pub const Token = struct {
    tag: Tag,
    loc: Loc,

    pub const Loc = struct {
        start: usize,
        end: usize,
    };

    pub const keywords = std.StaticStringMap(Tag).initComptime(.{
        .{ "addrspace", .keyword_addrspace },
        .{ "align", .keyword_align },
        .{ "allowzero", .keyword_allowzero },
        .{ "and", .keyword_and },
        .{ "anyframe", .keyword_anyframe },
        .{ "anytype", .keyword_anytype },
        .{ "asm", .keyword_asm },
        .{ "async", .keyword_async },
        .{ "await", .keyword_await },
        .{ "break", .keyword_break },
        .{ "callconv", .keyword_callconv },
        .{ "catch", .keyword_catch },
        .{ "comptime", .keyword_comptime },
        .{ "const", .keyword_const },
        .{ "continue", .keyword_continue },
        .{ "defer", .keyword_defer },
        .{ "else", .keyword_else },
        .{ "enum", .keyword_enum },
        .{ "errdefer", .keyword_errdefer },
        .{ "error", .keyword_error },
        .{ "export", .keyword_export },
        .{ "extern", .keyword_extern },
        .{ "fn", .keyword_fn },
        .{ "for", .keyword_for },
        .{ "if", .keyword_if },
        .{ "inline", .keyword_inline },
        .{ "noalias", .keyword_noalias },
        .{ "noinline", .keyword_noinline },
        .{ "nosuspend", .keyword_nosuspend },
        .{ "opaque", .keyword_opaque },
        .{ "or", .keyword_or },
        .{ "orelse", .keyword_orelse },
        .{ "packed", .keyword_packed },
        .{ "pub", .keyword_pub },
        .{ "resume", .keyword_resume },
        .{ "return", .keyword_return },
        .{ "linksection", .keyword_linksection },
        .{ "struct", .keyword_struct },
        .{ "suspend", .keyword_suspend },
        .{ "switch", .keyword_switch },
        .{ "test", .keyword_test },
        .{ "threadlocal", .keyword_threadlocal },
        .{ "try", .keyword_try },
        .{ "union", .keyword_union },
        .{ "unreachable", .keyword_unreachable },
        .{ "usingnamespace", .keyword_usingnamespace },
        .{ "var", .keyword_var },
        .{ "volatile", .keyword_volatile },
        .{ "while", .keyword_while },
    });

    pub fn getKeyword(bytes: []const u8) ?Tag {
        return keywords.get(bytes);
    }

    pub const Tag = enum {
        invalid,
        invalid_periodasterisks,
        identifier,
        string_literal,
        multiline_string_literal_line,
        char_literal,
        eof,
        builtin,
        bang,
        pipe,
        pipe_pipe,
        pipe_equal,
        equal,
        equal_equal,
        equal_angle_bracket_right,
        bang_equal,
        l_paren,
        r_paren,
        semicolon,
        percent,
        percent_equal,
        l_brace,
        r_brace,
        l_bracket,
        r_bracket,
        period,
        period_asterisk,
        ellipsis2,
        ellipsis3,
        caret,
        caret_equal,
        plus,
        plus_plus,
        plus_equal,
        plus_percent,
        plus_percent_equal,
        plus_pipe,
        plus_pipe_equal,
        minus,
        minus_equal,
        minus_percent,
        minus_percent_equal,
        minus_pipe,
        minus_pipe_equal,
        asterisk,
        asterisk_equal,
        asterisk_asterisk,
        asterisk_percent,
        asterisk_percent_equal,
        asterisk_pipe,
        asterisk_pipe_equal,
        arrow,
        colon,
        slash,
        slash_equal,
        comma,
        ampersand,
        ampersand_equal,
        question_mark,
        angle_bracket_left,
        angle_bracket_left_equal,
        angle_bracket_angle_bracket_left,
        angle_bracket_angle_bracket_left_equal,
        angle_bracket_angle_bracket_left_pipe,
        angle_bracket_angle_bracket_left_pipe_equal,
        angle_bracket_right,
        angle_bracket_right_equal,
        angle_bracket_angle_bracket_right,
        angle_bracket_angle_bracket_right_equal,
        tilde,
        number_literal,
        doc_comment,
        container_doc_comment,
        keyword_addrspace,
        keyword_align,
        keyword_allowzero,
        keyword_and,
        keyword_anyframe,
        keyword_anytype,
        keyword_asm,
        keyword_async,
        keyword_await,
        keyword_break,
        keyword_callconv,
        keyword_catch,
        keyword_comptime,
        keyword_const,
        keyword_continue,
        keyword_defer,
        keyword_else,
        keyword_enum,
        keyword_errdefer,
        keyword_error,
        keyword_export,
        keyword_extern,
        keyword_fn,
        keyword_for,
        keyword_if,
        keyword_inline,
        keyword_noalias,
        keyword_noinline,
        keyword_nosuspend,
        keyword_opaque,
        keyword_or,
        keyword_orelse,
        keyword_packed,
        keyword_pub,
        keyword_resume,
        keyword_return,
        keyword_linksection,
        keyword_struct,
        keyword_suspend,
        keyword_switch,
        keyword_test,
        keyword_threadlocal,
        keyword_try,
        keyword_union,
        keyword_unreachable,
        keyword_usingnamespace,
        keyword_var,
        keyword_volatile,
        keyword_while,

        pub fn lexeme(tag: Tag) ?[]const u8 {
            return switch (tag) {
                .invalid,
                .identifier,
                .string_literal,
                .multiline_string_literal_line,
                .char_literal,
                .eof,
                .builtin,
                .number_literal,
                .doc_comment,
                .container_doc_comment,
                => null,

                .invalid_periodasterisks => ".**",
                .bang => "!",
                .pipe => "|",
                .pipe_pipe => "||",
                .pipe_equal => "|=",
                .equal => "=",
                .equal_equal => "==",
                .equal_angle_bracket_right => "=>",
                .bang_equal => "!=",
                .l_paren => "(",
                .r_paren => ")",
                .semicolon => ";",
                .percent => "%",
                .percent_equal => "%=",
                .l_brace => "{",
                .r_brace => "}",
                .l_bracket => "[",
                .r_bracket => "]",
                .period => ".",
                .period_asterisk => ".*",
                .ellipsis2 => "..",
                .ellipsis3 => "...",
                .caret => "^",
                .caret_equal => "^=",
                .plus => "+",
                .plus_plus => "++",
                .plus_equal => "+=",
                .plus_percent => "+%",
                .plus_percent_equal => "+%=",
                .plus_pipe => "+|",
                .plus_pipe_equal => "+|=",
                .minus => "-",
                .minus_equal => "-=",
                .minus_percent => "-%",
                .minus_percent_equal => "-%=",
                .minus_pipe => "-|",
                .minus_pipe_equal => "-|=",
                .asterisk => "*",
                .asterisk_equal => "*=",
                .asterisk_asterisk => "**",
                .asterisk_percent => "*%",
                .asterisk_percent_equal => "*%=",
                .asterisk_pipe => "*|",
                .asterisk_pipe_equal => "*|=",
                .arrow => "->",
                .colon => ":",
                .slash => "/",
                .slash_equal => "/=",
                .comma => ",",
                .ampersand => "&",
                .ampersand_equal => "&=",
                .question_mark => "?",
                .angle_bracket_left => "<",
                .angle_bracket_left_equal => "<=",
                .angle_bracket_angle_bracket_left => "<<",
                .angle_bracket_angle_bracket_left_equal => "<<=",
                .angle_bracket_angle_bracket_left_pipe => "<<|",
                .angle_bracket_angle_bracket_left_pipe_equal => "<<|=",
                .angle_bracket_right => ">",
                .angle_bracket_right_equal => ">=",
                .angle_bracket_angle_bracket_right => ">>",
                .angle_bracket_angle_bracket_right_equal => ">>=",
                .tilde => "~",
                .keyword_addrspace => "addrspace",
                .keyword_align => "align",
                .keyword_allowzero => "allowzero",
                .keyword_and => "and",
                .keyword_anyframe => "anyframe",
                .keyword_anytype => "anytype",
                .keyword_asm => "asm",
                .keyword_async => "async",
                .keyword_await => "await",
                .keyword_break => "break",
                .keyword_callconv => "callconv",
                .keyword_catch => "catch",
                .keyword_comptime => "comptime",
                .keyword_const => "const",
                .keyword_continue => "continue",
                .keyword_defer => "defer",
                .keyword_else => "else",
                .keyword_enum => "enum",
                .keyword_errdefer => "errdefer",
                .keyword_error => "error",
                .keyword_export => "export",
                .keyword_extern => "extern",
                .keyword_fn => "fn",
                .keyword_for => "for",
                .keyword_if => "if",
                .keyword_inline => "inline",
                .keyword_noalias => "noalias",
                .keyword_noinline => "noinline",
                .keyword_nosuspend => "nosuspend",
                .keyword_opaque => "opaque",
                .keyword_or => "or",
                .keyword_orelse => "orelse",
                .keyword_packed => "packed",
                .keyword_pub => "pub",
                .keyword_resume => "resume",
                .keyword_return => "return",
                .keyword_linksection => "linksection",
                .keyword_struct => "struct",
                .keyword_suspend => "suspend",
                .keyword_switch => "switch",
                .keyword_test => "test",
                .keyword_threadlocal => "threadlocal",
                .keyword_try => "try",
                .keyword_union => "union",
                .keyword_unreachable => "unreachable",
                .keyword_usingnamespace => "usingnamespace",
                .keyword_var => "var",
                .keyword_volatile => "volatile",
                .keyword_while => "while",
            };
        }

        pub fn symbol(tag: Tag) []const u8 {
            return tag.lexeme() orelse switch (tag) {
                .invalid => "invalid token",
                .identifier => "an identifier",
                .string_literal, .multiline_string_literal_line => "a string literal",
                .char_literal => "a character literal",
                .eof => "EOF",
                .builtin => "a builtin function",
                .number_literal => "a number literal",
                .doc_comment, .container_doc_comment => "a document comment",
                else => unreachable,
            };
        }
    };
}