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[strings] fixing and simplifying string tree iterator. This version is inspired by Python's itertools.product (itertoolsmodule.c has so many goodies)

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Al
2016-12-31 03:22:17 -05:00
parent 261ec3888a
commit 475aa3dbfa
2 changed files with 21 additions and 63 deletions
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80
src/string_utils.c
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@@ -214,6 +214,11 @@ char *utf8_case(const char *s, casing_option_t casing, utf8proc_option_t options
return (char *)buffer;
}
typedef enum casing_option {
UTF8_LOWER,
UTF8_UPPER
} casing_option_t;
inline char *utf8_lower_options(const char *s, utf8proc_option_t options) {
return utf8_case(s, UTF8_LOWER, options);
}
@@ -1030,7 +1035,8 @@ inline uint32_t string_tree_num_strings(string_tree_t *self) {
inline uint32_t string_tree_num_alternatives(string_tree_t *self, uint32_t i) {
if (i >= self->token_indices->n) return 0;
return self->token_indices->a[i + 1] - self->token_indices->a[i];
uint32_t n = self->token_indices->a[i + 1] - self->token_indices->a[i];
return n > 0 ? n : 1;
}
void string_tree_destroy(string_tree_t *self) {
@@ -1047,10 +1053,6 @@ void string_tree_destroy(string_tree_t *self) {
free(self);
}
#define STRING_TREE_ITER_DIRECTION_LEFT -1
#define STRING_TREE_ITER_DIRECTION_RIGHT 1
string_tree_iterator_t *string_tree_iterator_new(string_tree_t *tree) {
string_tree_iterator_t *self = malloc(sizeof(string_tree_iterator_t));
self->tree = tree;
@@ -1061,8 +1063,6 @@ string_tree_iterator_t *string_tree_iterator_new(string_tree_t *tree) {
// calloc since the first path through the tree is all zeros
self->path = calloc(num_tokens, sizeof(uint32_t));
self->num_alternatives = calloc(num_tokens, sizeof(uint32_t));
uint32_t permutations = 1;
uint32_t num_strings;
@@ -1070,7 +1070,6 @@ string_tree_iterator_t *string_tree_iterator_new(string_tree_t *tree) {
// N + 1 indices stored in token_indices, so this is always valid
num_strings = string_tree_num_alternatives(tree, i);
if (num_strings > 0) {
self->num_alternatives[i] = num_strings;
// 1 or more strings in the string_tree means use those instead of the actual token
permutations *= num_strings;
}
@@ -1078,66 +1077,33 @@ string_tree_iterator_t *string_tree_iterator_new(string_tree_t *tree) {
if (permutations > 1) {
self->remaining = (uint32_t)permutations;
self->single_path = false;
} else{
self->remaining = 1;
self->single_path = true;
}
// Start on the right going backward
self->cursor = self->num_tokens - 1;
self->direction = -1;
return self;
}
static inline void string_tree_iterator_switch_direction(string_tree_iterator_t *self) {
self->direction *= -1;
}
static inline void string_tree_iterator_reset_right(string_tree_iterator_t *self) {
size_t offset = self->cursor + 1;
size_t num_bytes = self->num_tokens - offset;
memset(self->path + offset, 0, sizeof(uint32_t) * num_bytes);
}
static int string_tree_iterator_do_iteration(string_tree_iterator_t *self) {
uint32_t num_alternatives;
int32_t direction = self->direction;
uint32_t sentinel = (direction == STRING_TREE_ITER_DIRECTION_LEFT ? -1 : self->num_tokens);
for (uint32_t cursor = self->cursor; cursor != sentinel; cursor += direction) {
self->cursor = cursor;
num_alternatives = self->num_alternatives[cursor];
if (num_alternatives > 1 && self->path[cursor] < num_alternatives - 1) {
self->path[cursor]++;
if (direction == STRING_TREE_ITER_DIRECTION_LEFT && self->cursor < self->num_tokens - 1) {
string_tree_iterator_reset_right(self);
self->cursor++;
}
string_tree_iterator_switch_direction(self);
self->remaining--;
return 1;
}
}
return -1;
}
void string_tree_iterator_next(string_tree_iterator_t *self) {
if (!self->single_path && string_tree_iterator_do_iteration(self) == -1 && self->remaining > 0) {
string_tree_iterator_switch_direction(self);
if (string_tree_iterator_do_iteration(self) == -1) {
if (self->remaining > 0) {
int i;
for (i = self->num_tokens - 1; i >= 0; i--) {
self->path[i]++;
if (self->path[i] == string_tree_num_alternatives(self->tree, i)) {
self->path[i] = 0;
self->remaining--;
} else {
self->remaining--;
break;
}
}
if (i < 0) {
self->remaining = 0;
}
} else if (self->single_path) {
self->remaining--;
return;
}
}
char *string_tree_iterator_get_string(string_tree_iterator_t *self, uint32_t i) {
if (i >= self->num_tokens) {
return NULL;
@@ -1159,9 +1125,5 @@ void string_tree_iterator_destroy(string_tree_iterator_t *self) {
free(self->path);
}
if (self->num_alternatives) {
free(self->num_alternatives);
}
free(self);
}