StringSection¶
A substring.
Declaration¶
Syntax¶
StringSection(expr arg, expr? start, expr? end, expr? step, ttype type,
expr? value)
Arguments¶
Argument |
Description |
|---|---|
|
the string. |
|
the first index, counting from one. |
|
the last index. |
|
the stride. It must be present; one for an ordinary substring. |
|
the type of the result, whose length must be given explicitly. |
|
the compile time value of the expression, when the frontend could fold it; |
Return values¶
The value of the expression.
Description¶
s(i:j). The result is a value, not a reference: assigning to a substring is
an Assignment whose target is the
StringSection.
The verifier requires both step and a length expression on the result type,
so that a backend never has to work out how long the result is.
Examples¶
(StringSection
:arg (Var
:v (SymbolRef 1 "s")
)
:start (IntegerConstant
:n 2
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:end (IntegerConstant
:n 4
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:step (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (String
:kind 1
:len (IntegerConstant
:n 3
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
:value nil
)
It comes from this complete ASR text document:
(TranslationUnit
:symtab (SymbolTable
:id 0
:symbols {
"main" (Program
:symtab (SymbolTable
:id 1
:symbols {
"b" (Variable
:parent_symtab 1
:name "b"
: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 []
)
"c" (Variable
:parent_symtab 1
:name "c"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (String
:kind 1
:len (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
: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 []
)
"n" (Variable
:parent_symtab 1
:name "n"
: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 []
)
"s" (Variable
:parent_symtab 1
:name "s"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (String
:kind 1
:len (IntegerConstant
:n 5
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
: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 []
)
"t" (Variable
:parent_symtab 1
:name "t"
:dependencies []
:intent :Local
:symbolic_value nil
:value nil
:storage :Default
:type (Allocatable
:type (String
:kind 1
:len nil
:len_kind :DeferredLength
:physical_type :DescriptorString
)
)
: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 [
(Assignment
:target (Var
:v (SymbolRef 1 "s")
)
:value (StringConstant
:s "hello"
:type (String
:kind 1
:len (IntegerConstant
:n 5
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "t")
)
:value (StringConcat
:left (Var
:v (SymbolRef 1 "s")
)
:right (StringConstant
:s "!"
:type (String
:kind 1
:len (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
)
:type (String
:kind 1
:len nil
:len_kind :DeferredLength
:physical_type :DescriptorString
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "t")
)
:value (StringRepeat
:left (Var
:v (SymbolRef 1 "s")
)
:right (IntegerConstant
:n 3
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (String
:kind 1
:len nil
:len_kind :DeferredLength
:physical_type :DescriptorString
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "n")
)
:value (StringLen
:arg (Var
:v (SymbolRef 1 "s")
)
:type (Integer
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "c")
)
:value (StringItem
:arg (Var
:v (SymbolRef 1 "s")
)
:idx (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (String
:kind 1
:len (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "t")
)
:value (StringSection
:arg (Var
:v (SymbolRef 1 "s")
)
:start (IntegerConstant
:n 2
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:end (IntegerConstant
:n 4
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:step (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (String
:kind 1
:len (IntegerConstant
:n 3
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "b")
)
:value (StringCompare
:left (Var
:v (SymbolRef 1 "s")
)
:op :Eq
:right (StringConstant
:s "world"
:type (String
:kind 1
:len (IntegerConstant
:n 5
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
)
:type (Logical
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "b")
)
:value (StringContains
:substr (StringConstant
:s "ell"
:type (String
:kind 1
:len (IntegerConstant
:n 3
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
)
:str (Var
:v (SymbolRef 1 "s")
)
:type (Logical
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "n")
)
:value (StringOrd
:arg (Var
:v (SymbolRef 1 "c")
)
:type (Integer
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "c")
)
:value (StringChr
:arg (IntegerConstant
:n 65
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:type (String
:kind 1
:len (IntegerConstant
:n 1
:type (Integer
:kind 4
)
:intboz_type :Decimal
)
:len_kind :ExpressionLength
:physical_type :DescriptorString
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "n")
)
:value (Ichar
:arg (Var
:v (SymbolRef 1 "c")
)
:type (Integer
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
(Assignment
:target (Var
:v (SymbolRef 1 "n")
)
:value (Iachar
:arg (Var
:v (SymbolRef 1 "c")
)
:type (Integer
:kind 4
)
:value nil
)
:overloaded nil
:realloc_lhs false
:move_allocation false
)
]
)
}
)
:items []
)