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Last update: 1997-05-20
9945-2-73 _____________________________________________________________________________ Topic: extended regular expressions Relevant Sections: 2.8.4 Defect Report: ----------------------- Date: Tue, 9 Aug 1994 16:36:15 -0700 From: Fred Zlotnick <fred@mindcraft.com> I would like to an request official, binding interpretation from the WG15 concerning the following point in ISO/IEC 9945-2:1993 (POSIX.2). Subclause 2.8.4 of POSIX.2 specifies the syntax and semantics of Extended Regular Expressions. Subclause 2.8.4.6 describes the effects of anchoring EREs, including ERE subexpressions. The language of this subclause seems to clearly indicate that within ERE subexpressions but outside of bracket expressions the caret and the dollar sign are always treated as anchors. The issue on which I would like an interpretation has to do with nested anchored subexpressions. Are such subexpressions valid? For example, is the ERE ^(^(^a$)$)$ a valid expression, and does it match a single line containing only the character "a"? Interpretation Response: ------------------------ The rules specified in 2.4.8.3 item 1 and 2.8.4.6 clearly state that this is a valid ERE and as suggested shall match the character "a". Conforming implementations must conform to this. Rationale ------------- None. Forwarded to Interpretations group: 4 Aug 94 Proposed resolution sent for review: 19th Nov 94 Resolved: 10th Dec 94