D - is this intentional?
- Carlos (5/5) Jun 17 2002 why is ~= correct but ~ = is not? what's the point? does it happen also ...
- Russ Lewis (20/26) Jun 17 2002 Yeah, that's how C works. Some operators are made up of two characters,...
- Carlos (16/30) Jun 17 2002 and
- Russ Lewis (9/9) Jun 17 2002 It makes the tokenization easier if you don't have to deal with whitespa...
- Sean L. Palmer (15/47) Jun 17 2002 I feel for you Carlos. (<=== betcha a translator program will have a fi...
- Burton Radons (7/19) Jun 18 2002 The first lexers I wrote did this search, but then I realised that C
- Walter (5/7) Jun 17 2002 ~= (no space) is considered a single token, where as ~ space = is consid...
why is ~= correct but ~ = is not? what's the point? does it happen also to other operators? ------------------------- Carlos 8294 http://carlos3.netfirms.com/
Jun 17 2002
Yeah, that's how C works. Some operators are made up of two characters, and must be kept together. Other examples include: += -= *= /= %= &= |= != <==&& || and so on... Carlos wrote:why is ~= correct but ~ = is not? what's the point? does it happen also to other operators? ------------------------- Carlos 8294 http://carlos3.netfirms.com/-- The Villagers are Online! villagersonline.com .[ (the fox.(quick,brown)) jumped.over(the dog.lazy) ] .[ (a version.of(English).(precise.more)) is(possible) ] ?[ you want.to(help(develop(it))) ]
Jun 17 2002
"Russ Lewis" <spamhole-2001-07-16 deming-os.org> escribió en el mensaje news:3D0E4FAD.553C3DB deming-os.org...Yeah, that's how C works. Some operators are made up of two characters,andmust be kept together. Other examples include: += -= *= /= %= &= |= != <=ok. thanks for reminding me that. i understand || and &&, but why the others? what could possibly happen if there's something that's not a space (or tab or newline, etc.) between + and = ? error. that's the only. but if i write a + = b ; it should be ok. why a += b ; is ok and a + = b ; is not? i know c does it that way, but d is supposed to be better than c.=&& ||
Jun 17 2002
Russ Lewis <spamhole-2001-07-16 deming-os.org> It makes the tokenization easier if you don't have to deal with whitespace. Also, it makes the code easier to read if the various characters of a token aren't spread around the place. Other than that, I don't see any reason why it *has* to be this way...but I think it's better as it is, personally. -- The Villagers are Online! http://villagersonline.com .[ (the fox.(quick,brown)) jumped.over(the dog.lazy) ] .[ (a version.of(English).(precise.more)) is(possible) ] ?[ you want.to(help(develop(it))) ]
Jun 17 2002
I feel for you Carlos. (<=== betcha a translator program will have a field day with that one!) I suppose one could make a lexer work that way, but I've never done so. Can it be done? I think the problem there is that the lexer would need info from the parser syntax phase to determine what kind of token to return. However this can probably be kludged around by accepting multiple single tokens *or* one combined token in the parser because a + ( = b ) is not syntactically correct. However a + = b would have to be syntactically correct because of how it's used if it's joined so to differentiate between the two would have to be in the semantic analysis phase. Right? This is the kind of thing Walter is trying to avoid with D. Sean "Carlos" <carlos8294 msn.com> wrote in message news:aeljpk$dof$1 digitaldaemon.com..."Russ Lewis" <spamhole-2001-07-16 deming-os.org> escribió en el mensaje news:3D0E4FAD.553C3DB deming-os.org...iYeah, that's how C works. Some operators are made up of two characters,andmust be kept together. Other examples include: += -= *= /= %= &= |= != <=ok. thanks for reminding me that. i understand || and &&, but why the others? what could possibly happen if there's something that's not a space (or tab or newline, etc.) between + and = ? error. that's the only. but if=&& ||write a + = b ; it should be ok. why a += b ; is ok and a + = b ; is not? i know c does it that way, but d is supposed to be better than c.
Jun 17 2002
Sean L. Palmer wrote:I feel for you Carlos. (<=== betcha a translator program will have a field day with that one!) I suppose one could make a lexer work that way, but I've never done so. Can it be done? I think the problem there is that the lexer would need info from the parser syntax phase to determine what kind of token to return. However this can probably be kludged around by accepting multiple single tokens *or* one combined token in the parser because a + ( = b ) is not syntactically correct. However a + = b would have to be syntactically correct because of how it's used if it's joined so to differentiate between the two would have to be in the semantic analysis phase. Right? This is the kind of thing Walter is trying to avoid with D.The first lexers I wrote did this search, but then I realised that C couldn't handle it and thought that was a damned fine idea. It's identified in the lexer by knowing what tokens could be formed with additional characters and searching for those... there's no ambiguity, as C and D's operators are already carefully setup to never get false operator matches with valid combinations regardless of whitespace.
Jun 18 2002
"Burton Radons" <loth users.sourceforge.net> wrote in message news:3D0EE40D.1020902 users.sourceforge.net...The first lexers I wrote did this search, but then I realised that C couldn't handle it and thought that was a damned fine idea. It's identified in the lexer by knowing what tokens could be formed with additional characters and searching for those... there's no ambiguity, as C and D's operators are already carefully setup to never get false operator matches with valid combinations regardless of whitespace.C++ exhibits troubles one can get into with lexing ambiguities, the classic one being is >> a right shift or is it two separate nested template argument list closures?
Jun 18 2002
"Walter" <walter digitalmars.com> wrote in message news:aenor2$2jho$1 digitaldaemon.com..."Burton Radons" <loth users.sourceforge.net> wrote in message news:3D0EE40D.1020902 users.sourceforge.net...classicThe first lexers I wrote did this search, but then I realised that C couldn't handle it and thought that was a damned fine idea. It's identified in the lexer by knowing what tokens could be formed with additional characters and searching for those... there's no ambiguity, as C and D's operators are already carefully setup to never get false operator matches with valid combinations regardless of whitespace.C++ exhibits troubles one can get into with lexing ambiguities, theone being is >> a right shift or is it two separate nested templateargumentlist closures?Yeah, that one really sucks! -- Stijn OddesE_XYZ hotmail.com http://OddesE.cjb.net _________________________________________________ Remove _XYZ from my address when replying by mail
Jun 24 2002
"Carlos" <carlos8294 msn.com> wrote in message news:aelggm$act$1 digitaldaemon.com...why is ~= correct but ~ = is not? what's the point? does it happen also to other operators?~= (no space) is considered a single token, where as ~ space = is considered two separate tokens. The same holds true for the other assignment operators. -Walter
Jun 17 2002