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* eval.c (memoize_as_thunk_prototype): New static function.

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(scm_m_delay, scm_m_future): Use memoize_as_thunk_prototype.
	Avoid unnecessary consing when creating the memoized code.
This commit is contained in:
Dirk Herrmann 2003-10-12 07:13:46 +00:00
parent 9b9a35b601
commit 8ae95199fd
2 changed files with 34 additions and 8 deletions
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7
libguile/ChangeLog
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@ -1,3 +1,10 @@
2003-10-11 Dirk Herrmann <D.Herrmann@tu-bs.de>
* eval.c (memoize_as_thunk_prototype): New static function.
(scm_m_delay, scm_m_future): Use memoize_as_thunk_prototype.
Avoid unnecessary consing when creating the memoized code.
2003-10-12 Kevin Ryde <user42@zip.com.au>
* list.c (scm_append): Track argument number and use in error.

35
libguile/eval.c
View file

@ -101,11 +101,11 @@ char *alloca ();
static const char s_bad_expression[] = "Bad expression";
/* If a form is detected that holds less expressions than are required in that
* contect, a 'Missing expression' error is signalled. */
* context, a 'Missing expression' error is signalled. */
static const char s_missing_expression[] = "Missing expression in";
/* If a form is detected that holds more expressions than are allowed in that
* contect, an 'Extra expression' error is signalled. */
* context, an 'Extra expression' error is signalled. */
static const char s_extra_expression[] = "Extra expression in";
/* Case or cond expressions must have at least one clause. If a case or cond
@ -933,6 +933,23 @@ scm_m_define (SCM expr, SCM env)
}
/* This is a helper function for forms (<keyword> <expression>) that are
* transformed into (#@<keyword> '() <memoized_expression>) in order to allow
* for easy creation of a thunk (i. e. a closure without arguments) using the
* ('() <memoized_expression>) tail of the memoized form. */
static SCM
memoize_as_thunk_prototype (const SCM expr, const SCM env SCM_UNUSED)
{
const SCM cdr_expr = SCM_CDR (expr);
ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr);
ASSERT_SYNTAX (scm_ilength (cdr_expr) == 1, s_expression, expr);
SCM_SETCDR (expr, scm_cons (SCM_EOL, cdr_expr));
return expr;
}
SCM_SYNTAX (s_delay, "delay", scm_i_makbimacro, scm_m_delay);
SCM_GLOBAL_SYMBOL (scm_sym_delay, s_delay);
@ -941,10 +958,11 @@ SCM_GLOBAL_SYMBOL (scm_sym_delay, s_delay);
* the empty list represents the empty parameter list. This representation
* allows for easy creation of the closure during evaluation. */
SCM
scm_m_delay (SCM xorig, SCM env SCM_UNUSED)
scm_m_delay (SCM expr, SCM env)
{
SCM_ASSYNT (scm_ilength (xorig) == 2, s_expression, s_delay);
return scm_cons2 (SCM_IM_DELAY, SCM_EOL, SCM_CDR (xorig));
const SCM new_expr = memoize_as_thunk_prototype (expr, env);
SCM_SETCAR (new_expr, SCM_IM_DELAY);
return new_expr;
}
@ -1435,10 +1453,11 @@ SCM_GLOBAL_SYMBOL (scm_sym_future, s_future);
* empty parameter list. This representation allows for easy creation
* of the closure during evaluation. */
SCM
scm_m_future (SCM xorig, SCM env SCM_UNUSED)
scm_m_future (SCM expr, SCM env)
{
SCM_ASSYNT (scm_ilength (xorig) == 2, s_expression, s_future);
return scm_cons2 (SCM_IM_FUTURE, SCM_EOL, SCM_CDR (xorig));
const SCM new_expr = memoize_as_thunk_prototype (expr, env);
SCM_SETCAR (new_expr, SCM_IM_FUTURE);
return new_expr;
}