"where both a division and a RegularExpressionLiteral are permitted"

David-Sarah Hopwood david.hopwood at industrial-designers.co.uk
Sat Nov 29 17:41:05 PST 2008


Section 7 (Lexical Conventions):

# Note that contexts exist in the syntactic grammar where both a division
# and a RegularExpressionLiteral are permitted by the syntactic grammar;
# [...]

I believe this statement is incorrect [*1].
If I'm wrong, what is an example of such a context?


[*1] A DivisionPunctuator must be preceded by an expression.
     A RegularExpressionLiteral is itself an expression.
     Therefore, for there to exist syntactic contexts in which either
     a DivisionPunctuator or a RegularExpressionLiteral could occur,
     it would have to be possible for an expression to immediately
     follow [*2] another expression with no intervening operator.
     The only case in which that can occur is where a semicolon is
     automatically inserted between the two expressions.
     Assume that case: then the second expression cannot begin
     with [*2] a token whose first character is '/', because that
     would have been interpreted as a DivisionPunctuator, and so
     no semicolon insertion would have occurred (because semicolon
     insertion only occurs where there would otherwise have been a
     syntax error); contradiction.

[*2] Ignoring comments and whitespace.

-- 
David-Sarah Hopwood


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