Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;

import java.util.regex.*;

public class Main {
    /**
     * Pattern.pattern and Pattern.toString ignore any flags supplied to
     * Pattern.compile, so the regular expression you get out doesn't
     * correspond to what the Pattern was actually matching. This fixes that.
     * 
     * Note that there are some flags that can't be represented.
     * 
     * FIXME: why don't we use Pattern.LITERAL instead of home-grown escaping
     * code? Is it because you can't do the reverse transformation? Should we
     * integrate that code with this?
     */
    public static String toString(Pattern pattern) {
        String regex = pattern.pattern();
        final int flags = pattern.flags();
        if (flags != 0) {
            StringBuilder builder = new StringBuilder("(?");
            toStringHelper(builder, flags, Pattern.UNIX_LINES, 'd');
            toStringHelper(builder, flags, Pattern.CASE_INSENSITIVE, 'i');
            toStringHelper(builder, flags, Pattern.COMMENTS, 'x');
            toStringHelper(builder, flags, Pattern.MULTILINE, 'm');
            toStringHelper(builder, flags, Pattern.DOTALL, 's');
            toStringHelper(builder, flags, Pattern.UNICODE_CASE, 'u');
            builder.append(")");
            regex = builder.toString() + regex;
        }
        return regex;
    }

    private static void toStringHelper(StringBuilder result, int flags, int flag, char c) {
        if ((flags & flag) != 0) {
            result.append(c);
        }
    }
}