1 files changed, 79 insertions, 0 deletions
diff --git a/lib/std/buf_set.zig b/lib/std/buf_set.zig
new file mode 100644
index 0000000000..1a321e89c9
--- /dev/null
+++ b/lib/std/buf_set.zig
@@ -0,0 +1,79 @@
+const std = @import("std.zig");
+const StringHashMap = std.StringHashMap;
+const mem = @import("mem.zig");
+const Allocator = mem.Allocator;
+const testing = std.testing;
+
+pub const BufSet = struct {
+    hash_map: BufSetHashMap,
+
+    const BufSetHashMap = StringHashMap(void);
+
+    pub fn init(a: *Allocator) BufSet {
+        var self = BufSet{ .hash_map = BufSetHashMap.init(a) };
+        return self;
+    }
+
+    pub fn deinit(self: *const BufSet) void {
+        var it = self.hash_map.iterator();
+        while (true) {
+            const entry = it.next() orelse break;
+            self.free(entry.key);
+        }
+
+        self.hash_map.deinit();
+    }
+
+    pub fn put(self: *BufSet, key: []const u8) !void {
+        if (self.hash_map.get(key) == null) {
+            const key_copy = try self.copy(key);
+            errdefer self.free(key_copy);
+            _ = try self.hash_map.put(key_copy, {});
+        }
+    }
+
+    pub fn exists(self: BufSet, key: []const u8) bool {
+        return self.hash_map.get(key) != null;
+    }
+
+    pub fn delete(self: *BufSet, key: []const u8) void {
+        const entry = self.hash_map.remove(key) orelse return;
+        self.free(entry.key);
+    }
+
+    pub fn count(self: *const BufSet) usize {
+        return self.hash_map.count();
+    }
+
+    pub fn iterator(self: *const BufSet) BufSetHashMap.Iterator {
+        return self.hash_map.iterator();
+    }
+
+    pub fn allocator(self: *const BufSet) *Allocator {
+        return self.hash_map.allocator;
+    }
+
+    fn free(self: *const BufSet, value: []const u8) void {
+        self.hash_map.allocator.free(value);
+    }
+
+    fn copy(self: *const BufSet, value: []const u8) ![]const u8 {
+        const result = try self.hash_map.allocator.alloc(u8, value.len);
+        mem.copy(u8, result, value);
+        return result;
+    }
+};
+
+test "BufSet" {
+    var bufset = BufSet.init(std.heap.direct_allocator);
+    defer bufset.deinit();
+
+    try bufset.put("x");
+    testing.expect(bufset.count() == 1);
+    bufset.delete("x");
+    testing.expect(bufset.count() == 0);
+
+    try bufset.put("x");
+    try bufset.put("y");
+    try bufset.put("z");
+}