BabyCobol: NEXT SENTENCE

a statement to branch unconditionally to the beginning of the next sentence

Format

Semantics

The problems of implementing the NEXT SENTENCE statement come from the clash between the hierarchical tree-like structure of the program and its flat textual structure. The official semantics of the NEXT SENTENCE statement is that it transfers control to the first statement of the next sentence (after the dot). If the AST already incorporates the information about sentences in addition to statements, then implementing the NEXT SENTENCE statement should not be too difficult: we need to prepare a possibly useful target label at the beginning of each sentence, and use it when needed. Due to BabyCobol's simplified design, this is the only possible way in the language to essentially GO TO within a paragraph. Watch out for the interaction of NEXT SENTENCE with the other BabyCobol features:

NEXT SENTENCE as the last statement of the paragraph does nothing, because it has to end with a dot (as each paragraph consists of only full sentences!), so it ends a sentence itself and transfers control to the sentence after that.
If the transfer takes the execution away from the current context of LOOP, it cleans up call stack contents, temporary variables and other local effects of the context(s) being left behind.

Style

NEXT SENTENCE at the beginning of the paragraph can be used to comment out one of more of the immediately following statements, making them dead code without marking each line as an explicit comment.
NEXT SENTENCE. (with a dot) does nothing, since it transfers control to the next sentence that was about to be executed anyway. As such, it can be used in any place where a sentence is expected but no action is needed, similar to the role EXIT plays in COBOL, or comparable “no operation” statements in other languages.

Origins

COBOL   CONTINUE EXIT NEXT SENTENCE
FORTRAN   CONTINUE
PL/I   ;
REXX   NOP

BabyCobol is a project by Dr. Vadim Zaytsev a.k.a. @grammarware. Page last updated in October 2023.