[Bug 14828] com.livecode.byte: Add "the code of _".

peter-b · peter-b · commit e79a8f5ac015 · 2015-03-06T17:33:51.000Z
Obtain the value of a single-byte `Data` value as an integer.
diff --git a/libscript/src/byte.mlc b/libscript/src/byte.mlc
@@ -57,6 +57,7 @@ public foreign handler MCByteExecDeleteFirstByteOf(inout Target as Data) as unde
 public foreign handler MCDataExecRandomBytes(in Count as LCUIndex, out Value as Data) as undefined binds to "<builtin>"
 
 public foreign handler MCByteEvalByteWithCode(in Value as LCUInt, out Result as Data) as undefined binds to "<builtin>"
+public foreign handler MCByteEvalCodeOfByte(in Target as Data, out Result as LCUInt) as undefined binds to "<builtin>"
 
 --
 
@@ -445,9 +446,25 @@ Returns a byte of binary data, created using the given value.  The
 Tags: Binary
 */
 syntax ByteWithCode is prefix operator with precedence 2
-      "the" "byte" "with" "code" <Value: Expression>
+	"the" "byte" "with" "code" <Value: Expression>
 begin
 	MCByteEvalByteWithCode(Value, output)
 end syntax
 
+/*
+Summary:	Get the numeric value of a single byte.
+
+Target:	A 1-byte binary data value.
+
+Description:
+Returns the numeric representation of a single byte of binary data.
+
+Tags: Binary
+*/
+syntax CodeOfByte is prefix operator with precedence 2
+	"the" "code" "of" <Target: Expression>
+begin
+	MCByteEvalCodeOfByte(Target, output)
+end syntax
+
 end module
diff --git a/libscript/src/module-byte.cpp b/libscript/src/module-byte.cpp
@@ -236,6 +236,19 @@ MCByteEvalByteWithCode (uinteger_t p_value,
 	MCDataCreateWithBytes (&t_byte, 1, r_data);
 }
 
+extern "C" MC_DLLEXPORT void
+MCByteEvalCodeOfByte (MCDataRef p_data,
+                      uinteger_t & r_value)
+{
+	if (1 != MCDataGetLength (p_data))
+	{
+		MCErrorThrowGeneric(MCSTR("not a single byte"));
+		return;
+	}
+
+	r_value = MCDataGetByteAtIndex (p_data, 0);
+}
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 #ifdef _TEST
diff --git a/tests/lcb/stdlib/byte.lcb b/tests/lcb/stdlib/byte.lcb
@@ -35,4 +35,22 @@ public handler TestByteWithCode()
 	MCUnitTestHandlerThrows(TestByteWithCode_Overflow, "code->byte (overflow)")
 end handler
 
+handler TestCodeOfByte_Long()
+	variable t
+	put the byte with code 0 into t
+	put t after t
+	return the code of t
+end handler
+handler TestCodeOfByte_Empty()
+	variable t
+	put the empty data into t
+	return the code of t
+end handler
+public handler TestCodeOfByte()
+	test "byte->code" when the code of (the byte with code 1) is 1
+
+	MCUnitTestHandlerThrows(TestCodeOfByte_Long, "byte->code (multibyte)")
+	MCUnitTestHandlerThrows(TestCodeOfByte_Empty, "byte->code (empty)")
+end handler
+
 end module
