Support for Glulx and Glk interpreter systems.

§1. 

Part Four - Glulx and Glk (for Glulx only)

§2. Version numbering. 

Chapter - Version numbers

To decide which number is the major version of (V - version number):
    (- (VERSION_NUMBER_TY_Extract({V}, 0)) -).
To decide which number is the minor version of (V - version number):
    (- (VERSION_NUMBER_TY_Extract({V}, 1)) -).
To decide which number is the patch version of (V - version number):
    (- (VERSION_NUMBER_TY_Extract({V}, 2)) -).

§3. Feature testing. These phrases let us test for various interpreter features. While most features can use the generic functions, a few need special handling, and so individual phrases are defined for them. 

Chapter - Glk and Glulx feature testing

Definition: a glk feature is supported rather than unsupported if I6 routine
    "GlkFeatureTest" says so (it is supported by the interpreter).

To decide what version number is the glk version number/--
    (documented at ph_glkversion):
    (- VERSION_NUMBER_TY_NewFromPacked(Cached_Glk_Gestalts-->gestalt_Version) -).

Definition: a glulx feature is supported rather than unsupported if I6 routine
    "GlulxFeatureTest" says so (it is supported by the interpreter).

To decide what version number is the glulx version number/--:
    (- VERSION_NUMBER_TY_NewFromPacked(Cached_Glulx_Gestalts-->GLULX_GESTALT_GlulxVersion) -).

To decide what version number is the interpreter version number/--:
    (- VERSION_NUMBER_TY_NewFromPacked(Cached_Glulx_Gestalts-->GLULX_GESTALT_TerpVersion) -).

§4. Glk windows. Minimal support for Glk windows. Other extensions may extend the kind. 

Chapter - Glk windows

A glk window is a kind of abstract object.
The glk window kind is accessible to Inter as "K_Glk_Window".
The specification of a glk window is "Models the Glk window system."

A glk window has a glk window type called the window type.
The window type property translates into Inter as "glk_window_type".

A glk window has a number called the rock number.
The rock number property translates into Inter as "glk_rock".

A glk window has a number called the glk window handle.
The glk window handle property translates into Inter as "glk_ref".

§5. Setting window types is quite verbose, so we have some subkinds to make it easier. 

A graphics window is a kind of glk window.
The window type of a graphics window is graphics window type.
A text buffer window is a kind of glk window.
The window type of a text buffer window is text buffer window type.
A text grid window is a kind of glk window.
The window type of a text grid window is text grid window type.

§6. Create objects for each of the built in windows, as well as the "unknown window", which is used when there's a Glk event on a window that can't be identified. 

The main window is a text buffer window.
The main window object is accessible to Inter as "Main_Window".

The status window is a text grid window.
The status window object is accessible to Inter as "Status_Window".

The quote window is a text buffer window.
The quote window object is accessible to Inter as "Quote_Window".

The unknown window is a glk window.
The unknown window object is accessible to Inter as "Unknown_Glk_Window".

§7. Basic window functions. Some basic Glk window functions will be supported out of the box, but others will require extensions. 

Section - Glk windows

To clear (win - a glk window)
    (documented at ph_glkwindowclear):
    (- WindowClear({win}); -).

To focus (win - a glk window)
    (documented at ph_glkwindowfocus):
    (- WindowFocus({win}); -).

To decide what number is the height of (win - a glk window)
    (documented at ph_glkwindowheight):
    (- WindowGetSize({win}, 1) -).

To decide what number is the width of (win - a glk window)
    (documented at ph_glkwindowwidth):
    (- WindowGetSize({win}, 0) -).

To set (win - a glk window) cursor to row (row - a number) and/-- column (col - a number)
    (documented at ph_glksetcursor):
    (- WindowMoveCursor({win}, {col}, {row}); -).

§8. Glk events. Glk events can be handled with the glk event handling rules. 

Chapter - Glk events

The glk event handling rules is a glk event based rulebook.
The glk event handling rules is accessible to Inter as "GLK_EVENT_HANDLING_RB".

The glk event window is a glk window variable.
The glk event window variable translates into Inter as "Glk_Event_Struct_win".
The glk event value 1 is a number variable.
The glk event value 1 variable translates into Inter as "Glk_Event_Struct_val1".
The glk event value 2 is a number variable.
The glk event value 2 variable translates into Inter as "Glk_Event_Struct_val2".

Definition: a glk event is dependent on the player rather than independent of the player if
    it is character event or
    it is line event or
    it is mouse event or
    it is hyperlink event.

To set the/-- glk event type to (t - glk event):
    (- SetGlkEventType({t}); -).

To say current line input of (w - glk window):
    (- WindowBufferPrint({w}); -).

To decide what text is the current line input of (w - glk window):
    (- WindowBufferCopyToText({w}, {-new:text}) -).

To set the current line input of (w - glk window) to (t - text):
    (- WindowBufferSet({w}, {-by-reference:t}); -).

First glk event handling rule for a glk event (called the event) (this is the update input requests rule):
    It was too risky to set the text input status here, in case the author also sets a first glk event handling rule, so that property is reset within glk_select.
    if the event is hyperlink event:
        now the glk event window is not requesting hyperlink input;
    if the event is mouse event:
        now the glk event window is not requesting mouse input;

§9. Suspending input. These properties and phrases allow the author to suspend and resume input requests. 

Chapter - Suspending and resuming input

A glk window has a text input status.
The text input status property translates into Inter as "text_input_status".
A glk window can be requesting hyperlink input.
The requesting hyperlink input property translates into Inter as "requesting_hyperlink".
A glk window can be requesting mouse input.
The requesting mouse input property translates into Inter as "requesting_mouse".

To suspend text input in (win - a glk window), without input echoing:
    (- SuspendTextInput({win}, {phrase options}); -).

To resume text input in (win - a glk window):
    (- ResumeTextInput({win}); -).

§10. Glk object recovery. These rules are a low level system for managing Glk references. When a Glulx game restarts and restores, the current Glk IO state is not reset. All the old windows, sound channels etc. will be kept as they were, even though the game file might be expecting a different state. This extension allows Inform 7 game files to ensure that the IO state is as it should be. It does this in three stages: 

Chapter - Glk object recovery

The current glk object rock number is a number that varies.
The current glk object rock number variable translates into Inter as "current_glk_object_rock".
The current glk object reference number is a number that varies.
The current glk object reference number variable translates into Inter as "current_glk_object_reference".

The reset glk references rules is a rulebook.
The reset glk references rules is accessible to Inter as "RESET_GLK_REFERENCES_RB".
The identify glk windows rules is a rulebook.
The identify glk windows rules is accessible to Inter as "IDENTIFY_WINDOWS_RB".
The identify glk streams rules is a rulebook.
The identify glk streams rules is accessible to Inter as "IDENTIFY_STREAMS_RB".
The identify glk filerefs rules is a rulebook.
The identify glk filerefs rules is accessible to Inter as "IDENTIFY_FILEREFS_RB".
The identify glk sound channels rules is a rulebook.
The identify glk sound channels rules is accessible to Inter as "IDENTIFY_SCHANNELS_RB".
The glk object updating rules is a rulebook.
The glk object updating rules is accessible to Inter as "GLK_OBJECT_UPDATING_RB".

§11. And the standard rules, which may be replaced by extensions. 

The reset glk references for built in objects rule is listed first in the reset glk references rules.
The reset glk references for built in objects rule translates into Inter as "RESET_GLK_REFERENCES_R".

The cache gestalts rule is listed in the reset glk references rules.
The cache gestalts rule translates into Inter as "CACHE_GESTALTS_R".

The identify built in windows rule is listed first in the identify glk windows rules.
The identify built in windows rule translates into Inter as "IDENTIFY_WINDOWS_R".

The identify built in streams rule is listed first in the identify glk streams rules.
The identify built in streams rule translates into Inter as "IDENTIFY_STREAMS_R".

The identify built in filerefs rule is listed first in the identify glk filerefs rules.
The identify built in filerefs rule translates into Inter as "IDENTIFY_FILEREFS_R".

The identify built in sound channels rule is listed first in the identify glk sound channels rules.
The identify built in sound channels rule translates into Inter as "IDENTIFY_SCHANNELS_R".

The stop built in sound channels rule is listed in the glk object updating rules.
The stop built in sound channels rule translates into Inter as "STOP_SCHANNELS_R".