final public static FormattingTuple arrayFormat(final String messagePattern, final Object[] argArray, Throwable throwable) {

        if (messagePattern == null) {
            return new FormattingTuple(null, argArray, throwable);
        }

        if (argArray == null) {
            return new FormattingTuple(messagePattern);
        }

        int i = 0;
        int j;
        // use string builder for better multicore performance
        StringBuilder sbuf = new StringBuilder(messagePattern.length() + 50);

        int L;
        for (L = 0; L < argArray.length; L++) {

            j = messagePattern.indexOf(DELIM_STR, i);

            if (j == -1) {
                // no more variables
                if (i == 0) { // this is a simple string
                    return new FormattingTuple(messagePattern, argArray, throwable);
                } else { // add the tail string which contains no variables and return
                    // the result.
                    sbuf.append(messagePattern, i, messagePattern.length());
                    return new FormattingTuple(sbuf.toString(), argArray, throwable);
                }
            } else {
                if (isEscapedDelimeter(messagePattern, j)) {
                    if (!isDoubleEscaped(messagePattern, j)) {
                        L--; // DELIM_START was escaped, thus should not be incremented
                        sbuf.append(messagePattern, i, j - 1);
                        sbuf.append(DELIM_START);
                        i = j + 1;
                    } else {
                        // The escape character preceding the delimiter start is
                        // itself escaped: "abc x:\\{}"
                        // we have to consume one backward slash
                        sbuf.append(messagePattern, i, j - 1);
                        deeplyAppendParameter(sbuf, argArray[L], new HashMap<>());
                        i = j + 2;
                    }
                } else {
                    // normal case
                    sbuf.append(messagePattern, i, j);
                    deeplyAppendParameter(sbuf, argArray[L], new HashMap<>());
                    i = j + 2;
                }
            }
        }
        // append the characters following the last {} pair.
        sbuf.append(messagePattern, i, messagePattern.length());
        return new FormattingTuple(sbuf.toString(), argArray, throwable);
    }
Assumes that argArray only contains arguments with no throwable as last element.

@param messagePattern
@param argArray
slf4j-api/src/main/java/org/slf4j/helpers/MessageFormatter.java