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/*
* Copyright 1999-2017 Alibaba Group Holding Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package studio.raptor.sqlparser.util;
/**
*/
public class StringUtils {
private final static Log LOG = new Log();
/**
* Example: subString("12345","1","4")=23
*/
public static Integer subStringToInteger(String src, String start, String to) {
return stringToInteger(subString(src, start, to));
}
/**
* Example: subString("abcd","a","c")="b"
*
* @param start null while start from index=0
* @param to null while to index=src.length
*/
public static String subString(String src, String start, String to) {
int indexFrom = start == null ? 0 : src.indexOf(start);
int indexTo = to == null ? src.length() : src.indexOf(to);
if (indexFrom < 0 || indexTo < 0 || indexFrom > indexTo) {
return null;
}
if (null != start) {
indexFrom += start.length();
}
return src.substring(indexFrom, indexTo);
}
/**
* Example: subString("abcdc","a","c",true)="bcd"
*
* @param start null while start from index=0
* @param to null while to index=src.length
* @param toLast true while to index=src.lastIndexOf(to)
*/
public static String subString(String src, String start, String to, boolean toLast) {
if (!toLast) {
return subString(src, start, to);
}
int indexFrom = start == null ? 0 : src.indexOf(start);
int indexTo = to == null ? src.length() : src.lastIndexOf(to);
if (indexFrom < 0 || indexTo < 0 || indexFrom > indexTo) {
return null;
}
if (null != start) {
indexFrom += start.length();
}
return src.substring(indexFrom, indexTo);
}
/**
* @param in
* @return
*/
public static Integer stringToInteger(String in) {
if (in == null) {
return null;
}
in = in.trim();
if (in.length() == 0) {
return null;
}
try {
return Integer.parseInt(in);
} catch (NumberFormatException e) {
LOG.warn("stringToInteger fail,string=" + in, e);
return null;
}
}
public static boolean equals(String a, String b) {
if (a == null) {
return b == null;
}
return a.equals(b);
}
public static boolean equalsIgnoreCase(String a, String b) {
if (a == null) {
return b == null;
}
return a.equalsIgnoreCase(b);
}
public static boolean isEmpty(CharSequence value) {
if (value == null || value.length() == 0) {
return true;
}
return false;
}
public static int lowerHashCode(String text) {
if (text == null) {
return 0;
}
// return text.toLowerCase().hashCode();
int h = 0;
for (int i = 0; i < text.length(); ++i) {
char ch = text.charAt(i);
if (ch >= 'A' && ch <= 'Z') {
ch = (char) (ch + 32);
}
h = 31 * h + ch;
}
return h;
}
public static boolean isNumber(String str) {
if (isEmpty(str)) {
return false;
}
char[] chars = str.toCharArray();
int sz = chars.length;
boolean hasExp = false;
boolean hasDecPoint = false;
boolean allowSigns = false;
boolean foundDigit = false;
// deal with any possible sign up front
int start = (chars[0] == '-') ? 1 : 0;
if (sz > start + 1) {
if (chars[start] == '0' && chars[start + 1] == 'x') {
int i = start + 2;
if (i == sz) {
return false; // str == "0x"
}
// checking hex (it can't be anything else)
for (; i < chars.length; i++) {
if ((chars[i] < '0' || chars[i] > '9')
&& (chars[i] < 'a' || chars[i] > 'f')
&& (chars[i] < 'A' || chars[i] > 'F')) {
return false;
}
}
return true;
}
}
sz--; // don't want to loop to the last char, check it afterwords
// for type qualifiers
int i = start;
// loop to the next to last char or to the last char if we need another digit to
// make a valid number (e.g. chars[0..5] = "1234E")
while (i < sz || (i < sz + 1 && allowSigns && !foundDigit)) {
if (chars[i] >= '0' && chars[i] <= '9') {
foundDigit = true;
allowSigns = false;
} else if (chars[i] == '.') {
if (hasDecPoint || hasExp) {
// two decimal points or dec in exponent
return false;
}
hasDecPoint = true;
} else if (chars[i] == 'e' || chars[i] == 'E') {
// we've already taken care of hex.
if (hasExp) {
// two E's
return false;
}
if (!foundDigit) {
return false;
}
hasExp = true;
allowSigns = true;
} else if (chars[i] == '+' || chars[i] == '-') {
if (!allowSigns) {
return false;
}
allowSigns = false;
foundDigit = false; // we need a digit after the E
} else {
return false;
}
i++;
}
if (i < chars.length) {
if (chars[i] >= '0' && chars[i] <= '9') {
// no type qualifier, OK
return true;
}
if (chars[i] == 'e' || chars[i] == 'E') {
// can't have an E at the last byte
return false;
}
if (!allowSigns
&& (chars[i] == 'd'
|| chars[i] == 'D'
|| chars[i] == 'f'
|| chars[i] == 'F')) {
return foundDigit;
}
if (chars[i] == 'l'
|| chars[i] == 'L') {
// not allowing L with an exponent
return foundDigit && !hasExp;
}
// last character is illegal
return false;
}
// allowSigns is true iff the val ends in 'E'
// found digit it to make sure weird stuff like '.' and '1E-' doesn't pass
return !allowSigns && foundDigit;
}
}
