public void parse()

in log4j-core/src/main/java/org/apache/logging/log4j/core/pattern/PatternParser.java [333:491]
120 lines of code
25 McCabe index (conditional complexity)

    public void parse(final String pattern, final List<PatternConverter> patternConverters,
            final List<FormattingInfo> formattingInfos, final boolean disableAnsi,
            final boolean noConsoleNoAnsi, final boolean convertBackslashes) {
        Objects.requireNonNull(pattern, "pattern");

        final StringBuilder currentLiteral = new StringBuilder(BUF_SIZE);

        final int patternLength = pattern.length();
        ParserState state = ParserState.LITERAL_STATE;
        char c;
        int i = 0;
        FormattingInfo formattingInfo = FormattingInfo.getDefault();

        while (i < patternLength) {
            c = pattern.charAt(i++);

            switch (state) {
            case LITERAL_STATE:

                // In literal state, the last char is always a literal.
                if (i == patternLength) {
                    currentLiteral.append(c);

                    continue;
                }

                if (c == ESCAPE_CHAR) {
                    // peek at the next char.
                    switch (pattern.charAt(i)) {
                    case ESCAPE_CHAR:
                        currentLiteral.append(c);
                        i++; // move pointer

                        break;

                    default:

                        if (currentLiteral.length() != 0) {
                            patternConverters.add(literalPattern(currentLiteral.toString(), convertBackslashes));
                            formattingInfos.add(FormattingInfo.getDefault());
                        }

                        currentLiteral.setLength(0);
                        currentLiteral.append(c); // append %
                        state = ParserState.CONVERTER_STATE;
                        formattingInfo = FormattingInfo.getDefault();
                    }
                } else {
                    currentLiteral.append(c);
                }

                break;

            case CONVERTER_STATE:
                currentLiteral.append(c);

                switch (c) {
                case '0':
                    // a '0' directly after the % sign indicates zero-padding
                    formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
                            formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate(), true);
                    break;

                case '-':
                    formattingInfo = new FormattingInfo(true, formattingInfo.getMinLength(),
                            formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate(), formattingInfo.isZeroPad());
                    break;

                case '.':
                    state = ParserState.DOT_STATE;
                    break;

                default:

                    if (c >= '0' && c <= '9') {
                        formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), c - '0',
                                formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate(), formattingInfo.isZeroPad());
                        state = ParserState.MIN_STATE;
                    } else {
                        i = finalizeConverter(c, pattern, i, currentLiteral, formattingInfo, converterRules,
                                patternConverters, formattingInfos, disableAnsi, noConsoleNoAnsi, convertBackslashes);

                        // Next pattern is assumed to be a literal.
                        state = ParserState.LITERAL_STATE;
                        formattingInfo = FormattingInfo.getDefault();
                        currentLiteral.setLength(0);
                    }
                } // switch

                break;

            case MIN_STATE:
                currentLiteral.append(c);

                if (c >= '0' && c <= '9') {
                    // Multiply the existing value and add the value of the number just encountered.
                    formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength()
                            * DECIMAL + c - '0', formattingInfo.getMaxLength(), formattingInfo.isLeftTruncate(), formattingInfo.isZeroPad());
                } else if (c == '.') {
                    state = ParserState.DOT_STATE;
                } else {
                    i = finalizeConverter(c, pattern, i, currentLiteral, formattingInfo, converterRules,
                            patternConverters, formattingInfos, disableAnsi, noConsoleNoAnsi, convertBackslashes);
                    state = ParserState.LITERAL_STATE;
                    formattingInfo = FormattingInfo.getDefault();
                    currentLiteral.setLength(0);
                }

                break;

            case DOT_STATE:
                currentLiteral.append(c);
                switch (c) {
                case '-':
                    formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
                            formattingInfo.getMaxLength(),false, formattingInfo.isZeroPad());
                    break;

                default:

                    if (c >= '0' && c <= '9') {
                        formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
                                c - '0', formattingInfo.isLeftTruncate(), formattingInfo.isZeroPad());
                        state = ParserState.MAX_STATE;
                    } else {
                        LOGGER.error("Error occurred in position " + i + ".\n Was expecting digit, instead got char \"" + c
                                + "\".");

                        state = ParserState.LITERAL_STATE;
                    }
                }

                break;

            case MAX_STATE:
                currentLiteral.append(c);

                if (c >= '0' && c <= '9') {
                    // Multiply the existing value and add the value of the number just encountered.
                    formattingInfo = new FormattingInfo(formattingInfo.isLeftAligned(), formattingInfo.getMinLength(),
                            formattingInfo.getMaxLength() * DECIMAL + c - '0', formattingInfo.isLeftTruncate(), formattingInfo.isZeroPad());
                } else {
                    i = finalizeConverter(c, pattern, i, currentLiteral, formattingInfo, converterRules,
                            patternConverters, formattingInfos, disableAnsi, noConsoleNoAnsi, convertBackslashes);
                    state = ParserState.LITERAL_STATE;
                    formattingInfo = FormattingInfo.getDefault();
                    currentLiteral.setLength(0);
                }

                break;
            } // switch
        }

        // while
        if (currentLiteral.length() != 0) {
            patternConverters.add(literalPattern(currentLiteral.toString(), convertBackslashes));
            formattingInfos.add(FormattingInfo.getDefault());
        }
    }