From: Brendan Hansen <brendan.f.hansen@gmail.com>
Date: Tue, 20 Apr 2021 19:24:50 +0000 (-0500)
Subject: added iter.fold and iter.take
X-Git-Url: https://git.brendanfh.com/?a=commitdiff_plain;h=fdea2bf97788b74b28ffa0376ffe9137e476d21d;p=onyx.git

added iter.fold and iter.take
---

diff --git a/core/iter.onyx b/core/iter.onyx
index 032fa2e8..601fa08c 100644
--- a/core/iter.onyx
+++ b/core/iter.onyx
@@ -73,8 +73,42 @@ map :: (it: Iterator($T), transform: (T) -> $R) -> Iterator(R) {
     };
 }
 
-fold :: (it: Iterator($T), initial_value: R = __zero_value(R), combine: (T, $R) -> R) -> R {
-    assert(false, "Not implemented yet");
+take :: (it: Iterator($T), count: u32) -> Iterator(T) {
+    TakeIterator :: struct (T: type_expr) {
+        iterator:  Iterator(T);
+        remaining: u32;
+    }
+
+    take_iterator := new(#type TakeIterator(T));
+    take_iterator.iterator = it;
+    take_iterator.remaining = count;
+
+    next :: ($T: type_expr, data: rawptr) -> (T, bool) {
+        ti := cast(^TakeIterator(T)) data;
+        if ti.remaining == 0 do return __zero_value(T), false;
+
+        ti.remaining -= 1;
+        return ti.iterator.next(ti.iterator.data);
+    }
+
+    close :: ($T: type_expr, data: rawptr) {
+        ti := cast(^TakeIterator(T)) data;
+        ti.iterator.close(ti.iterator.data);
+        cfree(data);
+    }
+
+    return .{
+        data  = take_iterator,
+        next  = #solidify next  { T=T },
+        close = #solidify close { T=T },
+    };
+}
+
+fold :: (it: Iterator($T), initial_value: R, combine: (T, $R) -> R) -> R {
+    for value: it {
+        initial_value = combine(value, initial_value);
+    }
+    
     return initial_value;
 }
 
diff --git a/tests/lazy_iterators.onyx b/tests/lazy_iterators.onyx
index 58f48a25..0e75b701 100644
--- a/tests/lazy_iterators.onyx
+++ b/tests/lazy_iterators.onyx
@@ -37,20 +37,18 @@ count_iterator :: (lo: i32, hi: i32, step := 1) -> Iterator(i32) {
 main :: (args: [] cstr) {
 
     iterator := count_iterator(1, 10)
-                |> iter.map((x: i32) -> i32 do return x * 2;)
-                |> iter.filter((x: i32) -> bool do return x > 10;)
-                |> iter.map((x: i32) -> i32 do return x + 42;);
+                |> iter.map((x: i32) -> i32     { return x * 2; })
+                |> iter.filter((x: i32) -> bool { return x > 10; })
+                |> iter.map((x: i32) -> i32     { return x + 42; });
 
     println("Starting the iteration...");
-    for i: iterator {
-        println(i);
-    }
+    for i: iterator do println(i);
 
     arr := count_iterator(1, 10)
-                |> iter.map((x: i32) -> i32 do return x * 2;)
-                |> iter.filter((x: i32) -> bool do return x > 10;)
-                |> iter.map((x: i32) -> i32 do return x + 42;)
-                |> iter.to_array();
+            |> iter.map((x: i32) -> i32     { return x * 2; })
+            |> iter.filter((x: i32) -> bool { return x > 10; })
+            |> iter.map((x: i32) -> i32     { return x + 42; })
+            |> iter.to_array();
 
     println(arr[2]);
 }