Fixes #1149: add JsonParser.getNumberTypeFP()

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -18,6 +18,7 @@ a pure JSON library.
 
 #1145: `JsonPointer.appendProperty(String)` does not escape the property name
  (reported by Robert E)
+#1149: Add `JsonParser.getNumberTypeFP()`
 #1157: Use fast parser (FDP) for large `BigDecimal`s (500+ chars)
  (contributed by @pjfanning)
 #1169: `ArrayIndexOutOfBoundsException` for specific invalid content,

src/main/java/com/fasterxml/jackson/core/JsonParser.java

@@ -40,7 +40,47 @@ public abstract class JsonParser
      */
     public enum NumberType {
         INT, LONG, BIG_INTEGER, FLOAT, DOUBLE, BIG_DECIMAL
-    };
+    }
+
+    /**
+     * Enumeration of possible physical Floating-Point types that
+     * underlying format uses. Used to indicate most accurate (and
+     * efficient) representation if known (if not known,
+     * {@link NumberTypeFP#UNKNOWN} is used).
+     *
+     * @since 2.17
+     */
+    public enum NumberTypeFP {
+        /**
+         * Special "mini-float" that some binary formats support.
+         */
+        FLOAT16,
+        
+        /**
+         * Standard IEEE-754 single-precision 32-bit binary value
+         */
+        FLOAT32,
+        
+        /**
+         * Standard IEEE-754 double-precision 64-bit binary value
+         */
+        DOUBLE64,
+        
+        /**
+         * Unlimited precision, decimal (10-based) values
+         */
+        BIG_DECIMAL,
+
+        /**
+         * Constant used when type is not known, or there is no specific
+         * type to match: most commonly used for textual formats like JSON
+         * where representation does not necessarily have single easily detectable
+         * optimal representation (for example, value {@code 0.1} has no
+         * exact binary representation whereas {@code 0.25} has exact representation
+         * in every binary type supported)
+         */
+        UNKNOWN;
+    }
 
     /**
      * Default set of {@link StreamReadCapability}ies that may be used as
@@ -1715,7 +1755,7 @@ public Object getNumberValueDeferred() throws IOException {
      * If current token is of type
      * {@link JsonToken#VALUE_NUMBER_INT} or
      * {@link JsonToken#VALUE_NUMBER_FLOAT}, returns
-     * one of {@link NumberType} constants; otherwise returns null.
+     * one of {@link NumberType} constants; otherwise returns {@code null}.
      *
      * @return Type of current number, if parser points to numeric token; {@code null} otherwise
      *
@@ -1724,6 +1764,23 @@ public Object getNumberValueDeferred() throws IOException {
      */
     public abstract NumberType getNumberType() throws IOException;
 
+    /**
+     * If current token is of type
+     * {@link JsonToken#VALUE_NUMBER_FLOAT}, returns
+     * one of {@link NumberTypeFP} constants; otherwise returns
+     * {@link NumberTypeFP#UNKNOWN}.
+     *
+     * @return Type of current number, if parser points to numeric token; {@code null} otherwise
+     *
+     * @throws IOException for low-level read issues, or
+     *   {@link JsonParseException} for decoding problems
+     *
+     * @since 2.17
+     */
+    public NumberTypeFP getNumberTypeFP() throws IOException {
+        return NumberTypeFP.UNKNOWN;
+    }
+
     /**
      * Numeric accessor that can be called when the current
      * token is of type {@link JsonToken#VALUE_NUMBER_INT} and

src/main/java/com/fasterxml/jackson/core/util/JsonParserDelegate.java

@@ -244,6 +244,9 @@ public boolean requiresCustomCodec() {
     @Override
     public NumberType getNumberType() throws IOException { return delegate.getNumberType(); }
 
+    @Override
+    public NumberTypeFP getNumberTypeFP() throws IOException { return delegate.getNumberTypeFP(); }
+
     @Override
     public Number getNumberValue() throws IOException { return delegate.getNumberValue(); }
 

src/test/java/com/fasterxml/jackson/core/read/NumberParsingTest.java

@@ -71,6 +71,7 @@ private void _testSimpleInt(int EXP_I, int mode) throws Exception
         assertToken(JsonToken.START_ARRAY, p.nextToken());
         assertToken(JsonToken.VALUE_NUMBER_INT, p.nextToken());
         assertEquals(JsonParser.NumberType.INT, p.getNumberType());
+        assertEquals(JsonParser.NumberTypeFP.UNKNOWN, p.getNumberTypeFP());
         assertTrue(p.isExpectedNumberIntToken());
         assertEquals(""+EXP_I, p.getText());
 

src/test/java/com/fasterxml/jackson/core/util/TestDelegates.java

@@ -7,6 +7,7 @@
 
 import com.fasterxml.jackson.core.*;
 import com.fasterxml.jackson.core.JsonParser.NumberType;
+import com.fasterxml.jackson.core.JsonParser.NumberTypeFP;
 import com.fasterxml.jackson.core.type.ResolvedType;
 import com.fasterxml.jackson.core.type.TypeReference;
 
@@ -263,6 +264,7 @@ public void testParserDelegate() throws IOException
         assertFalse(del.isNaN());
         assertTrue(del.isExpectedNumberIntToken());
         assertEquals(NumberType.INT, del.getNumberType());
+        assertEquals(NumberTypeFP.UNKNOWN, del.getNumberTypeFP());
         assertEquals(Integer.valueOf(1), del.getNumberValue());
         assertNull(del.getEmbeddedObject());