* lib.c (acons): New function.

(set_diff): Optimize common case: list1 and list2
are the same, or list2 is substructure of list1.
Situations in which this won't be the case for variable bindings are
rare.

* lib.h (acons): Declared.

* match.c (match_line): Use acons rather than acons_new, when binding
variables that we know are new (the symbol is unbound).
When computing the set difference over bindings, use cons cell
equality, rather than symbol equality. Symbol equality is wrong
because a binding can be removed, and then a new binding can be
introduced using the same symbol. This must be treated as
a different binding.

1 files changed, 12 insertions, 12 deletions

diff --git a/match.c b/match.c
index 75e3bb0f..a5dbaacd 100644
--- a/match.c
+++ b/match.c
@@ -353,7 +353,7 @@ static val match_line(val bindings, val specline, val dataline,
               return nil;
             }
             LOG_MATCH("var positive regex", past);
-            bindings = acons_new(bindings, sym, sub_str(dataline, pos, past));
+            bindings = acons(bindings, sym, sub_str(dataline, pos, past));
             pos = past;
             /* This may have another variable attached */
             if (pat) {
@@ -368,7 +368,7 @@ static val match_line(val bindings, val specline, val dataline,
               return nil;
             }
             LOG_MATCH("count based var", past);
-            bindings = acons_new(bindings, sym, trim_str(sub_str(dataline, pos, past)));
+            bindings = acons(bindings, sym, trim_str(sub_str(dataline, pos, past)));
             pos = past;
             /* This may have another variable attached */
             if (pat) {
@@ -379,7 +379,7 @@ static val match_line(val bindings, val specline, val dataline,
             sem_error(spec_lineno, lit("invalid modifier ~s on variable ~s"),
                       modifier, sym, nao);
           } else if (pat == nil) { /* no modifier, no elem -> to end of line */
-            bindings = acons_new(bindings, sym, sub_str(dataline, pos, nil));
+            bindings = acons(bindings, sym, sub_str(dataline, pos, nil));
             pos = length_str(dataline);
           } else if (type(pat) == STR) {
             val find = search_str(dataline, pat, pos, modifier);
@@ -388,7 +388,7 @@ static val match_line(val bindings, val specline, val dataline,
               return nil;
             }
             LOG_MATCH("var delimiting string", find);
-            bindings = acons_new(bindings, sym, sub_str(dataline, pos, find));
+            bindings = acons(bindings, sym, sub_str(dataline, pos, find));
             pos = plus(find, length_str(pat));
           } else if (consp(pat) && regexp(first(pat))) {
             val find = search_regex(dataline, first(pat), pos, modifier);
@@ -399,7 +399,7 @@ static val match_line(val bindings, val specline, val dataline,
               return nil;
             }
             LOG_MATCH("var delimiting regex", fpos);
-            bindings = acons_new(bindings, sym, sub_str(dataline, pos, fpos));
+            bindings = acons(bindings, sym, sub_str(dataline, pos, fpos));
             pos = plus(fpos, flen);
           } else if (consp(pat) && first(pat) == var_s) {
             /* Unbound var followed by var: the following one must either
@@ -428,10 +428,10 @@ static val match_line(val bindings, val specline, val dataline,
 
               /* Text from here to start of regex match goes to this
                  variable. */
-              bindings = acons_new(bindings, sym, sub_str(dataline, pos, fpos));
+              bindings = acons(bindings, sym, sub_str(dataline, pos, fpos));
               /* Text from start of regex match to end goes to the
                  second variable */
-              bindings = acons_new(bindings, second_sym, sub_str(dataline, fpos, plus(fpos, flen)));
+              bindings = acons(bindings, second_sym, sub_str(dataline, fpos, plus(fpos, flen)));
               LOG_MATCH("double var regex (first var)", fpos);
               pos = fpos;
               LOG_MATCH("double var regex (second var)", plus(fpos, flen));
@@ -459,7 +459,7 @@ static val match_line(val bindings, val specline, val dataline,
               LOG_MISMATCH("string");
               return nil;
             }
-            bindings = acons_new(bindings, sym, sub_str(dataline, pos, find));
+            bindings = acons(bindings, sym, sub_str(dataline, pos, find));
             pos = plus(find, len);
           } else {
             sem_error(spec_lineno,
@@ -520,7 +520,7 @@ static val match_line(val bindings, val specline, val dataline,
                   LOG_MATCH("until/last", until_pos);
                   if (sym == last_s) {
                     last_bindings = set_diff(until_last_bindings,
-                                             new_bindings, eq_f, car_f);
+                                             new_bindings, eq_f, nil);
                     pos = until_pos;
                   }
                   break;
@@ -531,7 +531,7 @@ static val match_line(val bindings, val specline, val dataline,
 
               if (new_pos) {
                 val strictly_new_bindings = set_diff(new_bindings,
-                                                     bindings, eq_f, car_f);
+                                                     bindings, eq_f, nil);
                 LOG_MATCH("coll", new_pos);
 
                 for (iter = strictly_new_bindings; iter; iter = cdr(iter))
@@ -1544,7 +1544,7 @@ repeat_spec_same_data:
                 /* Until discards bindings and position, last keeps them. */
                 if (sym == last_s) {
                   last_bindings = set_diff(until_last_bindings,
-                                           new_bindings, eq_f, car_f);
+                                           new_bindings, eq_f, nil);
                   if (success == t) {
                     data = t;
                   } else {
@@ -1559,7 +1559,7 @@ repeat_spec_same_data:
 
             if (success) {
               val strictly_new_bindings = set_diff(new_bindings,
-                                                   bindings, eq_f, car_f);
+                                                   bindings, eq_f, nil);
 
               debuglf(spec_linenum, lit("collect matched ~a:~a"),
                       first(files), num(data_lineno), nao);