Merge branch 'stclib:master' into modifiedHEADmodified

1 files changed, 66 insertions, 0 deletions

diff --git a/misc/examples/coroutines/generator.c b/misc/examples/coroutines/generator.c
new file mode 100644
index 00000000..96498498
--- /dev/null
+++ b/misc/examples/coroutines/generator.c
@@ -0,0 +1,66 @@
+// https://quuxplusone.github.io/blog/2019/03/06/pythagorean-triples/
+
+#include <stdio.h>
+#include <stc/coroutine.h>
+#include <stc/algorithm.h>
+
+typedef struct {
+    int max_triples;
+    int a, b, c;
+} Triple;
+
+// Create an iterable generator over Triple with count items.
+// Requires coroutine Triple_next() and function Triple_begin() to be defined.
+cco_iter_struct(Triple,
+    int count;
+);
+
+int Triple_next(Triple_iter* it) {
+    Triple* g = it->ref; // note: before cco_routine
+    cco_routine(it)
+    {
+        for (g->c = 5;; ++g->c) {
+            for (g->a = 1; g->a < g->c; ++g->a) {
+                for (g->b = g->a; g->b < g->c; ++g->b) {
+                    if (g->a*g->a + g->b*g->b == g->c*g->c) {
+                        if (it->count++ == g->max_triples)
+                            cco_return;
+                        cco_yield();
+                    }
+                }
+            }
+        }
+        cco_final:
+        it->ref = NULL; // stop the iterator
+    }
+    return 0;
+}
+
+Triple_iter Triple_begin(Triple* g) {
+    Triple_iter it = {.ref=g};
+    Triple_next(&it);
+    return it;
+}
+
+
+int main(void)
+{
+    puts("Pythagorean triples.\nGet max 200 triples with c < 50:");
+    Triple triple = {.max_triples=200};
+
+    c_foreach (i, Triple, triple) {
+        if (i.ref->c < 50)
+            printf("%u: (%d, %d, %d)\n", i.count, i.ref->a, i.ref->b, i.ref->c);
+        else
+            cco_stop(&i);
+    }
+
+    puts("\nGet the 10 first triples with odd a's and a <= 20:");
+    c_forfilter (i, Triple, triple,
+                    i.ref->a <= 20 &&
+                    (i.ref->a & 1) &&
+                    c_flt_take(i, 10)
+    ){
+        printf("%d: (%d, %d, %d)\n", c_flt_getcount(i), i.ref->a, i.ref->b, i.ref->c);
+    }
+}