Android String Escape javaScriptUnescapeHelper(String s, int i, StringBuilder sb)

Description

Looks for an escape code starting at index i of s, and appends it to sb.

License

Apache License

Exception

Parameter	Description
IllegalArgumentException	if the escape codeis invalid

Return

the index of the first character in s after the escape code.

Declaration

private static int javaScriptUnescapeHelper(String s, int i,
        StringBuilder sb) 

Method Source Code

//package com.java2s;
/**//from   w w  w .  ja v  a2  s. co m
 * Copyright (c) 2000, Google Inc.
 *
 * 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.
 */

public class Main {
    /**
     * Looks for an escape code starting at index i of s,
     * and appends it to sb.
     * @return the index of the first character in s
     * after the escape code.
     * @throws IllegalArgumentException if the escape code
     * is invalid
     */
    private static int javaScriptUnescapeHelper(String s, int i,
            StringBuilder sb) {
        if (i >= s.length()) {
            throw new IllegalArgumentException(
                    "End-of-string after escape character in [" + s + "]");
        }

        char c = s.charAt(i++);
        switch (c) {
        case 'n':
            sb.append('\n');
            break;
        case 'r':
            sb.append('\r');
            break;
        case 't':
            sb.append('\t');
            break;
        case 'b':
            sb.append('\b');
            break;
        case 'f':
            sb.append('\f');
            break;
        case '\\':
        case '\"':
        case '\'':
        case '>':
            sb.append(c);
            break;
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
            --i; // backup to first octal digit
            int nOctalDigits = 1;
            int digitLimit = c < '4' ? 3 : 2;
            while (nOctalDigits < digitLimit
                    && i + nOctalDigits < s.length()
                    && isOctal(s.charAt(i + nOctalDigits))) {
                ++nOctalDigits;
            }
            sb.append((char) Integer.parseInt(
                    s.substring(i, i + nOctalDigits), 8));
            i += nOctalDigits;
            break;
        case 'x':
        case 'u':
            String hexCode;
            int nHexDigits = (c == 'u' ? 4 : 2);
            try {
                hexCode = s.substring(i, i + nHexDigits);
            } catch (IndexOutOfBoundsException ioobe) {
                throw new IllegalArgumentException(
                        "Invalid unicode sequence [" + s.substring(i)
                                + "] at index " + i + " in [" + s + "]");
            }
            int unicodeValue;
            try {
                unicodeValue = Integer.parseInt(hexCode, 16);
            } catch (NumberFormatException nfe) {
                throw new IllegalArgumentException(
                        "Invalid unicode sequence [" + hexCode
                                + "] at index " + i + " in [" + s + "]");
            }
            sb.append((char) unicodeValue);
            i += nHexDigits;
            break;
        default:
            throw new IllegalArgumentException("Unknown escape code [" + c
                    + "] at index " + i + " in [" + s + "]");
        }

        return i;
    }

    private static boolean isOctal(char c) {
        return (c >= '0') && (c <= '7');
    }
}

Related

1. javaScriptUnescape(String s)
2. unescapeCString(String s)
3. unescapeMySQLString(String s)
4. escapeString(String value)