Reference¶
The address of a variable, held by a member of a host frame.
Declaration¶
Syntax¶
Reference(ttype type)
Arguments¶
Argument |
Description |
|---|---|
|
the type of the variable whose address the member holds. |
Return values¶
None. A type is not evaluated.
Description¶
A Reference is the type of a member of a frame, the derived type that the
nested_vars pass declares in a host so that its internal procedures reach
the variables of the instance of the host that invoked them (see « Host
Association » in the design document). It is the type of such a member and of
nothing else: the verifier reports a Reference anywhere else, including inside
another type, as asr.verify.reference.member_only.
BindReference stores the address of a
variable in the member. A
StructInstanceMember of the
member then designates that variable itself and has type type, the type of
the variable, as asr.verify.reference.designator_type checks. It is the
symbolic_value of a variable of HostAssociated
storage, which stands for the variable in an
internal procedure.
Unlike a Pointer, a member of Reference type has no association
status and no value of its own, and nothing allocates, deallocates,
finalizes, copies or default-initializes it with the object that contains it:
generic code that does not know the type leaves it alone. A backend lays it
out as the address of the storage of a variable of type type.
Examples¶
(Reference
:type (Integer
:kind 4
)
)
It comes from this complete ASR text document:
(TranslationUnit
:symtab (SymbolTable
:id 0
:symbols {
"host_frame" (Program
:symtab (SymbolTable
:id 1
:symbols {
"k" (Variable
:parent_symtab 1
:name "k"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (Integer
:kind 4
)
:type_declaration nil
:abi :Source
:access :Public
:presence :Required
:value_attr false
:target_attr false
:contiguous_attr false
:bindc_name nil
:is_volatile false
:is_asynchronous false
:is_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
:common_block nil
)
"outer" (Function
:symtab (SymbolTable
:id 2
:symbols {
"1_frame_n" (ExternalSymbol
:parent_symtab 2
:name "1_frame_n"
:external (SymbolRef 3 "n")
:module_name "frame"
:scope_names []
:original_name "n"
:access :Public
)
"f" (Variable
:parent_symtab 2
:name "f"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (StructType
:data_member_types [
(Reference
:type (Integer
:kind 4
)
)
]
:member_function_types []
:is_cstruct true
:is_unlimited_polymorphic false
)
:type_declaration (SymbolRef 2 "frame")
:abi :Source
:access :Public
:presence :Required
:value_attr false
:target_attr false
:contiguous_attr false
:bindc_name nil
:is_volatile false
:is_asynchronous false
:is_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
:common_block nil
)
"frame" (Struct
:symtab (SymbolTable
:id 3
:symbols {
"n" (Variable
:parent_symtab 3
:name "n"
:dependencies []
:intent :Unspecified
:symbolic_value nil
:value nil
:storage :Default
:type (Reference
:type (Integer
:kind 4
)
)
:type_declaration nil
:abi :Source
:access :Public
:presence :Required
:value_attr false
:target_attr false
:contiguous_attr false
:bindc_name nil
:is_volatile false
:is_asynchronous false
:is_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
:common_block nil
)
}
)
:name "frame"
:struct_signature (StructType
:data_member_types [
(Reference
:type (Integer
:kind 4
)
)
]
:member_function_types []
:is_cstruct true
:is_unlimited_polymorphic false
)
:dependencies []
:members [
"n"
]
:member_functions []
:abi :Source
:access :Public
:is_packed false
:is_abstract false
:is_sequence false
:initializers []
:alignment nil
:parent nil
:kind_params []
)
"inner" (Function
:symtab (SymbolTable
:id 4
:symbols {
"f" (Variable
:parent_symtab 4
:name "f"
:dependencies []
:intent :In
:symbolic_value nil
:value nil
:storage :Default
:type (StructType
:data_member_types [
(Reference
:type (Integer
:kind 4
)
)
]
:member_function_types []
:is_cstruct true
:is_unlimited_polymorphic false
)
:type_declaration (SymbolRef 2 "frame")
:abi :Source
:access :Public
:presence :Required
:value_attr false
:target_attr false
:contiguous_attr false
:bindc_name nil
:is_volatile false
:is_asynchronous false
:is_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
:common_block nil
)
"n" (Variable
:parent_symtab 4
:name "n"
:dependencies [
"f"
]
:intent :Local
:symbolic_value (StructInstanceMember
:v (Var
:v (SymbolRef 4 "f")
)
:m (SymbolRef 2 "1_frame_n")
:type (Integer
:kind 4
)
:value nil
)
:value nil
:storage :HostAssociated
:type (Integer
:kind 4
)
:type_declaration nil
:abi :Source
:access :Public
:presence :Required
:value_attr false
:target_attr false
:contiguous_attr false
:bindc_name nil
:is_volatile false
:is_asynchronous false
:is_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
:common_block nil
)
}
)
:name "inner"
:function_signature (FunctionType
:arg_types [
(StructType
:data_member_types [
(Reference
:type (Integer
:kind 4
)
)
]
:member_function_types []
:is_cstruct true
:is_unlimited_polymorphic false
)
]
:return_var_type nil
:abi :Source
:deftype :Implementation
:bindc_name nil
:elemental false
:pure false
:module false
:inline false
:static false
:restrictions []
:is_restriction false
:exec_space :Host
)
:dependencies []
:args [
(Var
:v (SymbolRef 4 "f")
)
]
:body [
(Assignment
:target (Var
:v (SymbolRef 4 "n")
)
:value (IntegerBinOp
:left (Var
:v (SymbolRef 4 "n")
)
:op :Add
:right (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (Integer
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
:new_target false
:new_allocation false
)
]
:return_var nil
:access :Public
:deterministic true
:side_effect_free true
:module_file nil
)
"n" (Variable
:parent_symtab 2
:name "n"
:dependencies []
:intent :InOut
:symbolic_value nil
:value nil
:storage :Default
:type (Integer
:kind 4
)
:type_declaration nil
:abi :Source
:access :Public
:presence :Required
:value_attr false
:target_attr false
:contiguous_attr false
:bindc_name nil
:is_volatile false
:is_asynchronous false
:is_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
:common_block nil
)
}
)
:name "outer"
:function_signature (FunctionType
:arg_types [
(Integer
:kind 4
)
]
:return_var_type nil
:abi :Source
:deftype :Implementation
:bindc_name nil
:elemental false
:pure false
:module false
:inline false
:static false
:restrictions []
:is_restriction false
:exec_space :Host
)
:dependencies []
:args [
(Var
:v (SymbolRef 2 "n")
)
]
:body [
(BindReference
:reference (StructInstanceMember
:v (Var
:v (SymbolRef 2 "f")
)
:m (SymbolRef 2 "1_frame_n")
:type (Integer
:kind 4
)
:value nil
)
:variable (Var
:v (SymbolRef 2 "n")
)
)
(SubroutineCall
:name (SymbolRef 2 "inner")
:original_name nil
:args [
(call_arg
:value (Var
:v (SymbolRef 2 "f")
)
)
]
:dt nil
:strict_bounds_checking false
)
]
:return_var nil
:access :Public
:deterministic true
:side_effect_free true
:module_file nil
)
}
)
:name "host_frame"
:dependencies []
:body [
(Assignment
:target (Var
:v (SymbolRef 1 "k")
)
:value (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:overloaded nil
:realloc_lhs false
:move_allocation false
:new_target false
:new_allocation false
)
(SubroutineCall
:name (SymbolRef 1 "outer")
:original_name nil
:args [
(call_arg
:value (Var
:v (SymbolRef 1 "k")
)
)
]
:dt nil
:strict_bounds_checking false
)
(Print
:text (StringFormat
:fmt nil
:args [
(Var
:v (SymbolRef 1 "k")
)
]
:kind :FormatFortran
:dtio_bindings []
:dtio_unit nil
:type (Allocatable
:type (String
:kind 1
:len nil
:len_kind :DeferredLength
:physical_type :DescriptorString
)
)
:value nil
)
)
]
:global_init nil
)
}
)
:items []
:global_init nil
)