Template¶
A Template is a symbol node for declaring generic functions.
Declaration¶
Syntax¶
Template(symbol_table symtab, identifier name,
identifier* args, require_instantiation* requires)
Arguments¶
Argument Name |
Denotes |
|---|---|
|
symbol table of the template |
|
name of the template |
|
symbol names inside the template |
|
instantiating argument types through require calls |
Return values¶
Description¶
Generic functions are declared within the scope of a template. In the example below, a generic n-times multiplication is implemented in a template. A template can contain multiple generic functions that depend on one another.
name denotes the name of the template. Template names are needed for specifying which generic functions will be used in the program. In the example below, the name of the template is derive_semigroup.
args denotes the parameters of the template. The parameters of a template represent the generic elements that need to be instantiated with concrete types and functions so that the generic functions inside the template can be used during run-time. A warning is generated if there is no corresponding symbol found in the template’s symtab for a given parameter. In the example below, the parameters «(T, op)» make up the args of the derive_semigroup template.
require_instantiation (Require statements) are calls to requiremens that replace the types of the arguments with the corresponding parameters» types in the requirement. In the generic function stimes below, a is a variable with a generic type and op is a function utilizing such generic variable. To assign types to both, the statement require :: semigroup(T, op) maps the typing for T and op according to its signature in the semigroup.
Types¶
Examples¶
LFortran:
module semigroup_m
requirement semigroup(T, op)
...
end requirement
template derive_semigroup(T, op)
require :: semigroup(T, op)
contains
elemental function stimes(n, a) result(res)
integer, intent(in) :: n
type(T), intent(in) :: a
type(T) :: res
integer :: i
res = a
do i = 2, n
res = op(res, a)
end do
end function
end template
end semigroup
ASR:
semigroup_m:
(Module
(SymbolTable
2
{
derive_semigroup:
(Template
(SymbolTable
5
{
op:
(Function
(SymbolTable
6
{
combined:
(Variable
6
combined
[]
ReturnVar
()
()
Default
(TypeParameter
t
)
()
Source
Public
Required
.false.
),
x:
(Variable
6
x
[]
In
()
()
Default
(TypeParameter
t
)
()
Source
Public
Required
.false.
),
y:
(Variable
6
y
[]
In
()
()
Default
(TypeParameter
t
)
()
Source
Public
Required
.false.
)
})
op
(FunctionType
[(TypeParameter
t
)
(TypeParameter
t
)]
(TypeParameter
t
)
Source
Implementation
()
.true.
.false.
.false.
.false.
.false.
[]
.true.
)
[]
[(Var 6 x)
(Var 6 y)]
[]
(Var 6 combined)
Public
.false.
.false.
()
),
stimes:
(Function
(SymbolTable
7
{
a:
(Variable
7
a
[]
In
()
()
Default
(TypeParameter
t
)
()
Source
Public
Required
.false.
),
i:
(Variable
7
i
[]
Local
()
()
Default
(Integer 4)
()
Source
Public
Required
.false.
),
n:
(Variable
7
n
[]
In
()
()
Default
(Integer 4)
()
Source
Public
Required
.false.
),
res:
(Variable
7
res
[]
ReturnVar
()
()
Default
(TypeParameter
t
)
()
Source
Public
Required
.false.
)
})
stimes
(FunctionType
[(Integer 4)
(TypeParameter
t
)]
(TypeParameter
t
)
Source
Implementation
()
.true.
.false.
.false.
.false.
.false.
[]
.false.
)
[op]
[(Var 7 n)
(Var 7 a)]
[(Assignment
(Var 7 res)
(Var 7 a)
()
)
(DoLoop
()
((Var 7 i)
(IntegerConstant 2 (Integer 4))
(Var 7 n)
())
[(Assignment
(Var 7 res)
(FunctionCall
5 op
()
[((Var 7 res))
((Var 7 a))]
(TypeParameter
t
)
()
()
)
()
)]
)]
(Var 7 res)
Public
.false.
.false.
()
),
t:
(Variable
5
t
[]
In
()
()
Default
(TypeParameter
t
)
()
Source
Public
Required
.false.
)
})
derive_semigroup
[t
op]
[(Require
semigroup
[t
op]
)]
),
... (semigroup requirement's tree)
})
semigroup_m
[semigroup_m]
.false.
.false.
)