正则表达式的Python和Java实现对比举例

参考资料：

1. 正则表达式语法--菜鸟教程
2. Java正则表达式实现--韩顺平bilibili课程

简单批量替换

举例：将and 批量替换为&&

Python实现

import re
def transformSimple(fromRegex, toText, inText):
    return re.sub(fromRegex, toText,inText, flags =re.I)

if __name__ == "__main__":
    inText = "x =1 and y =2"
    fromRegex = " and "
    toText = " && "
    outText = transformSimple(fromRegex,toText,inText )
    print(outText)

	## OUTPUT： x =1 && y =2

Java实现

import java.util.*;
import java.util.regex.*;
public class RegexTest {
	private static String transformSimple(String regexPattern, String replText, String inText){
        return Pattern.compile(regexPattern, Pattern.CASE_INSENSITIVE).matcher(inText).replaceAll(replText);
    }
    public static void main(String[] args) {
	    String input = "x =1 and y =2";
        String patternString =" and ";
        String toText = " && ";
        String outText ="";
        outText = transformSimple(patternString, toText, input);
        System.out.println("RESULT: " + outText);
}


// RESULT: x =1 && y =2

复杂模板替换

举例：将 x in (1,2)批量替换为 [1,2].contains(x)

分析： 模板化

• 输入分组捕获 (\S+)\s+in\s*\((.+?)\)
• 输出分组填写 [@2].contains(@1) -- @1和@2分别对应分组捕获中的第1组和2组。

Python实现

import re
def transformComplex(fromRegex, toText, inText):
    regObj = re.compile(fromRegex, flags =re.I)
    for match in regObj.finditer(inText):
        index = 1
        outText = toText
        for group in match.groups():
            outText = outText.replace("@"+str(index), group)
            index +=1
        inText = inText.replace(match.group(0), outText)

    return inText

if __name__ == "__main__":
    fromRegex = "(\S+)\s+in\s*\((.+?)\)"
    toText = "[@2].contains(@1)"
    inText = "x in (1,2) and y in (3,4)"
    outText22 = transformComplex(fromRegex, toText, inText)
    print(outText22)
    
    ## OUTPUT: [1,2].contains(x) and [3,4].contains(y)

Java实现

import java.util.*;
import java.util.regex.*;
public class RegexTest {
	private static String transformComplex(String regexPattern, String replText, String inText){
        Pattern pattern = Pattern.compile(regexPattern, Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(inText);
        String outText ="";
        while (matcher.find()){
            outText =  replText;
            for (int i =1; i <= matcher.groupCount(); i++){
                outText = outText.replace("@"+i, matcher.group(i));
            }
            inText = inText.replace(matcher.group(0), outText);
        }
        return inText;
    }
    
    public static void main(String[] args) {
        String input = "x in (1,2) and y in (3,4)";
        String patternString ="(\\S+)\\s+in\\s*\\((.+?)\\)";
        String toText = "[@2].contains(@1)";
        String outText ="";
        outText = transformComplex(patternString, toText, input);
        System.out.println("RESULT: " + outText);

    }
}

// RESULT: [1,2].contains(x) and [3,4].contains(y)