git_config_set: do not use a state machine

While a neat theoretical construct, state machines are hard to read. In
this instance, it does not even make a whole lot of sense because we are
more interested in flags, anyway: has the section been seen? Has the key
been seen? Does the current section match the key we are looking for?

Besides, the state `SECTION_SEEN` was named in a misleading way: it did
not indicate that we saw the section matching the key we are looking
for, but it instead indicated that we are *currently* in that section.

Let's just replace the state machine logic by clear and obvious flags.

This will also make it easier to review the upcoming patches to use the
newly-introduced `event_fn` callback of the config parser.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.c b/config.c
index 9402acefa8c5da584e420480d4e82c86f08daea9..036bae205c11f945c4ddbe63added4b399fcca87 100644 (file)
--- a/config.c
+++ b/config.c
@@ -2296,7 +2296,7 @@ struct config_store_data {
        int multi_replace;
        size_t *seen;
        unsigned int seen_nr, seen_alloc;
-       enum { START, SECTION_SEEN, SECTION_END_SEEN, KEY_SEEN } state;
+       unsigned int key_seen:1, section_seen:1, is_keys_section:1;
 };
 
 static int matches(const char *key, const char *value,
@@ -2319,8 +2319,7 @@ static int store_aux(const char *key, const char *value, void *cb)
        size_t section_len;
        struct config_store_data *store = cb;
 
-       switch (store->state) {
-       case KEY_SEEN:
+       if (store->key_seen) {
                if (matches(key, value, store)) {
                        if (store->seen_nr == 1 && store->multi_replace == 0) {
                                warning(_("%s has multiple values"), key);
@@ -2332,8 +2331,8 @@ static int store_aux(const char *key, const char *value, void *cb)
                        store->seen[store->seen_nr] = cf->do_ftell(cf);
                        store->seen_nr++;
                }
-               break;
-       case SECTION_SEEN:
+               return 0;
+       } else if (store->is_keys_section) {
                /*
                 * What we are looking for is in store->key (both
                 * section and var), and its section part is baselen
@@ -2348,10 +2347,9 @@ static int store_aux(const char *key, const char *value, void *cb)
 
                if ((section_len != store->baselen) ||
                    memcmp(key, store->key, section_len+1)) {
-                       store->state = SECTION_END_SEEN;
-                       break;
+                       store->is_keys_section = 0;
+                       return 0;
                }
-
                /*
                 * Do not increment matches: this is no match, but we
                 * just made sure we are in the desired section.
@@ -2359,27 +2357,29 @@ static int store_aux(const char *key, const char *value, void *cb)
                ALLOC_GROW(store->seen, store->seen_nr + 1,
                           store->seen_alloc);
                store->seen[store->seen_nr] = cf->do_ftell(cf);
-               /* fallthru */
-       case SECTION_END_SEEN:
-       case START:
-               if (matches(key, value, store)) {
-                       ALLOC_GROW(store->seen, store->seen_nr + 1,
-                                  store->seen_alloc);
-                       store->seen[store->seen_nr] = cf->do_ftell(cf);
-                       store->state = KEY_SEEN;
-                       store->seen_nr++;
-               } else {
-                       if (strrchr(key, '.') - key == store->baselen &&
-                             !strncmp(key, store->key, store->baselen)) {
-                                       store->state = SECTION_SEEN;
-                                       ALLOC_GROW(store->seen,
-                                                  store->seen_nr + 1,
-                                                  store->seen_alloc);
-                                       store->seen[store->seen_nr] =
-                                               cf->do_ftell(cf);
-                       }
+       }
+
+       if (matches(key, value, store)) {
+               ALLOC_GROW(store->seen, store->seen_nr + 1,
+                          store->seen_alloc);
+               store->seen[store->seen_nr] = cf->do_ftell(cf);
+               store->seen_nr++;
+               store->key_seen = 1;
+               store->section_seen = 1;
+               store->is_keys_section = 1;
+       } else {
+               if (strrchr(key, '.') - key == store->baselen &&
+                     !strncmp(key, store->key, store->baselen)) {
+                               store->section_seen = 1;
+                               store->is_keys_section = 1;
+                               ALLOC_GROW(store->seen,
+                                          store->seen_nr + 1,
+                                          store->seen_alloc);
+                               store->seen[store->seen_nr] =
+                                       cf->do_ftell(cf);
                }
        }
+
        return 0;
 }
 
@@ -2637,7 +2637,6 @@ int git_config_set_multivar_in_file_gently(const char *config_filename,
 
                ALLOC_GROW(store.seen, 1, store.seen_alloc);
                store.seen[0] = 0;
-               store.state = START;
                store.seen_nr = 0;
 
                /*
@@ -2705,7 +2704,7 @@ int git_config_set_multivar_in_file_gently(const char *config_filename,
                        new_line = 0;
                        if (store.seen[i] == 0) {
                                store.seen[i] = copy_end = contents_sz;
-                       } else if (store.state != KEY_SEEN) {
+                       } else if (!store.key_seen) {
                                copy_end = store.seen[i];
                        } else
                                copy_end = find_beginning_of_line(
@@ -2729,7 +2728,7 @@ int git_config_set_multivar_in_file_gently(const char *config_filename,
 
                /* write the pair (value == NULL means unset) */
                if (value != NULL) {
-                       if (store.state == START) {
+                       if (!store.section_seen) {
                                if (write_section(fd, key, &store) < 0)
                                        goto write_err_out;
                        }