States of America 2: L_Foo 
1: Macedonia F.Y.R.   2: Xxx 
1: Macedonia F.Y.R.   2: S_Foo Bar 
1: Cyprus (Greek)   2: M_Foo 

Answer 3

試試這個（不區分大小寫）：

^([A-Z]+(?:\s+(?!Xxx)[A-Z]+)*(?:\s+\([^)]+\))?)(?:\s+(Xxx|(?:[-A-Z_.]+(?:\s+[-A-Z_.]+)*)))?$ 

它適用於你所有的例子。但坦率地說，你應該正確地分隔數據。

演示：

$ perl -ne '/^([A-Z]+(?:\s+(?!Xxx)[A-Z]+)*(?:\s+\([^)]+\))?)(?:\s+(Xxx|(?:[-A-Z_.]+(?:\s+[-A-Z_.]+)*)))?$/i and print "MATCH: group 1 is \"$1\", group 2 is \"$2\"\n"' 
> Belgium 
> Belgium M_Foo 
> Belgium A_Bar 
> Belgium M_FooBar 
> Belgium S_Whooptee Doo 
> Belgium Xxx 
> Belgium S_Foo Bar 
> United Kingdom 
> United Kingdom W_Foo-Bar 
> United Kingdom M_Yay 
> United Kingdom Xxx 
> United Kingdom S_Derp 
> United Kingdom F_Doh Lorem 
> United Kingdom S_Ipsum Dolor 
> United States of America L_Foo 
> Macedonia F.Y.R. Xxx 
> Macedonia F.Y.R. S_Foo Bar 
> Cyprus (Greek) M_Foo 
> Congo (Democratic Republic of) 
> Congo (Democratic Republic of) Q_Yolo 
> EOF 
MATCH: group 1 is "Belgium", group 2 is "" 
MATCH: group 1 is "Belgium", group 2 is "M_Foo" 
MATCH: group 1 is "Belgium", group 2 is "A_Bar" 
MATCH: group 1 is "Belgium", group 2 is "M_FooBar" 
MATCH: group 1 is "Belgium", group 2 is "S_Whooptee Doo" 
MATCH: group 1 is "Belgium", group 2 is "Xxx" 
MATCH: group 1 is "Belgium", group 2 is "S_Foo Bar" 
MATCH: group 1 is "United Kingdom", group 2 is "" 
MATCH: group 1 is "United Kingdom", group 2 is "W_Foo-Bar" 
MATCH: group 1 is "United Kingdom", group 2 is "M_Yay" 
MATCH: group 1 is "United Kingdom", group 2 is "Xxx" 
MATCH: group 1 is "United Kingdom", group 2 is "S_Derp" 
MATCH: group 1 is "United Kingdom", group 2 is "F_Doh Lorem" 
MATCH: group 1 is "United Kingdom", group 2 is "S_Ipsum Dolor" 
MATCH: group 1 is "United States of America", group 2 is "L_Foo" 
MATCH: group 1 is "Macedonia", group 2 is "F.Y.R. Xxx" 
MATCH: group 1 is "Macedonia", group 2 is "F.Y.R. S_Foo Bar" 
MATCH: group 1 is "Cyprus (Greek)", group 2 is "M_Foo" 
MATCH: group 1 is "Congo (Democratic Republic of)", group 2 is "" 
MATCH: group 1 is "Congo (Democratic Republic of)", group 2 is "Q_Yolo" 

Answer 4

/(?:^(.+)\s+(Xxx|[A-Z]_.+)$|^(.+)$)/gm會匹配所有字符串，然而，只能有一個國家將被放置在第三場比賽的任何行（所以檢查這是你通過你的結果） 。

Demo