Jackson Core Source Code

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-2.12.4-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Core Source Code below:

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com/fasterxml/jackson/core/io/NumberInput.java

package com.fasterxml.jackson.core.io;

import java.math.BigDecimal;

public final class NumberInput
{
    /**
     * Textual representation of a double constant that can cause nasty problems
     * with JDK (see http://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308).
     */
    public final static String NASTY_SMALL_DOUBLE = "2.2250738585072012e-308";

    /**
     * Constants needed for parsing longs from basic int parsing methods
     */
    final static long L_BILLION = 1000000000;

    final static String MIN_LONG_STR_NO_SIGN = String.valueOf(Long.MIN_VALUE).substring(1);
    final static String MAX_LONG_STR = String.valueOf(Long.MAX_VALUE);

    /**
     * Fast method for parsing unsigned integers that are known to fit into
     * regular 32-bit signed int type. This means that length is
     * between 1 and 9 digits (inclusive) and there is no sign character.
     *<p>
     * Note: public to let unit tests call it; not meant to be used by any
     * code outside this package.
     *
     * @param ch Buffer that contains integer value to decode
     * @param off Offset of the first digit character in buffer
     * @param len Length of the number to decode (in characters)
     *
     * @return Decoded {@code int} value
     */
    public static int parseInt(char[] ch, int off, int len)
    {
        int num = ch[off + len - 1] - '0';
        
        switch(len) {
        case 9: 
          num += (ch[off++] - '0') * 100000000;
        case 8: 
          num += (ch[off++] - '0') * 10000000;
        case 7: 
          num += (ch[off++] - '0') * 1000000;
        case 6: 
          num += (ch[off++] - '0') * 100000;
        case 5: 
          num += (ch[off++] - '0') * 10000;
        case 4: 
          num += (ch[off++] - '0') * 1000;
        case 3: 
          num += (ch[off++] - '0') * 100;
        case 2: 
          num += (ch[off] - '0') * 10;
        }
        return num;
    }

    /**
     * Helper method to (more) efficiently parse integer numbers from
     * String values. Input String must be simple Java integer value.
     * No range checks are made to verify that the value fits in 32-bit Java {@code int}:
     * caller is expected to only calls this in cases where this can be guaranteed
     * (basically: number of digits does not exceed 9)
     *<p>
     * NOTE: semantics differ significantly from {@link #parseInt(char[], int, int)}.
     *
     * @param s String that contains integer value to decode
     *
     * @return Decoded {@code int} value
     */
    public static int parseInt(String s)
    {
        /* Ok: let's keep strategy simple: ignoring optional minus sign,
         * we'll accept 1 - 9 digits and parse things efficiently;
         * otherwise just defer to JDK parse functionality.
         */
        char c = s.charAt(0);
        int len = s.length();
        boolean neg = (c == '-');
        int offset = 1;
        // must have 1 - 9 digits after optional sign:
        // negative?
        if (neg) {
            if (len == 1 || len > 10) {
                return Integer.parseInt(s);
            }
            c = s.charAt(offset++);
        } else {
            if (len > 9) {
                return Integer.parseInt(s);
            }
        }
        if (c > '9' || c < '0') {
            return Integer.parseInt(s);
        }
        int num = c - '0';
        if (offset < len) {
            c = s.charAt(offset++);
            if (c > '9' || c < '0') {
                return Integer.parseInt(s);
            }
            num = (num * 10) + (c - '0');
            if (offset < len) {
                c = s.charAt(offset++);
                if (c > '9' || c < '0') {
                    return Integer.parseInt(s);
                }
                num = (num * 10) + (c - '0');
                // Let's just loop if we have more than 3 digits:
                if (offset < len) {
                    do {
                        c = s.charAt(offset++);
                        if (c > '9' || c < '0') {
                            return Integer.parseInt(s);
                        }
                        num = (num * 10) + (c - '0');
                    } while (offset < len);
                }
            }
        }
        return neg ? -num : num;
    }

    public static long parseLong(char[] ch, int off, int len)
    {
        // Note: caller must ensure length is [10, 18]
        int len1 = len-9;
        long val = parseInt(ch, off, len1) * L_BILLION;
        return val + (long) parseInt(ch, off+len1, 9);
    }

    /**
     * Similar to {@link #parseInt(String)} but for {@code long} values.
     *
     * @param s String that contains {@code long} value to decode
     *
     * @return Decoded {@code long} value
     */
    public static long parseLong(String s)
    {
        // Ok, now; as the very first thing, let's just optimize case of "fake longs";
        // that is, if we know they must be ints, call int parsing
        int length = s.length();
        if (length <= 9) {
            return (long) parseInt(s);
        }
        // !!! TODO: implement efficient 2-int parsing...
        return Long.parseLong(s);
    }

    /**
     * Helper method for determining if given String representation of
     * an integral number would fit in 64-bit Java long or not.
     * Note that input String must NOT contain leading minus sign (even
     * if 'negative' is set to true).
     *
     * @param ch Buffer that contains long value to check
     * @param off Offset of the first digit character in buffer
     * @param len Length of the number to decode (in characters)
     * @param negative Whether original number had a minus sign (which is
     *    NOT passed to this method) or not
     *
     * @return {@code True} if specified String representation is within Java
     *   {@code long} range; {@code false} if not.
     */
    public static boolean inLongRange(char[] ch, int off, int len,
            boolean negative)
    {
        String cmpStr = negative ? MIN_LONG_STR_NO_SIGN : MAX_LONG_STR;
        int cmpLen = cmpStr.length();
        if (len < cmpLen) return true;
        if (len > cmpLen) return false;

        for (int i = 0; i < cmpLen; ++i) {
            int diff = ch[off+i] - cmpStr.charAt(i);
            if (diff != 0) {
                return (diff < 0);
            }
        }
        return true;
    }

    /**
     * Similar to {@link #inLongRange(char[],int,int,boolean)}, but
     * with String argument
     *
     * @param s String that contains {@code long} value to check
     * @param negative Whether original number had a minus sign (which is
     *    NOT passed to this method) or not
     *
     * @return {@code True} if specified String representation is within Java
     *   {@code long} range; {@code false} if not.
     */
    public static boolean inLongRange(String s, boolean negative)
    {
        String cmp = negative ? MIN_LONG_STR_NO_SIGN : MAX_LONG_STR;
        int cmpLen = cmp.length();
        int alen = s.length();
        if (alen < cmpLen) return true;
        if (alen > cmpLen) return false;

        // could perhaps just use String.compareTo()?
        for (int i = 0; i < cmpLen; ++i) {
            int diff = s.charAt(i) - cmp.charAt(i);
            if (diff != 0) {
                return (diff < 0);
            }
        }
        return true;
    }

    public static int parseAsInt(String s, int def)
    {
        if (s == null) {
            return def;
        }
        s = s.trim();
        int len = s.length();
        if (len == 0) {
            return def;
        }
        // One more thing: use integer parsing for 'simple'
        int i = 0;
        // skip leading sign, if any
        final char sign = s.charAt(0);
        if (sign == '+') { // for plus, actually physically remove
            s = s.substring(1);
            len = s.length();
        } else if (sign == '-') { // minus, just skip for checks, must retain
            i = 1;
        }
        for (; i < len; ++i) {
            char c = s.charAt(i);
            // if other symbols, parse as Double, coerce
            if (c > '9' || c < '0') {
                try {
                    return (int) parseDouble(s);
                } catch (NumberFormatException e) {
                    return def;
                }
            }
        }
        try {
            return Integer.parseInt(s);
        } catch (NumberFormatException e) { }
        return def;
    }

    public static long parseAsLong(String s, long def)
    {
        if (s == null) {
            return def;
        }
        s = s.trim();
        int len = s.length();
        if (len == 0) {
            return def;
        }
        // One more thing: use long parsing for 'simple'
        int i = 0;
        // skip leading sign, if any
        final char sign = s.charAt(0);
        if (sign == '+') { // for plus, actually physically remove
            s = s.substring(1);
            len = s.length();
        } else if (sign == '-') { // minus, just skip for checks, must retain
            i = 1;
        }
        for (; i < len; ++i) {
            char c = s.charAt(i);
            // if other symbols, parse as Double, coerce
            if (c > '9' || c < '0') {
                try {
                    return (long) parseDouble(s);
                } catch (NumberFormatException e) {
                    return def;
                }
            }
        }
        try {
            return Long.parseLong(s);
        } catch (NumberFormatException e) { }
        return def;
    }
    
    public static double parseAsDouble(String s, double def)
    {
        if (s == null) { return def; }
        s = s.trim();
        int len = s.length();
        if (len == 0) {
            return def;
        }
        try {
            return parseDouble(s);
        } catch (NumberFormatException e) { }
        return def;
    }

    public static double parseDouble(String s) throws NumberFormatException {
        // [JACKSON-486]: avoid some nasty float representations... but should it be MIN_NORMAL or MIN_VALUE?
        /* as per [JACKSON-827], let's use MIN_VALUE as it is available on all JDKs; normalized
         * only in JDK 1.6. In practice, should not really matter.
         */
        if (NASTY_SMALL_DOUBLE.equals(s)) {
            return Double.MIN_VALUE;
        }
        return Double.parseDouble(s);
    }

    public static BigDecimal parseBigDecimal(String s) throws NumberFormatException {
        try { return new BigDecimal(s); } catch (NumberFormatException e) {
            throw _badBD(s);
        }
    }

    public static BigDecimal parseBigDecimal(char[] b) throws NumberFormatException {
        return parseBigDecimal(b, 0, b.length);
    }
    
    public static BigDecimal parseBigDecimal(char[] b, int off, int len) throws NumberFormatException {
        try { return new BigDecimal(b, off, len); } catch (NumberFormatException e) {
            throw _badBD(new String(b, off, len));
        }
    }

    private static NumberFormatException _badBD(String s) {
        return new NumberFormatException("Value \""+s+"\" can not be represented as BigDecimal");
    }
}

com/fasterxml/jackson/core/io/NumberInput.java

 

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