add fast parser code from wrandelshofer/FastDoubleParser (#766)

Author: pjfanning

pom.xml

@@ -141,4 +141,19 @@ com.fasterxml.jackson.core.*;version=${project.version}
     </plugins>
   </build>
 
+  <dependencies>
+    <dependency>
+      <groupId>org.junit.vintage</groupId>
+      <artifactId>junit-vintage-engine</artifactId>
+      <version>5.8.2</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.8.2</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
 </project>

src/main/java/com/fasterxml/jackson/core/io/doubleparser/AbstractFloatValueFromCharSequence.java

@@ -0,0 +1,77 @@
+/**
+ * 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 FloatValue} 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 {
+    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;
+        }
+    }
+
+
+}

src/main/java/com/fasterxml/jackson/core/io/doubleparser/AbstractFloatValueParser.java

@@ -0,0 +1,74 @@
+/**
+ * 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;
+
+/**
+ * Parses a {@code double} from a {@link CharSequence}.
+ */
+public final class DoubleFromCharSequence extends AbstractFloatValueFromCharSequence {
+
+
+    /**
+     * Creates a new instance.
+     */
+    public DoubleFromCharSequence() {
+
+    }
+
+    @Override
+    long nan() {
+        return Double.doubleToRawLongBits(Double.NaN);
+    }
+
+    @Override
+    long negativeInfinity() {
+        return Double.doubleToRawLongBits(Double.NEGATIVE_INFINITY);
+    }
+
+    /**
+     * Parses a {@code FloatValue} from a {@link CharSequence} and converts it
+     * into a {@code double} value.
+     * <p>
+     * See {@link com.fasterxml.jackson.core.io.doubleparser} for the syntax of {@code FloatValue}.
+     *
+     * @param str    the string to be parsed
+     * @param offset the start offset of the {@code FloatValue} in {@code str}
+     * @param length the length of {@code FloatValue} in {@code str}
+     * @return the parsed double value
+     * @throws NumberFormatException if the string can not be parsed
+     */
+    public double parseDouble(CharSequence str, int offset, int length) throws NumberFormatException {
+        return Double.longBitsToDouble(parseFloatValue(str, offset, length));
+    }
+
+    @Override
+    long positiveInfinity() {
+        return Double.doubleToRawLongBits(Double.POSITIVE_INFINITY);
+    }
+
+    @Override
+    long valueOfFloatLiteral(CharSequence str, int startIndex, int endIndex, boolean isNegative,
+                             long significand, int exponent, boolean isSignificandTruncated,
+                             int exponentOfTruncatedSignificand) {
+        double d = FastDoubleMath.tryDecFloatToDoubleTruncated(isNegative, significand, exponent, isSignificandTruncated,
+                exponentOfTruncatedSignificand);
+        return Double.doubleToRawLongBits(Double.isNaN(d) ? Double.parseDouble(str.subSequence(startIndex, endIndex).toString()) : d);
+    }
+
+    @Override
+    long valueOfHexLiteral(
+            CharSequence str, int startIndex, int endIndex, boolean isNegative, long significand, int exponent,
+            boolean isSignificandTruncated, int exponentOfTruncatedSignificand) {
+        double d = FastDoubleMath.tryHexFloatToDoubleTruncated(isNegative, significand, exponent, isSignificandTruncated,
+                exponentOfTruncatedSignificand);
+        return Double.doubleToRawLongBits(Double.isNaN(d) ? Double.parseDouble(str.subSequence(startIndex, endIndex).toString()) : d);
+    }
+
+}