generating a substring. This avoids the allocation of a String object ech time a substring is parsed. Should affect CPU load during RWI transmission.pull/1/head
Michael Peter Christen
13 years ago
parent
7e0ddbd275
commit
cf47d94888
@ -0,0 +1,118 @@
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/**
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* NumberTools
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* Copyright 2012 by Sebastian Gaebel
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* First released 21.05.2012 at http://yacy.net
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program in the file lgpl21.txt
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* If not, see <http://www.gnu.org/licenses/>.
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*/
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package net.yacy.kelondro.util;
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public class NumberTools {
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/**
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* this method replaces Long.parseLong/2 where a substring of decimal numbers shall be parsed
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* Strings are also auto-trimmed, that means parsing stops at spaces without throwing a NumberFormatException
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* @param s
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* @param startPos
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* @return the number
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* @throws NumberFormatException
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*/
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public static final long parseLongDecSubstring(String s, int startPos) throws NumberFormatException {
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if (s == null) {
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throw new NumberFormatException("null");
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}
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final int len = s.length();
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if (len <= startPos) {
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throw new NumberFormatException(s);
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}
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long result = 0;
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boolean negative = false;
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int i = startPos;
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long limit = -Long.MAX_VALUE;
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final long multmin;
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int digit;
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char c;
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char firstChar = s.charAt(i);
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if (firstChar < '0') {
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if (firstChar == '-') {
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negative = true;
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limit = Long.MIN_VALUE;
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} else if (firstChar != '+') throw new NumberFormatException(s);
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if (len == 1) throw new NumberFormatException(s);
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i++;
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}
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multmin = limit / 10;
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while (i < len) {
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c = s.charAt(i++);
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if (c == ' ') break;
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digit = c - 48;
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if (digit < 0 || digit > 9 || result < multmin) throw new NumberFormatException(s);
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result *= 10;
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if (result < limit + digit) throw new NumberFormatException(s);
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result -= digit;
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}
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return negative ? result : -result;
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}
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public static final int parseIntDecSubstring(String s, int startPos) throws NumberFormatException {
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if (s == null) {
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throw new NumberFormatException("null");
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}
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final int len = s.length();
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if (len <= startPos) {
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throw new NumberFormatException(s);
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}
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int result = 0;
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boolean negative = false;
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int i = startPos;
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int limit = -Integer.MAX_VALUE;
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final int multmin;
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int digit;
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char c;
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char firstChar = s.charAt(i);
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if (firstChar < '0') {
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if (firstChar == '-') {
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negative = true;
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limit = Integer.MIN_VALUE;
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} else if (firstChar != '+') throw new NumberFormatException(s);
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if (len == 1) throw new NumberFormatException(s);
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i++;
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}
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multmin = limit / 10;
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while (i < len) {
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c = s.charAt(i++);
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if (c == ' ') break;
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digit = c - 48;
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if (digit < 0 || digit > 9 || result < multmin) throw new NumberFormatException(s);
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result *= 10;
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if (result < limit + digit) throw new NumberFormatException(s);
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result -= digit;
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}
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return negative ? result : -result;
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}
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public static void main(String[] args) {
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System.out.println("the number is " + parseLongDecSubstring("number=78 ", 7));
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}
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}
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