Union¶
A union: several members sharing one storage location.
Declaration¶
Syntax¶
Union(symbol_table symtab, identifier name, identifier* dependencies,
identifier* members, abi abi, access access,
call_arg* initializers, symbol? parent)
Arguments¶
Argument |
Description |
|---|---|
|
the symbol table of the union, with one Variable per member. |
|
the name of the union. |
|
the names of the symbols the definition refers to. |
|
the names of the members, in declaration order. |
|
|
|
|
|
the default initializers of the members. |
|
reserved for an extended union; |
Return values¶
None.
Description¶
A Union lays every member out at the same address, so its size is the size
of its largest member. Fortran has no union type of its own; this node exists
to describe a C union reached through bind(c), and to give LPython’s
Union a representation.
Reading a member that was not the one last written is not diagnosed by ASR.
Examples¶
An ASR text document that uses it:
(TranslationUnit
:symtab (SymbolTable
:id 0
:symbols {
"m" (Module
:symtab (SymbolTable
:id 1
:symbols {
"word" (Union
:symtab (SymbolTable
:id 2
:symbols {
"i" (Variable
:parent_symtab 2
:name "i"
: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_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
)
"r" (Variable
:parent_symtab 2
:name "r"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (Real
: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_protected false
:pass_attr :NotMethod
:self_argument nil
:codims []
)
}
)
:name "word"
:dependencies []
:members [
"i"
"r"
]
:abi :Source
:access :Public
:initializers []
:parent nil
)
}
)
:name "m"
:parent_module nil
:dependencies []
:loaded_from_mod false
:intrinsic false
:has_submodules false
)
"main" (Program
:symtab (SymbolTable
:id 3
:symbols {}
)
:name "main"
:dependencies []
:body []
)
}
)
:items []
)