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Filter: Implement soft scopes

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Soft scopes are anonymous scopes that most likely do not contain any
symbol, so allocating regular scope is postponed when it is really
needed.
This commit is contained in:
Ondrej Zajicek (work) 2022-03-06 16:37:30 +01:00
parent 77c41a72db
commit 23cf849851
3 changed files with 64 additions and 5 deletions
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56
conf/cf-lex.l
View File

@ -574,6 +574,8 @@ check_eof(void)
return 0;
}
static inline void cf_swap_soft_scope(void);
static struct symbol *
cf_new_symbol(const byte *c)
{
@ -583,6 +585,8 @@ cf_new_symbol(const byte *c)
if (l > SYM_MAX_LEN)
cf_error("Symbol too long");
cf_swap_soft_scope();
s = cfg_allocz(sizeof(struct symbol) + l + 1);
*s = (struct symbol) { .scope = conf_this_scope, .class = SYM_VOID, };
strcpy(s->name, c);
@ -656,8 +660,8 @@ cf_localize_symbol(struct symbol *sym)
return sym;
/* If the scope is the current, it is already defined in this scope. */
if (sym->scope == conf_this_scope)
cf_error("Symbol already defined");
if (cf_symbol_is_local(sym))
cf_error("Symbol '%s' already defined", sym->name);
/* Not allocated here yet, doing it now. */
return cf_new_symbol(sym->name);
@ -787,12 +791,60 @@ cf_push_scope(struct symbol *sym)
void
cf_pop_scope(void)
{
ASSERT(!conf_this_scope->soft_scopes);
conf_this_scope->active = 0;
conf_this_scope = conf_this_scope->next;
ASSERT(conf_this_scope);
}
/**
* cf_push_soft_scope - enter new soft scope
*
* If we want to enter a new anonymous scope that most likely will not contain
* any symbols, we can use cf_push_soft_scope() insteas of cf_push_scope().
* Such scope will be converted to a regular scope on first use.
*/
void
cf_push_soft_scope(void)
{
if (conf_this_scope->soft_scopes < 0xfe)
conf_this_scope->soft_scopes++;
else
cf_push_scope(NULL);
}
/**
* cf_pop_soft_scope - leave a soft scope
*
* Leave a soft scope entered by cf_push_soft_scope().
*/
void
cf_pop_soft_scope(void)
{
if (conf_this_scope->soft_scopes)
conf_this_scope->soft_scopes--;
else
cf_pop_scope();
}
/**
* cf_swap_soft_scope - convert soft scope to regular scope
*
* Soft scopes cannot hold symbols, so they must be converted to regular scopes
* on first use. It is done automatically by cf_new_symbol().
*/
static inline void
cf_swap_soft_scope(void)
{
if (conf_this_scope->soft_scopes)
{
conf_this_scope->soft_scopes--;
cf_push_scope(NULL);
}
}
/**
* cf_symbol_class_name - get name of a symbol class
* @sym: symbol

9
conf/conf.h
View File

@ -133,7 +133,8 @@ struct sym_scope {
struct sym_scope *next; /* Next on scope stack */
struct symbol *name; /* Name of this scope */
uint slots; /* Variable slots */
int active; /* Currently entered */
byte active; /* Currently entered */
byte soft_scopes; /* Number of soft scopes above */
};
struct bytestring {
@ -190,6 +191,9 @@ struct symbol *cf_get_symbol(const byte *c);
struct symbol *cf_default_name(char *template, int *counter);
struct symbol *cf_localize_symbol(struct symbol *sym);
static inline int cf_symbol_is_local(struct symbol *sym)
{ return (sym->scope == conf_this_scope) && !conf_this_scope->soft_scopes; }
/**
* cf_define_symbol - define meaning of a symbol
* @sym: symbol to be defined
@ -213,6 +217,9 @@ struct symbol *cf_localize_symbol(struct symbol *sym);
void cf_push_scope(struct symbol *);
void cf_pop_scope(void);
void cf_push_soft_scope(void);
void cf_pop_soft_scope(void);
char *cf_symbol_class_name(struct symbol *sym);
/* Parser */

2
sysdep/unix/main.c
View File

@ -116,7 +116,7 @@ add_num_const(char *name, int val, const char *file, const uint line)
struct f_val *v = cfg_alloc(sizeof(struct f_val));
*v = (struct f_val) { .type = T_INT, .val.i = val };
struct symbol *sym = cf_get_symbol(name);
if (sym->class && (sym->scope == conf_this_scope))
if (sym->class && cf_symbol_is_local(sym))
cf_error("Error reading value for %s from %s:%d: already defined", name, file, line);
cf_define_symbol(sym, SYM_CONSTANT | T_INT, val, v);