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Reorganize evaluation code

This commit is contained in:
Přemysl Eric Janouch 2017-05-21 17:20:15 +02:00
parent 1ede1ed686
commit ba2e31d81f
Signed by: p
GPG Key ID: B715679E3A361BE6
1 changed files with 71 additions and 75 deletions
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146
ell.c
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@ -755,6 +755,7 @@ static bool execute (struct context *ctx, struct item *body, struct item **);
static bool
execute_args (struct context *ctx, struct item *args, struct item **res) {
// TODO: prepend "(argument %d) ->" to any resulting error
for (; args; args = args->next) {
struct item *evaluated = NULL;
if (!execute_statement (ctx, args, &evaluated))
@ -777,33 +778,75 @@ set_arg (struct context *ctx, size_t arg, struct item *value) {
&& set (ctx, buf, value);
}
// TODO: we should probably maintain arguments in a separate list,
// either that or at least remember the count so that we can reset them
// NOTE: it even seems that storing arguments as numbers is completely useless
static bool
execute_and_set_args (struct context *ctx, struct item *following) {
struct item *args = NULL;
if (!execute_args (ctx, following, &args)) {
item_free_list (args);
return false;
}
execute_native (struct context *ctx, const char *name, struct item *args,
struct item **result) {
struct native_fn *fn = native_find (ctx, name);
if (!fn)
return set_error (ctx, "unknown function");
size_t i = 0;
for (struct item *arg = args; arg; arg = arg->next)
if (!set_arg (ctx, i++, arg))
return false;
item_free_list (args);
return true;
struct item *evaluated = NULL;
bool ok = execute_args (ctx, args, &evaluated)
&& fn->handler (ctx, evaluated, result);
item_free_list (evaluated);
return ok;
}
static bool
execute_native (struct context *ctx,
struct native_fn *fn, struct item *following, struct item **result) {
struct item *args = NULL;
bool ok = execute_args (ctx, following, &args)
&& fn->handler (ctx, args, result);
item_free_list (args);
return ok;
execute_resolved (struct context *ctx, struct item *body, struct item *args,
struct item **result) {
// Resolving names ecursively could be pretty fatal, let's not do that
if (body->type == ITEM_STRING)
return check (ctx, (*result = new_clone (body)));
struct item *evaluated = NULL;
if (!execute_args (ctx, args, &evaluated)) {
item_free_list (evaluated);
return false;
}
// TODO: we should probably maintain arguments in a separate list,
// either that or at least remember the count so that we can reset them
// NOTE: it even seems that storing them as numbers is completely useless
size_t i = 0;
for (struct item *arg = evaluated; arg; arg = arg->next)
if (!set_arg (ctx, i++, arg)) {
item_free_list (evaluated);
return false;
}
item_free_list (evaluated);
return execute (ctx, body->head, result);
}
static bool
execute_item (struct context *ctx, struct item *body, struct item **result) {
struct item *args = body->next;
if (body->type == ITEM_STRING) {
const char *name = body->value;
// TODO: these could be just regular handlers, only top priority
if (!strcmp (name, "quote"))
return !args || check (ctx, (*result = new_clone_list (args)));
if (!strcmp (name, "arg"))
return rename_arguments (ctx, args);
if ((body = get (ctx, name)))
return execute_resolved (ctx, body, args, result);
return execute_native (ctx, name, args, result);
}
// When someone tries to call a block directly, we must evaluate it;
// e.g. something like `{ choose [@f1 @f2 @f3] } arg1 arg2 arg3`.
struct item *evaluated = NULL;
if (!execute_statement (ctx, body, &evaluated))
return false;
// It might a bit confusing that this doesn't evaluate arguments
// but neither does "quote" and there's nothing to do here
if (!evaluated)
return true;
bool success = execute_resolved (ctx, evaluated, args, result);
item_free_list (evaluated);
return success;
}
static bool
@ -814,64 +857,17 @@ execute_statement
// Executing a nil value results in no value. It's not very different from
// calling a block that returns no value--it's for our callers to resolve.
struct item *body;
if (!(body = statement->head))
if (!statement->head
|| execute_item (ctx, statement->head, result))
return true;
struct item *following = body->next;
const char *name = "(anonymous)";
struct item *destroy = NULL;
if (body->type == ITEM_STRING) {
name = body->value;
// TODO: these could be just regular handlers, only top priority
// TODO: these should also get a stack trace the normal way
if (!strcmp (name, "quote"))
return !following
|| check (ctx, (*result = new_clone_list (following)));
if (!strcmp (name, "arg"))
return rename_arguments (ctx, following);
body = get (ctx, name);
} else {
// When someone tries to call a block directly, we must evaluate it;
// e.g. something like `{ choose [@f1 @f2 @f3] } arg1 arg2 arg3`.
struct item *evaluated = NULL;
if (!execute_statement (ctx, body, &evaluated))
return false;
// It might a bit confusing that this doesn't evaluate arguments
// but neither does "quote" and there's nothing to do here
if (!evaluated)
return true;
item_free_list (evaluated->next);
evaluated->next = NULL;
destroy = body = evaluated;
}
if (!body) {
struct native_fn *fn = native_find (ctx, name);
if (!fn)
return set_error (ctx, "unknown function: %s", name);
if (execute_native (ctx, fn, following, result))
return true;
} else if (body->type == ITEM_STRING) {
// Recursion could be pretty fatal, let's not do that
if (check (ctx, (*result = new_clone (body)))) {
item_free_list (destroy);
return true;
}
} else {
// FIXME: this creates a confusing backtrace for argument evaluation
if (execute_and_set_args (ctx, following)
&& execute (ctx, body->head, result)) {
item_free_list (destroy);
return true;
}
}
item_free_list (destroy);
item_free_list (*result);
*result = NULL;
const char *name = "(block)";
if (statement->head->type == ITEM_STRING)
name = statement->head->value;
// In that case, `error' is NULL and there's nothing else to do anyway.
// Errors starting with an underscore are exceptions and would not work
// with stack traces generated this way.