From 96709aa013e873cf5dba5dd3c2afb54a8d391eb0 Mon Sep 17 00:00:00 2001
From: tocariimaa <tocariimaa@firemail.cc>
Date: Wed, 5 Feb 2025 13:33:29 -0300
Subject: [PATCH] add `branch` word

---
 pila.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/pila.c b/pila.c
index 2a5a862..78d5d82 100644
--- a/pila.c
+++ b/pila.c
@@ -477,6 +477,24 @@ find_word_nat(RpnState *st)
 	push_val(st, BOX_INTN((u64)w));
 }
 
+void
+branch_nat(RpnState *st)
+{
+	Value predw = pop_val(st);
+	if (predw.kind != VAL_INT) {
+		return;
+	}
+	Str wn = next_word(st);
+	if (predw.intn == PILA_TRUE) {
+		Word *w = search_word(st, wn);
+		if (w == nil) {
+			signal_errorf(st, "no such word '%.*s'", (int)wn.len, wn.s);
+			return;
+		}
+		eval_word(st, w);
+	}
+}
+
 void
 add_word(RpnState *st, Word *w)
 {
@@ -682,6 +700,7 @@ main(int argc, char **argv)
 		{.name = Sl("emit"), .kind = WORD_NATIVE, .nat = emit_nat },
 		{.name = Sl("."), .kind = WORD_NATIVE, .nat = print_nat },
 		{.name = Sl(","), .kind = WORD_NATIVE, .nat = getch_nat },
+		{.name = Sl("branch"), .kind = WORD_NATIVE, .nat = branch_nat },
 	};
 	for (isize i = 0; i < countof(natws); ++i)
 		add_word(&st, &natws[i]);