[英]Efficiently finding all overlapping matches for a regular expression
这是与java regex匹配的所有重叠子字符串的后续操作。
有没有办法使此代码更快?
public static void allMatches(String text, String regex)
{
for (int i = 0; i < text.length(); ++i) {
for (int j = i + 1; j <= text.length(); ++j) {
String positionSpecificPattern = "((?<=^.{"+i+"})("+regex+")(?=.{"+(text.length() - j)+"}$))";
Matcher m = Pattern.compile(positionSpecificPattern).matcher(text);
if (m.find())
{
System.out.println("Match found: \"" + (m.group()) + "\" at position [" + i + ", " + j + ")");
}
}
}
}
在另一个问题中,您提到了Matcher的region()
方法,但没有充分利用它。 之所以如此有价值,是因为锚点将在该区域的边界处匹配,就好像它们是独立字符串的边界一样。 假设您已经设置了useAnchoringBounds()
选项,但这是默认设置。
public static void allMatches(String text, String regex)
{
Matcher m = Pattern.compile(regex).matcher(text);
int end = text.length();
for (int i = 0; i < end; ++i)
{
for (int j = i + 1; j <= end; ++j)
{
m.region(i, j);
if (m.find())
{
System.out.printf("Match found: \"%s\" at position [%d, %d)%n",
m.group(), i, j);
}
}
}
}
给定您的示例字符串和正则表达式:
allMatches("String t = 04/31 412-555-1235;", "^\\d\\d+$");
...我得到以下输出:
Match found: "04" at position [11, 13)
Match found: "31" at position [14, 16)
Match found: "41" at position [17, 19)
Match found: "412" at position [17, 20)
Match found: "12" at position [18, 20)
Match found: "55" at position [21, 23)
Match found: "555" at position [21, 24)
Match found: "55" at position [22, 24)
Match found: "12" at position [25, 27)
Match found: "123" at position [25, 28)
Match found: "1235" at position [25, 29)
Match found: "23" at position [26, 28)
Match found: "235" at position [26, 29)
Match found: "35" at position [27, 29)
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