On 11/16/2016 1:41 PM, Stephan Herrmann wrote:
On 11/16/2016 10:02 PM, Alex Buckley wrote:
[...]
Make a close reading of JLS 2.2. It's true that identifiers are
terminal symbols of the _syntactic grammar_. However, I want to
speak of 'open', 'module', et al as terminal symbols of the _lexical
grammar_. Basically I mean "a fixed width font presentation of
a reserved lexeme spelled o p e n".
JLS 2.2:
"A lexical grammar for the Java programming language is given in ยง3
(Lexical Structure).
This grammar has as its terminal symbols the characters of the Unicode
character set."
"open" is not a character of the Unicode character set.
That's why I concluded you must be speaking of terminals of the
syntactic grammar, which has as its terminals identifiers, keywords, etc.
Or is 2.2 going to be extended to include restricted keywords as
terminals of
the lexical grammar? But how can they be interpreted as identifiers if they
are already terminals of the lexical grammar?
Please disregard 'open' being a terminal symbol of the lexical grammar
... I was looking at the opening sentence to 2.4 at the time, which
smashes together the terminals of both grammars, and I got mixed up.
Nothing is changing in 2.2.
I say again: I agree identifiers are terminals in the syntactic grammar,
and that it's confusing for lang-vm to say that 'module' is a keyword
solely where it may appear as a terminal in ModuleDeclaration, since
here it appears as a terminal (Identifier) in the second-word place yet
plainly it should not be a keyword there:
module module { // second word is an identifier
But by "appears as a terminal", I didn't mean "can be parsed as the
terminal Identifier". I literally meant "appears in fixed width font
presentation on the RHS of a production under ModuleDeclaration".
BTW: has it been considered to use an escape character to explicitly turn a
restricted keyword into an identifier? That's the only way I can see that
a traditional parser can grok a ModuleDeclaration without "wasting"
keywords.
Frankly no.
Alex
