FIXED: Improve performance when searching for opener of a pair that doesn't exist

diff --git a/src/token_pairs.c b/src/token_pairs.c
index 29dd3da71a963cdbd3ff4bba2688dcf41631311b..5b70eaa8cfafc697fa929236a3bc69e52907f7ce 100644 (file)
--- a/src/token_pairs.c
+++ b/src/token_pairs.c
@@ -129,11 +129,6 @@ void token_pair_mate(token * a, token * b) {
 
 /// Search a token's childen for matching pairs
 void token_pairs_match_pairs_inside_token(token * parent, token_pair_engine * e, stack * s) {
-//     if ((parent == NULL) || 
-//             (parent->child == NULL) ||
-//             (e == NULL)) {
-//             return;
-//     }
 
        // Walk the child chain
        token * walker = parent->child;
@@ -145,6 +140,8 @@ void token_pairs_match_pairs_inside_token(token * parent, token_pair_engine * e,
        token * peek;
        unsigned short pair_type;
 
+       unsigned int opener_count[kMaxTokenTypes] = {0};        // Keep track of which token types are on the stack
+
        while (walker != NULL) {
 
                if (walker->child) {
@@ -152,10 +149,26 @@ void token_pairs_match_pairs_inside_token(token * parent, token_pair_engine * e,
                }
 
                // Is this a closer?
-               if (e->can_close_pair[walker->type] && walker->can_close && walker->unmatched ) {
-                       // Do we have a valid opener in the stack?
+               if (walker->can_close && e->can_close_pair[walker->type] && walker->unmatched ) {
                        i = s->size;
 
+                       // Do we even have a valid opener in the stack?
+                       // It's only worth checking if the stack is beyond a certain size
+                       if (i > start_counter + kLargeStackThreshold) {
+                               for (int j = 0; j < kMaxTokenTypes; ++j)
+                               {
+                                       if (opener_count[j]) {
+                                               if (e->pair_type[j][walker->type])
+                                                       goto close;
+                                       }
+                               }
+
+                               // No opener available for this as closer
+                               goto open;
+                       }
+
+                       close:
+                       // Find matching opener for this closer
                        while (i > start_counter) {
                                peek = stack_peek_index(s, i - 1);
 
@@ -182,8 +195,12 @@ void token_pairs_match_pairs_inside_token(token * parent, token_pair_engine * e,
 
                                        token_pair_mate(peek, walker);
 
+
                                        // Clear portion of stack between opener and closer as they are now unavailable for mating
-                                       s->size = i - 1;
+                                       while (s->size > (i - 1)) {
+                                               peek = stack_pop(s);
+                                               opener_count[peek->type]--;
+                                       }
 #ifndef NDEBUG
                                        fprintf(stderr, "stack now sized %lu\n", s->size);
 #endif
@@ -209,10 +226,11 @@ void token_pairs_match_pairs_inside_token(token * parent, token_pair_engine * e,
                        }
                }
 
+               open:
                // Is this an opener?
-               // \todo: Need to verify that token->type is a valid opening token for some pairing
-               if (e->can_open_pair[walker->type] && walker->can_open && walker->unmatched) {
+               if (walker->can_open && e->can_open_pair[walker->type] && walker->unmatched) {
                        stack_push(s, walker);
+                       opener_count[walker->type]++;
 #ifndef NDEBUG
                fprintf(stderr, "push token type %d to stack (%lu elements)\n", walker->type, s->size);
 #endif

diff --git a/src/token_pairs.h b/src/token_pairs.h
index 07f6b14abbd1488021e79f65aa9954845f604214..742accb749f478e39523c352a72fd76b0028b0d0 100644 (file)
--- a/src/token_pairs.h
+++ b/src/token_pairs.h
@@ -65,7 +65,9 @@
 #include "CuTest.h"
 #endif
 
-#define kMaxTokenTypes 200             // This needs to be larger than the largest token type being used
+#define kMaxTokenTypes 200                     // This needs to be larger than the largest token type being used
+#define kLargeStackThreshold 1000      // Avoid unnecessary searches of large stacks
+
 
 /// Store information about which tokens can be paired, and what actions to take when 
 /// pairing them.