Re: [sv-ac] match item

From: John Havlicek <john.havlicek_at_.....>
Date: Mon Oct 27 2008 - 07:25:58 PDT
Hi Doron:

The "[]" in the first production are not terminals.  (They should not
be in bold red.)  They indicate that the sequence_abbrev is optional,
and omitting the sequence_abbre allows

   (a ##1 b, v = 1)

as you expect.

J.H.

> 
> All,
> 
> =20
> 
> I am looking at 16.7 and there are some syntactic restrictions on the
> use of match item that I do not understand.
> 
> If I understand correctly there are only two syntax productions that
> allow adding match items:
> 
> =20
> 
> | ( sequence_expr {, sequence_match_item } ) [ sequence_abbrev ]
> 
> | first_match ( sequence_expr {, sequence_match_item} )
> 
> =20
> 
> So, one cannot write "(a ##1 b, v =3D 1)"  but can write "(a ##1 b, v =3D 1)
> [*1]" which is semantically equivalent.
> 
> =20
> 
> As far as I understand, we can always use the [*1] to do add the match
> item, so there is no semantic meaning to the syntactic restrictions.=20
> 
> =20
> 
> Does anyone remember a reason for that? Or is it something we
> overlooked?
> 
> =20
> 
> Thanks
> 
> =20
> 
> Doron
> 
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> Intel Israel (74) Limited
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> <div class=3DSection1>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>All,<o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>I am looking at 16.7 and there are some syntactic
> restrictions on the use of match item that I do not understand.<o:p></o:p><=
> /span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>If I understand correctly there are only two syntax
> productions that allow adding match items:<o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 color=3Dblack face=3D"Times New Roman">=
> <span
> style=3D'font-size:10.0pt;color:black'>| </span></font><b><font size=3D1 co=
> lor=3Dred
> face=3D"Courier New"><span style=3D'font-size:9.0pt;font-family:"Courier Ne=
> w";
> color:red;font-weight:bold'>( </span></font></b><font size=3D2 color=3Dblac=
> k><span
> style=3D'font-size:10.0pt;color:black'>sequence_expr {</span></font><b><font
> size=3D1 color=3Dred face=3D"Courier New"><span style=3D'font-size:9.0pt;fo=
> nt-family:
> "Courier New";color:red;font-weight:bold'>, </span></font></b><font size=3D2
> color=3Dblack><span style=3D'font-size:10.0pt;color:black'>sequence_match_i=
> tem } </span></font><b><font
> size=3D1 color=3Dred face=3D"Courier New"><span style=3D'font-size:9.0pt;fo=
> nt-family:
> "Courier New";color:red;font-weight:bold'>) </span></font></b><font size=3D2
> color=3Dblack><span style=3D'font-size:10.0pt;color:black'>[ sequence_abbre=
> v ]<o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 color=3Dblack face=3D"Times New Roman">=
> <span
> style=3D'font-size:10.0pt;color:black'>| </span></font><b><font size=3D1 co=
> lor=3Dred
> face=3D"Courier New"><span style=3D'font-size:9.0pt;font-family:"Courier Ne=
> w";
> color:red;font-weight:bold'>first_match ( </span></font></b><font size=3D2
> color=3Dblack><span style=3D'font-size:10.0pt;color:black'>sequence_expr {<=
> /span></font><b><font
> size=3D1 color=3Dred face=3D"Courier New"><span style=3D'font-size:9.0pt;fo=
> nt-family:
> "Courier New";color:red;font-weight:bold'>, </span></font></b><font size=3D2
> color=3Dblack><span style=3D'font-size:10.0pt;color:black'>sequence_match_i=
> tem} </span></font><b><font
> size=3D1 color=3Dred face=3D"Courier New"><span style=3D'font-size:9.0pt;fo=
> nt-family:
> "Courier New";color:red;font-weight:bold'>)<o:p></o:p></span></font></b></p>
> 
> <p class=3DMsoNormal><b><font size=3D1 color=3Dred face=3D"Courier New"><sp=
> an
> style=3D'font-size:9.0pt;font-family:"Courier New";color:red;font-weight:bo=
> ld'><o:p>&nbsp;</o:p></span></font></b></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>So, one cannot write &#8220;(a ##1 b, v =3D 1)&#8221; &n=
> bsp;but
> can write &#8220;(a ##1 b, v =3D 1) [*1]&#8221; which is semantically equiv=
> alent.<o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>As far as I understand, we can always use the [*1] to do=
>  add
> the match item, so there is no semantic meaning to the syntactic restrictio=
> ns. <o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>Does anyone remember a reason for that? Or is it somethi=
> ng
> we overlooked?<o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>Thanks<o:p></o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'><o:p>&nbsp;</o:p></span></font></p>
> 
> <p class=3DMsoNormal><font size=3D2 face=3DArial><span style=3D'font-size:1=
> 0.0pt;
> font-family:Arial'>Doron<o:p></o:p></span></font></p>
> 
> </div>
> 
> <pre>---------------------------------------------------------------------
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