Types

XPE has the following builtin data type
 

int	integer	32 bit 2's complement binary
float	real	32 bit ieee 754 single precision
$	string	NUL terminated 'C' string
struct	structure
array	array
SREF	structure reference
AREF	array reference
GENERATOR	generator context
CTL_ID	control structure reference
OBJ_ID	object structure reference

values are automatically coerced between simple types if possible

Determining the type of a value

is_valid(val)	return TRUE if the value is valid, return FALSE otherwise use invalidate(val) to invalidate a variable
is_struct(val)	return TRUE if the value is a structure or reference to a structure, return FALSE otherwise BEWARE this will not differentiate between shared and non shared structures
is_struct(val)   &&   ! is_sref(val)	return TRUE if the value is a structure, return FALSE otherwise
is_sref(val)	return TRUE if the value is a reference to a structure return FALSE otherwise
is_array(val)	return TRUE if the value is an array or reference to an array, return FALSE otherwise BEWARE this will not differentiate between shared and non shared arrays
is_array(val)   &&   ! is_aref(val)	return TRUE if the value is an array, return FALSE otherwise
is_aref(val)	return TRUE if the value is a reference to an array return FALSE otherwise

 

Type hierarchy

This diagram shows that:

• a value can consist of any of:
  • array
  • structure
  • aref
  • sref
  • int
  • float
  • string
  • generator
  • ctl_id
  • obj_id
• a variable consists of:
  • a value
• a structure consists of one or more:
  • variables
• an array consists of one or more:
  • variables
• an array reference (AREF) consists of one or more:
  • variables
• a structure reference (SREF) consists of one or more:
  • variables
• a token consists of either
  • a variable
  • a value

NOTE the recursive nature of the array and structure.