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author | Kaz Kylheku <kaz@kylheku.com> | 2015-10-06 06:37:40 -0700 |
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committer | Kaz Kylheku <kaz@kylheku.com> | 2015-10-06 12:24:27 -0700 |
commit | 5698af7271b5c21a4b8a2721e5c20f66ad0dd7e2 (patch) | |
tree | e02708f59a219d6ec5cdfbbd0828b33745b75074 /eval.c | |
parent | 037e9a2b91f982fc941af8a152b4b104e418755b (diff) | |
download | txr-5698af7271b5c21a4b8a2721e5c20f66ad0dd7e2.tar.gz txr-5698af7271b5c21a4b8a2721e5c20f66ad0dd7e2.tar.bz2 txr-5698af7271b5c21a4b8a2721e5c20f66ad0dd7e2.zip |
New function, expand-right.
* eval.c (expand_right_fun, expand_right): New static
functions.
(eval_init): Register expand-right intrinsic.
* txr.1: Documented expand-right.
Diffstat (limited to 'eval.c')
-rw-r--r-- | eval.c | 29 |
1 files changed, 29 insertions, 0 deletions
@@ -3633,6 +3633,34 @@ static val ginterate(val while_pred, val gen_fun, val init_val) } } +static val expand_right_fun(val env, val lcons) +{ + cons_bind (pair, gen_fun, env); + cons_bind (elem, init_val, pair); + + val next_pair = funcall1(gen_fun, init_val); + + rplaca(lcons, elem); + + if (next_pair) { + rplacd(lcons, make_lazy_cons(lcons_fun(lcons))); + rplaca(env, next_pair); + } else { + rplacd(lcons, nil); + } + + return nil; +} + +static val expand_right(val gen_fun, val init_val) +{ + val pair = funcall1(gen_fun, init_val); + + if (!pair) + return nil; + + return make_lazy_cons(func_f1(cons(pair, gen_fun), expand_right_fun)); +} static val repeat_infinite_func(val env, val lcons) { @@ -4659,6 +4687,7 @@ void eval_init(void) reg_fun(generate_s, func_n2(generate)); reg_fun(intern(lit("giterate"), user_package), func_n3o(giterate, 2)); reg_fun(intern(lit("ginterate"), user_package), func_n3o(ginterate, 2)); + reg_fun(intern(lit("expand-right"), user_package), func_n2(expand_right)); reg_fun(intern(lit("repeat"), user_package), func_n2o(repeat, 1)); reg_fun(intern(lit("pad"), user_package), func_n3o(pad, 1)); reg_fun(intern(lit("weave"), user_package), func_n0v(weavev)); |