Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Core Source Code files are provided in the source packge (jackson-core-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Core Source Code below:

⏎ com/fasterxml/jackson/core/io/doubleparser/AbstractFloatValueParser.java

/**
 * References:
 * <dl>
 *     <dt>This class has been derived from "FastDoubleParser".</dt>
 *     <dd>Copyright (c) Werner Randelshofer. Apache 2.0 License.
 *         <a href="https://github.com/wrandelshofer/FastDoubleParser">github.com</a>.</dd>
 * </dl>
 */

package com.fasterxml.jackson.core.io.doubleparser;

/**
 * Abstract base class for parsers that parse a {@code FloatingPointLiteral} from a
 * character sequence ({@code str}).
 * <p>
 * This is a C++ to Java port of Daniel Lemire's fast_double_parser.
 * <p>
 * References:
 * <dl>
 *     <dt>Daniel Lemire, fast_double_parser, 4x faster than strtod.
 *     Apache License 2.0 or Boost Software License.</dt>
 *     <dd><a href="https://github.com/lemire/fast_double_parser">github.com</a></dd>
 *
 *     <dt>Daniel Lemire, fast_float number parsing library: 4x faster than strtod.
 *     Apache License 2.0.</dt>
 *     <dd><a href="https://github.com/fastfloat/fast_float">github.com</a></dd>
 *
 *     <dt>Daniel Lemire, Number Parsing at a Gigabyte per Second,
 *     Software: Practice and Experience 51 (8), 2021.
 *     arXiv.2101.11408v3 [cs.DS] 24 Feb 2021</dt>
 *     <dd><a href="https://arxiv.org/pdf/2101.11408.pdf">arxiv.org</a></dd>
 * </dl>
 */
abstract class AbstractFloatValueParser {
    /**
     * This return value indicates that the input value is not a legal
     * production of the syntax rule for a float value.
     * <p>
     * The value is {@code -1L}.
     * <p>
     * Converting this value to a floating point number using
     * {@code Double.longBitsToDouble(-1L)}, or
     * {@code Float.intBitsToFloat((int) -1L)} yields a {@code NaN}.
     * <p>
     * Although this number yields {@code NaN}, the bit pattern of this value is
     * intentionally different from {@link Double#NaN}, and {@link Float#NaN}.
     */
    final static long PARSE_ERROR = -1L;
    final static long MINIMAL_NINETEEN_DIGIT_INTEGER = 1000_00000_00000_00000L;
    /**
     * The decimal exponent of a double has a range of -324 to +308.
     * The hexadecimal exponent of a double has a range of -1022 to +1023.
     */
    final static int MAX_EXPONENT_NUMBER = 1024;
    /**
     * Special value in {@link #CHAR_TO_HEX_MAP} for
     * the decimal point character.
     */
    static final byte DECIMAL_POINT_CLASS = -4;
    /**
     * Special value in {@link #CHAR_TO_HEX_MAP} for
     * characters that are neither a hex digit nor
     * a decimal point character..
     */
    static final byte OTHER_CLASS = -1;
    /**
     * Includes all non-negative values of a {@code byte}, so that we only have
     * to check for byte values {@literal <} 0 before accessing this array.
     */
    static final byte[] CHAR_TO_HEX_MAP = new byte[128];

    static {
        for (char ch = 0; ch < AbstractFloatValueParser.CHAR_TO_HEX_MAP.length; ch++) {
            AbstractFloatValueParser.CHAR_TO_HEX_MAP[ch] = AbstractFloatValueParser.OTHER_CLASS;
        }
        for (char ch = '0'; ch <= '9'; ch++) {
            AbstractFloatValueParser.CHAR_TO_HEX_MAP[ch] = (byte) (ch - '0');
        }
        for (char ch = 'A'; ch <= 'F'; ch++) {
            AbstractFloatValueParser.CHAR_TO_HEX_MAP[ch] = (byte) (ch - 'A' + 10);
        }
        for (char ch = 'a'; ch <= 'f'; ch++) {
            AbstractFloatValueParser.CHAR_TO_HEX_MAP[ch] = (byte) (ch - 'a' + 10);
        }
        for (char ch = '.'; ch <= '.'; ch++) {
            AbstractFloatValueParser.CHAR_TO_HEX_MAP[ch] = AbstractFloatValueParser.DECIMAL_POINT_CLASS;
        }
    }
}

⏎ com/fasterxml/jackson/core/io/doubleparser/AbstractFloatValueParser.java

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File name: jackson-core-2.14.0-sources.jar
File size: 497693 bytes
Release date: 2022-11-05
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