WhileLoop¶
A loop that runs while a condition holds.
Declaration¶
Syntax¶
WhileLoop(identifier? name, expr test, stmt* body, stmt* orelse)
Arguments¶
Argument |
Description |
|---|---|
|
the construct name, or |
|
the condition, checked before each iteration. |
|
the statements of the loop. |
|
statements to run when the loop ends because the condition became false rather than through an |
Return values¶
None.
Description¶
The condition is checked before the first iteration, so the body may never run. A DoLoop is the counted form and knows its trip count in advance; a WhileLoop does not.
Examples¶
(WhileLoop
:name nil
:test (IntegerCompare
:left (Var
:v (SymbolRef 1 "j")
)
:op :Lt
:right (IntegerConstant
:n 100
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (Logical
:kind 4
)
:value nil
)
:body [
(Assignment
:target (Var
:v (SymbolRef 1 "j")
)
:value (IntegerBinOp
:left (Var
:v (SymbolRef 1 "j")
)
: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
)
]
:orelse []
)
It comes from this complete ASR text document:
(TranslationUnit
:symtab (SymbolTable
:id 0
:symbols {
"main" (Program
:symtab (SymbolTable
:id 1
:symbols {
"i" (Variable
:parent_symtab 1
: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 []
)
"j" (Variable
:parent_symtab 1
:name "j"
: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 []
)
"p" (Variable
:parent_symtab 1
:name "p"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (Logical
: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 "main"
:dependencies []
:body [
(DoLoop
:name "loop"
:head (do_loop_head
:v (Var
:v (SymbolRef 1 "i")
)
:start (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:end (IntegerConstant
:n 10
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:increment (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
)
:body [
(If
:name nil
:test (IntegerCompare
:left (Var
:v (SymbolRef 1 "i")
)
:op :Eq
:right (IntegerConstant
:n 5
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (Logical
:kind 4
)
:value nil
)
:body [
(Cycle
:stmt_name "loop"
)
]
:orelse []
)
(If
:name nil
:test (Var
:v (SymbolRef 1 "p")
)
:body [
(Exit
:stmt_name "loop"
)
]
:orelse [
(Assignment
:target (Var
:v (SymbolRef 1 "j")
)
:value (Var
:v (SymbolRef 1 "i")
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
]
)
]
:orelse []
)
(WhileLoop
:name nil
:test (IntegerCompare
:left (Var
:v (SymbolRef 1 "j")
)
:op :Lt
:right (IntegerConstant
:n 100
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (Logical
:kind 4
)
:value nil
)
:body [
(Assignment
:target (Var
:v (SymbolRef 1 "j")
)
:value (IntegerBinOp
:left (Var
:v (SymbolRef 1 "j")
)
: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
)
]
:orelse []
)
(Assert
:test (IntegerCompare
:left (Var
:v (SymbolRef 1 "j")
)
:op :GtE
:right (IntegerConstant
:n 0
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (Logical
:kind 4
)
:value nil
)
:msg (StringConstant
:s "j is not negative"
:type (String
:kind 1
:len (IntegerConstant
:n 17
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
)
)
]
)
}
)
:items []
)