diff options
| author | aarne <aarne@cs.chalmers.se> | 2007-10-05 13:38:10 +0000 |
|---|---|---|
| committer | aarne <aarne@cs.chalmers.se> | 2007-10-05 13:38:10 +0000 |
| commit | 2905d5552c1530185609fe892e0e9e2c4994ca1d (patch) | |
| tree | 7b73558c7a1ea5ba21a597fe1a7a8e2f1c0929d6 /src/GF/GFCC | |
| parent | 1b4f7c9741b87f7085f0a8b70034e5ce7cfe668a (diff) | |
removed Canon/GFCC
Diffstat (limited to 'src/GF/GFCC')
| -rw-r--r-- | src/GF/GFCC/doc/Eng.gf | 13 | ||||
| -rw-r--r-- | src/GF/GFCC/doc/Ex.gf | 8 | ||||
| -rw-r--r-- | src/GF/GFCC/doc/Swe.gf | 13 | ||||
| -rw-r--r-- | src/GF/GFCC/doc/Test.gf | 64 | ||||
| -rw-r--r-- | src/GF/GFCC/doc/gfcc.html | 842 | ||||
| -rw-r--r-- | src/GF/GFCC/doc/gfcc.txt | 656 | ||||
| -rw-r--r-- | src/GF/GFCC/doc/old-GFCC.cf | 50 |
7 files changed, 1646 insertions, 0 deletions
diff --git a/src/GF/GFCC/doc/Eng.gf b/src/GF/GFCC/doc/Eng.gf new file mode 100644 index 000000000..c64f46313 --- /dev/null +++ b/src/GF/GFCC/doc/Eng.gf @@ -0,0 +1,13 @@ +concrete Eng of Ex = { + lincat + S = {s : Str} ; + NP = {s : Str ; n : Num} ; + VP = {s : Num => Str} ; + param + Num = Sg | Pl ; + lin + Pred np vp = {s = np.s ++ vp.s ! np.n} ; + She = {s = "she" ; n = Sg} ; + They = {s = "they" ; n = Pl} ; + Sleep = {s = table {Sg => "sleeps" ; Pl => "sleep"}} ; +} diff --git a/src/GF/GFCC/doc/Ex.gf b/src/GF/GFCC/doc/Ex.gf new file mode 100644 index 000000000..bd0b03483 --- /dev/null +++ b/src/GF/GFCC/doc/Ex.gf @@ -0,0 +1,8 @@ +abstract Ex = { + cat + S ; NP ; VP ; + fun + Pred : NP -> VP -> S ; + She, They : NP ; + Sleep : VP ; +} diff --git a/src/GF/GFCC/doc/Swe.gf b/src/GF/GFCC/doc/Swe.gf new file mode 100644 index 000000000..1d6672371 --- /dev/null +++ b/src/GF/GFCC/doc/Swe.gf @@ -0,0 +1,13 @@ +concrete Swe of Ex = { + lincat + S = {s : Str} ; + NP = {s : Str} ; + VP = {s : Str} ; + param + Num = Sg | Pl ; + lin + Pred np vp = {s = np.s ++ vp.s} ; + She = {s = "hon"} ; + They = {s = "de"} ; + Sleep = {s = "sover"} ; +} diff --git a/src/GF/GFCC/doc/Test.gf b/src/GF/GFCC/doc/Test.gf new file mode 100644 index 000000000..5cd4c5474 --- /dev/null +++ b/src/GF/GFCC/doc/Test.gf @@ -0,0 +1,64 @@ +-- to test GFCC compilation + +flags coding=utf8 ; + +cat S ; NP ; N ; VP ; + +fun Pred : NP -> VP -> S ; +fun Pred2 : NP -> VP -> NP -> S ; +fun Det, Dets : N -> NP ; +fun Mina, Sina, Me, Te : NP ; +fun Raha, Paska, Pallo : N ; +fun Puhua, Munia, Sanoa : VP ; + +param Person = P1 | P2 | P3 ; +param Number = Sg | Pl ; +param Case = Nom | Part ; + +param NForm = NF Number Case ; +param VForm = VF Number Person ; + +lincat N = Noun ; +lincat VP = Verb ; + +oper Noun = {s : NForm => Str} ; +oper Verb = {s : VForm => Str} ; + +lincat NP = {s : Case => Str ; a : {n : Number ; p : Person}} ; + +lin Pred np vp = {s = np.s ! Nom ++ vp.s ! VF np.a.n np.a.p} ; +lin Pred2 np vp ob = {s = np.s ! Nom ++ vp.s ! VF np.a.n np.a.p ++ ob.s ! Part} ; +lin Det no = {s = \\c => no.s ! NF Sg c ; a = {n = Sg ; p = P3}} ; +lin Dets no = {s = \\c => no.s ! NF Pl c ; a = {n = Pl ; p = P3}} ; +lin Mina = {s = table Case ["minä" ; "minua"] ; a = {n = Sg ; p = P1}} ; +lin Te = {s = table Case ["te" ; "teitä"] ; a = {n = Pl ; p = P2}} ; +lin Sina = {s = table Case ["sinä" ; "sinua"] ; a = {n = Sg ; p = P2}} ; +lin Me = {s = table Case ["me" ; "meitä"] ; a = {n = Pl ; p = P1}} ; + +lin Raha = mkN "raha" ; +lin Paska = mkN "paska" ; +lin Pallo = mkN "pallo" ; +lin Puhua = mkV "puhu" ; +lin Munia = mkV "muni" ; +lin Sanoa = mkV "sano" ; + +oper mkN : Str -> Noun = \raha -> { + s = table { + NF Sg Nom => raha ; + NF Sg Part => raha + "a" ; + NF Pl Nom => raha + "t" ; + NF Pl Part => Predef.tk 1 raha + "oja" + } + } ; + +oper mkV : Str -> Verb = \puhu -> { + s = table { + VF Sg P1 => puhu + "n" ; + VF Sg P2 => puhu + "t" ; + VF Sg P3 => puhu + Predef.dp 1 puhu ; + VF Pl P1 => puhu + "mme" ; + VF Pl P2 => puhu + "tte" ; + VF Pl P3 => puhu + "vat" + } + } ; + diff --git a/src/GF/GFCC/doc/gfcc.html b/src/GF/GFCC/doc/gfcc.html new file mode 100644 index 000000000..c43188e9f --- /dev/null +++ b/src/GF/GFCC/doc/gfcc.html @@ -0,0 +1,842 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> +<HTML> +<HEAD> +<META NAME="generator" CONTENT="http://txt2tags.sf.net"> +<TITLE>The GFCC Grammar Format</TITLE> +</HEAD><BODY BGCOLOR="white" TEXT="black"> +<P ALIGN="center"><CENTER><H1>The GFCC Grammar Format</H1> +<FONT SIZE="4"> +<I>Aarne Ranta</I><BR> +October 19, 2006 +</FONT></CENTER> + +<P></P> +<HR NOSHADE SIZE=1> +<P></P> + <UL> + <LI><A HREF="#toc1">What is GFCC</A> + <LI><A HREF="#toc2">GFCC vs. GFC</A> + <LI><A HREF="#toc3">The syntax of GFCC files</A> + <UL> + <LI><A HREF="#toc4">Top level</A> + <LI><A HREF="#toc5">Abstract syntax</A> + <LI><A HREF="#toc6">Concrete syntax</A> + </UL> + <LI><A HREF="#toc7">The semantics of concrete syntax terms</A> + <UL> + <LI><A HREF="#toc8">Linearization and realization</A> + <LI><A HREF="#toc9">Term evaluation</A> + <LI><A HREF="#toc10">The special term constructors</A> + </UL> + <LI><A HREF="#toc11">Compiling to GFCC</A> + <UL> + <LI><A HREF="#toc12">Problems in GFCC compilation</A> + <LI><A HREF="#toc13">The representation of linearization types</A> + <LI><A HREF="#toc14">Running the compiler and the GFCC interpreter</A> + </UL> + <LI><A HREF="#toc15">The reference interpreter</A> + <LI><A HREF="#toc16">Interpreter in C++</A> + <LI><A HREF="#toc17">Some things to do</A> + </UL> + +<P></P> +<HR NOSHADE SIZE=1> +<P></P> +<P> +Author's address: +<A HREF="http://www.cs.chalmers.se/~aarne"><CODE>http://www.cs.chalmers.se/~aarne</CODE></A> +</P> +<P> +History: +</P> +<UL> +<LI>19 Oct: translation of lincats, new figures on C++ +<LI>3 Oct 2006: first version +</UL> + +<A NAME="toc1"></A> +<H2>What is GFCC</H2> +<P> +GFCC is a low-level format for GF grammars. Its aim is to contain the minimum +that is needed to process GF grammars at runtime. This minimality has three +advantages: +</P> +<UL> +<LI>compact grammar files and run-time objects +<LI>time and space efficient processing +<LI>simple definition of interpreters +</UL> + +<P> +The idea is that all embedded GF applications are compiled to GFCC. +The GF system would be primarily used as a compiler and as a grammar +development tool. +</P> +<P> +Since GFCC is implemented in BNFC, a parser of the format is readily +available for C, C++, Haskell, Java, and OCaml. Also an XML +representation is generated in BNFC. A +<A HREF="../">reference implementation</A> +of linearization and some other functions has been written in Haskell. +</P> +<A NAME="toc2"></A> +<H2>GFCC vs. GFC</H2> +<P> +GFCC is aimed to replace GFC as the run-time grammar format. GFC was designed +to be a run-time format, but also to +support separate compilation of grammars, i.e. +to store the results of compiling +individual GF modules. But this means that GFC has to contain extra information, +such as type annotations, which is only needed in compilation and not at +run-time. In particular, the pattern matching syntax and semantics of GFC is +complex and therefore difficult to implement in new platforms. +</P> +<P> +The main differences of GFCC compared with GFC can be summarized as follows: +</P> +<UL> +<LI>there are no modules, and therefore no qualified names +<LI>a GFCC grammar is multilingual, and consists of a common abstract syntax + together with one concrete syntax per language +<LI>records and tables are replaced by arrays +<LI>record labels and parameter values are replaced by integers +<LI>record projection and table selection are replaced by array indexing +<LI>there is (so far) no support for dependent types or higher-order abstract + syntax (which would be easy to add, but make interpreters much more difficult + to write) +</UL> + +<P> +Here is an example of a GF grammar, consisting of three modules, +as translated to GFCC. The representations are aligned, with the exceptions +due to the alphabetical sorting of GFCC grammars. +</P> +<PRE> + grammar Ex(Eng,Swe); + + abstract Ex = { abstract { + cat + S ; NP ; VP ; + fun + Pred : NP -> VP -> S ; Pred : NP,VP -> S = (Pred); + She, They : NP ; She : -> NP = (She); + Sleep : VP ; Sleep : -> VP = (Sleep); + They : -> NP = (They); + } } ; + + concrete Eng of Ex = { concrete Eng { + lincat + S = {s : Str} ; + NP = {s : Str ; n : Num} ; + VP = {s : Num => Str} ; + param + Num = Sg | Pl ; + lin + Pred np vp = { Pred = [(($0!1),(($1!0)!($0!0)))]; + s = np.s ++ vp.s ! np.n} ; + She = {s = "she" ; n = Sg} ; She = [0, "she"]; + They = {s = "they" ; n = Pl} ; + Sleep = {s = table { Sleep = [("sleep" + ["s",""])]; + Sg => "sleeps" ; + Pl => "sleep" They = [1, "they"]; + } } ; + } ; + } + + concrete Swe of Ex = { concrete Swe { + lincat + S = {s : Str} ; + NP = {s : Str} ; + VP = {s : Str} ; + param + Num = Sg | Pl ; + lin + Pred np vp = { Pred = [(($0!0),($1!0))]; + s = np.s ++ vp.s} ; + She = {s = "hon"} ; She = ["hon"]; + They = {s = "de"} ; They = ["de"]; + Sleep = {s = "sover"} ; Sleep = ["sover"]; + } } ; +</PRE> +<P></P> +<A NAME="toc3"></A> +<H2>The syntax of GFCC files</H2> +<A NAME="toc4"></A> +<H3>Top level</H3> +<P> +A grammar has a header telling the name of the abstract syntax +(often specifying an application domain), and the names of +the concrete languages. The abstract syntax and the concrete +syntaxes themselves follow. +</P> +<PRE> + Grammar ::= Header ";" Abstract ";" [Concrete] ; + Header ::= "grammar" CId "(" [CId] ")" ; + Abstract ::= "abstract" "{" [AbsDef] "}" ; + Concrete ::= "concrete" CId "{" [CncDef] "}" ; +</PRE> +<P> +Abstract syntax judgements give typings and semantic definitions. +Concrete syntax judgements give linearizations. +</P> +<PRE> + AbsDef ::= CId ":" Type "=" Exp ; + CncDef ::= CId "=" Term ; +</PRE> +<P> +Also flags are possible, local to each "module" (i.e. abstract and concretes). +</P> +<PRE> + AbsDef ::= "%" CId "=" String ; + CncDef ::= "%" CId "=" String ; +</PRE> +<P> +For the run-time system, the reference implementation in Haskell +uses a structure that gives efficient look-up: +</P> +<PRE> + data GFCC = GFCC { + absname :: CId , + cncnames :: [CId] , + abstract :: Abstr , + concretes :: Map CId Concr + } + + data Abstr = Abstr { + funs :: Map CId Type, -- find the type of a fun + cats :: Map CId [CId] -- find the funs giving a cat + } + + type Concr = Map CId Term +</PRE> +<P></P> +<A NAME="toc5"></A> +<H3>Abstract syntax</H3> +<P> +Types are first-order function types built from +category symbols. Syntax trees (<CODE>Exp</CODE>) are +rose trees with the head (<CODE>Atom</CODE>) either a function +constant, a metavariable, or a string, integer, or float +literal. +</P> +<PRE> + Type ::= [CId] "->" CId ; + Exp ::= "(" Atom [Exp] ")" ; + Atom ::= CId ; -- function constant + Atom ::= "?" ; -- metavariable + 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. +Constructor names are shown to make the later code +examples readable. +</P> +<PRE> + R. Term ::= "[" [Term] "]" ; -- array + P. Term ::= "(" Term "!" Term ")" ; -- access to indexed field + S. Term ::= "(" [Term] ")" ; -- sequence with ++ + K. Term ::= Tokn ; -- token + V. Term ::= "$" Integer ; -- argument + C. Term ::= Integer ; -- array index + FV. Term ::= "[|" [Term] "|]" ; -- free variation + TM. Term ::= "?" ; -- linearization of metavariable +</PRE> +<P> +Tokens are strings or (maybe obsolescent) prefix-dependent +variant lists. +</P> +<PRE> + KS. Tokn ::= String ; + KP. Tokn ::= "[" "pre" [String] "[" [Variant] "]" "]" ; + Var. 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> + F. Term ::= CId ; -- global constant + W. Term ::= "(" String "+" Term ")" ; -- prefix + suffix table + RP. 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 -> TM + 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 + TM -> "?" +</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 presented in one-level pattern matching, to +enable reimplementations in languages that do not permit +deep patterns (such as Java and C++). +</P> +<PRE> + compute :: GFCC -> CId -> [Term] -> Term -> Term + compute mcfg lang args = comp where + comp trm = case trm of + P r p -> proj (comp r) (comp 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 -> idx args (fromInteger i) -- already computed + F c -> comp $ look c -- not computed (if contains V) + FV ts -> FV $ Prelude.map comp ts + S ts -> S $ Prelude.filter (/= S []) $ Prelude.map comp ts + _ -> trm + + look = lookLin mcfg lang + + idx xs i = xs !! i + + proj r p = case (r,p) of + (_, FV ts) -> FV $ Prelude.map (proj r) ts + (W s t, _) -> kks (s ++ getString (proj t p)) + _ -> comp $ getField r (getIndex p) + + getString t = case t of + K (KS s) -> s + _ -> trace ("ERROR in grammar compiler: string from "++ show t) "ERR" + + getIndex t = case t of + C i -> fromInteger i + RP p _ -> getIndex p + TM -> 0 -- default value for parameter + _ -> trace ("ERROR in grammar compiler: index from " ++ show t) 0 + + getField t i = case t of + R rs -> idx rs i + RP _ r -> getField r i + TM -> TM + _ -> trace ("ERROR in grammar compiler: field from " ++ show t) t +</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 @ _)) = (t ! 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 <CODE>np</CODE> is the first argument and that its +<CODE>Number</CODE> 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>The representation of linearization types</H3> +<P> +Linearization types (<CODE>lincat</CODE>) are not needed when generating with +GFCC, but they have been added to enable parser generation directly from +GFCC. The linearization type definitions are shown as a part of the +concrete syntax, by using terms to represent types. Here is the table +showing how different linearization types are encoded. +</P> +<PRE> + P* = size(P) -- parameter type + {_ : I ; __ : R}* = (I* @ R*) -- record of parameters + {r1 : T1 ; ... ; rn : Tn}* = [T1*,...,Tn*] -- other record + (P => T)* = [T* ,...,T*] -- size(P) times + Str* = () +</PRE> +<P> +The category symbols are prefixed with two underscores (<CODE>__</CODE>). +For example, the linearization type <CODE>present/CatEng.NP</CODE> is +translated as follows: +</P> +<PRE> + NP = { + a : { -- 6 = 2*3 values + n : {ParamX.Number} ; -- 2 values + p : {ParamX.Person} -- 3 values + } ; + s : {ResEng.Case} => Str -- 3 values + } + + __NP = [(6@[2,3]),[(),(),()]] +</PRE> +<P></P> +<A NAME="toc14"></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="toc15"></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="toc16"></A> +<H2>Interpreter in C++</H2> +<P> +A base-line interpreter in C++ has been started. +Its main functionality is random generation of trees and linearization of them. +</P> +<P> +Here are some results from running the different interpreters, compared +to running the same grammar in GF, saved in <CODE>.gfcm</CODE> format. +The grammar contains the English, German, and Norwegian +versions of Bronzeage. The experiment was carried out on +Ubuntu Linux laptop with 1.5 GHz Intel centrino processor. +</P> +<TABLE CELLPADDING="4" BORDER="1"> +<TR> +<TH></TH> +<TH>GF</TH> +<TH>gfcc(hs)</TH> +<TH>gfcc++</TH> +</TR> +<TR> +<TD>program size</TD> +<TD ALIGN="center">7249k</TD> +<TD ALIGN="center">803k</TD> +<TD ALIGN="right">113k</TD> +</TR> +<TR> +<TD>grammar size</TD> +<TD ALIGN="center">336k</TD> +<TD ALIGN="center">119k</TD> +<TD ALIGN="right">119k</TD> +</TR> +<TR> +<TD>read grammar</TD> +<TD ALIGN="center">1150ms</TD> +<TD ALIGN="center">510ms</TD> +<TD ALIGN="right">100ms</TD> +</TR> +<TR> +<TD>generate 222</TD> +<TD ALIGN="center">9500ms</TD> +<TD ALIGN="center">450ms</TD> +<TD ALIGN="right">800ms</TD> +</TR> +<TR> +<TD>memory</TD> +<TD ALIGN="center">21M</TD> +<TD ALIGN="center">10M</TD> +<TD ALIGN="right">20M</TD> +</TR> +</TABLE> + +<P></P> +<P> +To summarize: +</P> +<UL> +<LI>going from GF to gfcc is a major win in both code size and efficiency +<LI>going from Haskell to C++ interpreter is not a win yet, because of a space + leak in the C++ version +</UL> + +<A NAME="toc17"></A> +<H2>Some things to do</H2> +<P> +Interpreter in Java. +</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> +Hand-written parsers for GFCC grammars to reduce code size +(and efficiency?) of interpreters. +</P> +<P> +Binary format and/or 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> diff --git a/src/GF/GFCC/doc/gfcc.txt b/src/GF/GFCC/doc/gfcc.txt new file mode 100644 index 000000000..6ffd9bd64 --- /dev/null +++ b/src/GF/GFCC/doc/gfcc.txt @@ -0,0 +1,656 @@ +The GFCC Grammar Format +Aarne Ranta +October 19, 2006 + +Author's address: +[``http://www.cs.chalmers.se/~aarne`` http://www.cs.chalmers.se/~aarne] + +% to compile: txt2tags -thtml --toc gfcc.txt + +History: +- 19 Oct: translation of lincats, new figures on C++ +- 3 Oct 2006: first version + + +==What is GFCC== + +GFCC is a low-level format for GF grammars. Its aim is to contain the minimum +that is needed to process GF grammars at runtime. This minimality has three +advantages: +- compact grammar files and run-time objects +- time and space efficient processing +- simple definition of interpreters + + +The idea is that all embedded GF applications are compiled to GFCC. +The GF system would be primarily used as a compiler and as a grammar +development tool. + +Since GFCC is implemented in BNFC, a parser of the format is readily +available for C, C++, Haskell, Java, and OCaml. Also an XML +representation is generated in BNFC. A +[reference implementation ../] +of linearization and some other functions has been written in Haskell. + + +==GFCC vs. GFC== + +GFCC is aimed to replace GFC as the run-time grammar format. GFC was designed +to be a run-time format, but also to +support separate compilation of grammars, i.e. +to store the results of compiling +individual GF modules. But this means that GFC has to contain extra information, +such as type annotations, which is only needed in compilation and not at +run-time. In particular, the pattern matching syntax and semantics of GFC is +complex and therefore difficult to implement in new platforms. + +The main differences of GFCC compared with GFC can be summarized as follows: +- there are no modules, and therefore no qualified names +- a GFCC grammar is multilingual, and consists of a common abstract syntax + together with one concrete syntax per language +- records and tables are replaced by arrays +- record labels and parameter values are replaced by integers +- record projection and table selection are replaced by array indexing +- there is (so far) no support for dependent types or higher-order abstract + syntax (which would be easy to add, but make interpreters much more difficult + to write) + + +Here is an example of a GF grammar, consisting of three modules, +as translated to GFCC. The representations are aligned, with the exceptions +due to the alphabetical sorting of GFCC grammars. +``` + grammar Ex(Eng,Swe); + +abstract Ex = { abstract { + cat + S ; NP ; VP ; + fun + Pred : NP -> VP -> S ; Pred : NP,VP -> S = (Pred); + She, They : NP ; She : -> NP = (She); + Sleep : VP ; Sleep : -> VP = (Sleep); + They : -> NP = (They); +} } ; + +concrete Eng of Ex = { concrete Eng { + lincat + S = {s : Str} ; + NP = {s : Str ; n : Num} ; + VP = {s : Num => Str} ; + param + Num = Sg | Pl ; + lin + Pred np vp = { Pred = [(($0!1),(($1!0)!($0!0)))]; + s = np.s ++ vp.s ! np.n} ; + She = {s = "she" ; n = Sg} ; She = [0, "she"]; + They = {s = "they" ; n = Pl} ; + Sleep = {s = table { Sleep = [("sleep" + ["s",""])]; + Sg => "sleeps" ; + Pl => "sleep" They = [1, "they"]; + } } ; + } ; +} + +concrete Swe of Ex = { concrete Swe { + lincat + S = {s : Str} ; + NP = {s : Str} ; + VP = {s : Str} ; + param + Num = Sg | Pl ; + lin + Pred np vp = { Pred = [(($0!0),($1!0))]; + s = np.s ++ vp.s} ; + She = {s = "hon"} ; She = ["hon"]; + They = {s = "de"} ; They = ["de"]; + Sleep = {s = "sover"} ; Sleep = ["sover"]; +} } ; +``` + +==The syntax of GFCC files== + +===Top level=== + +A grammar has a header telling the name of the abstract syntax +(often specifying an application domain), and the names of +the concrete languages. The abstract syntax and the concrete +syntaxes themselves follow. +``` + Grammar ::= Header ";" Abstract ";" [Concrete] ; + Header ::= "grammar" CId "(" [CId] ")" ; + Abstract ::= "abstract" "{" [AbsDef] "}" ; + Concrete ::= "concrete" CId "{" [CncDef] "}" ; +``` +Abstract syntax judgements give typings and semantic definitions. +Concrete syntax judgements give linearizations. +``` + AbsDef ::= CId ":" Type "=" Exp ; + CncDef ::= CId "=" Term ; +``` +Also flags are possible, local to each "module" (i.e. abstract and concretes). +``` + AbsDef ::= "%" CId "=" String ; + CncDef ::= "%" CId "=" String ; +``` +For the run-time system, the reference implementation in Haskell +uses a structure that gives efficient look-up: +``` + data GFCC = GFCC { + absname :: CId , + cncnames :: [CId] , + abstract :: Abstr , + concretes :: Map CId Concr + } + + data Abstr = Abstr { + funs :: Map CId Type, -- find the type of a fun + cats :: Map CId [CId] -- find the funs giving a cat + } + + type Concr = Map CId Term +``` + + +===Abstract syntax=== + +Types are first-order function types built from +category symbols. Syntax trees (``Exp``) are +rose trees with the head (``Atom``) either a function +constant, a metavariable, or a string, integer, or float +literal. +``` + Type ::= [CId] "->" CId ; + Exp ::= "(" Atom [Exp] ")" ; + Atom ::= CId ; -- function constant + Atom ::= "?" ; -- metavariable + Atom ::= String ; -- string literal + Atom ::= Integer ; -- integer literal + Atom ::= Double ; -- float literal +``` + + +===Concrete syntax=== + +Linearization terms (``Term``) are built as follows. +Constructor names are shown to make the later code +examples readable. +``` + R. Term ::= "[" [Term] "]" ; -- array + P. Term ::= "(" Term "!" Term ")" ; -- access to indexed field + S. Term ::= "(" [Term] ")" ; -- sequence with ++ + K. Term ::= Tokn ; -- token + V. Term ::= "$" Integer ; -- argument + C. Term ::= Integer ; -- array index + FV. Term ::= "[|" [Term] "|]" ; -- free variation + TM. Term ::= "?" ; -- linearization of metavariable +``` +Tokens are strings or (maybe obsolescent) prefix-dependent +variant lists. +``` + KS. Tokn ::= String ; + KP. Tokn ::= "[" "pre" [String] "[" [Variant] "]" "]" ; + Var. Variant ::= [String] "/" [String] ; +``` +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. +``` + F. Term ::= CId ; -- global constant + W. Term ::= "(" String "+" Term ")" ; -- prefix + suffix table + RP. Term ::= "(" Term "@" Term ")"; -- record parameter alias +``` +Identifiers are like ``Ident`` in GF and GFC, except that +the compiler produces constants prefixed with ``_`` in +the common subterm elimination optimization. +``` + token CId (('_' | letter) (letter | digit | '\'' | '_')*) ; +``` + + +==The semantics of concrete syntax terms== + +===Linearization and realization=== + +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. +``` + 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 -> TM + where + lin = linExp mcfg lang + comp = compute mcfg lang + look = lookLin mcfg lang +``` +The result of linearization is usually a record, which is realized as +a string using the following algorithm. +``` + 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 + TM -> "?" +``` +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. + + +===Term evaluation=== + +Evaluation follows call-by-value order, with two environments +needed: +- the grammar (a concrete syntax) to give the global constants +- an array of terms to give the subtree linearizations + + +The code is presented in one-level pattern matching, to +enable reimplementations in languages that do not permit +deep patterns (such as Java and C++). +``` +compute :: GFCC -> CId -> [Term] -> Term -> Term +compute mcfg lang args = comp where + comp trm = case trm of + P r p -> proj (comp r) (comp 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 -> idx args (fromInteger i) -- already computed + F c -> comp $ look c -- not computed (if contains V) + FV ts -> FV $ Prelude.map comp ts + S ts -> S $ Prelude.filter (/= S []) $ Prelude.map comp ts + _ -> trm + + look = lookLin mcfg lang + + idx xs i = xs !! i + + proj r p = case (r,p) of + (_, FV ts) -> FV $ Prelude.map (proj r) ts + (W s t, _) -> kks (s ++ getString (proj t p)) + _ -> comp $ getField r (getIndex p) + + getString t = case t of + K (KS s) -> s + _ -> trace ("ERROR in grammar compiler: string from "++ show t) "ERR" + + getIndex t = case t of + C i -> fromInteger i + RP p _ -> getIndex p + TM -> 0 -- default value for parameter + _ -> trace ("ERROR in grammar compiler: index from " ++ show t) 0 + + getField t i = case t of + R rs -> idx rs i + RP _ r -> getField r i + TM -> TM + _ -> trace ("ERROR in grammar compiler: field from " ++ show t) t +``` + +===The special term constructors=== + +The three forms introduced by the compiler may a need special +explanation. + +Global constants +``` + Term ::= CId ; +``` +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. + +Prefix-suffix tables +``` + Term ::= "(" String "+" Term ")" ; +``` +represent tables of word forms divided to the longest common prefix +and its array of suffixes. In the example grammar above, we have +``` + Sleep = [("sleep" + ["s",""])] +``` +which in fact is equal to the array of full forms +``` + ["sleeps", "sleep"] +``` +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 +``` + "(" String "+" [String] ")" +``` +since we want the suffix part to be a ``Term`` for the optimization to +take effect. + +The most curious construct of GFCC is the parameter array alias, +``` + Term ::= "(" Term "@" Term ")"; +``` +This form is used as the value of parameter records, such as the type +``` + {n : Number ; p : Person} +``` +The problem with parameter records is their double role. +They can be used like parameter values, as indices in selection, +``` + VP.s ! {n = Sg ; p = P3} +``` +but also as records, from which parameters can be projected: +``` + {n = Sg ; p = P3}.n +``` +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 +``` + param Number = Sg | Pl ; Person = P1 | P2 | P3 ; +``` +we get the encoding +``` + {n = Sg ; p = P3} ---> (2 @ [0,2]) +``` +The GFCC computation rules are essentially +``` + (t ! (i @ _)) = (t ! i) + ((_ @ r) ! j) =(r ! j) +``` + + +==Compiling to GFCC== + +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. + +The compilation phases are the following ++ translate GF source to GFC, as always in GF ++ undo GFC back-end optimizations ++ perform the ``values`` optimization to normalize tables ++ create a symbol table mapping the GFC parameter and record types to + fixed-size arrays, and parameter values and record labels to integers ++ traverse the linearization rules replacing parameters and labels by integers ++ reorganize the created GFC grammar so that it has just one abstract syntax + and one concrete syntax per language ++ apply UTF8 encoding to the grammar, if not yet applied (this is told by the + ``coding`` flag) ++ translate the GFC syntax tree to a GFCC syntax tree, using a simple + compositional mapping ++ perform the word-suffix optimization on GFCC linearization terms ++ perform subexpression elimination on each concrete syntax module ++ print out the GFCC code + + +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. + + +===Problems in GFCC compilation=== + +Two major problems had to be solved in compiling GFC to GFCC: +- consistent order of tables and records, to permit the array translation +- run-time variables in complex parameter values. + + +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. + +The order problem is solved in different ways for tables and records. +For tables, the ``values`` optimization of GFC already manages to +maintain a canonical order. But this order can be destroyed by the +``share`` optimization. To make sure that GFCC compilation works properly, +it is safest to recompile the GF grammar by using the ``values`` +optimization flag. + +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 ``s`` 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. + +The canonical form of records is further complicated by lock fields, +i.e. dummy fields of form ``lock_C = <>``, 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. + +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 +``` + Number = Sg | Pl ; + Person = P1 | P2 | P3 ; + Agr = Ag Number Person ; +``` +The values can be translated to integers in the expected way, +``` + 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 +``` +However, an argument of ``Agr`` can be a run-time variable, as in +``` + Ag np.n P3 +``` +This expression must first be translated to a case expression, +``` + case np.n of { + 0 => 2 ; + 1 => 5 + } +``` +which can then be translated to the GFCC term +``` + ([2,5] ! ($0 ! $1)) +``` +assuming that the variable ``np`` is the first argument and that its +``Number`` field is the second in the record. + +This transformation of course has to be performed recursively, since +there can be several run-time variables in a parameter value: +``` + Ag np.n np.p +``` +A similar transformation would be possible to deal with the double +role of parameter records discussed above. Thus the type +``` + RNP = {n : Number ; p : Person} +``` +could be uniformly translated into the set ``{0,1,2,3,4,5}`` +as ``Agr`` above. Selections would be simple instances of indexing. +But any projection from the record should be translated into +a case expression, +``` + rnp.n ===> + case rnp of { + 0 => 0 ; + 1 => 0 ; + 2 => 0 ; + 3 => 1 ; + 4 => 1 ; + 5 => 1 + } +``` +To avoid the code bloat resulting from this, we chose the alias representation +which is easy enough to deal with in interpreters. + + +===The representation of linearization types=== + +Linearization types (``lincat``) are not needed when generating with +GFCC, but they have been added to enable parser generation directly from +GFCC. The linearization type definitions are shown as a part of the +concrete syntax, by using terms to represent types. Here is the table +showing how different linearization types are encoded. +``` + P* = size(P) -- parameter type + {_ : I ; __ : R}* = (I* @ R*) -- record of parameters + {r1 : T1 ; ... ; rn : Tn}* = [T1*,...,Tn*] -- other record + (P => T)* = [T* ,...,T*] -- size(P) times + Str* = () +``` +The category symbols are prefixed with two underscores (``__``). +For example, the linearization type ``present/CatEng.NP`` is +translated as follows: +``` + NP = { + a : { -- 6 = 2*3 values + n : {ParamX.Number} ; -- 2 values + p : {ParamX.Person} -- 3 values + } ; + s : {ResEng.Case} => Str -- 3 values + } + + __NP = [(6@[2,3]),[(),(),()]] +``` + + + + +===Running the compiler and the GFCC interpreter=== + +GFCC generation is a part of the +[developers' version http://www.cs.chalmers.se/Cs/Research/Language-technology/darcs/GF/doc/darcs.html] +of GF since September 2006. To invoke the compiler, the flag +``-printer=gfcc`` to the command +``pm = print_multi`` is used. It is wise to recompile the grammar from +source, since previously compiled libraries may not obey the canonical +order of records. To ``strip`` the grammar before +GFCC translation removes unnecessary interface references. +Here is an example, performed in +[example/bronzeage ../../../../../examples/bronzeage]. +``` + 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 +``` + + + +==The reference interpreter== + +The reference interpreter written in Haskell consists of the following files: +``` + -- 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 +``` +It is included in the +[developers' version http://www.cs.chalmers.se/Cs/Research/Language-technology/darcs/GF/doc/darcs.html] +of GF, in the subdirectory [``GF/src/GF/Canon/GFCC`` ../]. + +To compile the interpreter, type +``` + make gfcc +``` +in ``GF/src``. To run it, type +``` + ./gfcc <GFCC-file> +``` +The available commands are +- ``gr <Cat> <Int>``: generate a number of random trees in category. + and show their linearizations in all languages +- ``grt <Cat> <Int>``: generate a number of random trees in category. + and show the trees and their linearizations in all languages +- ``gt <Cat> <Int>``: generate a number of trees in category from smallest, + and show their linearizations in all languages +- ``gtt <Cat> <Int>``: generate a number of trees in category from smallest, + and show the trees and their linearizations in all languages +- ``p <Int> <Cat> <String>``: "parse", i.e. generate trees until match or + until the given number have been generated +- ``<Tree>``: linearize tree in all languages, also showing full records +- ``quit``: terminate the system cleanly + + +==Interpreter in C++== + +A base-line interpreter in C++ has been started. +Its main functionality is random generation of trees and linearization of them. + +Here are some results from running the different interpreters, compared +to running the same grammar in GF, saved in ``.gfcm`` format. +The grammar contains the English, German, and Norwegian +versions of Bronzeage. The experiment was carried out on +Ubuntu Linux laptop with 1.5 GHz Intel centrino processor. + +|| | GF | gfcc(hs) | gfcc++ | +| program size | 7249k | 803k | 113k +| grammar size | 336k | 119k | 119k +| read grammar | 1150ms | 510ms | 100ms +| generate 222 | 9500ms | 450ms | 800ms +| memory | 21M | 10M | 20M + + + +To summarize: +- going from GF to gfcc is a major win in both code size and efficiency +- going from Haskell to C++ interpreter is not a win yet, because of a space + leak in the C++ version + + + +==Some things to do== + +Interpreter in Java. + +Parsing via MCFG +- the FCFG format can possibly be simplified +- parser grammars should be saved in files to make interpreters easier + + +Hand-written parsers for GFCC grammars to reduce code size +(and efficiency?) of interpreters. + +Binary format and/or 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). + + + diff --git a/src/GF/GFCC/doc/old-GFCC.cf b/src/GF/GFCC/doc/old-GFCC.cf new file mode 100644 index 000000000..65657a259 --- /dev/null +++ b/src/GF/GFCC/doc/old-GFCC.cf @@ -0,0 +1,50 @@ +Grm. Grammar ::= Header ";" Abstract ";" [Concrete] ; +Hdr. Header ::= "grammar" CId "(" [CId] ")" ; +Abs. Abstract ::= "abstract" "{" [AbsDef] "}" ; +Cnc. Concrete ::= "concrete" CId "{" [CncDef] "}" ; + +Fun. AbsDef ::= CId ":" Type "=" Exp ; +--AFl. AbsDef ::= "%" CId "=" String ; -- flag +Lin. CncDef ::= CId "=" Term ; +--CFl. CncDef ::= "%" CId "=" String ; -- flag + +Typ. Type ::= [CId] "->" CId ; +Tr. Exp ::= "(" Atom [Exp] ")" ; +AC. Atom ::= CId ; +AS. Atom ::= String ; +AI. Atom ::= Integer ; +AF. Atom ::= Double ; +AM. Atom ::= "?" ; +trA. Exp ::= Atom ; +define trA a = Tr a [] ; + +R. Term ::= "[" [Term] "]" ; -- record/table +P. Term ::= "(" Term "!" Term ")" ; -- projection/selection +S. Term ::= "(" [Term] ")" ; -- sequence with ++ +K. Term ::= Tokn ; -- token +V. Term ::= "$" Integer ; -- argument +C. Term ::= Integer ; -- parameter value/label +F. Term ::= CId ; -- global constant +FV. Term ::= "[|" [Term] "|]" ; -- free variation +W. Term ::= "(" String "+" Term ")" ; -- prefix + suffix table +RP. Term ::= "(" Term "@" Term ")"; -- record parameter alias +TM. Term ::= "?" ; -- lin of metavariable + +L. Term ::= "(" CId "->" Term ")" ; -- lambda abstracted table +BV. Term ::= "#" CId ; -- lambda-bound variable + +KS. Tokn ::= String ; +KP. Tokn ::= "[" "pre" [String] "[" [Variant] "]" "]" ; +Var. Variant ::= [String] "/" [String] ; + + +terminator Concrete ";" ; +terminator AbsDef ";" ; +terminator CncDef ";" ; +separator CId "," ; +separator Term "," ; +terminator Exp "" ; +terminator String "" ; +separator Variant "," ; + +token CId (('_' | letter) (letter | digit | '\'' | '_')*) ; |