24 KiB
Table of Conents
- Top-level
- Class definitions
- Structure definitions
- Enumeration definitions
- Constant definitions
- Include directives
- Types
- Expressions and Operators
- Statements
- API
Examples:
- Class headers
- Class definitions
- Structure definitions
- Enumeration definitions
- Constant definitions
- Include directives
- Expression statements
- Conditional statements
- Switch statements
- Control flow statements
- Multi-assignment statements
Top-level
A ZScript file can have one of several things at the top level of the file:
- Class definitions
- Structure definitions
- Enumeration definitions
- Constant definitions
- Include directives
Class definitions
A class defines an object type within ZScript, and is most of what you'll be creating within the language.
All classes inherit from other classes. The base class can be set within the class header, but if it is not the class will automatically inherit from Object.
Classes are subject to Scoping. They are also implicitly reference values, and therefore can be null. Use new
to instantiate a new class object.
Classes that inherit from Actor can replace other actors when spawned in maps, and can also be used freely in DECORATE. Actors have states, which will not be explained in this document as they are already well-documented on the ZDoom wiki.
A class is formed with the syntax:
class Name [: BaseClass] [Class flags...]
{
[Class content...]
}
Or, alternatively, the rest of the file can be used as class content. Note that with this syntax you cannot use include directives afterward:
class Name [: BaseClass] [Class flags...];
[Class content...]
Class flags
Flag | Description |
---|---|
abstract |
Cannot be instantiated with new . |
ui |
Has UI scope. |
play |
Has Play scope. |
replaces ReplaceClass |
Replaces ReplaceClass with this class. Only works with descendants of Actor. |
native |
Class is from the engine. Do not use in user code. |
version("ver") |
Restricted to version ver. Do not use in user code. |
Class content
Class contents are an optional list of various things logically contained within the class, including:
- Member declarations
- Static array declarations
- State definitions
- Default definitions
- Property definitions
- Enumeration definitions
- Structure definitions
- Constant definitions
Examples: Class headers
Various class headers:
class MyCoolObject // automatically inherits Object
class MyCoolScopedObject play // has Play scope
class MyCoolThinker : Thinker // inherits Thinker
class MyCoolActor : Actor replaces OtherActor
class MyCoolInterface abstract // can only be inherited
Examples: Class definitions
Basic class definition with a member variable and member function:
class BasicClass
{
int m_thing;
void changeThing()
{
m_thing = 500;
}
}
Alternate syntax usage:
class TheWholeFileIsAClassOhNo;
int m_mymember;
// end of file
Structure definitions
A structure is an object type that does not inherit from Object and is not always a reference type, unlike classes. Structures are passed by-reference as arguments, however, and can be null when doing so.
Structures are preferred for basic compound data types that do not need to be instanced and are often used as a way of generalizing code. They cannot be returned from functions.
Structures are subject to Scoping, however their scope can be reset with the clearscope flag.
A structure takes the form of:
struct Name [Structure flags...]
{
[Structure content...]
}
Optionally followed by a semicolon.
Structure flags
Flag | Description |
---|---|
ui |
Has UI scope. |
play |
Has Play scope. |
clearscope |
Clears the default scope. |
native |
Structure is from the engine. Do not use in user code. |
version("ver") |
Restricted to version ver. Do not use in user code. |
Structure content
Structure contents are an optional list of various things logically contained within the structure, including:
- Member declarations
- Enumeration definitions
- Constant definitions
Examples: Structure definitions
Simple structure:
struct MyCoolStructure
{
int x;
int y;
int z;
}
Enumeration definitions
An enumeration is a list of named numbers, which by default will be incremental from 0. By default they decay to the type int
, but the default decay type can be set manually.
An enumeration definition takes the form:
enum Name [: IntegerType]
{
[Enumerator...]
}
Optionally followed by a semicolon.
Enumerators can either be incremental (from the last enumerator or 0 if there is none) or explicitly set with the basic syntax enumerator = value
. Enumerators must be followed by a comma unless it is the end of the list.
Examples: Enumeration definitions
Basic enumeration:
enum MyCoolEnum
{
A, // has value int(0)
B, // 1 ...
C, // 2 ...
D // and 3
}
Less trivial example:
enum MyCoolerEnum : int16
{
A = 500, // has value int16(500)
B, // 501
C = 200,
D, // 201
E, // 202
};
Constant definitions
Constants are simple named values. They are created with the syntax:
const Name = value;
Constants are not assignable. Their type is inferred from their value, so if you wish for them to have a specific type, you must cast the value to that type.
Examples: Constant definitions
Making an integer constant from a double:
const MyCoolInt = int(777.7777);
Include directives
Include directives include other files to be processed by the ZScript compiler, allowing you to orgnaize and separate code into different files. Their syntax is simple:
#include "filename"
Note that included filenames will conflict with other mods. If two mods have a file named zscript/MyCoolClasses.zsc
and both include it, expecting to get different files, the engine will fail to load with a script error.
To avoid this, it is suggested to place your ZScript code under a uniquely named sub-folder.
Examples: Include directives
Basic includes:
#include "zscript/MyCoolMod/MyCoolClasses.zsc"
Types
ZScript has several categories of types: Integer types, floating-point (decimal) types, strings, vectors, names, classes, et al. There are a wide variety of ways to use these types, as well as a wide variety of places they are used.
Types determine what kind of value an object stores, how it acts within an expression, etc. All objects, constants and enumerations have a type. Argument lists use types to ensure a function is used properly.
Integers
Integer types are basic integral numbers. They include:
Name | Bits | Lowest value | Highest value |
---|---|---|---|
int8 |
8 | -128 | 127 |
uint8 |
8 | 0 | 255 |
int16 |
16 | -32,768 | 32,767 |
uint16 |
16 | 0 | 65,535 |
int |
32 | -2,147,483,648 | 2,147,483,647 |
uint |
32 | 0 | 4,294,967,296 |
Floating-point types
Floating-point types hold exponents, generally represented as regular decimal numbers. There are two such types available to ZScript:
Name | Notes |
---|---|
float |
32-bit in structures and classes, 64-bit otherwise. |
double |
64-bit floating-point number. |
float32 |
32-bit floating-point number. Not implemented correctly, unusable. |
float64 |
Alias for double . |
Strings
The string
type is an immutable, garbage-collected string reference type. Strings are not structures or classes, however there are methods attached to the type, detailed in the API section.
Names
The name
type is an indexed string. While their contents are the same as a string, their actual value is merely an integer which can be compared far quicker than a string. Names are used for many internal purposes such as damage type names.
Color
The color
type can be converted from a string using the X11RGB lump or a hex color in the format #RRGGBB
. There are 4 accessible members in color
: r
, g
, b
, and a
, for each color channel.
Vectors
There are two vector types in ZScript, vector2
and vector3
, which hold two and three members, respectively. Their members can be accessed through x
, y
and (for vector3
,) z
. vector3
can additionally get the X and Y components as a vector2
with xy
.
Vectors can use many operators and even have special ones to themselves. See the Expressions and Operators section for more information.
Other types
Name | Description |
---|---|
bool |
Holds one of two values: true or false . |
sound |
Similar to int , but holds a sound identifier. |
textureid |
Similar to int , but holds a texture identifier. |
spriteid |
Similar to int , but holds a sprite identifier. |
state |
A reference to an actor state. |
statelabel |
The name of an actor state. Similar to name . |
void |
Alias for None . Unknown purpose. |
Fixed-size arrays
Fixed-size arrays take the form Type[size]
. They hold size
number of Type
elements, which can be accessed with the array access operator. Multi-dimensional arrays are also supported.
Dynamic-size arrays
Dynamically sized arrays take the form array<Type>
, and hold an arbitrary number of Type
elements, which can be accessed with the array access operator. Multi-dimensional dynamic arrays are not supported.
Maps
Map types take the form map<Type, Type>
. They are not yet implemented.
Class type references
Class type references are used to describe a concrete type rather than an object. They simply take the form class
, and can be restrained to descendants of a type with the syntax class<Type>
.
User types
Any other identifier used as a type will resolve to a user class, structure or enumeration type.
Identifiers prefixed with @
are internal types which are not exposed to ZScript. Do not use this in user code.
A type name that is within a specific scope can be accessed by prefixing it with a .
. The type .MyClass.MySubStructure
will resolve to the type MySubStructure
contained within MyClass
.
Read-only types
A read-only type, as its name implies, may only be read from, and is effectively immutable. They take the form readonly<Type>
.
Expressions and Operators
Literals
Much like C or most other programming languages, ZScript has object literals, including string literals, integer literals, float literals, name literals, boolean literals, and the null pointer.
String literals
String literals take the same form as in C:
"text here"
String literals have character escapes, which are formed with a backslash and a character. Character escapes include:
Spelling | Output |
---|---|
\" |
A literal " . |
\\ |
A literal \ . |
\ followed by newline |
Concatenates the next line with this one. |
String literals, also like C and C++, will be concatenated when put directly next to eachother. For example, this:
"text 1" "text 2"
Will be parsed as a single string literal with the text "text 1text 2"
.
Name literals
Name literals are similar to string literals, though they use apostrophes instead of quote marks:
'text here'
They do not concatenate like string literals, and do not have character escapes.
Integer literals
Integer literals are formed similarly to C. They may take one of three forms, and be typed uint
or int
based on whether there is a u
or U
at the end or not.
The parser also supports an optional l
/L
suffix as in C, though it does not actually do anything, and it is advised you do not use it for potential forward compatibility purposes.
Integer literals can be in the basic base-10/decimal form:
1234567890 // int
500u // uint
Base-16/hexadecimal form, which may use upper- or lower-case decimals and 0x
prefix, depending on user preference:
0x123456789ABCDEF0
0XaBcDeF0 // don't do this, please.
0x7fff
0x7FFFFFFF
And, base-8/octal form, prefixed with a 0
:
0777
0414444
Float literals
Float literals, much like integer literals, are formed similarly to C, but they do not support hex-float notation. Float literals support exponent notation.
The parser supports an optional f
/F
suffix as in C, though it does not actually do anything, and it is advised you do not use it for potential forward compatibility purposes.
Float literals can be formed in a few ways:
0.5 //=> 0.5
.5 //=> 0.5
1. //=> 1.0
And with exponents:
0.5e+2 //=> 50
50e-2 //=> 0.5
Boolean literals
The two boolean literals are spelled false
and true
, and much like C, can decay to the integer literals 0
and 1
.
Null pointer
The null pointer literal is spelled null
and represents an object that does not exist in memory. Unlike C++, it is not equivalent to the integer literal 0
.
Expressions
Primary expressions
Basic expressions, also known as primary expressions, can be one of:
- An identifier for a constant or variable.
- The
Super
keyword. - Any object literal.
- A vector literal.
- An expression in parentheses.
Identifiers work as you expect, they reference a variable or constant. The Super
keyword references the parent type or any member within it.
Vector literals
Vector literals are not under object literals as they are not constants in the same manner as other literals, since they contain expressions within them. As such, they are expressions, not proper value-based literals. They can be formed with:
(x, y) //=> vector2, where x is not a vector2
(x, y) //=> vector3, where x *is* a vector2
(x, y, z) //=> vector3
Postfix expressions
Postfix expressions are affixed at the end of an expression, and are used for a large variety of things, although the actual amount of postfix expressions is small:
Form | Description |
---|---|
a([Argument list...]) |
Function call. |
Type(a) |
Type cast. |
(class<Type>)(a) |
Class type reference cast. |
a[b] |
Array access. |
a.b |
Member access. |
a++ |
Post-increment. This increments (adds 1 to) the object after the expression is evaluated. |
a-- |
Post-decrement. This decrements (subtracts 1 from) the object after the expression is evaluated. |
Unary expressions
Unary expressions are affixed at the beginning of an expression. The simplest example of a unary expression is the negation operator, -
, as in -500
. Unary expressions include:
Form | Description |
---|---|
-a |
Negation. |
!a |
Logical negation, "not." |
++a |
Pre-increment. This adds 1 to the object and evaluates as the resulting value. |
--a |
Pre-decrement. This subtracts 1 from the object and evaluates as the resulting value. |
~a |
Bitwise negation. Flips all bits in an integer. |
+a |
Affirmation. Does not actually do anything. |
sizeof a |
Evaluates the size of the type of an expression. Unknown purpose. |
alignof a |
Evaluates the alignment of the type of an expression. Unknown purpose. |
Binary expressions
Binary expressions operate on two expressions, and are the most common kind of expression. They are used inline like regular math syntax, ie. 1 + 1
. Binary expressions include:
Form | Description |
---|---|
a + b |
Addition. |
a - b |
Subtraction. |
a * b |
Multiplication. |
a / b |
Division (quotient.) |
a % b |
Division (remainder,) also known as "modulus." Unlike C, this works on floats, too. |
a ** b |
Exponent/power of. |
a << b |
Left bitwise shift. |
a >> b |
Right bitwise shift. |
a >>> b |
Right unsigned bitwise shift. |
a cross b |
Vector cross-product. |
a dot b |
Vector dot-product. |
a .. b |
Concatenation, creates a string from two values. |
a < b |
true if a is less than b . |
a > b |
true if a is greater than b . |
a <= b |
true if a is less than or equal to b . |
a >= b |
true if a is greater than or equal to b . |
a == b |
true if a is equal to b . |
a != b |
true if a is not equal to b . |
a ~== b |
true if a is approximately equal to b . For strings this is a case-insensitive comparison, and for floats and vectors this checks if the difference between the two numbers is smaller than ε. |
a && b |
true if a and b are both true . |
a || b |
true if a or b is true . |
a is "b" |
true if a is the type, or a descendant of, b . |
a <>= b |
Signed difference between a and b . |
a & b |
Bitwise AND. |
a ^ b |
Bitwise XOR. |
a | b |
Bitwise OR. |
a::b |
Scope operator. Not implemented yet. |
Assignment expressions
Assignment expressions are a subset of binary expressions which are never constant expressions. They assign a value to another value, as one might guess.
Form | Description |
---|---|
a = b |
Assigns b to a . |
a += b |
Assigns a + b to a . |
a -= b |
Assigns a - b to a . |
a *= b |
Assigns a * b to a . |
a /= b |
Assigns a / b to a . |
a %= b |
Assigns a % b to a . |
a <<= b |
Assigns a << b to a . |
a >>= b |
Assigns a >> b to a . |
a >>>= b |
Assigns a >>> b to a . |
a |= b |
Assigns a | b to a . |
a &= b |
Assigns a & b to a . |
a ^= b |
Assigns a ^ b to a . |
Ternary expression
The ternary expression is formed a ? b : c
, and will evaluate to b
if a
is true
, or c
if it is false
.
Statements
All functions are made up of a list of statements enclosed with left and right braces, which in and of itself is a statement called a compound statement, or block.
Compound statements
A compound statement is formed as:
{
[Statement list...]
}
Note that the statement list is optional, so an empty compound statement {}
is entirely valid.
Expression statements
An expression statement is the single most common type of statement in just about any programming language. In ZScript, exactly like C and C++, an expression statement is simply formed with any expression followed by a semicolon. Function calls and variable assignments are expressions, for instance, so it is quite clear why they are common.
Examples: Expression statements
Some basic expressions:
myCoolFunction(5, 4);
m_myCoolMember = 500;
5 * 5; // does nothing of course, but valid
Conditional statements
A conditional statement will, conditionally, choose a statement (or none) to execute. They work the same as in C and ACS.
Examples: Conditional statements
Simple conditional:
if(a)
b();
Simple conditional, with else statement and a block:
if(a)
{
b();
c = d;
}
else
e = f;
Switch statements
A switch statement takes an integer or name and selects a labeled statement to run. They work the same as in C and ACS, though they accept name
as well as int
and enumeration types.
Examples: Switch statements
A switch demonstrating fallthrough and default cases:
switch(a)
{
case 500: Console.printf("a is 500"); break;
case 501: Console.printf("a is 501");
case 502: Console.printf("a is 501 or 502"); break;
default:
Console.printf("not sure what a is!");
}
Loop statements
ZScript has five loop statements, for
, while
, until
, do while
and do until
. for
, while
and do while
work the same as in C, C++ and ACS, while until
and do until
do the inverse of while
and do while
.
The for
loop takes a limited statement and two optional expressions: The statement for when the loop begins (which is scoped to the loop,) one expression for checking if the loop should break, and one which is executed every time the loop iterates.
The while
loop simply takes one expression for checking if the loop should break, equivalent to for(; a;)
.
The until
loop is equivalent to while(!a)
.
do while
and do until
will only check the expression after the first iteration is complete. The do while
and do until
loops are formed as such:
do
Statement
while(a)
do
Statement
until(a)
Control flow statements
As in C, there are three control flow statements that manipulate where the program will execute statements next, which are available contextually. They are continue
, break
and return
.
continue
is available in loop statements and will continue to the next iteration immediately.
break
is available in loop statements and switch statements, and will break out of the containing statement early.
return
is available in functions. If the function does not return any values, it may only be spelled return;
and will simply exit the function early. If the function does return values, it takes a comma-separated list for each value returned.
Examples: Control flow statements
Use of continue
:
for(int i = 0; i < 50; i++)
{
if(i == 25) continue; // don't do anything on 25!
doThing(i);
}
Use of break
:
for(int i = 0; i < 50; i++)
{
if(i == 25) break; // exit the loop at 25!
doThing(i);
}
Use of return
in various contexts:
void returnsNothing()
{
if(m_thing != 50) return; // exit early if m_thing isn't 50.
doThing(m_thing);
}
int returnsInt()
{
if(m_thing == 50)
return 50; // m_thing is 50, so return 50.
return 0; // must have a return eventually
}
int, int returnsTwoInts()
{
return 1, 2; // returns 1 and 2.
}
Local variable statements
Local variable statements are formed in one of 3 ways. The let
keyword can be used to automatically determine the type of the variable from the initializer, while the other two syntaxes use an explicit type, and initialization is optional.
Type a;
Type a[Expression]; // alternate syntax for local array
let a = b;
Type a = b;
Type a = {Expression list...}; // for fixed size array types
Type a[Expression] = {Expression list...};
Multi-assignment statements
Expressions or functions that return multiple values can be assigned into multiple variables with the syntax:
[Expression list...] = Expression;
Examples: Multi-assignment statements
Getting the actor out of A_SpawnItemEx
:
Actor mo;
bool spawned;
[spawned, mo] = A_SpawnItemEx("MyCoolActor");
Static array statements
Static arrays can be declared as normal as a statement.
Null statements
A null statement does nothing, and is formed ;
. It is similar to an empty compound statement.
API
String
Replace Format AppendFormat Mid Left Truncate Remove CharAt CharCodeAt Filter IndexOf LastIndexOf ToUpper ToLower ToInt ToDouble Split Length