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/* 
 * Copyright (C) 2018 V12 Technology Ltd.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Server Side Public License, version 1,
 * as published by MongoDB, Inc.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * Server Side Public License for more details.
 *
 * You should have received a copy of the Server Side Public License
 * along with this program.  If not, see 
 * .
 */
package com.fluxtion.ext.futext.api.ascii;

/**
 * Standard conversion functions from CharSequence to primitive types.
 *
 * @author gregp
 */
public interface Conversion {

    public static double atod(CharSequence sb) {
        return sb.length() == 0 ? 0 : Double.parseDouble(sb.toString());
    }

    public static long atol(CharSequence sb) {
        return sb.length() == 0 ? 0 : Long.parseLong(sb.toString());
    }

    public static int atoi(CharSequence s)
            throws NumberFormatException {
        if (s.length() == 0) {
            return 0;
        }
        int radix = 10;
        /*
         * WARNING: This method may be invoked early during VM initialization
         * before IntegerCache is initialized. Care must be taken to not use
         * the valueOf method.
         */

        if (s == null) {
            throw new NumberFormatException("null");
        }

        if (radix < Character.MIN_RADIX) {
            throw new NumberFormatException("radix " + radix
                    + " less than Character.MIN_RADIX");
        }

        if (radix > Character.MAX_RADIX) {
            throw new NumberFormatException("radix " + radix
                    + " greater than Character.MAX_RADIX");
        }

        int result = 0;
        boolean negative = false;
        int i = 0, len = s.length();
        int limit = -Integer.MAX_VALUE;
        int multmin;
        int digit;

        if (len > 0) {
            char firstChar = s.charAt(0);
            if (firstChar < '0') { // Possible leading "+" or "-"
                if (firstChar == '-') {
                    negative = true;
                    limit = Integer.MIN_VALUE;
                } else if (firstChar != '+') {
                    throw new NumberFormatException("For input string: \"" + s + "\"");
                }

                if (len == 1) // Cannot have lone "+" or "-"
                {
                    throw new NumberFormatException("For input string: \"" + s + "\"");
                }
                i++;
            }
            multmin = limit / radix;
            while (i < len) {
                // Accumulating negatively avoids surprises near MAX_VALUE
                digit = Character.digit(s.charAt(i++), radix);
                if (digit < 0) {
                    throw new NumberFormatException("For input string: \"" + s + "\"");
                }
                if (result < multmin) {
                    throw new NumberFormatException("For input string: \"" + s + "\"");
                }
                result *= radix;
                if (result < limit + digit) {
                    throw new NumberFormatException("For input string: \"" + s + "\"");
                }
                result -= digit;
            }
        } else {
            throw new NumberFormatException("For input string: \"" + s + "\"");
        }
        return negative ? result : -result;
    }
}