Associate

Binds a name to a target rather than copying a value.

声明

语法

Associate(expr target, expr value)

参数

Argument	描述
target	the pointer or associate name being bound.
value	what it is bound to.

返回值

无。

描述

Associate is pointer assignment, p => t, and it is what gives the names of an AssociateBlock their meaning. It makes the target refer to the same storage as the value; it does not copy anything, which is what distinguishes it from Assignment.

Associate with a PointerNullConstant value is how p => null() is represented, and Nullify is the equivalent statement form.

示例

(Associate
  :target (Var
    :v (SymbolRef 1 "p")
  )
  :value (GetPointer
    :arg (Var
      :v (SymbolRef 1 "target")
    )
    :type (Pointer
      :type (Integer
        :kind 4
      )
    )
    :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 (CPtr)
              :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 8
              )
              :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 (Pointer
                :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 []
            )
            "target" (Variable
              :parent_symtab 1
              :name "target"
              :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 true
              :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 "c")
            )
            :value (CLoc
              :arg (Var
                :v (SymbolRef 1 "target")
              )
              :type (CPtr)
              :value nil
            )
            :overloaded nil
            :realloc_lhs false
            :move_allocation false
          )
          (Assignment
            :target (Var
              :v (SymbolRef 1 "c")
            )
            :value (PointerToCPtr
              :arg (Var
                :v (SymbolRef 1 "p")
              )
              :type (CPtr)
              :value nil
            )
            :overloaded nil
            :realloc_lhs false
            :move_allocation false
          )
          (Associate
            :target (Var
              :v (SymbolRef 1 "p")
            )
            :value (GetPointer
              :arg (Var
                :v (SymbolRef 1 "target")
              )
              :type (Pointer
                :type (Integer
                  :kind 4
                )
              )
              :value nil
            )
          )
          (Assignment
            :target (Var
              :v (SymbolRef 1 "b")
            )
            :value (CPtrCompare
              :left (Var
                :v (SymbolRef 1 "c")
              )
              :op :Eq
              :right (Var
                :v (SymbolRef 1 "c")
              )
              :type (Logical
                :kind 4
              )
              :value nil
            )
            :overloaded nil
            :realloc_lhs false
            :move_allocation false
          )
          (Assignment
            :target (Var
              :v (SymbolRef 1 "b")
            )
            :value (PointerAssociated
              :ptr (Var
                :v (SymbolRef 1 "p")
              )
              :tgt (Var
                :v (SymbolRef 1 "target")
              )
              :type (Logical
                :kind 4
              )
              :value nil
            )
            :overloaded nil
            :realloc_lhs false
            :move_allocation false
          )
          (Assignment
            :target (Var
              :v (SymbolRef 1 "n")
            )
            :value (SizeOfType
              :arg (Integer
                :kind 4
              )
              :type (Integer
                :kind 8
              )
              :value nil
            )
            :overloaded nil
            :realloc_lhs false
            :move_allocation false
          )
        ]
      )
    }
  )
  :items []
)

也可以看看

Assignment, AssociateBlock, Nullify, GetPointer