## varhome.pkg -- Representing where a variable lives and how to access its value at runtime.
# Compiled by:
# src/lib/compiler/front/typer-stuff/typecheckdata.sublibstipulate
package tmp = highcode_codetemp; # highcode_codetemp is from src/lib/compiler/back/top/highcode/highcode-codetemp.pkg package err = error_message; # error_message is from src/lib/compiler/front/basics/errormsg/error-message.pkg package ph = picklehash; # picklehash is from src/lib/compiler/front/basics/map/picklehash.pkgherein
package varhome
: (weak) Varhome # Varhome is from src/lib/compiler/front/typer-stuff/basics/varhome.api {
fun bug msg
=
err::impossible("Bugs in access: " + msg);
Picklehash = ph::Picklehash;
Varhome # How to find a variable's value at runtime.
#
= HIGHCODE_VARIABLE tmp::Codetemp # A variable in the current compilation module.
| PATH (Varhome, Int) # A value/variable/fn in some other compilation module.
| EXTERN Picklehash # Another module. Usually used in a PATH.
| NO_VARHOME # Everything else. :-)
;
Valcon_Form # Picking representations for data constructors.
#
= UNTAGGED # 30 bit + 00; a pointer
| TAGGED Int # A pointer; 1st field is the tag
| TRANSPARENT # 32 bit value
| CONSTANT Int # tagged_int
#
| REFCELL_REP
| EXCEPTION Varhome
| SUSPENSION Null_Or( (Varhome, Varhome) )
#
| LISTCONS
| LISTNIL
;
#
Valcon_Signature
#
= CONSTRUCTOR_SIGNATURE (Int, Int)
| NULLARY_CONSTRUCTOR
;
# ***************************************************************************
# UTILITY FUNCTIONS ON VARHOME *
# ***************************************************************************
# Print an Varhome value:
#
fun print_varhome (HIGHCODE_VARIABLE i) => "HIGHCODE_VARIABLE(" + tmp::to_string i + ")";
print_varhome (PATH (a, i)) => "PATH(" + int::to_string i + ", "+ print_varhome a + ")";
print_varhome (EXTERN pid) => "EXTERN(" + ph::to_hex pid + ")";
print_varhome (NO_VARHOME) => "NO_VARHOME";
end;
# Print a Valcon_Form value:
#
fun print_representation (UNTAGGED) => "UT";
print_representation (TAGGED i) => "TG(" + int::to_string i + ")";
print_representation (TRANSPARENT) => "TN";
print_representation (CONSTANT i) => "CN(" + int::to_string i + ")";
print_representation (REFCELL_REP) => "RF";
print_representation (EXCEPTION acc) => "EXCEPTION" + print_varhome acc;
print_representation (LISTCONS) => "LC";
print_representation (LISTNIL) => "LN";
print_representation (SUSPENSION _) => "SS";
end;
# Print a constructor api value:
#
fun print_constructor_api (CONSTRUCTOR_SIGNATURE (i, j))
=>
"B" + int::to_string i + "U" + int::to_string j;
print_constructor_api (NULLARY_CONSTRUCTOR)
=>
"CNIL";
end;
# Testing whether a Valcon_Form is an exception:
#
fun is_exception (EXCEPTION _) => TRUE;
is_exception _ => FALSE;
end;
# Fetch a component out of a package varhome:
#
fun select_varhome (NO_VARHOME, _)
=>
NO_VARHOME; # Bug "Selecting from a NO_VARHOME !"
select_varhome (p, i)
=>
PATH (p, i);
end;
# Duplicating a varhome variable:
#
fun duplicate_varhome (v, make_var)
=
HIGHCODE_VARIABLE (make_var (tmp::highcode_codetemp_to_value_symbol (v)));
fun named_varhome (s, make_var) = HIGHCODE_VARIABLE (make_var (THE s));
fun make_varhome (make_var) = HIGHCODE_VARIABLE (make_var (NULL));
fun external_varhome pid = EXTERN pid;
null_varhome = NO_VARHOME;
fun highcode_variable_or_null (HIGHCODE_VARIABLE v) => THE v;
highcode_variable_or_null _ => NULL;
end;
}; # package varhome
end; # stipulate