Rational Developer for System z

Smart logical ordering scheme

The smart logical layout scheme has been introduced into Rational® Developer for System z® to overcome restrictions of the logical ordering scheme and to provide for the special requirements of programming languages.

The smart logical layout has been introduced in Rational Developer for System z to solve two main problems:

Round-trip problem
The implicit (logical) reordering algorithm has known restrictions that do not allow correct handling of some strings containing bidirectional text. As a result, users cannot easily generate certain presentations. These restrictions also create ambiguity during visual to logical conversion, which is usually performed when data is downloaded from a zSeries® remote system to a Windows or Java client.
Complex expressions handling
Text written in formal languages (such as programming languages) must obey rules that dictate the order of different tokens according to the appropriate syntax. If some of the tokens contain RTL (right-to-left) letters, the reordering performed for presentation according to the regular algorithm may cause the tokens to appear in an order different from the syntactical order. As a result, structured bidirectional data can be broken by visual-to-logical conversion, which is unaware of the data's structure. Assume, for example, that a COBOL file on an MVS™ system contains the following line of code in which the tokens are Arabic or Hebrew:
STRING "token1", "token2", "token3", "token4"
After visual-to-logical conversion, this row will look correct (the same as on the host) in any logical editor, but will be stored in the opposite order:
STRING "token4", "token3", "token2", "token1"

Solving the round-trip problem

To solve the round-trip problem, the bidirectional conversion algorithm has been supplied with a special option. When this option is specified (that is, when the smart logical client layout is defined by a Rational Developer for System z user), bidirectional text with potential ambiguity is preceded automatically by LRM or RLM marks. These marks are also called intra-token marks.

Solving the problem of complex expressions handling

Resolution of complex expressions problems is also based on use of LRM marks. Unfortunately, it is not possible to resolve this problem with a generic solution, because resolution is strongly dependent on particular language syntax. Visual-to-logical conversion for source programs written in COBOL, C/C++, PL/I, HLASM, and XML has been extended to support LRM marks insertion, when smart logical client layout is defined by the Rational Developer for System z user. Marks introduced by the smart logical algorithm to solve language-dependent syntax problems are called inter-token marks.


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