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[S-22]

Syntax Summary

==============

program:

--------

statement_list

statement_list:

---------------

statement statement ... statement

statement:

----------

identifier event_parameter_list :

case integer event_parameter_list :

case identifier event_parameter_list :

compound_statement

if prim_expr statement

if prim_expr statement else statement

while prim_expr statement

for ( statement ; expr ; statement_list ) statement

try compound_statement catch compound_statement

switch prim_expr compound_statement

break

continue

identifier event_parameter_list

nonident_prim_expr identifier event_parameter_list

nonident_prim_expr = expr

nonident_prim_expr += expr

nonident_prim_expr -= expr

nonident_prim_expr ++

nonident_prim_expr --

;

compound_statement:

-------------------

{ statement_list }

expr:

-----

expr && expr

expr || expr

expr & expr

expr | expr

expr ^ expr

expr == expr

expr != expr

expr

expr > expr

expr

expr >= expr

expr + expr

expr - expr

expr * expr

expr / expr

expr % expr

nonident_prim_expr

func_prim_expr

func_prim_expr:

---------------

identifier event_parameter_list

nonident_prim_expr identifier event_parameter_list

- func_prim_expr

~ func_prim_expr

! func_prim_expr

identifier :: prim_expr

nonident_prim_expr :: prim_expr

event_parameter_list:

---------------------

prim_expr prim_expr ... prim_expr

prim_expr:

----------

nonident_prim_expr

identifier_prim

prim_expr :: prim_expr

nonident_prim_expr:

-------------------

$ prim_expr

nonident_prim_expr . identifier

nonident_prim_expr . size

nonident_prim_expr [ expr ]

string

integer

float

( number number number )

game

level

local

parm

self

group

( expr )

- nonident_prim_expr

~ nonident_prim_expr

! nonident_prim_expr

NULL

NIL

number:

-------

float

integer

Automatically started scripts

=============================

1) maps/mapname.scr

A level script is associated with each map, and is loaded and started at the start of that map (and not for subsequent starts from a saved game). This script is used for triggering all map related dynamic objects such as doors, elevators, AI, etc. maps/mapname.scr corresponds to maps/mapname.bsp. A level script is optional.

2) maps/mapname_precache.scr

A level precache script is associated with each map, and is loaded and started whenever the map is loaded (even from a saved game). This script is used for precaching map specific resources. maps/mapname_precache.scr corresponds to maps/mapname.bsp. A level precache script is optional.

3) Scripts in the anim directory are executed to carry out animation behavior of AI characters. Which script is executed is determined by internal AI state or scripts such as global/shoot.scr.

Threads

=======

A thread executes commands in a script one at a time in order. Multiple threads can exist. The automatically started scripts start execution with a single thread at the start of the file.

All threads belong to a group of threads, denoted "group". The current thread is denoted "local". The group of threads that a thread belongs to will be discussed in the next section.

Methods of creation of threads

------------------------------

1) Automatic

The new thread initially is the only thread in its group.

2) Command: thread label

The new thread belongs to the same group of threads as the original thread.

3) Command: thread filename::label

The new thread initially is the only thread in its group.

4) Command: object thread label

The new thread initially is the only thread in its group.

5) Command: object thread filename::label

The new thread initially is the only thread in its group.

Predefined object references

============================

1) game

Refers to the unique game object which maintains its state across levels. Only primitive values (integers/floats/strings/vectors) will persist across levels.

2) level

Refers to the unique level object which maintains its state for the duration of a level.

3) local

Refers to the thread executing the current command.

4) parm

Refers to the unique parm object which can be used to pass parameters to new threads.

Note that any use of this variable could be coded "better" by using parameters in the creation of new threads.

5) self

Refers to the object that the thread is processing for. This object is the same for all threads in a group of threads.

6) group

Refers to the object representing the group of threads the thread executing the current command belongs to.

self object

===========

The "self" object has its value set at the creation of a group of threads. The following are some such situations:

1) Automatically started scripts

self is NULL for level scripts. self is the character for animation scripts.

2) Command: thread label

Since the new thread has the same group as the original thread, self in the new thread is equal to self in the original thread.

3) Command: thread filename::label

self in the new thread is set equal to self in the original thread.

4) Command: object thread label

self in the new thread is set equal to object.

5) Command: object thread filename::label

self in the new thread is set equal to object.

6) If a thread is initiated in response to an event of an object, then self is set equal to this object.

switch (selection) statement

============================

Standard usage

--------------

switch (expr)

{

label1:

statement

...

statement

break

label2:

statement

...

statement

break

case 0:

statement

...

statement

break

case 1:

statement

...

statement

break

default:

statement

...

statement

break

}

The expression expr is evaluated and cast to a string. Code execution tranfers to the matching label or to the optional default label if there is no match. The case prefix is required for integers, and optional for strings. The break command makes the switch statement finish.

if (conditional) statement

==========================

Standard usage

--------------

if (expr)

statement

if (expr)

statement

else

statement

if (expr)

{

statement

...

statement

}

if (expr)

{

statement

...

statement

}

else

{

statement

...

statement

}

arithmetic binary operators

===========================

precedence

----------

The operators are listed in order of later evaluation to sooner evaluation:

||

&&

|

^

&

== !=

=

+ -

* / %

descriptions

------------

|| logical or (outputs 0 or 1)

&& logical and (outputs 0 or 1)

| bitwise or (outputs integer)

^ bitwise exclusive or (outputs integer)

& bitwise and (outputs integer)

== equality (outputs 0 or 1)

!= inequality (outputs 0 or 1)

> gretaer than (outputs 0 or 1)

>= greater than or equal (outputs 0 or 1)

+ plus (numeric or string types)

- minus

* multiply

/ divide

% modulus (remainder after division by integer)

while statement

===============

Standard usage

--------------

while (expr)

statement

while (expr)

{

statement

...

statement

}

At the start of a cycle of the loop the expression expr is evaluated and cast to boolean (true or false). While the expression evaluates to true the statement(s) are executed.

A continue placed inside such a loop will move the code execution point to the end of the current cycle of the loop.

A break placed inside such a loop will terminate execution of the loop (code execution will continue sfter the loop).

Example

-------

local.n = 1

while (local.n ::c

println local.a[1][1] // prints a

println local.a[1][2] // prints b

println local.a[2] // prints c

Vector Examples

---------------

Vectors are accessed like arrays in the indices 0, 1, 2.

A vector could be set like

local.my_vector = (10 -2 60.1)

Then this vector could be accessed like:

println local.n[2]

which would print 60.1 to the console.

Example

-------

$player.origin += (5 6 7) // offset the player's origin by (5 6 7).

Make Array Example

------------------

local.Path1 = makeArray

t1 300 10 200

t2

t3

t4

t5

t6

t7 NIL 10 200

t8

t9

t10

t11

t12

t13

t14 0 10 200

endArray

println local.Path1[1][2]

println local.Path1[1][3]

println local.Path1[1][4]

println local.Path1[1][5]

println local.Path1[14][1]

println local.Path1[15][1]

end

results in:

300

10

200

NIL

t14

NIL

printed to console.

Automatic casting

=================

If a parameter in a statement is required to be of some type, then an automatic cast will be attempted.

Accessing characters of a string

================================

Characters of a string are accessed by the [] array operator. Indexing starts at 0.

For example, "abc"[2] evaluates to the string "c".

There is no character type, so characters are just strings of length 1.