[英]Converting regex code from php to java not working
I'm trying to convert this code from PHP to Java and I cannot make it work identically: 我正在尝试将此代码从PHP转换为Java,但我不能使它的工作方式相同:
PHP: PHP:
function check_syntax($str) {
// define the grammar
$number = "\d+(\.\d+)?";
$ident = "[a-z]\w*";
$atom = "[+-]?($number|$ident)";
$op = "[+*/-]";
$sexpr = "$atom($op$atom)*"; // simple expression
// step1. remove whitespace
$str = preg_replace('~\s+~', '', $str);
// step2. repeatedly replace parenthetic expressions with 'x'
$par = "~\($sexpr\)~";
while(preg_match($par, $str))
$str = preg_replace($par, 'x', $str);
// step3. no more parens, the string must be simple expression
return preg_match("~^$sexpr$~", $str);
}
Java: Java的:
private boolean validateExpressionSintax(String exp){
String number="\\d+(\\.\\d+)?";
String ident="[a-z]\\w*";
String atom="[+-]?("+number+"|"+ident+")";
String op="[+*/-]";
String sexpr=atom+"("+op+""+atom+")*"; //simple expression
// step1. remove whitespace
String str=exp.replaceAll("\\s+", "");
// step2. repeatedly replace parenthetic expressions with 'x'
String par = "\\("+sexpr+"\\)";
while(str.matches(par)){
str =str.replace(par,"x");
}
// step3. no more parens, the string must be simple expression
return str.matches("^"+sexpr+"$");
}
What am I doing wrong? 我究竟做错了什么? I'm using the expression teste1*(teste2+teste3)
And i'm getting a match in php code but not in the java one, the line while(str.matches(par))
fails at first try. 我正在使用表达式teste1*(teste2+teste3)
而且我在PHP代码中得到一个匹配但在java中没有匹配, while(str.matches(par))
第一次尝试while(str.matches(par))
失败了。 I assume this must be some problem with the matches method? 我认为这必须是匹配方法的一些问题?
String.matches
in Java will check that the whole string matches against the regex (as if the regex has ^
at the beginning and $
at the end). Java中的String.matches
将检查整个字符串是否与正则表达式匹配(就像正则表达式在开头有^
而在结尾有$
)。
You need Matcher
to find some text inside a string that matches some regex: 你需要Matcher
在匹配某些正则表达式的字符串中找到一些文本:
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(inputString);
while (matcher.find()) {
// Extract information from each match
}
In your case, since you are doing replacement: 在你的情况下,因为你正在做替换:
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(inputString);
StringBuffer replacedString = new StringBuffer();
while (matcher.find()) {
matcher.appendReplacement(replacedString, "x");
}
matcher.appendTail(replacedString);
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.