parser.pl

:- module(parser,
         [program/3]).

:- use_module(library(dcg/basics)).
:- use_module(tokenize).

program(X) -->
  decl_ast(Y),
  {X =.. [ctrs|Y]}.

decl_ast([]) --> [].
decl_ast([H|T]) -->
  decl(H),
  decl_ast(T).

decl(vars(X)) -->
  [punct("(")],
  [word("VAR")],
  id_ast(X),
  [punct(")")],
  {assertVars(X)}.
decl(rules(X)) -->
  [punct("(")],
  [word("RULES")],
  rule_ast(X),
  [punct(")")].

id_ast([]) --> [].
id_ast([H|T]) --> 
  id(H),
  id_ast(T).

id(X) -->
  [word(X)].

%decl --> ("VAR",id_ast); ("THEORY",thdecl_ast); ("RULES",rule);
%         ("STRATEGY",strategydecl); (id,anylist_opt).

condlist([H|T]) -->
  cond(H),
  cond_ast(T).

cond_ast([]) --> [].
cond_ast([H|T]) --> 
  [punct(",")],
  cond(H),
  cond_ast(T).

cond(cond(X,Y)) --> 
  term(X),
  [punct("-"),punct(">")],
  term(Y).
%cond(cond(X,Y)) --> 
%  term(X),
%  [punct("-"),punct(">"),punct("<"),punct("-")],
%  term(Y).

rule_ast([]) --> [].
rule_ast([H|T]) --> rule(H),rule_ast(T).

rule(rule(beta(void),X,Y,[])) -->
  term(X),
  [punct("-")],
  [punct(">")],
  term(Y).

rule(rule(beta(void),X,Y,Z)) -->
  term(X),
  [punct("-")],
  [punct(">")],
  term(Y),
  [punct("|")],
  condlist(Z).

term(term(X,[])) -->
  id(X).
term(term(X,[])) -->
  id(X),
  [punct("(")],
  [punct(")")].
term(term(X,Y)) -->
  id(X),
  [punct("(")],
  termlist(Y),
  [punct(")")].

termlist([H|T]) -->
  term(H),
  term_ast(T).

term_ast([]) --> [].
term_ast([H|T]) -->
  [punct(",")],
  term(H),
  term_ast(T).
%
%anylist_opt --> []; anylist.
%anylist_ast --> []; (",",anylist,anylist_ast).
%anylist --> any,anylist_ast.
%any --> id; string; ("(",anylist,")").
%thdecl --> id_ast; ("EQUATIONS",equation_ast).
%equation_ast --> []; (equation, equation_ast).
%thdecl_ast --> []; (thdecl,thdecl_ast).
%equation --> (term,"==",term).
%stratedecl --> "INNERMOST"; ("CONTEXTSENSITIVE",replacements_ast).
%replacements_ast --> []; (replacement,replacements_ast).
%replacement --> "(",id,int_ast,")".
%int_ast --> []; (int,int_ast).
%
%