0a2894f07a
When a text token was running, it wouldn't stop on a $-sign if it wasn't followed with a "[". This is good. But when a token was finished and the next char was a $-sign, it would consider it an MFMOpen, even when not followed by a "[". This is now fixed.
75 lines
1.4 KiB
Elixir
75 lines
1.4 KiB
Elixir
defmodule MfmParser.Lexer do
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alias MfmParser.Reader
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alias MfmParser.Token
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alias MfmParser.Token.MFM
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alias MfmParser.Token.Newline
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alias MfmParser.Token.Text
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def peek(input) do
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case next(input) do
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{token, _} -> token
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:eof -> :eof
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end
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end
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def next(input) do
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recursive_extract_next_token(Reader.next(input), get_empty_token(input))
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end
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defp recursive_extract_next_token(:eof, _) do
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:eof
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end
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defp recursive_extract_next_token({char, rest}, token) do
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if is_last_char_of_token?(char, rest, token) do
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{token |> Token.append(char), rest}
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else
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recursive_extract_next_token(Reader.next(rest), token |> Token.append(char))
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end
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end
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defp get_empty_token(input) do
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case Reader.peek(input) do
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:eof ->
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:eof
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"$" ->
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if Reader.peek(input, 2) == "[" do
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%MFM.Open{}
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else
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%Text{}
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end
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"]" ->
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%MFM.Close{}
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"\n" ->
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%Newline{}
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_ ->
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%Text{}
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end
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end
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defp is_last_char_of_token?(char, _, %MFM.Open{}) do
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char == " "
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end
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defp is_last_char_of_token?(_, _, %MFM.Close{}) do
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true
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end
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defp is_last_char_of_token?(_, _, %Newline{}) do
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true
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end
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defp is_last_char_of_token?(_, rest, %Text{}) do
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case Reader.next(rest) do
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:eof -> true
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{"]", _} -> true
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{"$", new_rest} -> Reader.peek(new_rest) == "["
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_ -> false
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end
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end
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end
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