sfall/artifacts/scripting/compiler/sslc_readme.md at 1b98bedd6f7b4ecdb001ecb436cebed3751d96bc

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NovaRain 1b98bedd6f Edits to sslc documents

* edited the description of command line options.
* removed old references of dos4gw.exe (only for pre-2.10) and FSE.

2024-03-11 10:08:31 +08:00

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SSLC

This is a modified copy of sslc, that has a few bugfixes from the original, that will recognise and compile the additional script functions provided by sfall, that can also understand some additional syntax, and that has an integrated preprocessor and optimizer.

Unlike the original script compiler, this has not been compiled as a DOS program. When using this in place of the original compile.exe but still using p.bat, you need to get rid of the dos4gw.exe reference from p.bat.

When compiling global or hook scripts for sfall 3.4 or below, you must include the line procedure start; before any #include files that define procedures to avoid a few weird problems. This is no longer required starting from 3.5.

This version of compiler was designed primarily for new sfall functions, but it can be safely used (and is recommended) with non-sfall scripts as well.

The original unmodified sslc source is over here: https://teamx.ru/site_arc/utils/index.html

Command line options

-q  don't wait for input on error
-n  no warnings
-b  use backward compatibility mode
-l  no logo
-p  preprocess source
-P  preprocess only (don't generate .int)
-F  write full file paths in "#line" directives
-O  optimize code (full optimization, see optimization.md)
-O<N>  set specific level of optimization (0 - none, 1 - basic, 2 - full, 3 - experimental)
-d  print debug messages
-D  output an abstract syntax tree of the program
-o  set output path (follows the input file name)
-s  enable short-circuit evaluation for all AND, OR operators
-m<macro>[=<val>]  define a macro named "macro" for conditional compilation
-I<path>  specify an additional directory to search for include files

The original command line option -w to turn on warnings no longer has an effect, since warnings are now on by default

Additional supported syntax

Syntax which requires sfall for compiled scripts to be interpreted is marked by asterisk (*).

Optional arguments in user-defined procedures. You can only use constants for default values. It basically puts those constants in place of omitted arguments.

new:

procedure test(variable x, variable y := 0, variable z := -1) begin
...
end
...
call test("value");

old:

procedure test(variable x, variable y, variable z) begin
...
end
...
call test("value", 0, -1);

New logical operators AndAlso, OrElse for short-circuit evaluation of logical expressions. Using these operators allow the right part of logical expressions not to be evaluated (executed, computed) if the result is already known. This can improve the performance of running scripts.

Example: if (obj andAlso obj_pid(obj) == PID_STIMPAK) then ...

If obj is null, the second condition will not be checked and your script won't fail with "obj is null" error in debug.log

This also has an effect that a value of last computed argument is returned as a result of whole expressions, instead of always false (0) or true (1):
```
obj := false;
display_msg(obj orElse "something");  // will print "something"
```
You can also use the -s option to enable short-circuit evaluation for all the AND, OR operators in the script.

NOTE: Be aware that it may break some old scripts because operators behavior is changed slightly.

Conditional expressions (Python-inspired), also known as ternary operator:

new:
```
X := value1 if (condition) else value2
```

old:

if (condition) then
  X := value1;
else
  X := value2;

To assign values, you can use the alternative assignment operator from C/Java instead of Pascal syntax.
- new:
```
x = 5;
```
- old:
```
x := 5;
```
Multiple variable declaration: Multiple variables can be declared on one line, separated by commas. This is an alternative to the ugly begin/end block, or the bulky single variable per line style.
- new:
```
variable a, b, c;
```
- old:
```
variable begin a; b; c; end
```
Variable initialization with expressions: You can now initialize local variables with complex expressions instead of constants.
- new:
```
variable tile := tile_num(dude_obj);
```
- old:
```
variable tile;
tile := tile_num(dude_obj);
```
NOTE: If your expression starts with a constant (eg. 2 + 2), enclose it in parentheses, otherwise compiler will be confused and give you errors.
Hexadecimal numerical constants: Simply prefix a number with 0x to create a hexadecimal. The numbers 0 to 9 and letters A to F are allowed in the number. The number may not have a decimal point.
- new:
```
a := 0x1000;
```
- old:
```
a := 4096;
```
Increment/decrement operators: ++ and -- can be used as shorthand for += 1 and -= 1 respectively. They are merely a syntactic shorthand to improve readability, and so their use is only allowed where += 1 would normally be allowed.
- new:
```
a++;
```
- old:
```
a += 1;
```

break & continue statements: They work just like in most high-level languages. break jumps out of the loop. continue jumps right to the beginning of the next iteration (see for and foreach sections for additional details).

new:

while (i < N) begin
  // ...
  if (/* some condition */) then break;
  // ...
end

old:

while (i < N and not(breakFlag)) begin
  // ...
  if (/* condition */) then breakFlag := true;
  // ...
end

new:

for (i := 0; i < N; i++) begin
  // ...
  if (/* condition */) then begin
    // action
    continue;
  end
  // else actions
end

old:

for (i := 0; i < N; i++) begin
  // ...
  if (/* condition */) then begin
    // action
  end else begin
    // else actions
  end
end

for loops: Another piece of syntactic shorthand, to shorten while loops in many cases. Parentheses around the loop statements are recommended but not required (when not using parentheses, a semicolon is required after the 3rd loop statement).
- new:
```
for (i := 0; i < 5; i++) begin
  display_msg("i = " + i);
end
```
- old:
```
i := 0;
while (i < 5) do begin
  display_msg("i = " + i);
  i++;
end
```
NOTE: continue statement in a for loop will recognize increment statement (third statement in parentheses) and will execute it before jumping back to the beginning of loop. This way you will not get an endless loop.

switch statements: A shorthand way of writing big if then else if... blocks

new:

switch get_attack_type begin
  case ATKTYPE_PUNCH: display_msg("punch");
  case ATKTYPE_KICK: display_msg("kick");
  default: display_msg("something else");
end

old:

variable tmp;
tmp := get_attack_type;
if tmp == ATKTYPE_PUNCH then begin
  display_msg("punch");
end else if tmp == ATKTYPE_KICK then begin
  display_msg("kick");
end else begin
  display_msg("something else");
end

Procedure stringify operator @: Designed to make callback-procedures a better option and allow for basic functional programming. Basically it replaces procedure names preceded by @ by a string constant.
- old:
```
callbackVar := "Node000";
call callbackVar;
```
- new:
```
callbackVar := @Node000;
call callbackVar;
```
Not many people know that since vanilla Fallout you can call procedures by "calling a variable" containing it's name as a string value. There was a couple of problems using this:
- optimizer wasn't aware that you are referencing a procedure, and could remove it, if you don't call it explicitly (can be solved by adding making procedure critical)
- you couldn't see all references of a procedure from a Script Editor
- it was completely not obvious that you could do such a thing, it was a confusing syntax
(*) Arrays: In vanilla Fallout, arrays had to be constructed by reserving a block of global/map variables. Since sfall 2.7, specific array targeted functions have been available, but they are fairly messy and long winded to use. The compiler provides additional syntactic shorthand for accessing and setting array variables, as well as for array creation. When declaring an array variable, put a constant integer in `[]`` to give the number of elements in the array. (before sfall 3.4 you had to specify size in bytes for array elements, now it's not required, see arrays.md for more information)
- new:
```
procedure bingle begin
  variable a[2];
  a[0] := 5;
  a[a[0] - 4] := a[0] + 4;
  display_msg("a[0]=" + a[0] + ", a[1]=" + a[1]);
end
```
- old:
```
procedure bingle begin
  variable a;
  a := temp_array(2, 4);
  set_array(a, 0, 5);
  set_array(a, get_array(a, 0) - 4, get_array(a, 0) + 4);
  display_msg("a[0]=" + get_array(a, 0) + ", a[1]=" + get_array(a, 1));
end
```
(*) Array expressions: Sometimes you need to construct an array of elements and you will probably want to do it in just one expression. This is now possible:
- new:
```
list := ["A", "B", "C", "D"];
```
- old:
```
list := temp_array(4, 2);
list[0] := "A";
list[1] := "B";
list[2] := "C";
list[3] := "D";
```
Syntax specific for associative arrays is also available. (see arrays.md for full introduction to this type of arrays).

(*) Map array expressions:

map := {5: "five", 10: "ten", 15: "fifteen", 20: "twelve"};

(*) The dot . syntax to access elements of associative arrays and allow to work with arrays like objects:
```
trap.radius := 3;
trap.tile := tile_num(dude_obj);
```
You can chain dot and bracket syntax to access elements of multi-dimensional arrays:
```
collectionList[5].objectList[5].name += " foo";
```
NOTE: When using incremental operators like +=, *=, ++, -- compiler will use additional temp variable to get an array at penultimate level in order to avoid making the same chain of get_array calls twice.
(*) foreach loops: A shorthand method of looping over all elements in an array. Syntax is foreach (<symbol> in <expression>).
- new:
```
procedure bingle begin
  variable critter;
  foreach (critter in list_as_array(LIST_CRITTERS)) begin
    display_msg("" + critter);
  end
end
```
- old:
```
procedure bingle begin
  variable begin critter; array; len; count; end
  array := list_as_array(LIST_CRITTERS);
  len := len_array(array);
  count := 0;
  while count < len do begin
    critter := array[count];
    display_msg("" + critter);
  end
end
```
If you want an index array element (or key for "maps") at each iteration, use syntax: foreach (<symbol>: <symbol> in <expression>)
```
foreach (pid: price in itemPriceMap) begin
  if (itemPid == pid) then
    itemPrice := price;
end
```
If you want to add additional condition for continuing the loop, use syntax: foreach (<symbol> in <expression> while <expression>). In this case loop will iterate over elements of an array until last element or until "while" expression is true (whatever comes first).

NOTE: Just like for loop, continue statement will respect increments of a hidden counter variable, so you can safely use it inside foreach.

Fixes

playmoviealpharect was using the token for playmoviealpha, breaking both functions in the process.
addbuttonflag had an entry in the token table, and could be parsed, but was missing an entry in the emit list. This resulted in the compiler accepting it as a valid function, but not outputting any code for it into the compiled script.
The function tokenize was missing an entry in the token table, and so would not be recognised by the compiler.
Fixed the check for the call "foo" syntax so that non-string constants will no longer be accepted.

Backward compatibility

There are several changes in this version of sslc which may result in problems for previously working scripts. A new command line option -b is available, which will turn off all new fixes and features which have the possibility of causing a previously compiling script to change its behaviour. (And only those features; anything which would not compile under the old sslc is not affected.) This includes the following:

Since for, foreach, break, continue, in and tokenize are now hardcoded names, existing scripts that use any of them as a variable or procedure name will no longer compile.
Missing a semicolon after a variable declaration is now a hard error. (Originally sslc would check for the semicolon, but would not complain if it was missing.)
The function addbuttonflag used to be recognised by the compiler, but would not emit any code into the int file.
The function playmoviealpharect compiled as playmoviealpha.

int2ssl note

int2ssl by Anchorite (TeamX) is included in sfall modderspack package. It was updated to support all additional opcodes of sfall, along with some syntax features. You can use it to decompile any sfall or non-sfall script.

Changelog

sfall 4.4:

fixed compiler crash when trying to define an exported procedure with variables
fixed compiler giving "symbol or string expected" error when trying to call procedure using a string literal
fixed optimizer not treating call string_variable as variable use
fixed unused arguments in a procedure being removed incorrectly by the optimizer
fixed unused string literals in an optimized-out procedure not being removed by the optimizer
fixed get_array syntax not working for exported variables
fixed optional arguments not working for imported procedures
fixed compiler crash when an exported procedure has no body

sfall 4.2.9:

added support for additional universal opcodes sfall_func7 and sfall_func8
fixed a compilation error when the script has a UTF-8 BOM

sfall 4.2.7:

added ability to declare local variables anywhere in the procedure body

sfall 4.2.3:

fixed compiler giving "assignment operator expected" error when a variable-like macro is not defined properly
added new logical operators AndAlso, OrElse for short-circuit evaluation of logical expressions
added an alternative (C/Java-style) assignment operator =
added support for new div operator (unsigned integer division)

sfall 4.2.2:

added support for new opcode reg_anim_callback

sfall 4.2.1:

the basic optimization is now enabled by default when not specifying any optimization options
added -m<macro[=val]> option to define a macro named "macro" for conditional compilation
added -I<path> option to specify an additional directory to search for include files
unreferenced critical procedures and procedures with the names Node998 and Node999 are now removed by the optimizer

sfall 4.2:

now it is possible to run preprocess or optimization passes in backward compatibility mode
added support for new opcode register_hook_proc_spec

sfall 4.0:

enabled code for ceil math function
fixed missing argument for how_much function
added desc_p_proc (from Fallout 1) to protected procedures that should not be removed by the optimizer
fixed compiler giving "division by zero" error when using zero as the second factor in multiplication

sfall 3.8:

added support for new universal opcodes sfall_funcX

sfall 3.6:

added Python-style ternary operator (conditional expression)
added -s short-circuit evaluation option for AND, OR expressions
int2ssl will detect and decompile conditional expressions and short-circuit logical operators
added -F option to include full file paths in #line directives after preprocessing
added -D option to write abstract syntax tree into .txt file
fixed compiler crash when number of arguments in procedure declaration does not match definition
fixed incorrect constant folding of bwnot operator
fixed more invalid results in constant folding
implemented optional arguments for user-defined procedures
implemented stringify procedure names using @ operator, which is helpful to pass procedures around to call them from variables (it will properly handle references)
logic for procedures passed as arguments to script functions was moved from code generation to parsing stage
now it is possible to call user-defined procedures inside argument list of script functions, without compiler attempting to treat them as procedure references and probably fail (procedures will still be passed, but only to appropriate script functions at appropriate argument positions)
int2ssl will now place empty parentheses after a call to user-defined procedure - this will distinct calls from passing procedures to some script functions (like giq_option)
fixed inline procedure "calls" not working when optimization is enabled
added column numbers to error/warning output
added code to simplify adding sfall opcodes into compiler (need to add code in 3 places, instead of 7 places for each opcode)
fixed bug when initializing variable with expression starting from a symbol
added division by zero constant check

sfall 3.5:

completed namespace compression optimization with respect to imported/exported variables
changed for and foreach syntax to allow parentheses which are easier to read IMHO
heavy code refactoring - split "parse.c" into several files, replaced all dirty workaround code in "lex()" (some syntax features) with parser-level equivalents
added syntax to reference elements in multi-dimensional arrays (unlimited sequence of brackets [] and dots .)
added fully featured break and continue statements for loops
moved some optimizations (namely constant propagation and variable reuse) to "experimental" because they were breaking my scripts
added ability to initialize variables with expressions

sfall 3.4:

added foreach .. while .. syntax
added array expressions for lists and maps
added foreach (key: value in ...) syntax for convenience
fixed crash bug in for loop parsing function
added ability to access array elements with string keys using OOP-like dot . syntax

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SSLC

Command line options

Additional supported syntax

Fixes

Backward compatibility

int2ssl note

Changelog

18 KiB

Raw Blame History