1 files changed, 38 insertions, 0 deletions
diff --git a/src/character.zig b/src/character.zig
new file mode 100644
index 0000000..bd11ccd
--- /dev/null
+++ b/src/character.zig
@@ -0,0 +1,38 @@
+const std = @import("std");
+
+pub const Character = union(enum) {
+	const Self = @This();
+
+	pub const EPSILON: u8 = '_';
+	pub const END: u8 = 0;
+
+	epsilon: void,
+	terminal: u8,
+	non_terminal: u8,
+
+	pub fn from_u8(c: u8) Self {
+		if (c == '_') {
+			return Self { .epsilon = void{} };
+		} else if (std.ascii.isUpper(c)) {
+			return Self { .non_terminal = c };
+		} else {
+			return Self { .terminal = c };
+		}
+	}
+
+	pub fn format(
+		self: *const Self,
+		comptime fmt: []const u8,
+		options: std.fmt.FormatOptions,
+		writer: anytype,
+	) !void {
+		_ = fmt;
+		_ = options;
+
+		switch (self.*) {
+			.epsilon => _ = try writer.writeAll("ε"),
+			.terminal => |c| try writer.writeByte(c),
+			.non_terminal => |c| try writer.writeByte(c),
+		}
+	}
+};