1 files changed, 91 insertions, 0 deletions
diff --git a/src/rule-list.zig b/src/rule-list.zig
new file mode 100644
index 0000000..a438750
--- /dev/null
+++ b/src/rule-list.zig
@@ -0,0 +1,91 @@
+const std = @import("std");
+const CharSet = @import("char-set.zig");
+const Character = @import("character.zig").Character;
+
+const Self = @This();
+const Rhs = []Character;
+
+name: u8,
+rhs: std.ArrayList(Rhs),
+first: CharSet,
+follows: CharSet,
+
+pub fn init(name: u8, allocator: std.mem.Allocator) Self {
+	return Self {
+		.name = name,
+		.rhs = std.ArrayList(Rhs).init(allocator),
+		.first = CharSet {},
+		.follows = CharSet {},
+	};
+}
+
+pub fn deinit(self: *Self, allocator: std.mem.Allocator) void {
+	for (self.rhs.items) |item| {
+		allocator.free(item);
+	}
+
+	self.rhs.deinit();
+}
+
+pub fn add_rule(self: *Self, rhs: Rhs) !void {
+	try self.rhs.append(rhs);
+}
+
+pub fn parse_rule(
+	buffer: []const u8,
+	allocator: std.mem.Allocator
+) !struct { u8, Rhs } {
+
+	var rhs = std.ArrayList(Character).init(allocator);
+	errdefer rhs.deinit();
+
+	var tokens = std.mem.tokenizeAny(u8, buffer, &std.ascii.whitespace);
+
+	const lhs = tokens.next() orelse return error.MissingLhs;
+	if (lhs.len > 1) return error.InvalidLhs;
+
+	const arrow = tokens.next() orelse return error.MissingArrow;
+	if (!std.mem.eql(u8, arrow, "->")) return error.InvalidArrow;
+
+	while (tokens.next()) |token| {
+		if (token.len > 1) return error.InvalidCharacter;
+		try rhs.append(Character.from_u8(token[0]));
+	}
+
+	if (rhs.items.len == 0) {
+		return error.EmptyProduction;
+	}
+
+	return .{ lhs[0], try rhs.toOwnedSlice() };
+}
+
+pub inline fn is_empty(self: *const Self) bool {
+	return self.rhs.items.len == 0;
+}
+
+pub fn format(
+	self: *const Self,
+	comptime fmt: []const u8,
+	options: std.fmt.FormatOptions,
+	writer: anytype,
+) !void {
+	_ = fmt;
+	_ = options;
+
+	try writer.print("[{c} -> ", .{ self.name });
+
+	if (self.rhs.items.len > 0) {
+		for (self.rhs.items[0]) |c| {
+			try writer.print("{}", .{c});
+		}
+
+		for (self.rhs.items[1..]) |r| {
+			try writer.print(" | ", .{});
+			for (r) |c| {
+				try writer.print("{}", .{c});
+			}
+		}
+	}
+
+	try writer.writeByte(']');
+}