StringFormat

A formatted string built from a format and a list of values.

Declaration

Syntax

StringFormat(expr? fmt, expr* args, string_format_kind kind,
    ttype type, expr? value)

Arguments

Argument	Description
fmt	the format, or nil for list-directed formatting.
args	the values to format.
kind	which formatting language the format is written in; see string_format_kind.
type	the string type of the result.
value	the compile time value of the expression, when the frontend could fold it; nil otherwise.

Return values

The value of the expression.

Description

Formatting is an expression producing a string, not a property of the I/O statements. Print and FileWrite therefore carry a StringFormat rather than a format and an output list of their own, and a backend that can build the string has already implemented both.

kind distinguishes Fortran edit descriptors from C’s printf and from Python’s several formatting languages, so one node serves every frontend.

Examples

(StringFormat
  :fmt nil
  :args [
    (Var
      :v (SymbolRef 1 "n")
    )
  ]
  :kind :FormatFortran
  :type (String
    :kind 1
    :len nil
    :len_kind :DeferredLength
    :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 {
            "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 []
            )
          }
        )
        :name "main"
        :dependencies []
        :body [
          (Print
            :text (StringFormat
              :fmt nil
              :args [
                (Var
                  :v (SymbolRef 1 "n")
                )
              ]
              :kind :FormatFortran
              :type (String
                :kind 1
                :len nil
                :len_kind :DeferredLength
                :physical_type :DescriptorString
              )
              :value nil
            )
          )
        ]
      )
    }
  )
  :items []
)

See Also

string_format_kind, Print, FileWrite, StringConstant