fix: Fix bug stringifying number-like keys and values

A string like "1e 6" will currently be stringified as 1e+6, which is
ambiguous because it looks like a number literal and it will be parsed
as one. This patch fixes the stringify code so that these strings are
quoted. AQF strings have a similar issue and this patch addresses them
as well.

Author: dmaccormack

module/jsonurl-core/src/main/java/org/jsonurl/text/JsonUrlTextAppender.java

@@ -520,6 +520,23 @@ private static <T extends Appendable> boolean appendLiteral(
             }
             return true;
         }
+        
+        if (NumberBuilder.isNumber(text, start, end, false, true, options)) {
+            //
+            // Special handling if this would look like a number literal once
+            // the space is replaced with '+' 
+            //
+            if (optionAQF(options)) {
+                dest.append('!');
+                encodeAqf(dest, text, start, end);
+
+            } else {
+                dest.append('\'');
+                encode(dest, text, start, end, true, false);
+                dest.append('\'');
+            }
+            return true;
+        }
 
         if (optionAQF(options)) {
             encodeAqf(dest, text, start, end);

module/jsonurl-core/src/main/java/org/jsonurl/text/NumberBuilder.java

@@ -124,6 +124,11 @@ public class NumberBuilder implements NumberText { // NOPMD
      * minus/dash.
      */
     private static final char PLUS = '+';
+
+    /**
+     * ASCII space.
+     */
+    private static final char SPACE = ' ';
 
     /**
      * Lookup table for exponent values.
@@ -382,7 +387,8 @@ public Exponent getExponentType() {
     private static NumberText.Exponent getExponentType(//NOPMD
             CharSequence text,
             int start,
-            int stop) {
+            int stop,
+            boolean spaceIsPlus) {
 
         if (stop <= start) {
             return NumberText.Exponent.NONE;
@@ -406,6 +412,11 @@ private static NumberText.Exponent getExponentType(//NOPMD
         char c = text.charAt(i); //NOPMD
 
         switch (c) {
+        case SPACE:
+            if (!spaceIsPlus) {
+                return NumberText.Exponent.NONE;    
+            }
+            // fall through
         case PLUS:
             i++;
             if (i == stop) {
@@ -521,7 +532,7 @@ public boolean parse(
             fractIndexStop = pos = digits(text, pos + 1, stop);
         }
 
-        exponentType = getExponentType(text, pos, stop);
+        exponentType = getExponentType(text, pos, stop, false);
 
         switch (exponentType) { // NOPMD - SwitchStmtsShouldHaveDefault
         case JUST_VALUE:
@@ -609,6 +620,27 @@ public static boolean isNumber(
         return isNumber(text, start, stop, false, options);
     }
 
+    /**
+     * Determine if the given CharSequence is a valid JSON&#x2192;URL number literal.
+     *
+     * <p>Convenience for {@link
+     * #isNumber(CharSequence, int, int, boolean, boolean, Set)
+     * isNumber(s, 0, stop, isNonFractional, false, options)}.
+     * @param text a valid CharSequence
+     * @param start an index
+     * @param stop an index
+     * @param options a valid set of options or {@code null}
+     * @return true if the CharSequence is a JSON&#x2192;URL number
+     */
+    public static boolean isNumber(
+            CharSequence text,
+            int start,
+            int stop,
+            boolean isNonFractional,
+            Set<JsonUrlOption> options) {
+        return isNumber(text, start, stop, isNonFractional, false, options);
+    }
+
     /**
      * Determine if the given CharSequence is a valid JSON&#x2192;URL number literal.
      * 
@@ -633,6 +665,7 @@ public static boolean isNumber(
             int start,
             int stop,
             boolean isNonFractional,
+            boolean spaceIsPlus,
             Set<JsonUrlOption> options) {
 
         int pos = start; //NOPMD - DataflowAnomalyAnalysis
@@ -677,7 +710,7 @@ public static boolean isNumber(
 
         final int expDigitSkip;
 
-        switch (getExponentType(text, pos, stop)) {
+        switch (getExponentType(text, pos, stop, spaceIsPlus)) {
         case JUST_VALUE:
             expDigitSkip = 1;
             pos = digits(text, pos + 1, stop);

module/jsonurl-core/src/test/java/org/jsonurl/stream/JsonUrlIteratorTest.java

@@ -414,6 +414,17 @@ static Stream<EventTest> testAQF() {
                         "(hello)",
                         JsonUrlEvent.END_STREAM}),
 
+                new EventTest(
+                    "(!1e+1:!1e+1)",
+                    new Object[] {
+                        JsonUrlEvent.START_OBJECT,
+                        JsonUrlEvent.KEY_NAME,
+                        "1e 1",
+                        JsonUrlEvent.VALUE_STRING,
+                        "1e 1",
+                        JsonUrlEvent.END_OBJECT,
+                        JsonUrlEvent.END_STREAM}),
+
             }));
     }
 
@@ -607,6 +618,17 @@ static Stream<EventTest> testNotAQF() {
                         "!(hello!)",
                         JsonUrlEvent.END_STREAM}),
 
+                new EventTest(
+                    "('1e+1':'1e+1')",
+                    new Object[] {
+                        JsonUrlEvent.START_OBJECT,
+                        JsonUrlEvent.KEY_NAME,
+                        "1e 1",
+                        JsonUrlEvent.VALUE_STRING,
+                        "1e 1",
+                        JsonUrlEvent.END_OBJECT,
+                        JsonUrlEvent.END_STREAM}),
+
             }));
     }
 
@@ -1295,6 +1317,17 @@ static Stream<EventTest> testNotAQF() {
                     JsonUrlEvent.END_OBJECT,
                     JsonUrlEvent.END_STREAM}),
 
+            new EventTest(
+                "(1e+1:1e+1)",
+                new Object[] {
+                    JsonUrlEvent.START_OBJECT,
+                    JsonUrlEvent.KEY_NAME,
+                    "1e+1",
+                    JsonUrlEvent.VALUE_NUMBER,
+                    "1e+1",
+                    JsonUrlEvent.END_OBJECT,
+                    JsonUrlEvent.END_STREAM}),
+
 
             // Exception
             new EventTest(

module/jsonurl-core/src/test/java/org/jsonurl/text/JsonUrlStringBuilderTest.java

@@ -527,6 +527,33 @@ void testText6() throws IOException {
              expected);
     }
 
+    @Test
+    void testText7() throws IOException {
+        String expectedAqf = "(!1e+3:1)";
+        assertEquals(
+            expectedAqf,
+            new JsonUrlStringBuilder(JsonUrlOption.AQF)
+            .beginObject()
+            .addKey("1e 3")
+            .nameSeparator()
+            .add(1)
+            .endObject()
+            .build(),
+            expectedAqf);
+
+        String expected = "('1e+3':1)";
+        assertEquals(
+            expected,
+            new JsonUrlStringBuilder()
+            .beginObject()
+            .addKey("1e 3")
+            .nameSeparator()
+            .add(1)
+            .endObject()
+            .build(),
+            expected);
+    }
+
     @ParameterizedTest
     @Tag("exception")
     @ValueSource(strings = {