* Copyright (c) 1999, 2006 Michael J. Roberts
* This file is part of TADS 3
* This header defines the t3vm intrinsic function set. These functions
* provide access to basic features of the Virtual Machine.
* include the LookupTable intrinsic class, since t3GetGlobalSymbols()
* returns an instance of this class
* T3 intrinsic function set definition
* Explicitly run garbage collection.
* Set the default output function or method. The return value is the
* old function pointer or method, depending on which one is being set
* with this call. (If 'val' is a function pointer, the return value
* will be the old function; if 'val' is a property ID, the return
* value is the old method.)
* The special values T3SetSayNoFunc and T3SetSayNoMethod can be passed
* to the function to remove any existing function or method,
* respectively, and are returned when appropriate to indicate that
* there was no previous setting.
* Get the VM version number. Returns the version number as an integer
* value, with the major version in the high-order 16 bits, the minor
* version number in the next 8 bits, and the patch number ("point
* release" number) in the low-order 8 bits. For example, version
* 3.0.10 is encoded as 0x0003000A.
* Get the VM identifier string. This returns the version number as a
* string, as in '3.0.10'.
* Get the VM banner string. This returns a string with the name of
* the VM, the version number, and a copyright string, in a format
* suitable for displaying to the user to identify the VM executable.
* Get the preinitialization mode flag. This returns true if the VM is
* running as part of the compiler's pre-initialization phase, nil if
* it's running as a normal interpreter.
* Debugger trace operations. This provides access to the interactive
* debugger subsystem, if the VM is running under a debugger. The
* 'mode' argument determines what the function does and what the
* additional arguments, if any, are for:
* T3DebugCheck - checks to see if an interactive debugger is present.
* No additional arguments; returns true if a debugger is present, nil
* if not.
* T3DebugBreak - breaks into the interactive debugger, pausing
* execution at the current code location so that the user can inspect
* the current machine state and determine how to proceed. No
* additional arguments; after the user proceeds with execution, the
* function returns true to indicate that a debugger is present. If no
* debugger is present, the function simply returns nil, and has no
* other effect.
* T3DebugLog - writes a message to the debug log. The second argument
* is a string with the text of the message to write. When running
* under an interactive debugger, the log is usually displayed as a
* window in the UI, or something similar. When running in a regular
* interpreter, the log is stored as a text file called tadslog.txt, in
* a directory location that varies by system. When a log file is
* used, the system automatically adds a timestamp to each message.
* Get the global symbol table or the global macro table.
* 'which' specifies which table to retrieve:
*. T3GlobalSymbols - return the global symbol table
*. T3PreprocMacros - return the preprocessor macro table
* If 'which' is omitted, the global symbol table is returned by
* If the requested symbol table is available, this returns a
* LookupTable object; otherwise, it returns nil.
* The symbol tables are available under two conditions. First, while
* pre-initialization is running during the program build (compiling)
* process, regardless of the debug/release mode being used for
* compilation. Second, during normal "t3run" execution, but only when
* the program has been compiled for debugging. When you compile in
* release mode, the compiler omits the debugging symbols from the .t3
* image file to save space, so the symbol tables won't be available
* when running a release build under the interpreter.
* If you want to access the symbol tables under normal execution
* (i.e., after preinit) in a release build, you can do it, but it
* requires an extra manual step. The trick is to call this function
* during preinit, when the symbol tables are definitely available
* regardless of the debug/release mode, and then save a reference to
* each desired table in an object property. This will ensure that the
* final image file saved after preinit completes includes the tables,
* because the object property reference ensures that the garbage
* collector won't delete them. Now, you *still* can't access the
* tables again at run-time by calling t3GetGlobalSymbols(), but you
* can instead get the same information from your saved object
* Allocate a new property. Returns a new property not yet used
* anywhere in the program. Note that property ID's are a somewhat
* limited resource - only approximately 65,000 total are available,
* including all of the properties that the program defines
* Get a stack trace. This returns a list of T3StackInfo objects.
* Each object represents a nesting level in the call stack. The first
* element in the list represents the currently active level (i.e., the
* level that called this function), the second element represents the
* caller of the first element, and so on.
* If 'level' is an integer, we'll return a single T3StackInfo object
* giving the context at the given stack level - 1 is the active level,
* 2 is its caller, and so on, so 'level' would simply be the index in
* the returned list when this argument is omitted. If 'level' is
* omitted or nil, we return a list of T3StackInfo objects giving the
* entire stack trace.
* If 'flags' is specified, it's a combination of T3GetStackXxx flags
* specifying additional options. If this isn't included, the default
* is 0 (i.e., all flags turned off).
* Get a named argument. This searches for the specified named
* argument, and returns the value of the argument if it's defined.
* 'name' is a string giving the name of the argument to search for.
* This must exactly match the name of an argument passed by a caller
* with the "name: value" syntax. The match is case-sensitive.
* 'defval' is an optional default value to return if the argument
* doesn't exist. If 'deval' is specified, and the argument doesn't
* exist, the function returns 'defval'. If 'defval' is omitted, and
* the argument doesn't exist, the function throws an error.
* Get a list of all named arguments currently in effect. This returns
* a list of strings, where each string is the name of a named argument
* that's currently active.
* t3DebugTrace() mode flags
/* check to see if the debugger is present */
#define T3DebugCheck 1
/* break into the debugger */
#define T3DebugBreak 2
/* log a message to the system/debug log */
#define T3DebugLog 3
* t3SetSay() special values. These can be passed in lieu of a function
* pointer or property ID when the caller wants to remove any existing
* function or method rather than install a new one.
#define T3SetSayNoFunc 1
#define T3SetSayNoMethod 2
* t3GetGlobalSymbols 'which' flag. One of these values can be specified
* as the function argument to specify which type of table is to be
#define T3GlobalSymbols 1
#define T3PreprocMacros 2
* t3GetStackTrace flags. These can be combined with the bitwise '|'
#define T3GetStackLocals 0x0001
#define T3GetStackDesc 0x0002
* Macro information flags.
#define T3MacroHasArgs 0x0001
#define T3MacroHasVarargs 0x0002
TADS 3 Library Manual
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