If a later module reused an existing name for a different class or struct type, this new name would completely shadow the old one, even in the base files.
Changed it so that each compilation unit (i.e. each ZScript and DECORATE lump) get their own symbol table and can only see the symbol tables that got defined in lower numbered resource files so that later definitions do not pollute the available list of symbols when running the compiler backend and code generator - which happens after everything has been parsed.
Another effect of this is that a mod that reuses the name of an internal global constant will only see its own constant, again reducing the risk of potential errors in case the internal definitions add some new values.
Global constants are still discouraged from being used because what this does not and can not handle is the case that a mod defines a global constant with the same name as a class variable. In such a case the class variable will always take precedence for code inside that class.
Note that the internal struct String had to be renamed for this because the stricter checks did not let the type String pass on the left side of a '.' anymore.
- made PEnum inherit from PInt and not from PNamedType.
The old inheritance broke nearly every check for integer compatibility in the compiler, so this hopefully leads to a working enum implementation.
There are a few which require explicit native construction or destruction that need to be exported to the VM, e.g. FCheckPosition.
The VM cannot handle this directly, it needs two special functions to be attached to handle such elements.
The original implementation just printed a mostly information-free message and then went on as if nothing has happened, making it ridiculously easy to write broken code and release it. Changed it to:
* Any VMAbortException will now terminate the game session and go back to the console.
* It will also print a VM stack trace with all open functions, including source file and line numbers pointing to the problem spots. For this the relevant information had to be added to the VMScriptFunction class.
An interesting effect here was that just throwing the exception object increased the VM's Exec function's stack size from 900 bytes to 70kb, because the compiler allocates a separate local buffer for every single instance of the exception object.
The obvious solution was to put this part into a subfunction so that it won't pollute the Exec function's own stack frame. Interesting side effect of this: Exec's stack requirement went down from 900 bytes to 600 bytes. This is still on the high side but already a lot better.
- throw a useful exception when a VM abort occurs, the simple enum was incapable of reporting anything more than the barest minimum, which at least for array index out of bounds errors was insufficient.
The current exception mechanism is still insufficient. It really has to report a proper crash location and print a stack trace to the maximum extent possible. Instead it just prints a message and happily goes on. This is not a good solution.
- added new VM instructions to access the constant tables with a variable index.
- refactored VMFunctionBuilder's constant tables so that they are not limited to one entry per value. While this works fine for single values, it makes it impossible to store constant arrays in here.
- fixed code generation for using local variables as array index. This must use a different register for the array element offset because the original register may not be overwritten.
- instead add a list of SpecialInits to VMScriptFunction so this can be done transparently when setting up and popping the stack frame. The only drawback is that this requires permanent allocation of stack objects for the entire lifetime of a function but this is a relatively small tradeoff for significantly reduced maintenance work throughout.
- removed most #include "vm.h", because nearly all files already pull this in through dobject.h.
* use the function build list instead of the function to pass the info. The function is permanent so not the best place for compile-time info.
* pass along the current state index which is needed to calculate the target state.
- added support for global variables to the code generator - not the compiler, though. For the handful of entries this is needed for it may just as well be done manually. So far FLevelLocals level is the only one being exported.
- fixed: The VM disassembler truncated 64 bit pointers to 15 digits because the output buffer was too small.
- resolve entire FxSequences instead of aborting on the first failed entry. This allows to output all errors at once.
- exported thinker iterator and drop item chain to scripting. Unlike its native counterpart the script-side iterator is wrapped into a DObject to allow proper handling for memory management.
- fixed: The VMFunctionBuilder only distinguished between member and action functions but failed on static ones.
- fixed: FxAssign did not add all needed type casts. Except for purely numeric types it will now wrap the expression in an FxTypeCast. Numeric handling remains unchanged for both performance reasons and not altering semantics for DECORATE.
- exported all internal flags as variables to scripting. They still cannot be used in an actor definition.
- make ATAG_STATE the same as ATAG_GENERIC. Since state pointers exist as actual variables they can take both values which on occasion can trigger some asserts.
- gave PClass a bExported flag, so that scripts cannot see purely internal classes. Especially the types like PInt can cause problems.
Todo: we need readonly references to safely expose the actor defaults. Right now some badly behaving code could overwrite them.
- create proper variable data from the function prototype instead of assuming that there's just 3 pointers.
- added a printable name to VMScriptFunction for error output during gameplay in case something goes wrong.
- added a truncation warning to FxIntCast, which only occurs with ZScript, not with DECORATE. FxBoolCast is intentionally left out because it would defeat the reason for this cast type.
* Allow PFunction to work without a VMFunction being attached.
* The Variant for a function must store the prototype itself instead of relying on the VMFunction it points to. Otherwise it would not be possible to reference a prototype during compilation of the function because it does not exist yet.
* Give the variant a list of the function's argument's names, because these are also needed to compile the function.
* create an anonymous function symbol when the function gets registered to the builder. At this point we have all the needed information to set it up correctly, but later this is no longer the case. This is the most convenient info to have here because it contains everything that's needed to compile the function in the proper context, so it has to be present when starting compilation.
* added some preparations to implement special handling for weapons and custom inventory items, which can run action functions in another actor's context. This part is not active yet but the basics are present in SetImplicitArgs.
* everything related to scripting is now placed in a subdirectory 'scripting', which itself is separated into DECORATE, ZSCRIPT, the VM and code generation.
* a few items have been moved to different headers so that the DECORATE parser definitions can mostly be kept local. The only exception at the moment is the flags interface on which 3 source files depend.
