1 files changed, 56 insertions, 20 deletions

diff --git a/src/gss.zig b/src/gss.zig
index 8f81d80..ef5d221 100644
--- a/src/gss.zig
+++ b/src/gss.zig
@@ -4,34 +4,39 @@ pub fn Node(T: type) type {
 	return struct {
 		const Self = @This();
 
-		parent: ?*Self = null,
+		parents: *std.ArrayList(*Self),
 		state: T,
+		is_toplevel: bool = false,
 
-		pub fn init(state: T) Self {
-			return Self { .state = state };
-		}
+		pub fn init(state: T, allocator: std.mem.Allocator) !Self {
+			const parents = try allocator.create(std.ArrayList(*Self));
+			parents.* = std.ArrayList(*Self).init(allocator);
 
-		pub fn push(self: *Self, state: T, allocator: std.mem.Allocator) !*Self {
-			const node = try allocator.create(Self);
-			node.parent = self;
-			node.state = state;
-			return node;
+			return Self {
+				.state = state,
+				.parents = parents,
+			};
 		}
 
-		pub fn clone(self: *Self, state: T, allocator: std.mem.Allocator) !*Self {
-			const node = try allocator.create(Self);
-			node.parent = self.parent;
-			node.state = state;
-			return node;
+		pub fn clone(self: *Self, state: T) !Self {
+			return Self {
+				.parents = self.parents,
+				.state = state,
+				.is_toplevel = self.is_toplevel,
+			};
 		}
 
-		pub fn pop(self: *Self, allocator: std.mem.Allocator) struct { T, ?*Self } {
-			const parent = self.parent;
-			const state = self.state;
+		pub fn push(self: *Self, state: T) !Self {
+			const parents = try self.parents.allocator.create(std.ArrayList(*Self));
+			parents.* = std.ArrayList(*Self).init(self.parents.allocator);
+			var other = Self {
+				.parents = parents,
+				.state = state,
+			};
 
-			allocator.destroy(self);
+			try other.parents.append(self);
 
-			return .{ state, parent };
+			return other;
 		}
 
 		pub fn format(
@@ -43,7 +48,38 @@ pub fn Node(T: type) type {
 			_ = fmt;
 			_ = options;
 
-			try writer.print("Node {{ {} }}", .{ self.state });
+			try writer.print("Node {{ {} }}", .{self.state});
+		}
+	};
+}
+
+pub fn Graph(T: type) type {
+	return struct {
+		const Self = @This();
+
+		allocator: std.mem.Allocator,
+
+		pub fn init(allocator: std.mem.Allocator) Self {
+			return Self { .allocator = allocator };
+		}
+
+		pub fn push(self: *Self, node: *Node(T), state: T) !*Node(T) {
+			const child = try self.allocator.create(Node(T));
+			child.* = try node.push(state);
+			return child;
+		}
+
+		pub fn add_toplevel(self: *Self, state: T) !*Node(T) {
+			const node = try self.allocator.create(Node(T));
+			node.* = try Node(T).init(state, self.allocator);
+			node.is_toplevel = true;
+			return node;
+		}
+
+		pub fn clone(self: *Self, node: *Node(T), state: T) !*Node(T) {
+			const sibling = try self.allocator.create(Node(T));
+			sibling.* = try node.clone(state);
+			return sibling;
 		}
 	};
 }