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Are there libraries for parsing "numeric expressions" such as 1,2-9,33- in Java

I don’t think it’s difficult, it’s just tiresome to write: a small free (like in a beer) library where I can insert a line like 1,2-9,33, and it can tell me the number matches this expression. Just like most programs in the print range dialog box. Special functions to match odd or even numbers or match each number that is 2 mod 5 (or something like that) would be nice, but not necessary.

The only operation I have to perform on this list is whether the range contains a given (non-negative) integer value; Of course, more operations like max / min (if they exist) or an iterator would be nice.

What is required is that he does not take up a lot of RAM if someone enters 1-10000000, but the only number I have ever requested is 12345 :-)

(To implement it, I analyzed the list for several pairs (min / max / value / mod), for example 1,10,0,1 for 1-10 or 11,33,1,2 for 1-33odd, or 12,62 , 2.10 for 12-62 / 10 (that is 12, 22, 32, ..., 62), and then check each number for all intervals. Open the intervals with Integer.MaxValue, etc. If there is no libs, any ideas to make this better / more efficient?)

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3 answers

I decided to encode it myself. Use at your own risk:-)

/* 
 * NumberExpression.java - a simple number expression parser
 * 
 * Copyright (c) 2010 Michael Schierl
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 *   
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *   
 * - Neither name of the copyright holders nor the names of its
 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *   
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND THE CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package numberexpression;

/**
 * An expression that matches nonnegative numbers. This supports cron-like
 * expressions, like <code>1,3-6,100-200,666,1000-3000/5,400-/7</code>,
 * <code>-100,102-</code> or <code>*</code>. Odd or even numbers can be
 * matched either by cron step syntax, or by suffixing a simple range
 * (without step values) with <code>e</code> or <code>o</code>.
 * 
 * @author Michael Schierl
 */
public class NumberExpression {

    private final NumberRange[] ranges;
    private final int min, max;

    /**
     * Create a new {@link NumberExpression}.
     * 
     * @param pattern
     *            the expression pattern.
     * @throws IllegalArgumentException
     *             if the pattern is malformed
     */
    public NumberExpression(String pattern) {
        String[] parts = pattern.toLowerCase().split(",",-1);
        ranges = new NumberRange[parts.length];
        int min = Integer.MAX_VALUE, max = 0;
        for (int i = 0; i < ranges.length; i++) {
            String part = parts[i];
            try {
                if (part.equals("*")) {
                    ranges[i] = new NumberRange(0, Integer.MAX_VALUE, 0, 1);
                } else if (part.matches("\\*/\\d+")) {
                    ranges[i] = new NumberRange(0, Integer.MAX_VALUE, 0, Integer.parseInt(part.substring(2)));
                } else if (part.matches("\\d+")) {
                    int value = Integer.parseInt(part);
                    ranges[i] = new NumberRange(value, value, 0, 1);
                } else if (part.matches("\\d*-\\d*")) {
                    String[] limits = part.split("-", -1);
                    int from = limits[0].length() == 0 ? 0 : Integer.parseInt(limits[0]);
                    int to = limits[1].length() == 0 ? Integer.MAX_VALUE : Integer.parseInt(limits[1]);
                    if (to < from)
                        throw new IllegalArgumentException("Invalid pattern: " + part);
                    ranges[i] = new NumberRange(from, to, 0, 1);
                } else if (part.matches("\\d*-\\d*/\\d+")) {
                    String[] rangeAndModulus = part.split("/", -1);
                    String[] limits = rangeAndModulus[0].split("-", -1);
                    int from = limits[0].length() == 0 ? 0 : Integer.parseInt(limits[0]);
                    int to = limits[1].length() == 0 ? Integer.MAX_VALUE : Integer.parseInt(limits[1]);
                    int modulus = Integer.parseInt(rangeAndModulus[1]);
                    if (to < from)
                        throw new IllegalArgumentException("Invalid pattern: " + part);
                    ranges[i] = new NumberRange(from, to, from % modulus, modulus);
                } else if (part.matches("\\d*-\\d*[eo]")) {
                    String[] limits = part.substring(0, part.length() - 1).split("-", -1);
                    int from = limits[0].length() == 0 ? 0 : Integer.parseInt(limits[0]);
                    int to = limits[1].length() == 0 ? Integer.MAX_VALUE : Integer.parseInt(limits[1]);
                    if (to < from)
                        throw new IllegalArgumentException("Invalid pattern: " + part);
                    ranges[i] = new NumberRange(from, to, part.charAt(part.length() - 1) == 'o' ? 1 : 0, 2);
                } else {
                    throw new IllegalArgumentException("Invalid pattern: " + part);
                }
                max = Math.max(max, ranges[i].getMax());
                min = Math.min(min, ranges[i].getMin());
            } catch (NumberFormatException ex) {
                throw new IllegalArgumentException("Invalid pattern: " + part);
            }
        }
        this.max = max;
        this.min = min;
    }

    /**
     * Check whether this number expression matches the given number.
     * 
     * @param number
     *            the number to check against
     * @return whether the expression matches the number
     */
    public boolean matches(int number) {
        if (number < min || number > max)
            return false;
        for (int i = 0; i < ranges.length; i++) {
            if (ranges[i].matches(number))
                return true;
        }
        return false;
    }

    /**
     * Return the minimum number that can be matched.
     */
    public int getMinimum() { return min; }

    /**
     * Return the maximum number that can be matched.
     */
    public int getMaximum() { return max; }

    private static class NumberRange {
        private final int min, max, remainder, modulus;

        NumberRange(int min, int max, int remainder, int modulus) {
            this.min = min;
            this.max = max;
            this.remainder = remainder;
            this.modulus = modulus;
        }

        boolean matches(int number) {
            return number >= min && number <= max && number % modulus == remainder;
        }

        int getMin() { return min; }  
        int getMax() { return max; }
    }
}
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, .

python, .

>>> def f(n, pattern):
...     ranges = [r.split('-') for r in pattern.split(',')]
...     for a,b in ranges:
...             if (not a or int(a) <= n) and (not b or int(b) >= n):
...                     return True
...     return False
... 
>>> f(4, '-1,2-9,33-')
True
>>> f(11, '-1,2-9,33-')
False
>>> f(100, '-1,2-9,33-')
True
>>>

. IntervalTree, . .

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