CORRESPONDING - mapping - ABAP Keyword Documentation

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CORRESPONDING - mapping

Syntax

... [ MAPPING {t1 = s1}|( t1 = s1 [MAPPING ...] [EXCEPT ...] )
            {t2 = s2}|( t2 = s2 [MAPPING ...] [EXCEPT ...] )
              ...  ]
    [ EXCEPT {ti tj ...}|* ] ...

Additions

1. ... MAPPING t1 = s1 t2 = s2 ...

2. ... EXCEPT {t1 t2 ...}|*

Effect

Mapping rule for the component operator CORRESPONDING. The optional mapping rule overrides the default assignment of identically named components only. The additions MAPPING and EXCEPT can be used individually or together. EXCEPT must always be specified after MAPPING.

Notes

It is best to use the component operator (see the example) for mapping tasks that can be solved using either the component operator or table comprehensions.

When using the basic form with a mapping rule, assignments can currently only be made to the same structure or internal table specified as an argument if this is statically identifiable. The information need to create the necessary temporary copy of the target object is missing at runtime and a runtime error occurs.

The system class CL_ABAP_CORRESPONDING is provided for assignments between structures or internal tables with a dynamic mapping rule.

Addition 1

... MAPPING t1 = s1 t2 = s2 ...

Effect

After MAPPING, t1, t2, ... are used to assign the components s1, s2,... of a source structure or source table in mapping relationships to the components of a target structure or target table.

If the components specified on the left and right of an equals sign of a mapping relationship are themselves structured or tabular with a structured row type, a separate mapping rule can be nested for these components. Here, the mapping relationship is set in parentheses ( ... ) and a further mapping rule MAPPING ... and/or EXCEPT ... is specified after the mapping relationship in accordance with the same rules as on the top level. The parentheses are not allowed if a nested mapping rule is not used.

A component of a target object cannot appear more than once in a list after MAPPING and the structure component selector cannot be used to access subcomponents. Neither of these rules apply to components of the source object. If MAPPING is used, the table types involved must also have structured row types in the basic form and the addition DEEP is set implicitly.

In the basic form, t1, t2, ... are components of the target type and s1, s2, ... are components of the parameter struct or itab.

In the variant with lookup table, t1, t2, ... are columns of the parameter itab and s1, s2, ... are columns of the parameter lookup_tab.

The content of the component specified on the right side of an equals sign in a mapping relationship is assigned to each component specified on the left side. If there is an identically named component in the target structure for a component specified on the right side, it is also assigned content (unless it is specified on the left side of a mapping relationship itself). In elementary components the assignment is made in accordance with the associated assignment rules. In structured and tabular components, the assignment is made in accordance with the rules of MOVE-CORRESPONDING with the addition EXPANDING NESTED TABLES.

Identically named components can also be specified on the right and left side of the equals sign. This is a good idea in the following cases:

If the variant with lookup table are used, identically named components in a mapping relationship override the rule that the components s1, s2, ... and t1, t2, ... used for searches are not assigned by default.

Identically named components must be specified in a mapping relationship if a nested mapping rule is to be specified for these components.

Note

The pseudo component table_line cannot be specified as a component of an internal table in the mapping rule.

Addition 2

... EXCEPT {t1 t2 ...}|*

Effect

After EXCEPT, components t1, t2, ... of the target structure or target table that are not specified in a preceding mapping relationship or an asterisk, *, can be specified:

If explicit components t1, t2, ... are specified, these components of the result are not assigned content and remain initial.

If an asterisk, *, is specified, all components of the result are initial that are not specified explicitly in a preceding mapping relationship.

Access to subcomponents of components of the target object using the structure component selector is not allowed in the list after EXCEPT either.

Notes

If there are identically named components in the source and target object that are not compatible or convertible, they can be excluded from the assignment using EXCEPT. This avoids syntax errors or runtime errors.

If EXCEPT * is specified without preceding mapping relationships, all components of the result remain initial.

Example

Assigns the components of the structure struct1 to the components of the structure struct2 using mapping rules for the components at the top level and the components of the substructure.

DATA: BEGIN OF struct1,
        mcomp1 TYPE i VALUE 1,
        mcomp2 TYPE i VALUE 2,
        BEGIN OF substruc,
          subcomp1 TYPE i VALUE 1,
          subcomp2 TYPE i VALUE 2,
          subcomp3 TYPE i VALUE 3,
        END OF substruc,
      END OF struct1.

DATA: BEGIN OF struct2,
        comp2 TYPE i,
        comp1 TYPE i,
        BEGIN OF substruc,
          comp3 TYPE i,
          comp2 TYPE i,
          comp1 TYPE i,
        END OF substruc,
      END OF struct2.

struct2 =
  CORRESPONDING #(
    struct1 MAPPING comp1    = mcomp1
                    comp2    = mcomp2
                  ( substruc = substruc MAPPING comp1 = subcomp1
                                                comp2 = subcomp2
                                                comp3 = subcomp3 ) ) .

Examples

See

Component Operator, Mapping Rule

Component Operator, Nested Mapping Rule