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optimize scm_from_latin1_symboln

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* libguile/symbols.c (lookup_interned_latin1_symbol): New helper.
  (scm_from_latin1_symboln): Use lookup_interned_latin1_symbol, so we
  avoid allocating a string in that case.
This commit is contained in:
Andy Wingo 2011-01-07 09:03:12 -08:00
parent 17072fd2c6
commit 30c282bf93
1 changed files with 58 additions and 2 deletions
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60
libguile/symbols.c
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@ -121,6 +121,49 @@ lookup_interned_symbol (SCM name, unsigned long raw_hash)
return SCM_BOOL_F;
}
struct latin1_lookup_data
{
const char *str;
size_t len;
unsigned long string_hash;
};
static int
latin1_lookup_predicate_fn (SCM sym, void *closure)
{
struct latin1_lookup_data *data = closure;
return scm_i_symbol_hash (sym) == data->string_hash
&& scm_i_is_narrow_symbol (sym)
&& scm_i_symbol_length (sym) == data->len
&& strncmp (scm_i_symbol_chars (sym), data->str, data->len) == 0;
}
static SCM
lookup_interned_latin1_symbol (const char *str, size_t len,
unsigned long raw_hash)
{
struct latin1_lookup_data data;
SCM handle;
data.str = str;
data.len = len;
data.string_hash = raw_hash;
/* Strictly speaking, we should take a lock here. But instead we rely
on the fact that if this fails, we do take the lock on the
intern_symbol path; and since nothing deletes from the hash table
except GC, we should be OK. */
handle = scm_hash_fn_get_handle_by_hash (symbols, raw_hash,
latin1_lookup_predicate_fn,
&data);
if (scm_is_true (handle))
return SCM_CAR (handle);
else
return SCM_BOOL_F;
}
static unsigned long
symbol_lookup_hash_fn (SCM obj, unsigned long max, void *closure)
{
@ -422,8 +465,21 @@ scm_from_latin1_symbol (const char *sym)
SCM
scm_from_latin1_symboln (const char *sym, size_t len)
{
SCM str = scm_from_latin1_stringn (sym, len);
return scm_i_str2symbol (str);
unsigned long hash;
SCM ret;
if (len == (size_t) -1)
len = strlen (sym);
hash = scm_i_latin1_string_hash (sym, len);
ret = lookup_interned_latin1_symbol (sym, len, hash);
if (scm_is_false (ret))
{
SCM str = scm_from_latin1_stringn (sym, len);
ret = scm_i_str2symbol (str);
}
return ret;
}
SCM