By John R. Metzner, Robert L. Ashenhurst, Bruce H. Barnes
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A curious variant of this is used in BETAB-68 , of which ALGOL 60 is the host language. A decision table is activated when control enters its immediately enclosing block. The table may also be given a label for iterative reactivation from within the block. The enrichment of the host language with new verbs to accommodate decision tables can be limited to a single statement of the "GO TO TABLE n" type. In this case, returns to the main control stream must be effected by unconditional transfers or the use of indexed branching facilities.
01 STATE TXT (NCH) = " # " TXT (NCH) = "," TXT (NCH) = *' " OR "/' PICTURE 9 USAGE COMP. 01 TLGTH TXT (NCH) = " " TXT (NCH) = " ( " 01 TLEVEL PICTURE 9 USAGE COMP. PICTURE 9 USAGE COMP. 01 FLAG 01 BLANKS PICTURE X(8) VALUE " TINIT REDEFINES Q PICTURE X(8). 02 TFLD OCCURS 8 TIMES PICTURE X. 01 $ STATE = 3 01 TXT (NCH) = " ) " STATE = 2 Q. STATE = 1 DATA DIVISION. 1 ONEXT-ITEM WORKING-STORAGE SECTION. PROGRAM-ID. FIELD-FINDER. γ - X ADO 2 TO ERROR GO TO TOP GO BACK. X - - - - - - - _ Y - - - - - - - X - - - - - - γ - Y MOVE TLEVEL TO LVL (NUMBR).
The outermost level (no nesting) is assigned the level 1. Grouped parameters will be assigned higher level values. An integer through which the number of atomic parameters isolated is to be reported. An integer through which detected errors are reported according to the following: 0 1 2 3 No error was encountered. A parameter nesting error was detected. A parameter whose text exceeded eight characters has been encountered. Both of the above errors have occurred. 4. The program implementing the lexical analyzer of this example employs two decision tables and has a single-loop structure.
Decision Table Languages and Systems by John R. Metzner, Robert L. Ashenhurst, Bruce H. Barnes