implemented nullable type notation

src/lib/common/defs.h

@@ -12,4 +12,6 @@
 #define TYPENAME_BUFFER "Buffer"
 
 #define TYPENAME_FILE      "File"
-#define TYPENAME_DIRECTORY "Directory"
+#define TYPENAME_DIRECTORY "Directory"
+
+#define TYPENAME_NULLABLE "NullableType"

src/lib/common/executable.c

@@ -82,6 +82,7 @@ static const InstrInfo instr_table[] = {
 	[OPCODE_GRT]     = {"GRT",  0, NULL},
 	[OPCODE_LEQ]     = {"LEQ",  0, NULL},
 	[OPCODE_GEQ]     = {"GEQ",  0, NULL},
+	[OPCODE_NLB]     = {"NLB",  0, NULL},
 	[OPCODE_ASS]     = {"ASS",  1, (OperandType[]) {OPTP_STRING}},
 	[OPCODE_POP]     = {"POP",  1, (OperandType[]) {OPTP_INT}},
 	[OPCODE_CALL]    = {"CALL", 2, (OperandType[]) {OPTP_INT, OPTP_INT}},

src/lib/common/executable.h

@@ -67,6 +67,7 @@ typedef enum {
 	OPCODE_GRT,
 	OPCODE_LEQ,
 	OPCODE_GEQ,
+	OPCODE_NLB,
 	OPCODE_ASS,
 	OPCODE_POP,
 	OPCODE_CALL,