MidiMessage: Added VariableLengthValue::isValid() and removed assertion from MidiMessage::readVariableLengthValue()

modules/juce_audio_basics/midi/juce_MidiFile.cpp

@@ -231,7 +231,7 @@ namespace MidiFileHelpers
         {
             const auto delay = MidiMessage::readVariableLengthValue (data, (int) size);
 
-            if (delay.bytesUsed == 0)
+            if (! delay.isValid())
                 break;
 
             data += delay.bytesUsed;

modules/juce_audio_basics/midi/juce_MidiMessage.cpp

@@ -79,7 +79,6 @@ MidiMessage::VariableLengthValue MidiMessage::readVariableLengthValue (const uin
     // bytes of input to construct a full value, or no terminating byte was
     // found. This implementation only supports variable-length values of up
     // to four bytes.
-    jassertfalse;
     return {};
 }
 
@@ -1225,6 +1224,7 @@ struct MidiMessageTest  : public UnitTest
                 const auto result = MidiMessage::readVariableLengthValue (copy.data(),
                                                                           (int) copy.size());
 
+                expect (result.isValid());
                 expectEquals (result.value, outputs[index]);
                 expectEquals (result.bytesUsed, (int) inputs[index].size());
 
@@ -1252,6 +1252,7 @@ struct MidiMessageTest  : public UnitTest
                 const auto result = MidiMessage::readVariableLengthValue (input.data(),
                                                                           (int) input.size());
 
+                expect (! result.isValid());
                 expectEquals (result.value, 0);
                 expectEquals (result.bytesUsed, 0);
             }

modules/juce_audio_basics/midi/juce_MidiMessage.h

@@ -872,7 +872,6 @@ public:
         from a stream of bytes.
 
         A valid value requires that `bytesUsed` is greater than 0.
-        If `bytesUsed <= 0` this object should be considered invalid.
     */
     struct VariableLengthValue
     {
@@ -881,6 +880,8 @@ public:
         VariableLengthValue (int valueIn, int bytesUsedIn)
             : value (valueIn), bytesUsed (bytesUsedIn) {}
 
+        bool isValid() const noexcept  { return bytesUsed > 0; }
+
         int value = 0;
         int bytesUsed = 0;
     };
@@ -891,7 +892,8 @@ public:
         @param maxBytesToUse    the number of bytes in the region following `data`
         @returns                a struct containing the parsed value, and the number
                                 of bytes that were read. If parsing fails, both the
-                                `value` and `bytesUsed` fields will be set to 0.
+                                `value` and `bytesUsed` fields will be set to 0 and
+                                `isValid()` will return false
     */
     static VariableLengthValue readVariableLengthValue (const uint8* data,
                                                         int maxBytesToUse) noexcept;