public static void escapeJson()

in log4j-api/src/main/java/org/apache/logging/log4j/util/StringBuilders.java [232:300]
60 lines of code
19 McCabe index (conditional complexity)

    public static void escapeJson(final StringBuilder toAppendTo, final int start) {
        int escapeCount = 0;
        for (int i = start; i < toAppendTo.length(); i++) {
            final char c = toAppendTo.charAt(i);
            switch (c) {
                case '\b':
                case '\t':
                case '\f':
                case '\n':
                case '\r':
                case '"':
                case '\\':
                    escapeCount++;
                    break;
                default:
                    if (Character.isISOControl(c)) {
                        escapeCount += 5;
                    }
            }
        }

        final int lastChar = toAppendTo.length() - 1;
        toAppendTo.setLength(toAppendTo.length() + escapeCount);
        int lastPos = toAppendTo.length() - 1;

        for (int i = lastChar; lastPos > i; i--) {
            final char c = toAppendTo.charAt(i);
            switch (c) {
                case '\b':
                    lastPos = escapeAndDecrement(toAppendTo, lastPos, 'b');
                    break;

                case '\t':
                    lastPos = escapeAndDecrement(toAppendTo, lastPos, 't');
                    break;

                case '\f':
                    lastPos = escapeAndDecrement(toAppendTo, lastPos, 'f');
                    break;

                case '\n':
                    lastPos = escapeAndDecrement(toAppendTo, lastPos, 'n');
                    break;

                case '\r':
                    lastPos = escapeAndDecrement(toAppendTo, lastPos, 'r');
                    break;

                case '"':
                case '\\':
                    lastPos = escapeAndDecrement(toAppendTo, lastPos, c);
                    break;

                default:
                    if (Character.isISOControl(c)) {
                        // all iso control characters are in U+00xx, JSON output format is "\\u00XX"
                        toAppendTo.setCharAt(lastPos--, Chars.getUpperCaseHex(c & 0xF));
                        toAppendTo.setCharAt(lastPos--, Chars.getUpperCaseHex((c & 0xF0) >> 4));
                        toAppendTo.setCharAt(lastPos--, '0');
                        toAppendTo.setCharAt(lastPos--, '0');
                        toAppendTo.setCharAt(lastPos--, 'u');
                        toAppendTo.setCharAt(lastPos--, '\\');
                    } else {
                        toAppendTo.setCharAt(lastPos, c);
                        lastPos--;
                    }
            }
        }
    }