require "./lib.cr"

module Lex
    class Lexer
        def initialize
            @config = LibLex::EvalConfig.new
            LibLex.eval_config_init(pointerof(@config))
        end

        def add_pattern(pattern : String, id : Int32)
            LibLex.eval_config_add(pointerof(@config), pattern, id)
        end

        def lex(string)
            # Initialize variables
            tokens = [] of Tuple(String, Int32)
            list = LibDs::Ll.new

            # Initialize the list the list
            LibDs.ll_init(pointerof(list))
            # Perform the lexing operation
            result = LibLex.eval_all(string, 0, 
                                     pointerof(@config), 
                                     pointerof(list))

            # Transform void* matches into actual tuples.
            if result == LibLex::Result::Success
                node = list.head
                while node
                    match = node.value.data.as(LibLex::Match*)
                    str = string[match.value.from...match.value.to]
                    tokens << { str, match.value.pattern }
                    node = node.value.next
                end
            end

            # Clean up.
            LibDs.ll_foreach(pointerof(list), nil,
                             ->LibDs.compare_always,
                             ->LibLex.eval_foreach_match_free)
            LibDs.ll_free(pointerof(list))

            return tokens
        end

        def finalize
            LibLex.eval_config_free(pointerof(@config))
        end
    end
end