SAP ST PATTERN documentation, setup help and example usage

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ST - Pattern
When conditional transformations are deserialized, the fact that the template content is also a pattern is used as a criterion for the assessment. 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, then the condition has a positive result if an XML with this name follows in the current position in the XML input stream.
Marker constructs are:

Literal XML element with or without content

Non-literal attribute with content

Non-empty literal text

Explict empty template content

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 .

Transformations with conditions also propagate markers. If differences in cases exist or groupings, then 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

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