Corrected operator precedence table.

- [ This commit is part of a larger script engine related update ]
- Operator precedence rules now closely follow those of languages such
  as C and derivates/related (C++, Java, PHP, etc.)
- Please note that if you had custom scripts with non parenthesized
  expressions containing bitwise |, &, ^ operators, they may behave
  incorrectly now (or perhaps they were already behaving incorrectly,
  since the previous behavior was undocumented).
- Added an up to date operator precedence/associativity table in the
  script documentation.
- Added an operator/keyword self-test script in the npc/custom folder,
  in case if may be of some use for future regression-testing.

6 files changed, 535 insertions, 24 deletions

diff --git a/doc/script_commands.txt b/doc/script_commands.txt
index 0912cb556..9186ba714 100644
--- a/doc/script_commands.txt
+++ b/doc/script_commands.txt
@@ -578,6 +578,29 @@ Operators section described below. All operators listed there may be
 placed in-front of the '=' sign when modifying variables to perform the 
 action as required.
 
+Increment and decrement operators are also provided, for your convenience.
+Pre-increment and pre-decrement operators:
+
+    ++@x; // same as @x = @x + 1
+    --@x; // same as @x = @x - 1
+
+Post-increment and post-decrement operators:
+
+    @x++; // similar to @x = @x + 1
+    @x--; // similar to @x = @x - 1
+
+The difference between pre- and post- increment/decrement operators is that,
+when used in an expression, the pre- ones will be executed before evaluating
+the expression, while the post- ones will be executed after. For example:
+
+    @x = 1;
+    @y = ++@x; // After this line is executed, both @y and @x will be 2
+    @x = 1;
+    @y = @x++; // After this line is executed, @y will be 1, @x will be 2
+
+Note: The pre-increment/pre-decrement operators are, by design, faster (or at
+least not slower) than their respective post- equivalent.
+
 Note:
 
  !! Currently the scripting engine does not support directly copying array 
@@ -854,6 +877,74 @@ and are the following:
 	mentioning that ?: has low priority and has to be enclosed with
 	parenthesis in most (if not all) cases.
 
+Operator Precedence and Associativity
+
+Operator precedence and associativity work more or less like they do in
+mathematics. The rules can be summarized with the following table:
+
+Precedence  |  Description                                  | Associativity
+---------------------------------------------------------------------------
+1 (highest) | []  Array subscripting                        | None
+---------------------------------------------------------------------------
+2           | ++  Increment                                 | None
+            | --  Decrement                                 |
+---------------------------------------------------------------------------
+2           |  -  Unary minus                               | Right to left
+            |  !  Logical NOT                               |
+            |  ~  Bitwise NOT (One's Complement)            |
+---------------------------------------------------------------------------
+3           |  *  Multiplication                            | Left to right
+            |  /  Division                                  |
+            |  %  Modulo (remainder)                        |
+---------------------------------------------------------------------------
+4           |  +  Addition                                  | Left to right
+            |  -  Subtraction                               |
+---------------------------------------------------------------------------
+5           | <<  Bitwise left shift                        | Left to right
+            | >>  Bitwise right shift                       |
+---------------------------------------------------------------------------
+6           |  <  Less than                                 | Left to right
+            | <=  Less than or equal to                     |
+            |  >  Greater than                              |
+            | >=  Greater than or equal to                  |
+---------------------------------------------------------------------------
+7           | ==  Equal to                                  | Left to right
+            | !=  Not equal to                              |
+---------------------------------------------------------------------------
+8           |  &  Bitwise AND                               | Left to right
+---------------------------------------------------------------------------
+9           |  ^  Bitwise XOR (exclusive or)                | Left to right
+---------------------------------------------------------------------------
+10          |  |  Bitwise OR (inclusive or)                 | Left to right
+---------------------------------------------------------------------------
+11          | &&  Logical AND                               | Left to right
+---------------------------------------------------------------------------
+12          | ||  Logical OR                                | Left to right
+---------------------------------------------------------------------------
+13          | ?:  Ternary conditional                       | Right to left
+---------------------------------------------------------------------------
+14          |  =  Direct assignment                         | Right to left
+(lowest)    | +=  Assignment by sum                         |
+            | -=  Assignment by difference                  |
+            | *=  Assignment by product                     |
+            | /=  Assignment by quotient                    |
+            | %=  Assignment by remainder                   |
+            | <<= Assignment by bitwise left shift          |
+            | >>= Assignment by bitwise right shift         |
+            | &=  Assignment by bitwise AND                 |
+            | ^=  Assignment by bitwise XOR                 |
+            | |=  Assignment by bitwise OR                  |
+
+Operator precedence means some operators are evaluated before others. For
+example, in 2 + 4 * 5 , the multiplication has higher precedence so 4 * 5 is
+evaluated first yielding 2 + 20 == 22 and not 6 * 5 == 30 .
+
+Operator associativity defines what happens if a sequence of the same
+operators is used one after another: whether the evaluator will evaluate the
+left operations first or the right. For example, in 8 - 4 - 2 , subtraction is
+left associative so the expression is evaluated left to right. 8 - 4 is
+evaluated first making the expression 4 - 2 == 2 and not 8 - 2 == 6 .
+
 Labels
 ------
 
diff --git a/npc/custom/breeder.txt b/npc/custom/breeder.txt
index 3eef8af0a..0222f5b3a 100644
--- a/npc/custom/breeder.txt
+++ b/npc/custom/breeder.txt
@@ -15,7 +15,7 @@ prontera,124,201,1	script	Universal Rental NPC	4_F_JOB_BLACKSMITH,{
 		message strcharinfo(0),"You must first remove your mount.";
 		end;
 	}
-	else if ((eaclass()&EAJ_THIRDMASK==EAJ_RANGER) && !countitem(6124)) {
+	else if ((eaclass()&EAJ_THIRDMASK) == EAJ_RANGER && !countitem(6124)) {
 		if (!checkfalcon() && getskilllv("HT_FALCON") && !checkoption(Option_Wug) && !checkoption(Option_Wugrider)) {
 			if(select(" ~ Falcon: ~ Warg")==1) setfalcon;
 			else getitem 6124,1;
@@ -24,7 +24,7 @@ prontera,124,201,1	script	Universal Rental NPC	4_F_JOB_BLACKSMITH,{
 		}
 		else getitem 6124,1;
 	}
-	else if ((eaclass()&EAJ_THIRDMASK==EAJ_MECHANIC) && !checkcart() && getskilllv("MC_PUSHCART")) {
+	else if ((eaclass()&EAJ_THIRDMASK) == EAJ_MECHANIC && !checkcart() && getskilllv("MC_PUSHCART")) {
 		if (!checkmadogear() && getskilllv("NC_MADOLICENCE")) {
 			if(select(" ~ Cart: ~ Mado")==1) setcart;
 			else setmadogear;
@@ -36,7 +36,7 @@ prontera,124,201,1	script	Universal Rental NPC	4_F_JOB_BLACKSMITH,{
 	else if (!checkcart() && getskilllv("MC_PUSHCART")) setcart;
 	else if (!checkfalcon() && getskilllv("HT_FALCON") && !checkoption(Option_Wug) && !checkoption(Option_Wugrider)) setfalcon;
 	else if (!checkriding() && getskilllv("KN_RIDING")) {
-		if (eaclass()&EAJ_THIRDMASK==EAJ_RUNE_KNIGHT) setdragon;
+		if ((eaclass()&EAJ_THIRDMASK) == EAJ_RUNE_KNIGHT) setdragon;
 		else setriding;
 	}
 	else if (!checkmadogear() && getskilllv("NC_MADOLICENCE")) setmadogear;
diff --git a/npc/custom/test.txt b/npc/custom/test.txt
new file mode 100644
index 000000000..bfd297f5d
--- /dev/null
+++ b/npc/custom/test.txt
@@ -0,0 +1,416 @@
+//===== Hercules Script ======================================
+//= Script engine self-tests
+//===== By: ==================================================
+//= Haru
+//===== Current Version: =====================================
+//= 1.0
+//===== Description: =========================================
+//= Script to test operators and possibly other elements of
+//= the script engine, useful for regression testing.
+
+-	script	HerculesSelfTest	-1,{
+	end;
+OnCheck:
+	.@msg$ = getarg(0,"Unknown Error");
+	.@val = getarg(1,0);
+	.@ref = getarg(2,1);
+	if (.@val != .@ref) {
+		debugmes "Error: "+.@msg$+": '"+.@val+"' != '"+.@ref+"'";
+		//end;
+	}
+	return;
+OnInit:
+	// Array subscript
+	setarray .@a, 3, 2, 1;
+	callsub(OnCheck, "Array subscript", .@a[2]);
+
+
+	// Increment and decrement operators ++, --
+	.@x = 1;
+	.@y = .@x++; // .@y = .@x; .@x = .@x + 1;
+	callsub(OnCheck, "Suffix increment ++", .@y);
+	callsub(OnCheck, "Suffix increment ++", .@x, 2);
+	.@x = 1;
+	.@y = .@x--; // .@y = .@x; .@x = .@x - 1;
+	callsub(OnCheck, "Suffix decrement --", .@y);
+	callsub(OnCheck, "Suffix decrement --", .@x, 0);
+	.@x = 0;
+	.@y = ++.@x; // .@x = .@x + 1; .@y = .@x;
+	callsub(OnCheck, "Prefix increment ++", .@y);
+	callsub(OnCheck, "Prefix increment ++", .@x);
+	.@x = 2;
+	.@y = --.@x; // .@x = .@x - 1; .@y = .@x;
+	callsub(OnCheck, "Prefix decrement --", .@y);
+	callsub(OnCheck, "Prefix decrement --", .@x);
+
+	// Order of [] and --/++
+	.@a[1] = 0;
+	.@a[1]++; // .@a[1] = .@a[1] + 1;
+	callsub(OnCheck, "Order of [] and ++", .@a[1]);
+	.@a[1] = 2;
+	.@a[1]--; // .@a[1] = .@a[1] - 1;
+	callsub(OnCheck, "Order of [] and --", .@a[1]);
+
+
+	// Unary operators -, !, ~
+	.@x = 1;
+	.@y = -.@x; // .@y = 0 - .@x;
+	callsub(OnCheck, "Unary operator -", .@y, -1);
+	.@x = 1;
+	.@y = !.@x; // if(.@x == 0) .@y = 1; else .@y = 0;
+	callsub(OnCheck, "Unary operator !", .@y, 0);
+	.@x = 0x00000001;
+	.@y = ~.@x; // One's complement of 0x00000001 is 0xfffffffe, which is -2
+	callsub(OnCheck, "Unary operator ~", .@y, -2);
+
+	// Associativity of unary operators -, !, ~
+	.@x = 1;
+	.@y = ~ ! .@x; // .@y = ~(!.@x);
+	callsub(OnCheck, "Associativity of unary ~ and !", .@y, -1);
+	.@x = 0;
+	.@y = - ! .@x; // .@y = -(!.@x);
+	callsub(OnCheck, "Associativity of unary - and !", .@y, -1);
+	.@x = 1;
+	.@y = ~ - .@x; // .@y = ~(-.@x);
+	callsub(OnCheck, "Associativity of unary ~ and -", .@y, 0);
+	.@x = 1;
+	.@y = - ~ .@x; // .@y = -(~.@x);
+	callsub(OnCheck, "Associativity of unary - and ~", .@y, 2);
+
+	// Order of unary -, !, ~ and prefix/suffix ++/--
+	.@x = 2;
+	.@y = - --.@x; // .@y = -(--.@x);
+	callsub(OnCheck, "Order of unary - and prefix --", .@y, -1);
+	callsub(OnCheck, "Order of unary - and prefix --", .@x);
+	.@x = 1;
+	.@y = - .@x--; // .@y = -(.@x--);
+	callsub(OnCheck, "Order of unary - and suffix --", .@y, -1);
+	callsub(OnCheck, "Order of unary - and suffix --", .@x, 0);
+	.@x = 0;
+	.@y = - ++.@x; // .@y = -(++.@x);
+	callsub(OnCheck, "Order of unary - and prefix ++", .@y, -1);
+	callsub(OnCheck, "Order of unary - and prefix ++", .@x);
+	.@x = 1;
+	.@y = - .@x++; // .@y = -(.@x++);
+	callsub(OnCheck, "Order of unary - and suffix ++", .@y, -1);
+	callsub(OnCheck, "Order of unary - and suffix ++", .@x, 2);
+	.@x = 1;
+	.@y = !--.@x; // .@y = !(--.@x);
+	callsub(OnCheck, "Order of unary ! and prefix --", .@y);
+	callsub(OnCheck, "Order of unary ! and prefix --", .@x, 0);
+	.@x = 1;
+	.@y = !.@x--; // .@y = !(.@x--);
+	callsub(OnCheck, "Order of unary ! and suffix --", .@y, 0);
+	callsub(OnCheck, "Order of unary ! and suffix --", .@x, 0);
+	.@x = 0;
+	.@y = !++.@x; // .@y = !(++.@x);
+	callsub(OnCheck, "Order of unary ! and prefix ++", .@y, 0);
+	callsub(OnCheck, "Order of unary ! and prefix ++", .@x);
+	.@x = 0;
+	.@y = !.@x++; // .@y = !(.@x++);
+	callsub(OnCheck, "Order of unary ! and suffix ++", .@y);
+	callsub(OnCheck, "Order of unary ! and suffix ++", .@x);
+	.@x = 2;
+	.@y = ~--.@x; // .@y = ~(--.@x);
+	callsub(OnCheck, "Order of unary ~ and prefix --", .@y, -2);
+	callsub(OnCheck, "Order of unary ~ and prefix --", .@x, 1);
+	.@x = 1;
+	.@y = ~.@x--; // .@y = ~(.@x--);
+	callsub(OnCheck, "Order of unary ~ and suffix --", .@y, -2);
+	callsub(OnCheck, "Order of unary ~ and suffix --", .@x, 0);
+	.@x = 0;
+	.@y = ~++.@x; // .@y = ~(++.@x);
+	callsub(OnCheck, "Order of unary ~ and prefix ++", .@y, -2);
+	callsub(OnCheck, "Order of unary ~ and prefix ++", .@x, 1);
+	.@x = 1;
+	.@y = ~.@x++; // .@y = ~(.@x++);
+	callsub(OnCheck, "Order of unary ~ and suffix ++", .@y, -2);
+	callsub(OnCheck, "Order of unary ~ and suffix ++", .@x, 2);
+
+	// Binary *, /, % operators
+	.@x = 2 * 3; // .@x = 6;
+	callsub(OnCheck, "Binary * operator", .@x, 6);
+	.@x = 7 / 2; // .@x = 3;
+	callsub(OnCheck, "Binary / operator", .@x, 3);
+	.@x = 7 % 2; // .@x = 1;
+	callsub(OnCheck, "Binary % operator", .@x, 1);
+
+	// Associativity of *, /, %
+	.@x = 8 * 3 / 2; // .@x = (8 * 3) / 2;
+	callsub(OnCheck, "Associativity of * and /", .@x, 12);
+
+	// Order of binary *%/ and unary !-~
+	.@x = 2 * ! 3; // .@x = 2 * (!3);
+	callsub(OnCheck, "Order of binary * and unary !", .@x, 0);
+	.@x = ~ 1 * 2; // .@x = (~1) * 2;
+	callsub(OnCheck, "Order of unary ~ and binary *", .@x, -4);
+
+
+	// Binary +, - operators
+	.@x = 1 + 3; // .@x = 4;
+	callsub(OnCheck, "Binary + operator", .@x, 4);
+	.@x = 1 - 3; // .@x = -2;
+	callsub(OnCheck, "Binary - operator", .@x, -2);
+
+	// Associativity of +,-
+	.@x = 0x7fffffff - 0x7ffffff0 + 1; // .@x = (0x7fffffff - 0x7ffffff0) + 1; (without overflow)
+	callsub(OnCheck, "Associativity of + and -", .@x, 16);
+
+	// Order of +, - and *, /, %
+	.@x = 1 + 3 * 2; // .@x = 1 + (3 * 2);
+	callsub(OnCheck, "Order of + and *", .@x, 7);
+
+
+	// << and >> operators
+	.@x = 1<<3; // .@x = 1*2*2*2;
+	callsub(OnCheck, "Left shift << operator", .@x, 8);
+	.@x = 12>>2; // .@x = 12/2/2;
+	callsub(OnCheck, "Right shift >> operator", .@x, 3);
+
+	// Associativity of << and >>
+	.@x = 0x40000000 >> 4 << 2; // .@x = (0x40000000 >> 4) << 2
+	callsub(OnCheck, "Associativity of >> and <<", .@x, 0x10000000);
+
+	// Order of <</>> and +/-
+	.@x = 4 << 2 + 1; // .@x = 4 << (2+1);
+	callsub(OnCheck, "Order of << and +", .@x, 32);
+
+
+	// <, <=, >, >= operators
+	.@x = (1 < 2); // true
+	.@y = (2 < 2); // false
+	callsub(OnCheck, "< operator", .@x);
+	callsub(OnCheck, "< operator", .@y, 0);
+	.@x = (1 <= 2); // true
+	.@y = (2 <= 2); // true
+	callsub(OnCheck, "<= operator", .@x);
+	callsub(OnCheck, "<= operator", .@y);
+	.@x = (2 > 1); // true
+	.@y = (2 > 2); // false
+	callsub(OnCheck, "> operator", .@x);
+	callsub(OnCheck, "> operator", .@y, 0);
+	.@x = (2 >= 1); // true
+	.@y = (2 >= 2); // true
+	callsub(OnCheck, ">= operator", .@x);
+	callsub(OnCheck, ">= operator", .@y);
+
+	// Associativity of <,<=,>,>=
+	.@x = 1 > 0 > 0; // (1 > 0) > 0  -->  1 > 0  -->  true
+	callsub(OnCheck, "Associativity of > operators", .@x);
+
+	// Order of >>/<< and </<=/>/>=
+	.@x = 1 < 1 << 2; // .@x = 1 < (1<<2);
+	callsub(OnCheck, "Order of < and <<", .@x);
+
+
+	// ==, != operators
+	.@x = (0 == 0); // true
+	.@y = (1 == 0); // false
+	callsub(OnCheck, "== operator", .@x);
+	callsub(OnCheck, "== operator", .@y, 0);
+	.@x = (1 != 0); // true
+	.@y = (1 != 1); // false
+	callsub(OnCheck, "!= operator", .@x);
+	callsub(OnCheck, "!= operator", .@y, 0);
+
+	// Associativity of ==, !=
+	.@x = (1 == 0 == 0); // (1 == 0) == 0  -->  0 == 0  --> 1
+	.@y = (1 != 0 == 0); // (1 != 0) == 0  -->  1 == 0  --> 0
+	callsub(OnCheck, "Associativity of != and == operators", .@x);
+	callsub(OnCheck, "Associativity of != and == operators", .@y, 0);
+
+	// Order of </<=/>/>= and ==/!=
+	.@x = (1 == 2 > 1); // true
+	.@y = (1 < 2 == 1); // true
+	callsub(OnCheck, "Order of <,>,==", .@x);
+	callsub(OnCheck, "Order of <,>,==", .@y);
+
+
+	// Bitwise & operator
+	.@x = (7&4); // 0111 & 0100 --> 0100
+	.@y = (4&1); // 0100 & 0001 --> 0000
+	callsub(OnCheck, "Bitwise & operator", .@x, 4);
+	callsub(OnCheck, "Bitwise & operator", .@y, 0);
+
+	// Order of & and ==/!=
+	.@x = (4 == 7 & 4); // (4 == 7)&4
+	.@y = (1 & 3 != 1); // 1 & (3 != 1)
+	callsub(OnCheck, "Order of ==/!= and &", .@x, 0);
+	callsub(OnCheck, "Order of ==/!= and &", .@y);
+
+
+	// Bitwise ^ operator
+	.@x = (3^1); // 0011 ^ 0001 --> 0010
+	callsub(OnCheck, "Bitwise ^ operator", .@x, 2);
+
+	// Order of ^ and &
+	.@x = (0 & 2 ^ 2); // (0 & 2) ^ 2 --> (0000 & 0010) | 0010 --> 0000 ^ 0010 --> 0010
+	.@y = (2 ^ 2 & 0); // 2 ^ (2 & 0) --> 0010 | (0010 & 0000) --> 0010 ^ 0000 --> 0010
+	callsub(OnCheck, "Order of ^ and &", .@x, 2);
+	callsub(OnCheck, "Order of ^ and &", .@y, 2);
+
+
+	// Bitwise | operator
+	.@x = (3|4); // 0011 | 0100 --> 0111
+	.@y = (4|1); // 0100 | 0001 --> 0101
+	callsub(OnCheck, "Bitwise | operator", .@x, 7);
+	callsub(OnCheck, "Bitwise | operator", .@y, 5);
+
+	// Order of ^ and |
+	.@x = (2 ^ 2 | 2); // (2 ^ 1) | 4 --> (0010 ^ 0010) | 0010 --> 0000 | 0010 --> 0010
+	.@y = (2 | 2 ^ 2); // 4 | (1 ^ 2) --> 0010 | (0010 ^ 0010) --> 0010 | 0000 --> 0010
+	callsub(OnCheck, "Order of | and ^", .@x, 2);
+	callsub(OnCheck, "Order of | and ^", .@y, 2);
+
+
+	// Logical && operator
+	.@x = (1 && 1); // true
+	.@y = (0 && 1); // false
+	callsub(OnCheck, "Logical && operator", .@x);
+	callsub(OnCheck, "Logical && operator", .@y, 0);
+
+	// Associativity of && and short-circuit
+	.@x = 0;
+	.@y = (1 && 0 && (.@x = 1)); // should short circuit as false before evaluating the assignment
+	//FIXME callsub(OnCheck, "Short-circuit of &&", .@x, 0);
+	callsub(OnCheck, "Associativity of &&", .@y, 0);
+
+	// Order of bitwise | and logical &&
+	.@x = (1 && 0 | 4); // 1 && (0|4)
+	.@y = (4 | 0 && 1); // (4|0) && 1
+	callsub(OnCheck, "Order of && and |", .@x);
+	callsub(OnCheck, "Order of && and |", .@y);
+
+
+	// Logical || operator
+	.@x = (1 || 1); // true
+	.@y = (0 || 1); // true
+	callsub(OnCheck, "Logical || operator", .@x);
+	callsub(OnCheck, "Logical || operator", .@y);
+
+	// Associativity of || and short-circuit
+	.@x = 0;
+	.@y = (1 || 0 || (.@x = 1)); // should short circuit as true before evaluating the assignment
+	//FIXME callsub(OnCheck, "Short-circuit of ||", .@x, 0);
+	callsub(OnCheck, "Associativity of ||", .@y);
+
+	// Order of logical && and ||
+	.@x = (0 && 1 || 1); // (0 && 1) || 1
+	.@y = (1 || 1 && 0); // 1 || (1 && 0)
+	callsub(OnCheck, "Order of && and ||", .@x);
+	callsub(OnCheck, "Order of && and ||", .@y);
+
+	// Ternary conditional operator ?:
+	.@x = (1 ? 2 : 3); // 2
+	.@y = (0 ? 2 : 3); // 3
+	callsub(OnCheck, "Ternary conditional operator", .@x, 2);
+	callsub(OnCheck, "Ternary conditional operator", .@y, 3);
+
+	// Associativity of ?:
+	.@x = (1 ? 2 : 0 ? 3 : 4);
+	.@y = (1 ? 1 ? 2 : 3 : 5);
+	callsub(OnCheck, "Associativity of ?:", .@x, 2);
+	callsub(OnCheck, "Associativity of ?:", .@y, 2);
+
+	// Order of logical || and ternary ?:
+	.@x = (1 ? 0 : 0 || 1); // 1 ? 0 : (0 || 1) --> false
+	callsub(OnCheck, "Order of || and ?:", .@x, 0);
+
+
+	// Assignment operators
+	.@x = 1;
+	callsub(OnCheck, "Direct assignment operator =", .@x);
+	.@x += 7; // 1 + 7
+	callsub(OnCheck, "Assignment by sum +=", .@x, 8);
+	.@x -= 1; // 8 - 1
+	callsub(OnCheck, "Assignment by difference -=", .@x, 7);
+	.@x *= 2; // 7 * 2
+	callsub(OnCheck, "Assignment by product *=", .@x, 14);
+	.@x /= 2; // 14 / 2
+	callsub(OnCheck, "Assignment by quotient /=", .@x, 7);
+	.@x %= 4; // 7 % 4
+	callsub(OnCheck, "Assignment by remainder %=", .@x, 3);
+	.@x <<= 2; // 3 << 2
+	callsub(OnCheck, "Assignment by bitwise left shift <<=", .@x, 12);
+	.@x >>= 1; // 12 >> 1
+	callsub(OnCheck, "Assignment by bitwise right shift >>=", .@x, 6);
+	.@x &= 5; // 6 & 5 (0110 & 0101 --> 0100)
+	callsub(OnCheck, "Assignment by bitwise and &=", .@x, 4);
+	.@x ^= 5; // 4 ^ 5 (0100 ^ 0101 --> 0001)
+	callsub(OnCheck, "Assignment by bitwise xor ^=", .@x, 1);
+	.@x |= 2; // 1 | 2 (0001 | 0010 --> 0011)
+	callsub(OnCheck, "Assignment by bitwise or |=", .@x, 3);
+
+	// Associativity of assignment operators
+	.@x = 0; .@y = 0;
+	.@x = .@y = 1;
+	callsub(OnCheck, "1Associativity of =", .@x);
+	callsub(OnCheck, "2Associativity of =", .@y);
+	.@x = 0; .@y = 1;
+	.@x = .@y += 4;
+	callsub(OnCheck, "3Associativity of =", .@x, 5);
+	callsub(OnCheck, "4Associativity of =", .@y, 5);
+	.@x = 5; .@y = 3;
+	.@z = 8;
+/*
+ * 0001b4 C_NAME setr
+ * 0001b8 C_ARG
+ * 0001b9 C_NAME .@x
+ * 0001bd C_REF
+ * 0001bd C_INT 16
+ * 0001bf C_MUL
+ * 0001c0 C_FUNC
+ * 0001c1 C_EOL
+ */
+	/* FIXME
+	.@x *= (.@y += 1);
+	//set(.@x, .@x * set(.@y, .@y + 1));
+	//.@x = (.@x * (.@y = .@y + 1));
+	*/
+/*
+ *  0001c2 C_NAME setr
+ *  0001c6 C_ARG
+ *  0001c7 C_NAME .@x
+ *   0001cb C_REF
+ *    0001cc C_NAME setr
+ *    0001d0 C_ARG
+ *    0001d1 C_NAME .@y
+ *     0001d5 C_REF
+ *     0001d5 C_INT 1
+ *     0001d7 C_ADD
+ *    0001d8 C_FUNC
+ *   0001d9 C_MUL
+ *  0001da C_FUNC
+ * 0001db C_EOL
+ */
+/*
+ * 0001c2 C_NAME setr
+ * 0001c6 C_ARG
+ * 0001c7 C_NAME .@x
+ * 0001cb C_REF
+ * 0001cc C_NAME setr
+ * 0001d0 C_ARG
+ * 0001d1 C_NAME .@y
+ * 0001d4 C_INT 2
+ * 0001d6 C_FUNC
+ * 0001d7 C_MUL
+ * 0001d8 C_FUNC
+ * 0001d9 C_EOL
+ */
+	/*
+	callsub(OnCheck, "5Associativity of =", .@x, 20);
+	callsub(OnCheck, "6Associativity of =", .@y, 4);
+	*/
+
+	.@x = 0;
+	if (0)
+		if (1)
+			.@x = 2;
+		else
+			.@x = 3;
+	callsub(OnCheck, "Dangling else", .@x, 0);
+
+	debugmes "Script engine self-test   [ PASSED ]";
+}
+
+// vim: set ft=ath :
diff --git a/npc/other/arena/arena_aco.txt b/npc/other/arena/arena_aco.txt
index 725e8c58f..cc0b4b640 100644
--- a/npc/other/arena/arena_aco.txt
+++ b/npc/other/arena/arena_aco.txt
@@ -1084,7 +1084,7 @@ prt_are_in,25,31,3	script	Staff#aco-2	1_F_02,{
 	set .@hour_endaco, .@end_timeaco / 10000;
 	set .@min_endaco, ((.@end_timeaco % 10000) / 100);
 	set .@sec_endaco, .@end_timeaco % 100;
-	if ((.@hour_startaco == 23) & (.@hour_endaco == 0)) {
+	if ((.@hour_startaco == 23) && (.@hour_endaco == 0)) {
 		set .@hour_endaco,24;
 	}
 	set .@st_to_secaco, ((.@hour_startaco * 3600) + (.@min_startaco * 60) + (.@sec_startaco));
diff --git a/npc/scripts_custom.conf b/npc/scripts_custom.conf
index aeae9e22f..b4283502c 100644
--- a/npc/scripts_custom.conf
+++ b/npc/scripts_custom.conf
@@ -104,3 +104,7 @@
 //npc: npc/custom/battleground/bg_kvm01.txt
 //npc: npc/custom/battleground/bg_kvm02.txt
 //npc: npc/custom/battleground/bg_kvm03.txt
+
+// ----------------------- Misc Scripts -----------------------------
+// Self-test script (for development use only)
+//npc: npc/custom/test.txt
diff --git a/src/map/script.c b/src/map/script.c
index 2c4178d9b..73aaafab2 100644
--- a/src/map/script.c
+++ b/src/map/script.c
@@ -1158,32 +1158,32 @@ const char* script_parse_subexpr(const char* p,int limit) {
 	if( (op=C_ADD_PRE,p[0]=='+'&&p[1]=='+') || (op=C_SUB_PRE,p[0]=='-'&&p[1]=='-') ) { // Pre ++ -- operators
 		p=script->parse_variable(p);
 	} else if( (op=C_NEG,*p=='-') || (op=C_LNOT,*p=='!') || (op=C_NOT,*p=='~') ) { // Unary - ! ~ operators
-		p=script->parse_subexpr(p+1,10);
+		p=script->parse_subexpr(p+1,11);
 		script->addc(op);
 	} else {
 		p=script->parse_simpleexpr(p);
 	}
 	p=script->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_LAND,   opl=2,len=2,*p=='&' && p[1]=='&') // &&
-	|| (op=C_AND,    opl=6,len=1,*p=='&')              // &
-	|| (op=C_LOR,    opl=1,len=2,*p=='|' && p[1]=='|') // ||
-	|| (op=C_OR,     opl=5,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=='<')              // <
+	   (op=C_OP3,    opl=0, 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=5, len=1,*p=='&')              // &
+	|| (op=C_LOR,    opl=1, len=2,*p=='|' && p[1]=='|') // ||
+	|| (op=C_OR,     opl=3, len=1,*p=='|')              // |
+	|| (op=C_XOR,    opl=4, len=1,*p=='^')              // ^
+	|| (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) {