/* 

 *   Copyright (c) 1999, 2006 Michael J. Roberts

 *   

 *   This file is part of TADS 3

 *   

 *   This header defines the tads-gen intrinsic function set.  This function

 *   set provides some miscellaneous functions, including data conversions,

 *   object iteration, regular expressions, and state persistence operations.

 */

/*

 *   TADS basic data manipulation intrinsic function set 

 */

#ifndef TADSGEN_H

#define TADSGEN_H

/*

 *   The tads-gen function set 

 */

intrinsic 'tads-gen/030006'

{

    /*

     *   Get the type of the given value.  This returns a TypeXxx value.

     */

    dataType(val);

    /*

     *   Get the given parameter to the current function.  'idx' is 1 for the

     *   first argument in left-to-right order, 2 for the second, and so on. 

     */

    getArg(idx);

    /*

     *   Get the first object in memory.  If 'cls' is provided, we return the

     *   first object of the given class; otherwise we return the first

     *   object of any kind.  'flags' is an optional bitwise combination of

     *   ObjXxx values, specifying whether classes, instances, or both are

     *   desired.  If this isn't specified, ObjAll is assumed.  This is used

     *   in conjunction with nextObj() to iterate over all objects in memory,

     *   or all objects of a given class.  

     */

    firstObj(cls?, flags?);

    /*

     *   Get the next object in memory after the given object, optionally of

     *   the given class and optionally limiting to instances, classes, or

     *   both.  This is used to continue an iteration started with

     *   firstObj().  

     */

    nextObj(obj, cls?, flags?);

    /*

     *   Seed the random-number generator.  This uses unpredictable

     *   information from the external operating system environment (which

     *   might be something like the current time of day, but the exact

     *   information used varies by system) to seed the rand() generator with

     *   a new starting position.  Since rand() is a pseudo-random number

     *   generator, its sequence is deterministic - each time it's started

     *   with a given seed value, the identical sequence will result.  This

     *   function helps produce apparent randomness by effectively

     *   randomizing the starting point of the sequence.

     *   

     *   Note that if randomize() is never called, the system will use a

     *   fixed initial seed, so rand() will return the same sequence each

     *   time the program is run.  This is intentional, because it makes the

     *   program's behavior exactly repeatable, even if the program calls

     *   rand() to select random numbers.  This type of repeatable,

     *   deterministic behavior is especially useful for testing purposes,

     *   since it allows you to run the program through a fixed set of input

     *   and compare the results against a fixed set of output, knowing the

     *   the random number sequence will be the same on each run.  Typically,

     *   what you'd want to do is check at start-up to see if you're in

     *   "testing" mode (however you wish to define that), and call

     *   randomize() only if you're not in testing mode.  This will create

     *   apparently random behavior on normal runs, but produce repeatable

     *   behavior during testing.  

     */

    randomize();

    /*

     *   Select a random number or a random value.

     *   

     *   If only one argument is supplied, and this argument is an integer

     *   value, the function returns an integer from 0 to one less than the

     *   argument value.  For example, rand(10) returns a number from 0 to 9

     *   inclusive.

     *   

     *   If one argument is supplied, and the argument is a list, the

     *   function randomly selects one of the values from the list and

     *   returns it.

     *   

     *   If more than one argument is supplied, the function randomly selects

     *   one of the arguments and returns it.  (Note that since this is an

     *   ordinary function call, all of the arguments are evaluated,

     *   triggering any side effects of those evaluations.)

     *   

     *   In all cases, the random number selection is uniformly distributed,

     *   meaning that each possible return value has equal probability.  

     */

    rand(x, ...);

    /*

     *   Convert the given value to a string representation.  'val' can be an

     *   integer, in which case it's converted to a string representation in

     *   the numeric base given by 'radix' (which can be any value from 2 to

     *   36), or base 10 (decimal) if 'radix' is omitted; nil or true, in

     *   which case the string 'nil' or 'true' is returned; a string, which

     *   is returned unchanged; or a BigNumber, in which case the value is

     *   converted to a string representation in decimal.  (Note that in the

     *   case of BigNumber, you might prefer to use BigNumber.formatString(),

     *   as that gives you much more control over the formatting.)  

     */

    toString(val, radix?);

    /*

     *   Convert the given value to an integer.  If 'val' is a string, the

     *   function parses the value as an integer value in the numeric base

     *   given by 'radix' (which can be one of 2, 8, 10, or 16), or base 10

     *   (decimal) if 'radix' is omitted.  If 'val' is the string 'true' or

     *   'nil', the function returns true or nil, respectively.  If 'val' is

     *   a BigNumber value, the value is rounded to the nearest integer; an

     *   exception ("numeric overflow") is thrown if the number is out of

     *   range for a 32-bit integer.  

     */

    toInteger(val, radix?);

    /* 

     *   Get the current local time.

     *   

     *   If timeType is GetTimeDateAndTime (or is omitted), this returns the

     *   calendar date and wall-clock time, as a list: [year, month,

     *   dayOfMonth, dayOfWeek, dayOfYear, hour, minute, second, timer].

     *   Year is the year AD (for example, 2006); month is the current month,

     *   from 1 (January) to 12 (December); dayOfMonth is the calendar day of

     *   the month, from 1 to 31; dayOfWeek is the day of the week, from 1

     *   (Sunday) to 7 (Saturday); dayOfYear is the current day of the year,

     *   from 1 (January 1) to 366 (December 31 in a leap year); hour is the

     *   hour on a 24-hour clock, ranging from 0 (midnight) to 23 (11pm);

     *   minute is the minute of the hour, from 0 to 59; second is the second

     *   of the minute, from 0 to 59; and timer is the number of seconds

     *   elapsed since the "epoch," defined arbitrarily as midnight, January

     *   1, 1970.

     *   

     *   If timeType is GetTimeTicks, this return the number of milliseconds

     *   since an arbitrary starting time.  The first call to get this

     *   information sets the starting time, so it will return zero;

     *   subsequent calls will return the amount of time elapsed from that

     *   starting time.  Note that because a signed 32-bit integer can only

     *   hold values up to about 2 billion, the maximum elapsed time that

     *   this value can represent is about 24.8 days; so, if your program

     *   runs continuously for more than this, the timer value will roll

     *   around to zero at each 24.8 day multiple.  So, it's possible for

     *   this function to return a smaller value than on a previous

     *   invocation, if the two invocations straddle a 24.8-day boundary.  

     */

    getTime(timeType?);

    /*

     *   Match a string to a regular expression pattern.  'pat' can be either

     *   a string giving the regular expression, or can be a RexPattern

     *   object.  'str' is the string to match, and 'index' is the starting

     *   character index (the first character is at index 1) at which to

     *   start matching.  Returns the length in characters of the match, or

     *   nil if the string doesn't match the pattern.  (Note that a return

     *   value of zero doesn't indicate failure - rather, it indicates a

     *   successful match of the pattern to zero characters.  This is

     *   possible for a pattern with a zero-or-more closure, such as 'x*' or

     *   'x?'.)  

     */

    rexMatch(pat, str, index?);

    /*

     *   Search the given string for the given regular expression pattern.

     *   'pat' is a string giving the regular expression, or a RexPattern

     *   object.  'str' is the string to search, and 'index' is the optional

     *   starting index (the first character is at index 1).  If the pattern

     *   cannot be found, returns nil.  If the pattern is found, the return

     *   value is a list: [index, length, string], where index is the

     *   starting character index of the match, length is the length in

     *   characters of the match, and string is the text of the match.  

     */

    rexSearch(pat, str, index?);

    /*

     *   Get the given regular expression group.  This can be called after a

     *   successful rexMatch() or rexSearch() call to retrieve information on

     *   the substring that matched the given "group" within the regular

     *   expression.  A group is a parenthesized sub-pattern within the

     *   regular expression; groups are numbered left to right by the open

     *   parenthesis, starting at group 1.  If there is no such group in the

     *   last regular expression searched or matched, or the group wasn't

     *   part of the match (for example, because it was part of an

     *   alternation that wasn't matched), the return value is nil.  If the

     *   group is valid and was part of the match, the return value is a

     *   list: [index, length, string], where index is the character index

     *   within the matched or searched string of the start of the group

     *   match, length is the character length of the group match, and string

     *   is the text of the group match.  

     */

    rexGroup(groupNum);

    /*

     *   Search for the given regular expression pattern (which can be given

     *   as a regular expression string or as a RexPattern object) within the

     *   given string, and replace one or more occurrences of the pattern

     *   with the given replacement text.  If 'flags' includes ReplaceAll,

     *   all occurrences of the pattern are replaced; otherwise only the

     *   first occurrence is replaced.  'index', if provided, is the starting

     *   character index of the search; instances of the pattern before this

     *   index will be ignored.  Returns the result string with all of the

     *   desired replacements.  When an instance of the pattern is found and

     *   then replaced, the replacement string is not rescanned for further

     *   occurrences of the text, so there's no danger of infinite recursion;

     *   instead, scanning proceeds from the next character after the

     *   replacement text.

     *   

     *   The replacement text can use "%n" sequences to substitute group

     *   matches from the input into the output.  %1 is replaced by the match

     *   to the first group, %2 the second, and so on.  %* is replaced by the

     *   entire matched input.  (Because of the special meaning of "%", you

     *   must use "%%" to include a percent sign in the replacement text.)  

     */

    rexReplace(pat, str, replacement, flags, index?);

    /*

     *   Create an UNDO savepoint.  This adds a marker to the VM's internal

     *   UNDO log, establishing a point in time for a future UNDO operation.

     */

    savepoint();

    /*

     *   UNDO to the most recent savepoint.  This uses the VM's internal UNDO

     *   log to undo all changes to persistent objects, up to the most recent

     *   savepoint.  Returns true if the operation succeeded, nil if not.  A

     *   nil return means that there's no further UNDO information recorded,

     *   which could be because the program has already undone everything

     *   back to the start of the session, or because the UNDO log was

     *   truncated due to memory size such that no savepoints are recorded.

     *   (The system automatically limits the UNDO log's total memory

     *   consumption, according to local system parameters.  This function

     *   requires at least one savepoint to be present, because otherwise it

     *   could create an inconsistent state.)  

     */

    undo();

    /*

     *   Save the current system state into the given file.  This uses the

     *   VM's internal state-save mechanism to store the current state of all

     *   persistent objects in the given file.  Any existing file is

     *   overwritten.  

     */

    saveGame(filename);

    /*

     *   Restore a previously saved state file.  This loads the states of all

     *   persistent objects stored in the given file.  The file must have

     *   been saved by the current version of the current running program; if

     *   not, an exception is thrown.  

     */

    restoreGame(filename);

    /*

     *   Restart the program from the beginning.  This resets all persistent

     *   objects to their initial state, as they were when the program was

     *   first started.  

     */

    restartGame();

    /*

     *   Get the maximum of the given arguments.  The values must be

     *   comparable with the ordinary "<" and ">" operators.  Note that

     *   because this is an ordinary function call, all of the arguments are

     *   evaluated (which means any side effects of these evaluations will be

     *   triggered).  

     */

    max(val1, ...);

    /*

     *   Get the minimum of the given arguments.  The values must be

     *   comparable with the ordinary "<" and ">" operators. Note that

     *   because this is an ordinary function call, all of the arguments are

     *   evaluated (which means any side effects of these evaluations will be

     *   triggered).  

     */

    min(val1, ...);

    /*

     *   Create a string by repeating the given value the given number of

     *   times.  If the repeat count isn't specified, the default is 1.

     *   'val' can be a string, in which case the string is simply repeated

     *   the given number of times; an integer, in which case the given

     *   Unicode character is repeated; or a list of integers, in which case

     *   the given Unicode characters are repeated, in the order of the list.

     *   The list format can be used to create a string from a list of

     *   Unicode characters that you've been manipulating as a character

     *   array, which is sometimes a more convenient or efficient way to do

     *   certain types of string handling than using the actual string type.

     */

    makeString(val, repeatCount?);

    /*

     *   Get a description of the parameters to the given function.  'func'

     *   is a function pointer.  This function returns a list: [minArgs,

     *   optionalArgs, isVarargs], where minArgs is the minimum number of

     *   arguments required by the function, optionalArgs is the additional

     *   number of arguments that can be optionally provided to the function,

     *   and isVarargs is true if the function takes any number of additional

     *   ("varying") arguments, nil if not.  

     */

    getFuncParams(func);

}

/*

 *   flags for firstObj() and nextObj()

 */

#define ObjInstances  0x0001

#define ObjClasses    0x0002

#define ObjAll        (ObjInstances | ObjClasses)

/*

 *   rexReplace() flags 

 */

#define ReplaceOnce  0x0000

#define ReplaceAll   0x0001

/*

 *   getTime() flags 

 */

#define GetTimeDateAndTime  1

#define GetTimeTicks        2

#endif /* TADSGEN_H */