(octave.info)Parser

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F.2 Parser
==========

The parser has a number of variables that affect its internal operation.
These variables are generally documented in the manual alongside the
code that they affect.

   In addition, there are three non-specific parser customization
functions.  ‘add_input_event_hook’ can be used to schedule a user
function for periodic evaluation.  ‘remove_input_event_hook’ will stop a
user function from being evaluated periodically.

 -- : ID = add_input_event_hook (FCN)
 -- : ID = add_input_event_hook (FCN, DATA)
     Add the named function or function handle FCN to the list of
     functions to call periodically when Octave is waiting for input.

     The function should have the form

          FCN (DATA)

     If DATA is omitted, Octave calls the function without any
     arguments.

     The returned identifier may be used to remove the function handle
     from the list of input hook functions.

     See also: *note remove_input_event_hook:
     XREFremove_input_event_hook.

 -- : remove_input_event_hook (NAME)
 -- : remove_input_event_hook (FCN_ID)
     Remove the named function or function handle with the given
     identifier from the list of functions to call periodically when
     Octave is waiting for input.

     See also: Note: add_input_event_hook.

   Finally, when the parser cannot identify an input token it calls a
particular function to handle this.  By default, this is the internal
function "__unimplemented__" which makes suggestions about possible
Octave substitutes for MATLAB functions.

 -- : VAL = missing_function_hook ()
 -- : OLD_VAL = missing_function_hook (NEW_VAL)
 -- : missing_function_hook (NEW_VAL, "local")
     Query or set the internal variable that specifies the function to
     call when an unknown identifier is requested.

     When called from inside a function with the "local" option, the
     variable is changed locally for the function and any subroutines it
     calls.  The original variable value is restored when exiting the
     function.

     See also: Note: missing_component_hook.