mirror of
https://github.com/GrammaticalFramework/gf-core.git
synced 2026-04-22 19:22:50 -06:00
removed a silly bug with gfcc generation for multiple languages
This commit is contained in:
@@ -119,6 +119,16 @@ reorder cg = M.MGrammar $
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(i,mo) <- mos, M.isModCnc mo, elem i (M.allExtends cg la),
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(i,mo) <- mos, M.isModCnc mo, elem i (M.allExtends cg la),
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finfo <- tree2list (M.jments mo)]
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finfo <- tree2list (M.jments mo)]
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-- one grammar per language - needed for symtab generation
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repartition :: CanonGrammar -> [CanonGrammar]
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repartition cg = [M.partOfGrammar cg (lang,mo) |
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let abs = maybe (error "no abstract") id $ M.greatestAbstract cg,
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let mos = M.allModMod cg,
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lang <- M.allConcretes cg abs,
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let mo = errVal
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(error ("no module found for " ++ A.prt lang)) $ M.lookupModule cg lang
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]
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-- convert to UTF8 if not yet converted
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-- convert to UTF8 if not yet converted
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utf8Conv :: CanonGrammar -> CanonGrammar
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utf8Conv :: CanonGrammar -> CanonGrammar
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utf8Conv = M.MGrammar . map toUTF8 . M.modules where
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utf8Conv = M.MGrammar . map toUTF8 . M.modules where
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@@ -136,22 +146,25 @@ utf8Conv = M.MGrammar . map toUTF8 . M.modules where
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-- translate tables and records to arrays, parameters and labels to indices
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-- translate tables and records to arrays, parameters and labels to indices
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canon2canon :: CanonGrammar -> CanonGrammar
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canon2canon :: CanonGrammar -> CanonGrammar
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canon2canon cg = tr $ M.MGrammar $ map c2c $ M.modules cg where
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canon2canon = recollect . map cl2cl . repartition where
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c2c (c,m) = case m of
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recollect =
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M.ModMod mo@(M.Module _ _ _ _ _ js) ->
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M.MGrammar . nubBy (\ (i,_) (j,_) -> i==j) . concatMap M.modules
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(c, M.ModMod $ M.replaceJudgements mo $ mapTree j2j js)
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cl2cl cg = tr $ M.MGrammar $ map c2c $ M.modules cg where
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_ -> (c,m)
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c2c (c,m) = case m of
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j2j (f,j) = case j of
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M.ModMod mo@(M.Module _ _ _ _ _ js) ->
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GFC.CncFun x y tr z -> (f,GFC.CncFun x y (t2t tr) z)
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(c, M.ModMod $ M.replaceJudgements mo $ mapTree j2j js)
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_ -> (f,j)
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_ -> (c,m)
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t2t = term2term cg pv
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j2j (f,j) = case j of
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pv@(labels,untyps,typs) = paramValues cg
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GFC.CncFun x y tr z -> (f,GFC.CncFun x y (t2t tr) z)
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tr = trace $
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_ -> (f,j)
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(unlines [A.prt c ++ "." ++ unwords (map A.prt l) +++ "=" +++ show i |
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t2t = term2term cg pv
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pv@(labels,untyps,typs) = paramValues cg
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tr = trace $
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(unlines [A.prt c ++ "." ++ unwords (map A.prt l) +++ "=" +++ show i |
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((c,l),i) <- Map.toList labels]) ++
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((c,l),i) <- Map.toList labels]) ++
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(unlines [A.prt t +++ "=" +++ show i |
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(unlines [A.prt t +++ "=" +++ show i |
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(t,i) <- Map.toList untyps]) ++
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(t,i) <- Map.toList untyps]) ++
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(unlines [A.prt t |
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(unlines [A.prt t |
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(t,_) <- Map.toList typs])
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(t,_) <- Map.toList typs])
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type ParamEnv =
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type ParamEnv =
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721
src/GF/Canon/GFCC/doc/gfcc.html
Normal file
721
src/GF/Canon/GFCC/doc/gfcc.html
Normal file
@@ -0,0 +1,721 @@
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML>
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<HEAD>
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<META NAME="generator" CONTENT="http://txt2tags.sf.net">
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<TITLE>The GFCC Grammar Format</TITLE>
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</HEAD><BODY BGCOLOR="white" TEXT="black">
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<P ALIGN="center"><CENTER><H1>The GFCC Grammar Format</H1>
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<FONT SIZE="4">
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<I>Aarne Ranta</I><BR>
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October 3, 2006
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</FONT></CENTER>
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<P></P>
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<HR NOSHADE SIZE=1>
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<P></P>
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<UL>
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<LI><A HREF="#toc1">What is GFCC</A>
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<LI><A HREF="#toc2">GFCC vs. GFC</A>
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<LI><A HREF="#toc3">The syntax of GFCC files</A>
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<UL>
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<LI><A HREF="#toc4">Top level</A>
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<LI><A HREF="#toc5">Abstract syntax</A>
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<LI><A HREF="#toc6">Concrete syntax</A>
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</UL>
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<LI><A HREF="#toc7">The semantics of concrete syntax terms</A>
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<UL>
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<LI><A HREF="#toc8">Linearization and realization</A>
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<LI><A HREF="#toc9">Term evaluation</A>
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<LI><A HREF="#toc10">The special term constructors</A>
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</UL>
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<LI><A HREF="#toc11">Compiling to GFCC</A>
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<UL>
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<LI><A HREF="#toc12">Problems in GFCC compilation</A>
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<LI><A HREF="#toc13">Running the compiler and the GFCC interpreter</A>
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</UL>
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<LI><A HREF="#toc14">The reference interpreter</A>
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<LI><A HREF="#toc15">Some things to do</A>
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</UL>
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<P></P>
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<HR NOSHADE SIZE=1>
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<P></P>
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<P>
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Author's address:
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<A HREF="http://www.cs.chalmers.se/~aarne"><CODE>http://www.cs.chalmers.se/~aarne</CODE></A>
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</P>
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<A NAME="toc1"></A>
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<H2>What is GFCC</H2>
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<P>
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GFCC is a low-level format for GF grammars. Its aim is to contain the minimum
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that is needed to process GF grammars at runtime. This minimality has three
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advantages:
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</P>
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<UL>
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<LI>compact grammar files and run-time objects
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<LI>time and space efficient processing
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<LI>simple definition of interpreters
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</UL>
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<P>
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The idea is that all embedded GF applications are compiled to GFCC.
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The GF system would be primarily used as a compiler and as a grammar
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development tool.
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</P>
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<P>
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Since GFCC is implemented in BNFC, a parser of the format is readily
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available for C, C++, Haskell, Java, and OCaml. Also an XML
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representation is generated in BNFC. A
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<A HREF="../">reference implementation</A>
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of linearization and some other functions has been written in Haskell.
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</P>
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<A NAME="toc2"></A>
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<H2>GFCC vs. GFC</H2>
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<P>
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GFCC is aimed to replace GFC as the run-time grammar format. GFC was designed
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to be a run-time format, but also to
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support separate compilation of grammars, i.e.
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to store the results of compiling
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individual GF modules. But this means that GFC has to contain extra information,
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such as type annotations, which is only needed in compilation and not at
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run-time. In particular, the pattern matching syntax and semantics of GFC is
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complex and therefore difficult to implement in new platforms.
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</P>
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<P>
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The main differences of GFCC compared with GFC can be summarized as follows:
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</P>
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<UL>
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<LI>there are no modules, and therefore no qualified names
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<LI>a GFCC grammar is multilingual, and consists of a common abstract syntax
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together with one concrete syntax per language
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<LI>records and tables are replaced by arrays
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<LI>record labels and parameter values are replaced by integers
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<LI>record projection and table selection are replaced by array indexing
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<LI>there is (so far) no support for dependent types or higher-order abstract
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syntax (which would be easy to add, but make interpreters much more difficult
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to write)
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</UL>
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<P>
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Here is an example of a GF grammar, consisting of three modules,
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as translated to GFCC. The representations are aligned, with the exceptions
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due to the alphabetical sorting of GFCC grammars.
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</P>
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<PRE>
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grammar Ex (Eng Swe);
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abstract Ex = { abstract {
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cat
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S ; NP ; VP ;
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fun
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Pred : NP -> VP -> S ; Pred : NP VP -> S = (Pred);
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She, They : NP ; She : -> NP = (She);
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Sleep : VP ; Sleep : -> VP = (Sleep);
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They : -> NP = (They);
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} } ;
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;
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concrete Eng of Ex = { concrete Eng {
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lincat
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S = {s : Str} ;
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NP = {s : Str ; n : Num} ;
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VP = {s : Num => Str} ;
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param
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Num = Sg | Pl ;
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lin
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Pred np vp = { Pred = [($0[1], $1[0][$0[0]])] ;
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s = np.s ++ vp.s ! np.n} ;
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She = {s = "she" ; n = Sg} ; She = [0, "she"];
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They = {s = "they" ; n = Pl} ;
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Sleep = {s = table { Sleep = [("sleep" + ["s",""])];
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Sg => "sleeps" ;
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Pl => "sleep" They = [1, "they"];
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} } ;
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} ;
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}
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concrete Swe of Ex = { concrete Swe {
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lincat
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S = {s : Str} ;
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NP = {s : Str} ;
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VP = {s : Str} ;
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param
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Num = Sg | Pl ;
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lin
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Pred np vp = { Pred = [($0[1], $1[0])];
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s = np.s ++ vp.s} ;
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She = {s = "hon"} ; She = ["hon"];
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They = {s = "de"} ; They = ["de"];
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Sleep = {s = "sover"} ; Sleep = ["sover"];
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} ;
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} ;
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</PRE>
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<P></P>
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<A NAME="toc3"></A>
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<H2>The syntax of GFCC files</H2>
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<A NAME="toc4"></A>
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<H3>Top level</H3>
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<P>
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A grammar has a header telling the name of the abstract syntax
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(often specifying an application domain), and the names of
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the concrete languages. The abstract syntax and the concrete
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|
syntaxes themselves follow.
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|
</P>
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<PRE>
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|
Grammar ::= Header ";" Abstract ";" [Concrete] ";" ;
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Header ::= "grammar" CId "(" [CId] ")" ;
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Abstract ::= "abstract" "{" [AbsDef] "}" ";" ;
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Concrete ::= "concrete" CId "{" [CncDef] "}" ;
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|
</PRE>
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|
<P>
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|
Abstract syntax judgements give typings and semantic definitions.
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|
Concrete syntax judgements give linearizations.
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|
</P>
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|
<PRE>
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|
AbsDef ::= CId ":" Type "=" Exp ;
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CncDef ::= CId "=" Term ;
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|
</PRE>
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|
<P>
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|
Also flags are possible, local to each "module" (i.e. abstract and concretes).
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|
</P>
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|
<PRE>
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|
AbsDef ::= "%" CId "=" String ;
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|
CncDef ::= "%" CId "=" String ;
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|
</PRE>
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|
<P>
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|
For the run-time system, the reference implementation in Haskell
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|
uses a structure that gives efficient look-up:
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|
</P>
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|
<PRE>
|
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|
data GFCC = GFCC {
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|
absname :: CId ,
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|
cncnames :: [CId] ,
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|
abstract :: Abstr ,
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|
concretes :: Map CId Concr
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|
}
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|
|
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|
data Abstr = Abstr {
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|
funs :: Map CId Type, -- find the type of a fun
|
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|
cats :: Map CId [CId] -- find the funs giving a cat
|
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|
}
|
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|
|
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|
type Concr = Map CId Term
|
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|
</PRE>
|
||||||
|
<P></P>
|
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|
<A NAME="toc5"></A>
|
||||||
|
<H3>Abstract syntax</H3>
|
||||||
|
<P>
|
||||||
|
Types are first-order function types built from
|
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|
category symbols. Syntax trees (<CODE>Exp</CODE>) are
|
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|
rose trees with the head (<CODE>Atom</CODE>) either a function
|
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|
constant, a metavariable, or a string, integer, or float
|
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|
literal.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Type ::= [CId] "->" CId ;
|
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|
Exp ::= "(" Atom [Exp] ")" ;
|
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|
Atom ::= CId ; -- function constant
|
||||||
|
Atom ::= "?" ; -- metavariable
|
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|
Atom ::= String ; -- string literal
|
||||||
|
Atom ::= Integer ; -- integer literal
|
||||||
|
Atom ::= Double ; -- float literal
|
||||||
|
</PRE>
|
||||||
|
<P></P>
|
||||||
|
<A NAME="toc6"></A>
|
||||||
|
<H3>Concrete syntax</H3>
|
||||||
|
<P>
|
||||||
|
Linearization terms (<CODE>Term</CODE>) are built as follows.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Term ::= "[" [Term] "]" ; -- array
|
||||||
|
Term ::= Term "[" Term "]" ; -- access to indexed field
|
||||||
|
Term ::= "(" [Term] ")" ; -- sequence with ++
|
||||||
|
Term ::= Tokn ; -- token
|
||||||
|
Term ::= "$" Integer ; -- argument subtree
|
||||||
|
Term ::= Integer ; -- array index
|
||||||
|
Term ::= "[|" [Term] "|]" ; -- free variation
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
Tokens are strings or (maybe obsolescent) prefix-dependent
|
||||||
|
variant lists.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Tokn ::= String ;
|
||||||
|
Tokn ::= "[" "pre" [String] "[" [Variant] "]" "]" ;
|
||||||
|
Variant ::= [String] "/" [String] ;
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
Three special forms of terms are introduced by the compiler
|
||||||
|
as optimizations. They can in principle be eliminated, but
|
||||||
|
their presence makes grammars much more compact. Their semantics
|
||||||
|
will be explained in a later section.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Term ::= CId ; -- global constant
|
||||||
|
Term ::= "(" String "+" Term ")" ; -- prefix + suffix table
|
||||||
|
Term ::= "(" Term "@" Term ")"; -- record parameter alias
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
Identifiers are like <CODE>Ident</CODE> in GF and GFC, except that
|
||||||
|
the compiler produces constants prefixed with <CODE>_</CODE> in
|
||||||
|
the common subterm elimination optimization.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
token CId (('_' | letter) (letter | digit | '\'' | '_')*) ;
|
||||||
|
</PRE>
|
||||||
|
<P></P>
|
||||||
|
<A NAME="toc7"></A>
|
||||||
|
<H2>The semantics of concrete syntax terms</H2>
|
||||||
|
<A NAME="toc8"></A>
|
||||||
|
<H3>Linearization and realization</H3>
|
||||||
|
<P>
|
||||||
|
The linearization algorithm is essentially the same as in
|
||||||
|
GFC: a tree is linearized by evaluating its linearization term
|
||||||
|
in the environment of the linearizations of the subtrees.
|
||||||
|
Literal atoms are linearized in the obvious way.
|
||||||
|
The function also needs to know the language (i.e. concrete syntax)
|
||||||
|
in which linearization is performed.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
linExp :: GFCC -> CId -> Exp -> Term
|
||||||
|
linExp mcfg lang tree@(Tr at trees) = case at of
|
||||||
|
AC fun -> comp (Prelude.map lin trees) $ look fun
|
||||||
|
AS s -> R [kks (show s)] -- quoted
|
||||||
|
AI i -> R [kks (show i)]
|
||||||
|
AF d -> R [kks (show d)]
|
||||||
|
AM -> R [kks "?"] ---- TODO: proper lincat
|
||||||
|
where
|
||||||
|
lin = linExp mcfg lang
|
||||||
|
comp = compute mcfg lang
|
||||||
|
look = lookLin mcfg lang
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
The result of linearization is usually a record, which is realized as
|
||||||
|
a string using the following algorithm.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
realize :: Term -> String
|
||||||
|
realize trm = case trm of
|
||||||
|
R (t:_) -> realize t
|
||||||
|
S ss -> unwords $ Prelude.map realize ss
|
||||||
|
K (KS s) -> s
|
||||||
|
K (KP s _) -> unwords s ---- prefix choice TODO
|
||||||
|
W s t -> s ++ realize t
|
||||||
|
FV (t:_) -> realize t
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
Since the order of record fields is not necessarily
|
||||||
|
the same as in GF source,
|
||||||
|
this realization does not work securely for
|
||||||
|
categories whose lincats more than one field.
|
||||||
|
</P>
|
||||||
|
<A NAME="toc9"></A>
|
||||||
|
<H3>Term evaluation</H3>
|
||||||
|
<P>
|
||||||
|
Evaluation follows call-by-value order, with two environments
|
||||||
|
needed:
|
||||||
|
</P>
|
||||||
|
<UL>
|
||||||
|
<LI>the grammar (a concrete syntax) to give the global constants
|
||||||
|
<LI>an array of terms to give the subtree linearizations
|
||||||
|
</UL>
|
||||||
|
|
||||||
|
<P>
|
||||||
|
The code is cleaned from debugging information present in the working
|
||||||
|
version.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
compute :: GFCC -> CId -> [Term] -> Term -> Term
|
||||||
|
compute mcfg lang args = comp where
|
||||||
|
comp trm = case trm of
|
||||||
|
P r (FV ts) -> FV $ Prelude.map (comp . P r) ts
|
||||||
|
|
||||||
|
P r p -> case (comp r, comp p) of
|
||||||
|
|
||||||
|
-- for the suffix optimization
|
||||||
|
(W s (R ss), p') -> case comp $ idx ss (getIndex p') of
|
||||||
|
K (KS u) -> kks (s ++ u)
|
||||||
|
|
||||||
|
(r', p') -> comp $ (getFields r') !! (getIndex p')
|
||||||
|
|
||||||
|
RP i t -> RP (comp i) (comp t)
|
||||||
|
W s t -> W s (comp t)
|
||||||
|
R ts -> R $ Prelude.map comp ts
|
||||||
|
V i -> args !! (fromInteger i) -- already computed
|
||||||
|
S ts -> S $ Prelude.filter (/= S []) $ Prelude.map comp ts
|
||||||
|
F c -> comp $ lookLin mcfg lang -- not yet computed
|
||||||
|
FV ts -> FV $ Prelude.map comp ts
|
||||||
|
_ -> trm
|
||||||
|
|
||||||
|
getIndex t = case t of
|
||||||
|
C i -> fromInteger i
|
||||||
|
RP p _ -> getIndex p
|
||||||
|
|
||||||
|
getFields t = case t of
|
||||||
|
R rs -> rs
|
||||||
|
RP _ r -> getFields r
|
||||||
|
</PRE>
|
||||||
|
<P></P>
|
||||||
|
<A NAME="toc10"></A>
|
||||||
|
<H3>The special term constructors</H3>
|
||||||
|
<P>
|
||||||
|
The three forms introduced by the compiler may a need special
|
||||||
|
explanation.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
Global constants
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Term ::= CId ;
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
are shorthands for complex terms. They are produced by the
|
||||||
|
compiler by (iterated) common subexpression elimination.
|
||||||
|
They are often more powerful than hand-devised code sharing in the source
|
||||||
|
code. They could be computed off-line by replacing each identifier by
|
||||||
|
its definition.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
Prefix-suffix tables
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Term ::= "(" String "+" Term ")" ;
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
represent tables of word forms divided to the longest common prefix
|
||||||
|
and its array of suffixes. In the example grammar above, we have
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Sleep = [("sleep" + ["s",""])]
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
which in fact is equal to the array of full forms
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
["sleeps", "sleep"]
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
The power of this construction comes from the fact that suffix sets
|
||||||
|
tend to be repeated in a language, and can therefore be collected
|
||||||
|
by common subexpression elimination. It is this technique that
|
||||||
|
explains the used syntax rather than the more accurate
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
"(" String "+" [String] ")"
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
since we want the suffix part to be a <CODE>Term</CODE> for the optimization to
|
||||||
|
take effect.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
The most curious construct of GFCC is the parameter array alias,
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Term ::= "(" Term "@" Term ")";
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
This form is used as the value of parameter records, such as the type
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
{n : Number ; p : Person}
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
The problem with parameter records is their double role.
|
||||||
|
They can be used like parameter values, as indices in selection,
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
VP.s ! {n = Sg ; p = P3}
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
but also as records, from which parameters can be projected:
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
{n = Sg ; p = P3}.n
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
Whichever use is selected as primary, a prohibitively complex
|
||||||
|
case expression must be generated at compilation to GFCC to get the
|
||||||
|
other use. The adopted
|
||||||
|
solution is to generate a pair containing both a parameter value index
|
||||||
|
and an array of indices of record fields. For instance, if we have
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
param Number = Sg | Pl ; Person = P1 | P2 | P3 ;
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
we get the encoding
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
{n = Sg ; p = P3} ---> (2 @ [0,2])
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
The GFCC computation rules are essentially
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
t [(i @ r)] = t[i]
|
||||||
|
(i @ r) [j] = r[j]
|
||||||
|
</PRE>
|
||||||
|
<P></P>
|
||||||
|
<A NAME="toc11"></A>
|
||||||
|
<H2>Compiling to GFCC</H2>
|
||||||
|
<P>
|
||||||
|
Compilation to GFCC is performed by the GF grammar compiler, and
|
||||||
|
GFCC interpreters need not know what it does. For grammar writers,
|
||||||
|
however, it might be interesting to know what happens to the grammars
|
||||||
|
in the process.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
The compilation phases are the following
|
||||||
|
</P>
|
||||||
|
<OL>
|
||||||
|
<LI>translate GF source to GFC, as always in GF
|
||||||
|
<LI>undo GFC back-end optimizations
|
||||||
|
<LI>perform the <CODE>values</CODE> optimization to normalize tables
|
||||||
|
<LI>create a symbol table mapping the GFC parameter and record types to
|
||||||
|
fixed-size arrays, and parameter values and record labels to integers
|
||||||
|
<LI>traverse the linearization rules replacing parameters and labels by integers
|
||||||
|
<LI>reorganize the created GFC grammar so that it has just one abstract syntax
|
||||||
|
and one concrete syntax per language
|
||||||
|
<LI>apply UTF8 encoding to the grammar, if not yet applied (this is told by the
|
||||||
|
<CODE>coding</CODE> flag)
|
||||||
|
<LI>translate the GFC syntax tree to a GFCC syntax tree, using a simple
|
||||||
|
compositional mapping
|
||||||
|
<LI>perform the word-suffix optimization on GFCC linearization terms
|
||||||
|
<LI>perform subexpression elimination on each concrete syntax module
|
||||||
|
<LI>print out the GFCC code
|
||||||
|
</OL>
|
||||||
|
|
||||||
|
<P>
|
||||||
|
Notice that a major part of the compilation is done within GFC, so that
|
||||||
|
GFC-related tasks (such as parser generation) could be performed by
|
||||||
|
using the old algorithms.
|
||||||
|
</P>
|
||||||
|
<A NAME="toc12"></A>
|
||||||
|
<H3>Problems in GFCC compilation</H3>
|
||||||
|
<P>
|
||||||
|
Two major problems had to be solved in compiling GFC to GFCC:
|
||||||
|
</P>
|
||||||
|
<UL>
|
||||||
|
<LI>consistent order of tables and records, to permit the array translation
|
||||||
|
<LI>run-time variables in complex parameter values.
|
||||||
|
</UL>
|
||||||
|
|
||||||
|
<P>
|
||||||
|
The current implementation is still experimental and may fail
|
||||||
|
to generate correct code. Any errors remaining are likely to be
|
||||||
|
related to the two problems just mentioned.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
The order problem is solved in different ways for tables and records.
|
||||||
|
For tables, the <CODE>values</CODE> optimization of GFC already manages to
|
||||||
|
maintain a canonical order. But this order can be destroyed by the
|
||||||
|
<CODE>share</CODE> optimization. To make sure that GFCC compilation works properly,
|
||||||
|
it is safest to recompile the GF grammar by using the <CODE>values</CODE>
|
||||||
|
optimization flag.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
Records can be canonically ordered by sorting them by labels.
|
||||||
|
In fact, this was done in connection of the GFCC work as a part
|
||||||
|
of the GFC generation, to guarantee consistency. This means that
|
||||||
|
e.g. the <CODE>s</CODE> field will in general no longer appear as the first
|
||||||
|
field, even if it does so in the GF source code. But relying on the
|
||||||
|
order of fields in a labelled record would be misplaced anyway.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
The canonical form of records is further complicated by lock fields,
|
||||||
|
i.e. dummy fields of form <CODE>lock_C = <></CODE>, which are added to grammar
|
||||||
|
libraries to force intensionality of linearization types. The problem
|
||||||
|
is that the absence of a lock field only generates a warning, not
|
||||||
|
an error. Therefore a GFC grammar can contain objects of the same
|
||||||
|
type with and without a lock field. This problem was solved in GFCC
|
||||||
|
generation by just removing all lock fields (defined as fields whose
|
||||||
|
type is the empty record type). This has the further advantage of
|
||||||
|
(slightly) reducing the grammar size. More importantly, it is safe
|
||||||
|
to remove lock fields, because they are never used in computation,
|
||||||
|
and because intensional types are only needed in grammars reused
|
||||||
|
as libraries, not in grammars used at runtime.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
While the order problem is rather bureaucratic in nature, run-time
|
||||||
|
variables are an interesting problem. They arise in the presence
|
||||||
|
of complex parameter values, created by argument-taking constructors
|
||||||
|
and parameter records. To give an example, consider the GF parameter
|
||||||
|
type system
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Number = Sg | Pl ;
|
||||||
|
Person = P1 | P2 | P3 ;
|
||||||
|
Agr = Ag Number Person ;
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
The values can be translated to integers in the expected way,
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Sg = 0, Pl = 1
|
||||||
|
P1 = 0, P2 = 1, P3 = 2
|
||||||
|
Ag Sg P1 = 0, Ag Sg P2 = 1, Ag Sg P3 = 2,
|
||||||
|
Ag Pl P1 = 3, Ag Pl P2 = 4, Ag Pl P3 = 5
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
However, an argument of <CODE>Agr</CODE> can be a run-time variable, as in
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Ag np.n P3
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
This expression must first be translated to a case expression,
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
case np.n of {
|
||||||
|
0 => 2 ;
|
||||||
|
1 => 5
|
||||||
|
}
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
which can then be translated to the GFCC term
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
[2,5][$0[$1]]
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
assuming that the variable $np$ is the first argument and that its
|
||||||
|
$Number$ field is the second in the record.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
This transformation of course has to be performed recursively, since
|
||||||
|
there can be several run-time variables in a parameter value:
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
Ag np.n np.p
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
A similar transformation would be possible to deal with the double
|
||||||
|
role of parameter records discussed above. Thus the type
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
RNP = {n : Number ; p : Person}
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
could be uniformly translated into the set <CODE>{0,1,2,3,4,5}</CODE>
|
||||||
|
as <CODE>Agr</CODE> above. Selections would be simple instances of indexing.
|
||||||
|
But any projection from the record should be translated into
|
||||||
|
a case expression,
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
rnp.n ===>
|
||||||
|
case rnp of {
|
||||||
|
0 => 0 ;
|
||||||
|
1 => 0 ;
|
||||||
|
2 => 0 ;
|
||||||
|
3 => 1 ;
|
||||||
|
4 => 1 ;
|
||||||
|
5 => 1
|
||||||
|
}
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
To avoid the code bloat resulting from this, we chose the alias representation
|
||||||
|
which is easy enough to deal with in interpreters.
|
||||||
|
</P>
|
||||||
|
<A NAME="toc13"></A>
|
||||||
|
<H3>Running the compiler and the GFCC interpreter</H3>
|
||||||
|
<P>
|
||||||
|
GFCC generation is a part of the
|
||||||
|
<A HREF="http://www.cs.chalmers.se/Cs/Research/Language-technology/darcs/GF/doc/darcs.html">developers' version</A>
|
||||||
|
of GF since September 2006. To invoke the compiler, the flag
|
||||||
|
<CODE>-printer=gfcc</CODE> to the command
|
||||||
|
<CODE>pm = print_multi</CODE> is used. It is wise to recompile the grammar from
|
||||||
|
source, since previously compiled libraries may not obey the canonical
|
||||||
|
order of records. To <CODE>strip</CODE> the grammar before
|
||||||
|
GFCC translation removes unnecessary interface references.
|
||||||
|
Here is an example, performed in
|
||||||
|
<A HREF="../../../../../examples/bronzeage">example/bronzeage</A>.
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
i -src -path=.:prelude:resource-1.0/* -optimize=all_subs BronzeageEng.gf
|
||||||
|
i -src -path=.:prelude:resource-1.0/* -optimize=all_subs BronzeageGer.gf
|
||||||
|
strip
|
||||||
|
pm -printer=gfcc | wf bronze.gfcc
|
||||||
|
</PRE>
|
||||||
|
<P></P>
|
||||||
|
<A NAME="toc14"></A>
|
||||||
|
<H2>The reference interpreter</H2>
|
||||||
|
<P>
|
||||||
|
The reference interpreter written in Haskell consists of the following files:
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
-- source file for BNFC
|
||||||
|
GFCC.cf -- labelled BNF grammar of gfcc
|
||||||
|
|
||||||
|
-- files generated by BNFC
|
||||||
|
AbsGFCC.hs -- abstrac syntax of gfcc
|
||||||
|
ErrM.hs -- error monad used internally
|
||||||
|
LexGFCC.hs -- lexer of gfcc files
|
||||||
|
ParGFCC.hs -- parser of gfcc files and syntax trees
|
||||||
|
PrintGFCC.hs -- printer of gfcc files and syntax trees
|
||||||
|
|
||||||
|
-- hand-written files
|
||||||
|
DataGFCC.hs -- post-parser grammar creation, linearization and evaluation
|
||||||
|
GenGFCC.hs -- random and exhaustive generation, generate-and-test parsing
|
||||||
|
RunGFCC.hs -- main function - a simple command interpreter
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
It is included in the
|
||||||
|
<A HREF="http://www.cs.chalmers.se/Cs/Research/Language-technology/darcs/GF/doc/darcs.html">developers' version</A>
|
||||||
|
of GF, in the subdirectory <A HREF="../"><CODE>GF/src/GF/Canon/GFCC</CODE></A>.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
To compile the interpreter, type
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
make gfcc
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
in <CODE>GF/src</CODE>. To run it, type
|
||||||
|
</P>
|
||||||
|
<PRE>
|
||||||
|
./gfcc <GFCC-file>
|
||||||
|
</PRE>
|
||||||
|
<P>
|
||||||
|
The available commands are
|
||||||
|
</P>
|
||||||
|
<UL>
|
||||||
|
<LI><CODE>gr <Cat> <Int></CODE>: generate a number of random trees in category.
|
||||||
|
and show their linearizations in all languages
|
||||||
|
<LI><CODE>grt <Cat> <Int></CODE>: generate a number of random trees in category.
|
||||||
|
and show the trees and their linearizations in all languages
|
||||||
|
<LI><CODE>gt <Cat> <Int></CODE>: generate a number of trees in category from smallest,
|
||||||
|
and show their linearizations in all languages
|
||||||
|
<LI><CODE>gtt <Cat> <Int></CODE>: generate a number of trees in category from smallest,
|
||||||
|
and show the trees and their linearizations in all languages
|
||||||
|
<LI><CODE>p <Int> <Cat> <String></CODE>: "parse", i.e. generate trees until match or
|
||||||
|
until the given number have been generated
|
||||||
|
<LI><CODE><Tree></CODE>: linearize tree in all languages, also showing full records
|
||||||
|
<LI><CODE>quit</CODE>: terminate the system cleanly
|
||||||
|
</UL>
|
||||||
|
|
||||||
|
<A NAME="toc15"></A>
|
||||||
|
<H2>Some things to do</H2>
|
||||||
|
<P>
|
||||||
|
Interpreters in Java and C++.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
Parsing via MCFG
|
||||||
|
</P>
|
||||||
|
<UL>
|
||||||
|
<LI>the FCFG format can possibly be simplified
|
||||||
|
<LI>parser grammars should be saved in files to make interpreters easier
|
||||||
|
</UL>
|
||||||
|
|
||||||
|
<P>
|
||||||
|
File compression of GFCC output.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
Syntax editor based on GFCC.
|
||||||
|
</P>
|
||||||
|
<P>
|
||||||
|
Rewriting of resource libraries in order to exploit the
|
||||||
|
word-suffix sharing better (depth-one tables, as in FM).
|
||||||
|
</P>
|
||||||
|
|
||||||
|
<!-- html code generated by txt2tags 2.3 (http://txt2tags.sf.net) -->
|
||||||
|
<!-- cmdline: txt2tags -thtml -\-toc gfcc.txt -->
|
||||||
|
</BODY></HTML>
|
||||||
@@ -504,8 +504,8 @@ GFCC translation removes unnecessary interface references.
|
|||||||
Here is an example, performed in
|
Here is an example, performed in
|
||||||
[example/bronzeage ../../../../../examples/bronzeage].
|
[example/bronzeage ../../../../../examples/bronzeage].
|
||||||
```
|
```
|
||||||
i -src -path=.:prelude:resource-1.0/* -optimize=values BronzeageEng.gf
|
i -src -path=.:prelude:resource-1.0/* -optimize=all_subs BronzeageEng.gf
|
||||||
i -src -path=.:prelude:resource-1.0/* -optimize=values BronzeageGer.gf
|
i -src -path=.:prelude:resource-1.0/* -optimize=all_subs BronzeageGer.gf
|
||||||
strip
|
strip
|
||||||
pm -printer=gfcc | wf bronze.gfcc
|
pm -printer=gfcc | wf bronze.gfcc
|
||||||
```
|
```
|
||||||
@@ -528,7 +528,7 @@ The reference interpreter written in Haskell consists of the following files:
|
|||||||
|
|
||||||
-- hand-written files
|
-- hand-written files
|
||||||
DataGFCC.hs -- post-parser grammar creation, linearization and evaluation
|
DataGFCC.hs -- post-parser grammar creation, linearization and evaluation
|
||||||
GenGFCC.hs -- random and exhaustive generation, gen-and-test parsing
|
GenGFCC.hs -- random and exhaustive generation, generate-and-test parsing
|
||||||
RunGFCC.hs -- main function - a simple command interpreter
|
RunGFCC.hs -- main function - a simple command interpreter
|
||||||
```
|
```
|
||||||
It is included in the
|
It is included in the
|
||||||
@@ -558,3 +558,21 @@ The available commands are
|
|||||||
- ``quit``: terminate the system cleanly
|
- ``quit``: terminate the system cleanly
|
||||||
|
|
||||||
|
|
||||||
|
==Some things to do==
|
||||||
|
|
||||||
|
Interpreters in Java and C++.
|
||||||
|
|
||||||
|
Parsing via MCFG
|
||||||
|
- the FCFG format can possibly be simplified
|
||||||
|
- parser grammars should be saved in files to make interpreters easier
|
||||||
|
|
||||||
|
|
||||||
|
File compression of GFCC output.
|
||||||
|
|
||||||
|
Syntax editor based on GFCC.
|
||||||
|
|
||||||
|
Rewriting of resource libraries in order to exploit the
|
||||||
|
word-suffix sharing better (depth-one tables, as in FM).
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|||||||
Reference in New Issue
Block a user