1 files changed, 33 insertions, 0 deletions
diff --git a/src/builder.zig b/src/builder.zig
new file mode 100644
index 000000000..19daa0a20
--- /dev/null
+++ b/src/builder.zig
@@ -0,0 +1,33 @@
+const Allocator = @import("std").mem.Allocator;
+const assert = @import("std").debug.assert;
+const copy = @import("std").mem.copy;
+const io = @import("io");
+pub fn Builder(comptime Type: type) type {
+    return struct {
+        const This = @This();
+
+        len: usize = 0,
+        cap: usize = 0,
+        ptr: ?[*]Type = null,
+
+        pub fn count(this: *This, slice: Type) void {
+            this.cap += slice.len;
+        }
+
+        pub fn allocate(this: *This, allocator: *Allocator) !void {
+            var slice = try allocator.alloc(Type, this.cap);
+            this.ptr = slice.ptr;
+            this.len = 0;
+        }
+
+        pub fn append(this: *This, item: Type) *const Type {
+            assert(this.len <= this.cap); // didn't count everything
+            assert(this.ptr != null); // must call allocate first
+            var result = &this.ptr.?[this.len];
+            result.* = item;
+            this.len += 1;
+            assert(this.len <= this.cap);
+            return result;
+        }
+    };
+}