circuitpython/py/qstr.c

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#include <assert.h>
#include <string.h>
#include "misc.h"
#include "mpqstr.h"
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// NOTE: we are using linear arrays to store and search for qstr's (unique strings, interned strings)
// ultimately we will replace this with a static hash table of some kind
// also probably need to include the length in the string data, to allow null bytes in the string
#if 0 // print debugging info
#include <stdio.h>
#define DEBUG_printf(args...) printf(args)
#else // don't print debugging info
#define DEBUG_printf(args...) (void)0
#endif
typedef struct _qstr_pool_t {
struct _qstr_pool_t *prev;
uint total_prev_len;
uint alloc;
uint len;
const char *qstrs[];
} qstr_pool_t;
const static qstr_pool_t const_pool = {
NULL, // no previous pool
0, // no previous pool
10, // set so that the first dynamically allocated pool is twice this size; must be <= the len (just below)
MP_QSTR_number_of, // corresponds to number of strings in array just below
{
"nil", // must be first, since 0 qstr is nil
#define Q(id) #id,
#include "mpqstrraw.h"
#undef Q
},
};
static qstr_pool_t *last_pool;
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void qstr_init(void) {
last_pool = (qstr_pool_t*)&const_pool; // we won't modify the const_pool since it has no allocated room left
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}
static qstr qstr_add(const char *str) {
DEBUG_printf("QSTR: add %s\n", str);
// make sure we have room in the pool for a new qstr
if (last_pool->len >= last_pool->alloc) {
qstr_pool_t *pool = m_new_obj_var(qstr_pool_t, const char*, last_pool->alloc * 2);
pool->prev = last_pool;
pool->total_prev_len = last_pool->total_prev_len + last_pool->len;
pool->alloc = last_pool->alloc * 2;
pool->len = 0;
last_pool = pool;
DEBUG_printf("QSTR: allocate new pool of size %d\n", last_pool->alloc);
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}
// add the new qstr
last_pool->qstrs[last_pool->len++] = str;
// return id for the newly-added qstr
return last_pool->total_prev_len + last_pool->len - 1;
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}
qstr qstr_from_str_static(const char *str) {
for (qstr_pool_t *pool = last_pool; pool != NULL; pool = pool->prev) {
for (const char **qstr = pool->qstrs, **qstr_top = pool->qstrs + pool->len; qstr < qstr_top; qstr++) {
if (strcmp(*qstr, str) == 0) {
return pool->total_prev_len + (qstr - pool->qstrs);
}
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}
}
return qstr_add(str);
}
qstr qstr_from_str_take(char *str, int alloc_len) {
for (qstr_pool_t *pool = last_pool; pool != NULL; pool = pool->prev) {
for (const char **qstr = pool->qstrs, **qstr_top = pool->qstrs + pool->len; qstr < qstr_top; qstr++) {
if (strcmp(*qstr, str) == 0) {
m_del(char, str, alloc_len);
return pool->total_prev_len + (qstr - pool->qstrs);
}
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}
}
return qstr_add(str);
}
qstr qstr_from_strn_copy(const char *str, int len) {
for (qstr_pool_t *pool = last_pool; pool != NULL; pool = pool->prev) {
for (const char **qstr = pool->qstrs, **qstr_top = pool->qstrs + pool->len; qstr < qstr_top; qstr++) {
if (strncmp(*qstr, str, len) == 0 && (*qstr)[len] == '\0') {
return pool->total_prev_len + (qstr - pool->qstrs);
}
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}
}
return qstr_add(strndup(str, len));
}
// convert qstr id to pointer to its string
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const char *qstr_str(qstr qstr) {
// search
for (qstr_pool_t *pool = last_pool; pool != NULL; pool = pool->prev) {
if (qstr >= pool->total_prev_len) {
return pool->qstrs[qstr - pool->total_prev_len];
}
}
// not found, return nil
return const_pool.qstrs[0];
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}