Script engine fixes/additions (fixes #1212)

* Follow up to c3193f3.
* Resolved some issues with += and -= operators.
* Cleaned up post ++ and -- operators.
* Implemented pre ++ and -- operators.
Thanks to Hercules!

src/map/script.c

@@ -383,6 +383,8 @@ const char* script_op2name(int op)
 	RETURN_OP_NAME(C_USERFUNC);
 	RETURN_OP_NAME(C_USERFUNC_POS);
 
+	RETURN_OP_NAME(C_REF);
+
 	// operators
 	RETURN_OP_NAME(C_OP3);
 	RETURN_OP_NAME(C_LOR);
@@ -406,6 +408,10 @@ const char* script_op2name(int op)
 	RETURN_OP_NAME(C_NOT);
 	RETURN_OP_NAME(C_R_SHIFT);
 	RETURN_OP_NAME(C_L_SHIFT);
+	RETURN_OP_NAME(C_ADD_POST);
+	RETURN_OP_NAME(C_SUB_POST);
+	RETURN_OP_NAME(C_ADD_PRE);
+	RETURN_OP_NAME(C_SUB_PRE);
 
 	default:
 		ShowDebug("script_op2name: unexpected op=%d\n", op);
@@ -1024,6 +1030,34 @@ static void parse_nextline(bool first, const char* p)
 	str_data[LABEL_NEXTLINE].label     = -1;
 }
 
+/**
+ * Pushes a variable into stack, processing its array index if needed.
+ * @see parse_variable
+ */
+void parse_variable_sub_push(int word, const char *p2)
+{
+	if( p2 ) { // Process the variable index
+		const char *p3 = NULL;
+
+		// Push the getelementofarray method into the stack
+		add_scriptl(buildin_getelementofarray_ref);
+		add_scriptc(C_ARG);
+		add_scriptl(word);
+
+		// Process the sub-expression for this assignment
+		p3 = parse_subexpr(p2 + 1, 1);
+		p3 = skip_space(p3);
+
+		if( *p3 != ']' ) // Closing parenthesis is required for this script
+			disp_error_message("Missing closing ']' parenthesis for the variable assignment.", p3);
+
+		// Push the closing function stack operator onto the stack
+		add_scriptc(C_FUNC);
+		p3++;
+	} else // No array index, simply push the variable or value onto the stack
+		add_scriptl(word);
+}
+
 /// Parse a variable assignment using the direct equals operator
 /// @param p script position where the function should run from
 /// @return NULL if not a variable assignment, the new position otherwise
@@ -1033,6 +1067,10 @@ const char* parse_variable(const char* p) {
 	const char *p2 = NULL;
 	const char *var = p;
 
+	if ((p[0] == '+' && p[1] == '+' && (type = C_ADD_PRE)) // pre ++
+	 || (p[0] == '-' && p[1] == '-' && (type = C_SUB_PRE))) // pre --
+		var = p = skip_space(&p[2]);
+
 	// skip the variable where applicable
 	p = skip_word(p);
 	p = skip_space(p);
@@ -1064,8 +1102,8 @@ const char* parse_variable(const char* p) {
 	|| ( p[0] == '/' && p[1] == '=' && (type = C_DIV) ) // /=
 	|| ( p[0] == '%' && p[1] == '=' && (type = C_MOD) ) // %=
 	|| ( p[0] == '~' && p[1] == '=' && (type = C_NOT) ) // ~=
-	|| ( p[0] == '+' && p[1] == '+' && (type = C_ADD_PP) ) // ++
-	|| ( p[0] == '-' && p[1] == '-' && (type = C_SUB_PP) ) // --
+	|| ( p[0] == '+' && p[1] == '+' && (type = C_ADD_POST) ) // post ++
+	|| ( p[0] == '-' && p[1] == '-' && (type = C_SUB_POST) ) // post --
 	|| ( p[0] == '<' && p[1] == '<' && p[2] == '=' && (type = C_L_SHIFT) ) // <<=
 	|| ( p[0] == '>' && p[1] == '>' && p[2] == '=' && (type = C_R_SHIFT) ) // >>=
 	) )
@@ -1074,6 +1112,11 @@ const char* parse_variable(const char* p) {
 	}
 
 	switch( type ) {
+		case C_ADD_PRE: // pre ++
+		case C_SUB_PRE: // pre --
+			// Nothing more to skip
+		break;
+
 		case C_EQ: {// incremental modifier
 			p = skip_space( &p[1] );
 		}
@@ -1109,41 +1152,22 @@ const char* parse_variable(const char* p) {
 	// parse the variable currently being modified
 	word = add_word(var);
 
-	if( str_data[word].type == C_FUNC || str_data[word].type == C_USERFUNC || str_data[word].type == C_USERFUNC_POS )
-	{// cannot assign a variable which exists as a function or label
+	if( str_data[word].type == C_FUNC || str_data[word].type == C_USERFUNC || str_data[word].type == C_USERFUNC_POS ) // cannot assign a variable which exists as a function or label
 		disp_error_message("Cannot modify a variable which has the same name as a function or label.", p);
-	}
 
-	if( p2 ) {// process the variable index
-		const char* p3 = NULL;
-
-		// push the getelementofarray method into the stack
-		add_scriptl(buildin_getelementofarray_ref);
-		add_scriptc(C_ARG);
-		add_scriptl(word);
-
-		// process the sub-expression for this assignment
-		p3 = parse_subexpr(p2 + 1, 1);
-		p3 = skip_space(p3);
-
-		if( *p3 != ']' ) {// closing parenthesis is required for this script
-			disp_error_message("Missing closing ']' parenthesis for the variable assignment.", p3);
-		}
-
-		// push the closing function stack operator onto the stack
-		add_scriptc(C_FUNC);
-		p3 ++;
-	} else {// simply push the variable or value onto the stack
-		add_scriptl(word);
-	}
+	parse_variable_sub_push(word, p2); // Push variable onto the stack
 
 	if( type != C_EQ )
-		add_scriptc(C_REF);
+		parse_variable_sub_push(word, p2); // Push variable onto the stack once again (first argument of setr)
 
-	if( type == C_ADD_PP || type == C_SUB_PP ) {// incremental operator for the method
+	if( type == C_ADD_POST || type == C_SUB_POST ) { // post ++ / --
 		add_scripti(1);
-		add_scriptc(type == C_ADD_PP ? C_ADD : C_SUB);
-	} else {// process the value as an expression
+		add_scriptc(type == C_ADD_POST ? C_ADD : C_SUB);
+		parse_variable_sub_push(word, p2); // Push variable onto the stack (third argument of setr)
+	} else if( type == C_ADD_PRE || type == C_SUB_PRE ) { // pre ++ / --
+		add_scripti(1);
+		add_scriptc(type == C_ADD_PRE ? C_ADD : C_SUB);
+	} else { // Process the value as an expression
 		p = parse_subexpr(p, -1);
 
 		if( type != C_EQ )
@@ -1326,32 +1350,34 @@ const char* parse_subexpr(const char* p,int limit)
 		}
 	}
 
-	if((op=C_NEG,*p=='-') || (op=C_LNOT,*p=='!') || (op=C_NOT,*p=='~')){
-		p=parse_subexpr(p+1,10);
+	if( (op = C_ADD_PRE, p[0] == '+' && p[1] == '+') || (op = C_SUB_PRE, p[0] == '-' && p[1] == '-') ) // Pre ++ -- operators
+		p = parse_variable(p);
+	else if( (op = C_NEG, *p == '-') || (op = C_LNOT, *p == '!') || (op = C_NOT, *p == '~') ) { // Unary - ! ~ operators
+		p = parse_subexpr(p + 1, 11);
 		add_scriptc(op);
 	} else
-		p=parse_simpleexpr(p);
-	p=skip_space(p);
+		p = parse_simpleexpr(p);
+	p = skip_space(p);
 	while((
 			(op=C_OP3,opl=0,len=1,*p=='?') ||
-			(op=C_ADD,opl=8,len=1,*p=='+') ||
-			(op=C_SUB,opl=8,len=1,*p=='-') ||
-			(op=C_MUL,opl=9,len=1,*p=='*') ||
-			(op=C_DIV,opl=9,len=1,*p=='/') ||
-			(op=C_MOD,opl=9,len=1,*p=='%') ||
+			(op=C_ADD,opl=9,len=1,*p=='+') ||
+			(op=C_SUB,opl=9,len=1,*p=='-') ||
+			(op=C_MUL,opl=10,len=1,*p=='*') ||
+			(op=C_DIV,opl=10,len=1,*p=='/') ||
+			(op=C_MOD,opl=10,len=1,*p=='%') ||
 			(op=C_LAND,opl=2,len=2,*p=='&' && p[1]=='&') ||
-			(op=C_AND,opl=6,len=1,*p=='&') ||
+			(op=C_AND,opl=5,len=1,*p=='&') ||
 			(op=C_LOR,opl=1,len=2,*p=='|' && p[1]=='|') ||
-			(op=C_OR,opl=5,len=1,*p=='|') ||
+			(op=C_OR,opl=3,len=1,*p=='|') ||
 			(op=C_XOR,opl=4,len=1,*p=='^') ||
-			(op=C_EQ,opl=3,len=2,*p=='=' && p[1]=='=') ||
-			(op=C_NE,opl=3,len=2,*p=='!' && p[1]=='=') ||
-			(op=C_R_SHIFT,opl=7,len=2,*p=='>' && p[1]=='>') ||
-			(op=C_GE,opl=3,len=2,*p=='>' && p[1]=='=') ||
-			(op=C_GT,opl=3,len=1,*p=='>') ||
-			(op=C_L_SHIFT,opl=7,len=2,*p=='<' && p[1]=='<') ||
-			(op=C_LE,opl=3,len=2,*p=='<' && p[1]=='=') ||
-			(op=C_LT,opl=3,len=1,*p=='<')) && opl>limit){
+			(op=C_EQ,opl=6,len=2,*p=='=' && p[1]=='=') ||
+			(op=C_NE,opl=6,len=2,*p=='!' && p[1]=='=') ||
+			(op=C_R_SHIFT,opl=8,len=2,*p=='>' && p[1]=='>') ||
+			(op=C_GE,opl=7,len=2,*p=='>' && p[1]=='=') ||
+			(op=C_GT,opl=7,len=1,*p=='>') ||
+			(op=C_L_SHIFT,opl=8,len=2,*p=='<' && p[1]=='<') ||
+			(op=C_LE,opl=7,len=2,*p=='<' && p[1]=='=') ||
+			(op=C_LT,opl=7,len=1,*p=='<')) && opl>limit){
 		p+=len;
 		if(op == C_OP3) {
 			p=parse_subexpr(p,-1);
@@ -2148,7 +2174,7 @@ static void add_buildin_func(void)
 			str_data[n].val = i;
 			str_data[n].func = buildin_func[i].func;
 
-			if (!strcmp(buildin_func[i].name, "set")) buildin_set_ref = n;
+			if (!strcmp(buildin_func[i].name, "setr")) buildin_set_ref = n;
 			else if (!strcmp(buildin_func[i].name, "callsub")) buildin_callsub_ref = n;
 			else if (!strcmp(buildin_func[i].name, "callfunc")) buildin_callfunc_ref = n;
 			else if( !strcmp(buildin_func[i].name, "getelementofarray") ) buildin_getelementofarray_ref = n;
@@ -5933,7 +5959,7 @@ BUILDIN_FUNC(copyarray);
 /// The value is converted to the type of the variable.
 ///
 /// set(<variable>,<value>{,<charid>})
-BUILDIN_FUNC(set)
+BUILDIN_FUNC(setr)
 {
 	TBL_PC* sd = NULL;
 	struct script_data* data;
@@ -5989,14 +6015,19 @@ BUILDIN_FUNC(set)
 	}
 #endif
 
+	if( script_hasdata(st, 4) ) { // Optional argument used by post-increment/post-decrement constructs to return the previous value
+		if( is_string_variable(name) )
+			script_pushstrcopy(st,script_getstr(st, 4));
+		else
+			script_pushint(st,script_getnum(st, 4));
+	} else // Return a copy of the variable reference
+		script_pushcopy(st, 2);
+
 	if( is_string_variable(name) )
 		set_reg(st,sd,num,name,(void*)script_getstr(st,3),script_getref(st,2));
 	else
 		set_reg(st,sd,num,name,(void*)__64BPRTSIZE(script_getnum(st,3)),script_getref(st,2));
 
-	// return a copy of the variable reference
-	script_pushcopy(st,2);
-
 	return SCRIPT_CMD_SUCCESS;
 }
 
@@ -21520,7 +21551,8 @@ struct script_function buildin_func[] = {
 	BUILDIN_DEF(warpguild,"siii"), // [Fredzilla]
 	BUILDIN_DEF(setlook,"ii?"),
 	BUILDIN_DEF(changelook,"ii?"), // Simulates but don't Store it
-	BUILDIN_DEF(set,"rv?"),
+	BUILDIN_DEF2(setr,"set","rv"),
+	BUILDIN_DEF(setr,"rv?"), // Not meant to be used directly, required for var++/var--
 	BUILDIN_DEF(setarray,"rv*"),
 	BUILDIN_DEF(cleararray,"rvi"),
 	BUILDIN_DEF(copyarray,"rri"),

src/map/script.h

@@ -201,8 +201,10 @@ typedef enum c_op {
 	C_NOT, // ~ a
 	C_R_SHIFT, // a >> b
 	C_L_SHIFT, // a << b
-	C_ADD_PP, // ++a
-	C_SUB_PP, // --a
+	C_ADD_POST, // a++
+	C_SUB_POST, // a--
+	C_ADD_PRE, // ++a
+	C_SUB_PRE, // --a
 } c_op;
 
 /**