S-Record lexer: add future-proof highlighting for unknown record types

An S4 record for example, which is not defined in the S-Record
specification, will now be highlighted until record end (checksum)
instead of aborting after the "byte count" field. The former behaviour
looked a bit half-baked.

Since the size of the address field is unknown, the address and data
fields are highlighted with the same style in the new state
SCE_SREC_DATA_UNKNOWN. Alternating styles (ODD/EVEN) for readability of
the data field of valid record types are not applied.

2 files changed, 16 insertions, 12 deletions

diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index 30593426e..70b46e0d4 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -4563,6 +4563,8 @@ val SCE_SREC_DATA_ODD=9
 val SCE_SREC_DATA_EVEN=10
 val SCE_SREC_CHECKSUM=11
 val SCE_SREC_CHECKSUM_WRONG=12
+val SCE_SREC_ADDRESSFIELD_UNKNOWN=13
+val SCE_SREC_DATA_UNKNOWN=14
 
 # Events
 
diff --git a/lexers/LexHex.cxx b/lexers/LexHex.cxx
index 9b35732f6..05cb7e636 100644
--- a/lexers/LexHex.cxx
+++ b/lexers/LexHex.cxx
@@ -22,9 +22,9 @@
  *  +----------+
  *  | count    |  2        SCE_SREC_BYTECOUNT, SCE_SREC_BYTECOUNT_WRONG
  *  +----------+
- *  | address  |  4/6/8    SCE_SREC_NOADDRESS, SCE_SREC_DATAADDRESS, SCE_SREC_RECCOUNT, SCE_SREC_STARTADDRESS
+ *  | address  |  4/6/8    SCE_SREC_NOADDRESS, SCE_SREC_DATAADDRESS, SCE_SREC_RECCOUNT, SCE_SREC_STARTADDRESS, (SCE_SREC_ADDRESSFIELD_UNKNOWN)
  *  +----------+
- *  | data     |  0..500   SCE_SREC_DATA_ODD, SCE_SREC_DATA_EVEN
+ *  | data     |  0..500   SCE_SREC_DATA_ODD, SCE_SREC_DATA_EVEN, (SCE_SREC_DATA_UNKNOWN)
  *  +----------+
  *  | checksum |  2        SCE_SREC_CHECKSUM, SCE_SREC_CHECKSUM_WRONG
  *  +----------+
@@ -228,8 +228,8 @@ static int GetSrecAddressFieldType(unsigned int recStartPos, Accessor &styler)
 		case '9':
 			return SCE_SREC_STARTADDRESS;
 
-		default:
-			return SCE_SREC_DEFAULT;
+		default: // handle possible format extension in the future
+			return SCE_SREC_ADDRESSFIELD_UNKNOWN;
 	}
 }
 
@@ -307,25 +307,26 @@ static void ColouriseSrecDoc(unsigned int startPos, int length, int initStyle, W
 				addrFieldSize = GetSrecAddressFieldSize(recStartPos, styler);
 				addrFieldType = GetSrecAddressFieldType(recStartPos, styler);
 
-				if (addrFieldSize > 0) {
-					sc.SetState(addrFieldType);
-					ForwardWithinLine(sc, addrFieldSize * 2);
-				} else {
-					// malformed
-					sc.SetState(SCE_SREC_DEFAULT);
-					ForwardWithinLine(sc);
-				}
+				sc.SetState(addrFieldType);
+				ForwardWithinLine(sc, addrFieldSize * 2);
 				break;
 
 			case SCE_SREC_NOADDRESS:
 			case SCE_SREC_DATAADDRESS:
 			case SCE_SREC_RECCOUNT:
 			case SCE_SREC_STARTADDRESS:
+			case SCE_SREC_ADDRESSFIELD_UNKNOWN:
 				recStartPos = GetSrecRecStartPosition(sc.currentPos, styler);
 				byteCount = GetSrecByteCount(recStartPos, styler);
 				addrFieldSize = GetSrecAddressFieldSize(recStartPos, styler);
 				dataFieldSize = byteCount - addrFieldSize - 1; // -1 for checksum field
 
+				if (sc.state == SCE_SREC_ADDRESSFIELD_UNKNOWN) {
+					sc.SetState(SCE_SREC_DATA_UNKNOWN);
+					ForwardWithinLine(sc, dataFieldSize * 2);
+					break;
+				}
+
 				sc.SetState(SCE_SREC_DATA_ODD);
 
 				for (int i = 0; i < dataFieldSize * 2; i++) {
@@ -343,6 +344,7 @@ static void ColouriseSrecDoc(unsigned int startPos, int length, int initStyle, W
 
 			case SCE_SREC_DATA_ODD:
 			case SCE_SREC_DATA_EVEN:
+			case SCE_SREC_DATA_UNKNOWN:
 				recStartPos = GetSrecRecStartPosition(sc.currentPos, styler);
 				cs1 = CalcSrecChecksum(recStartPos, styler);
 				cs2 = GetSrecChecksum(recStartPos, styler);