From 4029344a2b9f6c441576fd723e9b712ed4a3ca05 Mon Sep 17 00:00:00 2001
From: Salvador Abreu <spa@debian.org>
Date: Thu, 2 Jul 2015 18:07:47 +0900
Subject: [PATCH] now using free-ended symbol table model. refactor accordingly.

---
 fzn-parser/semantic.pl | 24 ++++++++++++------------
 fzn-parser/stable.pl   | 11 +++++++----
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/fzn-parser/semantic.pl b/fzn-parser/semantic.pl
index 278f5e8..aed4a30 100644
--- a/fzn-parser/semantic.pl
+++ b/fzn-parser/semantic.pl
@@ -2,31 +2,31 @@
 
 sa_names(fzn(preds(IP), vars(IV), constrs(IC), SOLVE),
 	 fzn(preds(OP), vars(OV), constrs(OC), SOLVE, ST)) :-
-    sa_n_traverse(IP, OP, [], ST1),  % predicates
-    sa_n_traverse(IV, OV, ST1, ST2), % variables
-    sa_n_traverse(IC, OC, ST2, ST).  % constraints
+    sa_n_traverse(IP, OP, ST),  % predicates
+    sa_n_traverse(IV, OV, ST),	% variables
+    sa_n_traverse(IC, OC, ST).  % constraints
 
 % -----------------------------------------------------------------------------
 
-sa_n_traverse([], [], ST, ST).
-sa_n_traverse([N|Ns], [NN|NNs], IST, OST) :-
-    sa_n(N, NN, IST, MST),
-    sa_n_traverse(Ns, NNs, MST, OST).
+sa_n_traverse([], [], ST).
+sa_n_traverse([N|Ns], [NN|NNs], ST) :-
+    sa_n(N, NN, ST),
+    sa_n_traverse(Ns, NNs, ST).
 
 
 % - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 %
-% sa_n(AST_N_IN, AST_N_OUT, ST_IN, ST_OUT)
+% sa_n(AST_N_IN, AST_N_OUT, ST)
 
-sa_n(var(N,T,I,A), var(N,T), IST, OST) :-
-    sa_attribs(A, AX, IST, ST1),
-    st_insert(ST1, N, var(N,T,I,AX), OST).
+sa_n(var(N,T,I,A), var(N,T), ST) :-
+    sa_attribs(A, AX, ST),
+    st_insert(ST, N, var(N,T,I,AX)).
 
 sa_n(constraint(_C)).
 
 % - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-sa_attribs(A, NA, IST, OST) :-
+sa_attribs(A, NA, IST) :-
     true.
 
 % -----------------------------------------------------------------------------
diff --git a/fzn-parser/stable.pl b/fzn-parser/stable.pl
index 0f79695..6f2fa30 100644
--- a/fzn-parser/stable.pl
+++ b/fzn-parser/stable.pl
@@ -1,10 +1,13 @@
 % == No, Emacs this is -*-Prolog-*- code, not what you thought... =============
 
 % -- Symbol table -------------------------------------------------------------
+%
+% Open-ended model.
 
+st_lookup(ST,      _, _) :- var(ST), !, fail.
 st_lookup([K=V|_], K, V).
-st_lookup([_|ST], K, V) :- st_lookup(ST, K, V).
+st_lookup([_|ST],  K, V) :- st_lookup(ST, K, V).
 
-st_insert([], K, V, [K=V]) :- !.
-st_insert([K=_|_], K, _, _) :- !, throw(duplicate(K)).
-st_insert([KV0|ST], K, V, [KV0|STx]) :- st_insert(ST, K, V, STx).
+st_insert(ST,      K, V) :- var(ST), !, ST=[K=V|_].
+st_insert([K=_|_], K, _) :- !, throw(duplicate(K)).
+st_insert([_|ST],  K, V) :- st_insert(ST, K, V).
--
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