[C#] Cast numInGroup representation to be an int. Check cast safety during generation.

Author: ZachBray

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/csharp/CSharpGenerator.java

@@ -181,14 +181,24 @@ private void generateGroupClassHeader(
  dimensionsClassName,
  parentMessageClassName));
 
+ final Token numInGroupToken = tokens.get(index + 3);
+ final boolean isIntCastSafe = isRepresentableByInt32(numInGroupToken.encoding());
+
+ if (!isIntCastSafe)
+ {
+ throw new IllegalArgumentException(String.format(
+ "%s.numInGroup - cannot be represented safely by an int. Please constrain the maxValue.",
+ groupName));
+ }
+
  sb.append(String.format("\n" +
  indent + INDENT + "public void WrapForDecode(%s parentMessage, DirectBuffer buffer, int actingVersion)\n" +
  indent + INDENT + "{\n" +
  indent + INDENT + INDENT + "_parentMessage = parentMessage;\n" +
  indent + INDENT + INDENT + "_buffer = buffer;\n" +
  indent + INDENT + INDENT + "_dimensions.Wrap(buffer, parentMessage.Limit, actingVersion);\n" +
  indent + INDENT + INDENT + "_blockLength = _dimensions.BlockLength;\n" +
- indent + INDENT + INDENT + "_count = _dimensions.NumInGroup;\n" +
+ indent + INDENT + INDENT + "_count = (int) _dimensions.NumInGroup;\n" + // cast safety checked above
  indent + INDENT + INDENT + "_actingVersion = actingVersion;\n" +
  indent + INDENT + INDENT + "_index = -1;\n" +
  indent + INDENT + INDENT + "_parentMessage.Limit = parentMessage.Limit + SbeHeaderSize;\n" +
@@ -197,7 +207,6 @@ private void generateGroupClassHeader(
 
  final int blockLength = tokens.get(index).encodedLength();
  final String typeForBlockLength = cSharpTypeName(tokens.get(index + 2).encoding().primitiveType());
- final Token numInGroupToken = tokens.get(index + 3);
  final String typeForNumInGroup = cSharpTypeName(numInGroupToken.encoding().primitiveType());
 
  sb.append(String.format("\n" +
@@ -233,6 +242,11 @@ private void generateGroupClassHeader(
  blockLength,
  dimensionHeaderLength));
 
+ generateGroupEnumerator(sb, groupName, indent);
+ }
+
+ private void generateGroupEnumerator(final StringBuilder sb, final String groupName, final String indent)
+ {
  sb.append(
  indent + INDENT + "public int ActingBlockLength { get { return _blockLength; } }\n\n" +
  indent + INDENT + "public int Count { get { return _count; } }\n\n" +
@@ -262,6 +276,13 @@ private void generateGroupClassHeader(
  indent + INDENT + "}\n");
  }
 
+ private boolean isRepresentableByInt32(final Encoding encoding)
+ {
+ // These min and max values are the same in .NET
+ return encoding.applicableMinValue().longValue() >= Integer.MIN_VALUE &&
+ encoding.applicableMaxValue().longValue() <= Integer.MAX_VALUE;
+ }
+
  private CharSequence generateGroupProperty(final String groupName, final Token token, final String indent)
  {
  final StringBuilder sb = new StringBuilder();