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string-list: replace negative index encoding with "exact_match" parameter

The "string_list_find_insert_index()" function is used to determine
the correct insertion index for a new string within the string list.
The function also doubles up to convey if the string is already
existing in the list, this is done by returning a negative index
"-1 -index". Users are expected to decode this information. This
approach has several limitations:

1. It requires the callers to look into the detail of the function to
understand how to decode the negative index encoding.
2. Using int for indices can cause overflow issues when dealing with
large string lists.

To address these limitations, change the function to return size_t for
the index value and use a separate bool parameter to indicate whether
the index refers to an existing entry or an insertion point.

In some cases, the callers of "string_list_find_insert_index" only need
the index position and don't care whether an exact match is found.
However, "get_entry_index" currently requires a non-NULL "exact_match"
parameter, forcing these callers to declare unnecessary variables.
Let's allow callers to pass NULL for the "exact_match" parameter when
they don't need this information, reducing unnecessary variable
declarations in calling code.

Signed-off-by: shejialuo <shejialuo@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

authored by

shejialuo and committed by
Junio C Hamano e8a32e76 03ef7762

+15 -17
unified split
+4 -3
add-interactive.c
··· 221 222 static ssize_t find_unique(const char *string, struct prefix_item_list *list) 223 { 224 - int index = string_list_find_insert_index(&list->sorted, string, 1); 225 struct string_list_item *item; 226 227 if (list->items.nr != list->sorted.nr) ··· 229 " vs %"PRIuMAX")", 230 (uintmax_t)list->items.nr, (uintmax_t)list->sorted.nr); 231 232 - if (index < 0) 233 - item = list->sorted.items[-1 - index].util; 234 else if (index > 0 && 235 starts_with(list->sorted.items[index - 1].string, string)) 236 return -1;
··· 221 222 static ssize_t find_unique(const char *string, struct prefix_item_list *list) 223 { 224 + bool exact_match; 225 + int index = string_list_find_insert_index(&list->sorted, string, &exact_match); 226 struct string_list_item *item; 227 228 if (list->items.nr != list->sorted.nr) ··· 230 " vs %"PRIuMAX")", 231 (uintmax_t)list->items.nr, (uintmax_t)list->sorted.nr); 232 233 + if (exact_match) 234 + item = list->sorted.items[index].util; 235 else if (index > 0 && 236 starts_with(list->sorted.items[index - 1].string, string)) 237 return -1;
+3 -4
mailmap.c
··· 243 static struct string_list_item *lookup_prefix(struct string_list *map, 244 const char *string, size_t len) 245 { 246 - int i = string_list_find_insert_index(map, string, 1); 247 - if (i < 0) { 248 - /* exact match */ 249 - i = -1 - i; 250 if (!string[len]) 251 return &map->items[i]; 252 /*
··· 243 static struct string_list_item *lookup_prefix(struct string_list *map, 244 const char *string, size_t len) 245 { 246 + bool exact_match; 247 + int i = string_list_find_insert_index(map, string, &exact_match); 248 + if (exact_match) { 249 if (!string[len]) 250 return &map->items[i]; 251 /*
+1 -1
refs.c
··· 1699 * with dirname (remember, dirname includes the trailing 1700 * slash) and is not in skip, then we have a conflict. 1701 */ 1702 - for (pos = string_list_find_insert_index(extras, dirname, 0); 1703 pos < extras->nr; pos++) { 1704 const char *extra_refname = extras->items[pos].string; 1705
··· 1699 * with dirname (remember, dirname includes the trailing 1700 * slash) and is not in skip, then we have a conflict. 1701 */ 1702 + for (pos = string_list_find_insert_index(extras, dirname, NULL); 1703 pos < extras->nr; pos++) { 1704 const char *extra_refname = extras->items[pos].string; 1705
+6 -8
string-list.c
··· 29 else if (compare > 0) 30 left = middle + 1; 31 else { 32 - *exact_match = true; 33 return middle; 34 } 35 } 36 37 - *exact_match = false; 38 return right; 39 } 40 ··· 90 } 91 92 int string_list_find_insert_index(const struct string_list *list, const char *string, 93 - int negative_existing_index) 94 { 95 - bool exact_match; 96 - int index = get_entry_index(list, string, &exact_match); 97 - if (exact_match) 98 - index = -1 - (negative_existing_index ? index : 0); 99 - return index; 100 } 101 102 struct string_list_item *string_list_lookup(struct string_list *list, const char *string)
··· 29 else if (compare > 0) 30 left = middle + 1; 31 else { 32 + if (exact_match) 33 + *exact_match = true; 34 return middle; 35 } 36 } 37 38 + if (exact_match) 39 + *exact_match = false; 40 return right; 41 } 42 ··· 92 } 93 94 int string_list_find_insert_index(const struct string_list *list, const char *string, 95 + bool *exact_match) 96 { 97 + return get_entry_index(list, string, exact_match); 98 } 99 100 struct string_list_item *string_list_lookup(struct string_list *list, const char *string)
+1 -1
string-list.h
··· 174 /** Determine if the string_list has a given string or not. */ 175 bool string_list_has_string(const struct string_list *list, const char *string); 176 int string_list_find_insert_index(const struct string_list *list, const char *string, 177 - int negative_existing_index); 178 179 /** 180 * Insert a new element to the string_list. The returned pointer can
··· 174 /** Determine if the string_list has a given string or not. */ 175 bool string_list_has_string(const struct string_list *list, const char *string); 176 int string_list_find_insert_index(const struct string_list *list, const char *string, 177 + bool *exact_match); 178 179 /** 180 * Insert a new element to the string_list. The returned pointer can