1 files changed, 27 insertions, 5 deletions
diff --git a/src/filter.zig b/src/filter.zig
index b9e2167..2395dda 100644
--- a/src/filter.zig
+++ b/src/filter.zig
@@ -7,16 +7,38 @@ const typeVerify = @import("util.zig").typeVerify;
 /// Filters a slice, only keeping items give `true` when passed into `func`
 /// Type signature: `(a -> bool) -> [a] -> [a]`
 /// `func` is of type `a -> bool`, where `items` is of type `[a]`
-pub fn filter(
+pub fn filterAlloc(
+    allocator: std.mem.Allocator,
     func: anytype,
     items: []typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn".params[0].type.?,
-) []typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn".params[0].type.? {
-    var output = items;
+) ![]typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn".params[0].type.? {
+    var tmp = items;
     var i: u32 = 0;
     for (items) |it|
         if (func(it)) {
-            output[i] = it;
+            tmp[i] = it;
             i = i + 1;
         };
-    return output[0..i];
+
+    const output = try allocator.alloc(typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn".params[0].type.?, i);
+    for (0..i) |j|
+        output[j] = tmp[i];
+    return output;
+}
+
+pub fn filterBuff(
+    func: anytype,
+    items: []typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn".params[0].type.?,
+    buffer: *[]typeVerify(@TypeOf(func), .{ .@"fn" }).@"fn".params[0].type.?,
+) void {
+    var tmp = items;
+    var i: u32 = 0;
+    for (items) |it|
+        if (func(it)) {
+            tmp[i] = it;
+            i = i + 1;
+        };
+
+    for (0..i) |j|
+        buffer[j] = tmp[i];
 }