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digitalmars.D.learn - Are Delimited strings and HereDoc strings just here to suck ?

reply "Klaus" <Klaus.Vanderbruck gmx.nl> writes:
I mean when writing a D lexer, you necessarly reach the moment 
when you think:

"Oh no! is this feature just here to suck ?"
Aug 11 2014
next sibling parent reply "H. S. Teoh via Digitalmars-d-learn" <digitalmars-d-learn puremagic.com> writes:
On Mon, Aug 11, 2014 at 07:47:44PM +0000, Klaus via Digitalmars-d-learn wrote:

 I mean when writing a D lexer, you necessarly reach the moment when
 you think:
 
 "Oh no! is this feature just here to suck ?"


I use heredocs every now and then when I need to embed long strings in
my program. It's one of the things I *like* about D, in fact. Nobody
wants to manually parenthesize every quoted line with '"...\n"' when the
program need to incorporate several pages of built-in help text, for
example.

Delimited strings are useful when writing code/text generators when you
need to be able to use ' and " as literal characters without crazy
leaning-toothpick syndrome \"x\"y\"z\"w\"'s sprinkled everywhere.

The crazy variety of ways to write string literals in D, OTOH, *is* a
bit over the top, as I found out myself when I also tried writing a D
lexer.  :-P


T

-- 
LINUX = Lousy Interface for Nefarious Unix Xenophobes.
Aug 11 2014
parent "Klaus" <Klaus.Vanderbruck gmx.nl> writes:
On Monday, 11 August 2014 at 20:10:47 UTC, H. S. Teoh via 
Digitalmars-d-learn wrote:

 On Mon, Aug 11, 2014 at 07:47:44PM +0000, Klaus via 
 Digitalmars-d-learn wrote:

 I mean when writing a D lexer, you necessarly reach the moment 
 when
 you think:
 
 "Oh no! is this feature just here to suck ?"


 I use heredocs every now and then when I need to embed long 
 strings in
 my program. It's one of the things I *like* about D, in fact. 
 Nobody
 wants to manually parenthesize every quoted line with '"...\n"' 
 when the
 program need to incorporate several pages of built-in help 
 text, for
 example.

 Delimited strings are useful when writing code/text generators 
 when you
 need to be able to use ' and " as literal characters without 
 crazy
 leaning-toothpick syndrome \"x\"y\"z\"w\"'s sprinkled 
 everywhere.

 The crazy variety of ways to write string literals in D, OTOH, 
 *is* a
 bit over the top, as I found out myself when I also tried 
 writing a D
 lexer.  :-P


 T


Yep I think you get what I mean: "clearly over the top", 
particularly when each element of your arm is 50% over the top 
and then when you try to show the top with an over-sized arm then 
it's clearly an "over-toped position".
Aug 11 2014
prev sibling next sibling parent Philippe Sigaud via Digitalmars-d-learn writes:
On Mon, Aug 11, 2014 at 10:09 PM, H. S. Teoh via Digitalmars-d-learn
<digitalmars-d-learn puremagic.com> wrote:

 On Mon, Aug 11, 2014 at 07:47:44PM +0000, Klaus via Digitalmars-d-learn wrote:

 I mean when writing a D lexer, you necessarly reach the moment when
 you think:

 "Oh no! is this feature just here to suck ?"






 The crazy variety of ways to write string literals in D, OTOH, *is* a
 bit over the top, as I found out myself when I also tried writing a D
 lexer.  :-P


Out of curiosity, how does a lexer deal with heredocs? It's a sort
of... user-defined token, right?
Aug 11 2014
prev sibling next sibling parent "H. S. Teoh via Digitalmars-d-learn" <digitalmars-d-learn puremagic.com> writes:
On Mon, Aug 11, 2014 at 10:50:34PM +0200, Philippe Sigaud via
Digitalmars-d-learn wrote:

 On Mon, Aug 11, 2014 at 10:09 PM, H. S. Teoh via Digitalmars-d-learn
 <digitalmars-d-learn puremagic.com> wrote:

 On Mon, Aug 11, 2014 at 07:47:44PM +0000, Klaus via Digitalmars-d-learn wrote:

 I mean when writing a D lexer, you necessarly reach the moment when
 you think:

 "Oh no! is this feature just here to suck ?"




 
 

 The crazy variety of ways to write string literals in D, OTOH, *is*
 a bit over the top, as I found out myself when I also tried writing
 a D lexer.  :-P


 
 Out of curiosity, how does a lexer deal with heredocs? It's a sort
 of... user-defined token, right?


In Flex, one way you can implement heredocs is to have a separate "mode"
where the lexer is scanning for the ending string.  So basically you
have a sub-lexer that treats the heredoc as three tokens, one that
defines the ending string for the heredoc (which is never returned to
the caller), one that contains the content of the heredoc, and the
terminating token (also never returned to the caller).

It's not that much different from any other string literal scanning (the
lexer must switch into "string literal mode" where things like \n and \t
have a different meaning than in the program code proper, and it exits
that mode when it encounters the terminating '"'), except that here, the
terminating delimiter is variable.


T

-- 
Real men don't take backups. They put their source on a public FTP-server and
let the world mirror it. -- Linus Torvalds
Aug 11 2014
prev sibling next sibling parent Philippe Sigaud via Digitalmars-d-learn writes:
On Mon, Aug 11, 2014 at 10:58 PM, H. S. Teoh via Digitalmars-d-learn
<digitalmars-d-learn puremagic.com> wrote:


 In Flex, one way you can implement heredocs is to have a separate "mode"
 where the lexer is scanning for the ending string.  So basically you
 have a sub-lexer that treats the heredoc as three tokens, one that
 defines the ending string for the heredoc (which is never returned to
 the caller), one that contains the content of the heredoc, and the
 terminating token (also never returned to the caller).


Ah, a small, specialized sub-lexer. OK, I get it.
Aug 11 2014
prev sibling parent reply "Brian Schott" <briancschott gmail.com> writes:
On Monday, 11 August 2014 at 19:47:46 UTC, Klaus wrote:

 I mean when writing a D lexer, you necessarly reach the moment 
 when you think:

 "Oh no! is this feature just here to suck ?"


They are and they do.
Aug 11 2014
parent reply "Brian Schott" <briancschott gmail.com> writes:
On Monday, 11 August 2014 at 22:20:54 UTC, Brian Schott wrote:

 On Monday, 11 August 2014 at 19:47:46 UTC, Klaus wrote:

 I mean when writing a D lexer, you necessarly reach the moment 
 when you think:

 "Oh no! is this feature just here to suck ?"


 They are and they do.


Also, use this: https://github.com/Hackerpilot/libdparse
Aug 11 2014
parent reply "Klaus" <Klaus.Vanderbruck gmx.nl> writes:
On Monday, 11 August 2014 at 22:24:28 UTC, Brian Schott wrote:

 On Monday, 11 August 2014 at 22:20:54 UTC, Brian Schott wrote:

 On Monday, 11 August 2014 at 19:47:46 UTC, Klaus wrote:

 I mean when writing a D lexer, you necessarly reach the 
 moment when you think:

 "Oh no! is this feature just here to suck ?"


 They are and they do.


 Also, use this: https://github.com/Hackerpilot/libdparse


Sorry...I've been stupid...how could I missed that...Sometime I 
hate myself.
Aug 11 2014
parent "Klaus" <Klaus.Vanderbruck gmx.nl> writes:
On Monday, 11 August 2014 at 22:56:27 UTC, Klaus wrote:

 On Monday, 11 August 2014 at 22:24:28 UTC, Brian Schott wrote:

 On Monday, 11 August 2014 at 22:20:54 UTC, Brian Schott wrote:

 On Monday, 11 August 2014 at 19:47:46 UTC, Klaus wrote:

 I mean when writing a D lexer, you necessarly reach the 
 moment when you think:

 "Oh no! is this feature just here to suck ?"


 They are and they do.


 Also, use this: https://github.com/Hackerpilot/libdparse


 Sorry...I've been stupid...how could I missed that...Sometime I 
 hate myself.


https://github.com/search?l=D&o=desc&q=stars%3A>%3D0&ref=advsearch&s=updated&type=Repositories
Aug 11 2014