Fixed #631

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -23,6 +23,7 @@ JSON library.
 #627: Add `JsonParser.isExpectedNumberIntToken()` convenience method
 #630: Add `StreamWriteCapability` for further format-based/format-agnostic
   handling improvements
+#631: Add `JsonParser.getNumberValueExact()` to allow precision-retaining buffering
 - Deprecate `JsonParser.getCurrentTokenId()` (use `#currentTokenId()` instead)
 
 2.11.1 (25-Jun-2020)

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

@@ -1315,9 +1315,40 @@ public int getText(Writer writer) throws IOException, UnsupportedOperationExcept
      * all kinds of numeric values. It will return the optimal
      * (simplest/smallest possible) wrapper object that can
      * express the numeric value just parsed.
+     *
+     * @return Numeric value of the current token in its most optimal
+     *   representation
+     *
+     * @throws IOException Problem with access: {@link JsonParseException} if
+     *    the current token is not numeric, or if decoding of the value fails
+     *    (invalid format for numbers); plain {@link IOException} if underlying
+     *    content read fails (possible if values are extracted lazily)
      */
     public abstract Number getNumberValue() throws IOException;
 
+    /**
+     * Method similar to {@link #getNumberValue} with the difference that
+     * for floating-point numbers value returned may be {@link BigDecimal}
+     * if the underlying format does not store floating-point numbers using
+     * native representation: for example, textual formats represent numbers
+     * as Strings (which are 10-based), and conversion to {@link java.lang.Double}
+     * is potentially lossy operation.
+     *<p>
+     * Default implementation simply returns {@link #getNumberValue()}
+     *
+     * @return Numeric value of the current token using most accurate representation
+     *
+     * @throws IOException Problem with access: {@link JsonParseException} if
+     *    the current token is not numeric, or if decoding of the value fails
+     *    (invalid format for numbers); plain {@link IOException} if underlying
+     *    content read fails (possible if values are extracted lazily)
+     *
+     * @since 2.12
+     */
+    public Number getNumberValueExact() throws IOException {
+        return getNumberValue();
+    }
+
     /**
      * If current token is of type 
      * {@link JsonToken#VALUE_NUMBER_INT} or

src/main/java/com/fasterxml/jackson/core/base/ParserBase.java

@@ -614,7 +614,7 @@ public Number getNumberValue() throws IOException
         }
         return _numberDouble;
     }
-    
+
     @Override
     public NumberType getNumberType() throws IOException
     {

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

@@ -193,12 +193,15 @@ public JsonParser overrideFormatFeatures(int values, int mask) {
     @Override
     public Number getNumberValue() throws IOException { return delegate.getNumberValue(); }
 
+    @Override
+    public Number getNumberValueExact() throws IOException { return delegate.getNumberValueExact(); }
+
     /*
     /**********************************************************
     /* Public API, access to token information, coercion/conversion
     /**********************************************************
      */
-    
+
     @Override public int getValueAsInt() throws IOException { return delegate.getValueAsInt(); }
     @Override public int getValueAsInt(int defaultValue) throws IOException { return delegate.getValueAsInt(defaultValue); }
     @Override public long getValueAsLong() throws IOException { return delegate.getValueAsLong(); }
@@ -209,7 +212,7 @@ public JsonParser overrideFormatFeatures(int values, int mask) {
     @Override public boolean getValueAsBoolean(boolean defaultValue) throws IOException { return delegate.getValueAsBoolean(defaultValue); }
     @Override public String getValueAsString() throws IOException { return delegate.getValueAsString(); }
     @Override public String getValueAsString(String defaultValue) throws IOException { return delegate.getValueAsString(defaultValue); }
-    
+
     /*
     /**********************************************************
     /* Public API, access to token values, other