From 39f392be9c4240e1f57b54f1d1f9813c78bbfb02 Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Fri, 1 Jun 2012 13:16:29 +0100
Subject: [PATCH] allow finer control over indexing sub-terms. improve flag
 code a bit.

---
 C/index.c    |  7 ++++---
 C/init.c     |  3 ++-
 H/Yap.h      |  5 ++---
 docs/yap.tex |  7 ++++++-
 pl/flags.yap | 13 +++++++++++++
 5 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/C/index.c b/C/index.c
index 8d4c05803..0922d5779 100644
--- a/C/index.c
+++ b/C/index.c
@@ -2545,12 +2545,13 @@ do_compound_index(ClauseDef *min0, ClauseDef* max0, Term* sreg, struct intermedi
     /* base case, just commit to the current code */
     return emit_single_switch_case(min0, cint, first, clleft, fail_l);
   }
-  if (yap_flags[INDEXING_MODE_FLAG] == INDEX_MODE_SINGLE && ap->PredFlags & LogUpdatePredFlag) {
+  if ((yap_flags[INDEXING_MODE_FLAG] == INDEX_MODE_SINGLE && ap->PredFlags & LogUpdatePredFlag) ||
+      (yap_flags[INDEXING_TERM_DEPTH_FLAG] && cint->term_depth - cint->last_index_new_depth > yap_flags[INDEXING_TERM_DEPTH_FLAG])) {
     *newlabp = 
       do_var_clauses(min0, max0, FALSE, cint, first, clleft, fail_l, ap->ArityOfPE+1);
-    return ret_lab;
+   return ret_lab;
   }
-  if (sreg == NULL || cint->term_depth > 20) {
+  if (sreg == NULL) {
     return suspend_indexing(min0, max0, ap, cint);
   }
   cint->term_depth++;
diff --git a/C/init.c b/C/init.c
index ab764c9df..c9e4473ba 100644
--- a/C/init.c
+++ b/C/init.c
@@ -915,6 +915,7 @@ InitFlags(void)
   yap_flags[INDEXING_MODE_FLAG] = INDEX_MODE_MULTI;
   yap_flags[TABLING_MODE_FLAG] = 0;
   yap_flags[QUIET_MODE_FLAG] = FALSE;
+  yap_flags[INDEXING_TERM_DEPTH_FLAG] = 0L;
 }
 
 static void
@@ -1316,7 +1317,7 @@ Yap_InitWorkspace(UInt Heap, UInt Stack, UInt Trail, UInt Atts, UInt max_table_s
   Yap_InitTime();
   /* InitAbsmi must be done before InitCodes */
   /* This must be done before initialising predicates */
-  for (i = 0; i <= LAST_FLAG; i++) {
+  for (i = 0; i <= NUMBER_OF_YAP_FLAGS; i++) {
     yap_flags[i] = 0;
   }
 #ifdef MPW
diff --git a/H/Yap.h b/H/Yap.h
index 768906d2d..4005904a7 100755
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -453,8 +453,9 @@ typedef enum
   TABLING_MODE_FLAG = 20,
   VARS_CAN_HAVE_QUOTE_FLAG = 21,
   QUIET_MODE_FLAG = 22,
+  INDEXING_TERM_DEPTH_FLAG = 23,
   /* let this be the last one */
-  LAST_FLAG = 23
+  NUMBER_OF_YAP_FLAGS = 24
 } yap_flags;
 
 #define STRING_AS_CHARS		0
@@ -501,8 +502,6 @@ typedef enum
   YAP_FAIL_SIGNAL = 0x100000	/* P = FAILCODE */
 } yap_signals;
 
-#define NUMBER_OF_YAP_FLAGS  LAST_FLAG
-
 typedef enum
 {
   GPROF_NO_EVENT,
diff --git a/docs/yap.tex b/docs/yap.tex
index ada1ed178..0885ca694 100644
--- a/docs/yap.tex
+++ b/docs/yap.tex
@@ -8078,8 +8078,13 @@ for which YAP was compiled and Operating System information.
 
 @item  index
 @findex index (yap_flag/2 option)
+@* If @code{on} allow indexing (default), if @code{off} disable it, if
+@code{single} allow on first argument only.
+
+@item  index_sub_term_search_depth
+@findex index (yap_flag/2 option)
 @*
-If @code{on} allow indexing (default), if @code{off} disable it.
+Maximum bound on searching sub-terms for indexing, if @code{0} (default) no bound.
 
 @item  informational_messages
 @findex informational_messages (yap_flag/2 option)
diff --git a/pl/flags.yap b/pl/flags.yap
index da0ed4b14..e0593418e 100644
--- a/pl/flags.yap
+++ b/pl/flags.yap
@@ -236,6 +236,18 @@ yap_flag(index,X)  :-
 yap_flag(index,X) :-
 	'$do_error'(domain_error(flag_value,index+X),yap_flag(index,X)).
 
+% do or do not indexation
+yap_flag(index_sub_term_search_depth,X) :- var(X),
+	'$access_yap_flags'(23, X), !.
+yap_flag(index_sub_term_search_depth,X,X)  :-
+	integer(X), X > 0,
+	'$set_yap_flags'(23,X1).
+yap_flag(index_sub_term_search_depth,X,X)  :-
+	\+ integer(X),
+	'$do_error'(type_error(integer,X),yap_flag(index_sub_term_search_depth,X)).
+yap_flag(index_sub_term_search_depth,X,X) :-
+	'$do_error'(domain_error(out_of_range,index_sub_term_search_depth+X),yap_flag(index_sub_term_search_depth,X)).
+
 yap_flag(home,X) :-
 	'$yap_home'(X).
 
@@ -869,6 +881,7 @@ yap_flag(dialect,yap).
 '$yap_system_flag'(home ).
 '$yap_system_flag'(host_type ).
 '$yap_system_flag'(index).
+'$yap_system_flag'(index_sub_term_search_depth).
 '$yap_system_flag'(tabling_mode).
 '$yap_system_flag'(informational_messages).
 '$yap_system_flag'(integer_rounding_function).