Kontakt

Ansicht
Dokumentation

ABENST_PATTERN - ST PATTERN

ABENST_PATTERN - ST PATTERN

PERFORM Short Reference   BAL Application Log Documentation  
This documentation is copyright by SAP AG.
SAP E-Book

- Pattern

When conditional transformations are deserialized, the criterion for the evaluation is whether the template content is also a pattern. A pattern contains one or more constructs that are used as markers. The most common form of a marker is a literal XML element: if the content of the condition consists of exactly one XML element, the condition has exactly one positive result if an XML element with this name follows at the current position in the XML input stream.

Marker constructs are:

Each of these constructs can be compared with the input stream in an obvious way.

A pattern can usually contain multiple markers. For example, the sequence

<tt:cond>
  <X> ... </X>
</tt:cond>
<Y> ... </Y>

is also a pattern; it contains the markers X and Y. A condition with this pattern is determined positively by element X as well as by element Y in the input stream (in the second case, condition is determined negatively with X).

The number of marker constructs M(c) contained in template content c is defined recursively below. Template content c is a pattern if M(c) is not empty. In summary, M(c) consists of the markers that can be used to positively determine pattern c, where conditions in an initial part of c can also be determined negatively.

  • M(c) = {c} for marker c. This means that each marker is a (primitive) pattern and the marker set for this pattern consists of the marker itself.

Some constructs propagate markers externally:

  • M(tt:deserialize) = M(tt:ref) = M(c) for the content c of the construct in question.
  • M(tt:apply) = M(c) for the body c of the called template.
  • M(tt:loop) = M(c) for the loop body c.

Conditional transformations also propagate markers. In the case of case distinctions and groupings, the union of all cases is determined:

  • M(tt:$[d-$]cond) = M(c) for the condition body c.
  • M(tt:group) = M(tt:switch) = M(c1) U ... U M(cn) for all cases ci = tt:$[d-$]cond

For all other instructions c, M(c) is empty.

For c1 c2 ... sequences in template content, the following applies:

  • M(c1 c2 ...) = M(c1) U M(c2 ...), if c1 is a prepattern, otherwise M(c1)

Template content is a pre-pattern if its deserialization is possible without the use of content from the input stream. In detail:

  • All constructs with an empty deserialization are pre-patterns. These are tt:s-cond, tt:assign, tt:clear, tt:serialize, tt:write, and compositions of these with tt:cond-var, tt:switch-var, and tt:apply.
  • tt:$[d-$]cond is a pre-pattern if the condition body is a pattern. (If the pattern cannot be compared, the condition is determined negatively and is skipped.)

tt:deserialize, tt:ref, and tt:apply propagate the pre-pattern property.

Example

The content of the following element tt:cond is a pattern with marker elements {f1, f2, f3} (but not fx).

tt:cond s-check="not-initial(F3) and initial(F6)">
  tt:clear ref="F3"/>
  tt:cond check="not-initial(F1) or not-initial(F2)">
    tt:cond check="not-initial(F1)">
      tt:clear ref="F1"/>
      tt:serialize>
        f1 a="v" tt:value-ref="F1"/>
      /tt:serialize>
      tt:deserialize>
        f1 tt:value-ref="F1"/>
      /tt:deserialize>
    /tt:cond>
    f2 tt:value-ref="F2"/>
  /tt:cond>
  f3 tt:value-ref="F3"/>
  fx> ... /fx>
/tt:cond>






Addresses (Business Address Services)   PERFORM Short Reference  
This documentation is copyright by SAP AG.

Length: 7939 Date: 20240420 Time: 034408     sap01-206 ( 71 ms )