Avoid unnecessary zeros when writing double values to XML or JSON

modules/juce_core/javascript/juce_JSON.cpp

@@ -351,9 +351,14 @@ struct JSONFormatter
             auto d = static_cast<double> (v);
 
             if (juce_isfinite (d))
-                out << String (d, maximumDecimalPlaces);
+            {
+                String doubleString (d, maximumDecimalPlaces);
+                out << doubleString.substring (0, (int) CharacterFunctions::findLengthWithoutTrailingZeros (doubleString.getCharPointer()));
+            }
             else
+            {
                 out << "null";
+            }
         }
         else if (v.isArray())
         {

modules/juce_core/text/juce_CharacterFunctions.h

@@ -378,6 +378,35 @@ public:
         return readDoubleValue (text);
     }
 
+    /** If the input is a string representation of a floating-point number, this will
+        find the length of the string without any trailing zeros.
+    */
+    template <typename CharPointerType>
+    static size_t findLengthWithoutTrailingZeros (CharPointerType text)
+    {
+        auto start = text;
+        auto end = text + ((int) text.length());
+
+        for (auto e = end; e > start + 1; --e)
+        {
+            auto lastChar = *(e - 1);
+
+            if (lastChar != '0')
+            {
+                if (lastChar == '.')
+                    return (size_t) (e + 1 - start);
+
+                for (auto s = start; s < e; ++s)
+                    if (*s == '.')
+                        return (size_t) (e - start);
+
+                break;
+            }
+        }
+
+        return (size_t) (end - start);
+    }
+
     //==============================================================================
     /** Parses a character string, to read an integer value. */
     template <typename IntType, typename CharPointerType>

modules/juce_core/xml/juce_XmlElement.cpp

@@ -578,26 +578,11 @@ void XmlElement::setAttribute (const Identifier& attributeName, const int number
     setAttribute (attributeName, String (number));
 }
 
-static String trimTrailingZeros (const String& input)
-{
-    auto pointPos = input.indexOfChar ('.');
-
-    if (pointPos == -1)
-        return input;
-
-    auto start = input.getCharPointer();
-    auto minPos = start + pointPos + 1;
-    auto ptr = start + input.length() - 1;
-
-    while (ptr != minPos && *ptr == '0')
-        --ptr;
-
-    return input.substring (0, (int) (ptr - start) + 1);
-}
-
 void XmlElement::setAttribute (const Identifier& attributeName, const double number)
 {
-    setAttribute (attributeName, trimTrailingZeros ({ number, 20 }));
+    String doubleString (number, 20);
+    setAttribute (attributeName,
+                  doubleString.substring (0, (int) CharacterFunctions::findLengthWithoutTrailingZeros (doubleString.getCharPointer())));
 }
 
 void XmlElement::removeAttribute (const Identifier& attributeName) noexcept