Re: PCODE Interpereters 101

"Scott.David.Daniels" <Scott.Daniels@Acm.Org>
2 Mar 1999 14:12:06 -0500

          From comp.compilers

Related articles
[7 earlier articles]
Re: PCODE Interpereters 101 sam@cogent.ca (Sam Roberts) (1999-02-12)
Re: PCODE Interpereters 101 kevin.b.smith@intel.com (Kevin B. Smith) (1999-02-15)
Re: PCODE Interpereters 101 cfc@world.std.com (Chris F Clark) (1999-02-15)
Re: PCODE Interpereters 101 toring@inet.uni2.dk (Torben Ring) (1999-02-18)
Re: PCODE Interpereters 101 aduncan@cs.ucsb.edu (aduncan) (1999-02-21)
Re: PCODE Interpereters 101 albaugh@agames.com (1999-02-24)
Re: PCODE Interpereters 101 Scott.Daniels@Acm.Org (Scott.David.Daniels) (1999-03-02)
| List of all articles for this month |

From: "Scott.David.Daniels" <Scott.Daniels@Acm.Org>
Newsgroups: comp.compilers
Date: 2 Mar 1999 14:12:06 -0500
Organization: Northwest Link
References: 99-01-079 99-01-117 99-02-094 99-02-110 99-02-116
Keywords: Pascal

Dynamic links are, I believe necessary for languages where nested
declarations occur and up-level access is allowed. An example that is
tough (read: I think impossible) to execute properly without displays
is:


begin
string procedure foo( integer depth, string arg, string procedure
takeNote(string) )
{
string procedure parenthesized( string inArg )
{
return "(" & depth & ": " arg & " :" & inArg & ")";
}


  return (if 0 = depth then takeNote( arg )
eif 2 = depth then foo( depth-1, "<" & arg & ">", parenthesized )
else foo( depth-1, "[" & arg & "]", parenthesized )
}
string procedure braces( string inArg ) { return "{" & arg & "}"; }


foo( 4, "x", braces );
end




= foo(3, [x], braces)
= foo(2, [[x]], braces)
= foo(1, <[[x]]>, paren'2)
= foo(0, [<[[x]]>], paren'2)
= (2: [<[[x]]>], [[x]])




Where this comes up:
1) implementing an interpreter with stack allocation via recursive calls
to the interpreter.
2) implementing unification.


-Scott David Daniels
Scott.Daniels@Acm.Org


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