Empty $''

Empty $''

[Bart Schaefer]

On Mar 3,  3:34pm, Bart Schaefer wrote:
}
} $'...' is not a quoted expression, it's a substitution (at least as far
} as zsh is concerned).
} 
} This does appear to be out of step with other shells.

Comments on the below?


diff --git a/Src/subst.c b/Src/subst.c
index bb1dd89..efb62b8 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -146,7 +146,7 @@ stringsubstquote(char *strstart, char **pstrdpos)
     } else if (strdpos[len])
 	strret = dyncat(strsub, strdpos + len);
     else
-	strret = strsub;
+	strret = dyncat(strsub, nulstring);
 
     *pstrdpos = strret + (strdpos - strstart) + strlen(strsub);
 

Re: Empty $''

[Peter Stephenson]

On Thu, 03 Mar 2016 15:36:47 -0800
Bart Schaefer <schaefer@brasslantern.com> wrote:
> On Mar 3,  3:34pm, Bart Schaefer wrote:
> }
> } $'...' is not a quoted expression, it's a substitution (at least as far
> } as zsh is concerned).
> } 
> } This does appear to be out of step with other shells.
> 
> Comments on the below?

nulstring always confused me, but something like this appears to be
correct, so as long as this passes tests (we should presumably add
another).

Hmm... actually, isn't the usual logic for using nulstring more like

    if (!*strsub)
      strret = dupstring(nulstring);

?

pws

Re: Empty $''

[Peter Stephenson]

On Fri, 4 Mar 2016 10:35:02 +0000
Peter Stephenson <p.stephenson@samsung.com> wrote:
> nulstring always confused me, but something like this appears to be
> correct, so as long as this passes tests (we should presumably add
> another).
> 
> Hmm... actually, isn't the usual logic for using nulstring more like
> 
>     if (!*strsub)
>       strret = dupstring(nulstring);

Was thinking of something like...

diff --git a/Src/subst.c b/Src/subst.c
index bb1dd89..f2d0f65 100644
--- a/Src/subst.c
+++ b/Src/subst.c
@@ -145,8 +145,12 @@ stringsubstquote(char *strstart, char **pstrdpos)
 	    strret = dyncat(strstart, strsub);
     } else if (strdpos[len])
 	strret = dyncat(strsub, strdpos + len);
-    else
+    else if (*strsub)
 	strret = strsub;
+    else {
+	/* This ensures a $'' doesn't get elided. */
+	strret = dupstring(nulstring);
+    }
 
     *pstrdpos = strret + (strdpos - strstart) + strlen(strsub);
 
diff --git a/Test/A03quoting.ztst b/Test/A03quoting.ztst
index 0cf0e8a..da3ce35 100644
--- a/Test/A03quoting.ztst
+++ b/Test/A03quoting.ztst
@@ -74,3 +74,7 @@
 >16#61
 >16#62
 >16#64
+
+ () { print $# } '' "" $''
+0:$'' should not be elided, in common with other empty quotes
+>3

Re: Empty $''

[Bart Schaefer]

On Mar 4, 12:14pm, Peter Stephenson wrote:
} Subject: Re: Empty $''
}
} -    else
} +    else if (*strsub)
}  	strret = strsub;
} +    else {
} +	/* This ensures a $'' doesn't get elided. */
} +	strret = dupstring(nulstring);
} +    }

This looks fine; I wasn't sure whether (*strsub) was ever nonzero in
this case but it should be harmless to append a Nulstring to another
string (happens with e.g. foo"" already I think) so I took a shortcut.