Fix #1308: allow trailing dot for "Stringified numbers" (#1309)

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -14,6 +14,11 @@ a pure JSON library.
 === Releases ===
 ------------------------------------------------------------------------
 
+2.17.2 (not yet released)
+
+#1308: Relax validation by `NumberInput.looksLikeValidNumber()` to allow
+  trailing dot (like `3.`)
+
 2.17.1 (04-May-2024)
 
 #1241: Fix `NumberInput.looksLikeValidNumber()` implementation

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

@@ -35,12 +35,22 @@ public final class NumberInput
     /**
      * Regexp used to pre-validate "Stringified Numbers": slightly looser than
      * JSON Number definition (allows leading zeroes, positive sign).
-     * 
+     *
      * @since 2.17
      */
     private final static Pattern PATTERN_FLOAT = Pattern.compile(
           "[+-]?[0-9]*[\\.]?[0-9]+([eE][+-]?[0-9]+)?");
 
+
+    /**
+     * Secondary regexp used along with {@code PATTERN_FLOAT} to cover
+     * case where number ends with dot, like {@code "+12."}
+     *
+     * @since 2.17.2
+     */
+    private final static Pattern PATTERN_FLOAT_TRAILING_DOT = Pattern.compile(
+            "[+-]?[0-9]+[\\.]");
+    
     /**
      * Fast method for parsing unsigned integers that are known to fit into
      * regular 32-bit signed int type. This means that length is
@@ -589,6 +599,7 @@ public static boolean looksLikeValidNumber(final String s) {
             char c = s.charAt(0);
             return (c <= '9') && (c >= '0');
         }
-        return PATTERN_FLOAT.matcher(s).matches();
+        return PATTERN_FLOAT.matcher(s).matches()
+                || PATTERN_FLOAT_TRAILING_DOT.matcher(s).matches();
     }
 }

src/test/java/com/fasterxml/jackson/core/io/NumberInputTest.java

@@ -73,7 +73,7 @@ void parseBigIntegerFailsWithENotation()
     }
 
     @Test
-    void looksLikeValidNumber()
+    void looksLikeValidNumberTrue()
     {
         assertTrue(NumberInput.looksLikeValidNumber("0"));
         assertTrue(NumberInput.looksLikeValidNumber("1"));
@@ -83,10 +83,11 @@ void looksLikeValidNumber()
 
         // https://github.com/FasterXML/jackson-databind/issues/4435
         assertTrue(NumberInput.looksLikeValidNumber(".0"));
+        assertTrue(NumberInput.looksLikeValidNumber("-.0"));
+        assertTrue(NumberInput.looksLikeValidNumber("+.0"));
         assertTrue(NumberInput.looksLikeValidNumber(".01"));
-        assertTrue(NumberInput.looksLikeValidNumber("+.01"));
         assertTrue(NumberInput.looksLikeValidNumber("-.01"));
-        assertTrue(NumberInput.looksLikeValidNumber("-.0"));
+        assertTrue(NumberInput.looksLikeValidNumber("+.01"));
 
         assertTrue(NumberInput.looksLikeValidNumber("0.01"));
         assertTrue(NumberInput.looksLikeValidNumber("-0.10"));
@@ -104,11 +105,39 @@ void looksLikeValidNumber()
         assertTrue(NumberInput.looksLikeValidNumber("1.4E-45"));
         assertTrue(NumberInput.looksLikeValidNumber("1.4e+45"));
 
+        // https://github.com/FasterXML/jackson-core/issues/1308
+        assertTrue(NumberInput.looksLikeValidNumber("0."));
+        assertTrue(NumberInput.looksLikeValidNumber("6."));
+        assertTrue(NumberInput.looksLikeValidNumber("65."));
+        assertTrue(NumberInput.looksLikeValidNumber("654."));
+        assertTrue(NumberInput.looksLikeValidNumber("65432."));
+        assertTrue(NumberInput.looksLikeValidNumber("-0."));
+        assertTrue(NumberInput.looksLikeValidNumber("-6."));
+        assertTrue(NumberInput.looksLikeValidNumber("-65."));
+        assertTrue(NumberInput.looksLikeValidNumber("-654."));
+        assertTrue(NumberInput.looksLikeValidNumber("-65432."));
+        assertTrue(NumberInput.looksLikeValidNumber("+0."));
+        assertTrue(NumberInput.looksLikeValidNumber("+6."));
+        assertTrue(NumberInput.looksLikeValidNumber("+65."));
+        assertTrue(NumberInput.looksLikeValidNumber("+654."));
+        assertTrue(NumberInput.looksLikeValidNumber("+65432."));
+    }
+
+    @Test
+    void looksLikeValidNumberFalse()
+    {
+        // https://github.com/FasterXML/jackson-databind/issues/4435 and
+        // https://github.com/FasterXML/jackson-core/issues/1308
         assertFalse(NumberInput.looksLikeValidNumber(""));
         assertFalse(NumberInput.looksLikeValidNumber(" "));
         assertFalse(NumberInput.looksLikeValidNumber("   "));
         assertFalse(NumberInput.looksLikeValidNumber("."));
-        assertFalse(NumberInput.looksLikeValidNumber("0."));
         assertFalse(NumberInput.looksLikeValidNumber("10_000"));
+        assertFalse(NumberInput.looksLikeValidNumber("-"));
+        assertFalse(NumberInput.looksLikeValidNumber("+"));
+        assertFalse(NumberInput.looksLikeValidNumber("-."));
+        assertFalse(NumberInput.looksLikeValidNumber("+."));
+        assertFalse(NumberInput.looksLikeValidNumber("-E"));
+        assertFalse(NumberInput.looksLikeValidNumber("+E"));
     }
 }