51 lines
1.1 KiB
Crystal
51 lines
1.1 KiB
Crystal
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class CBOR::Decoder
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@lexer : Lexer
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@current_token : Token::T?
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def initialize(input)
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@lexer = Lexer.new(input)
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@current_token = @lexer.next_token
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end
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def read_string : String
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case token = @current_token
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when Token::StringT
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finish_token!
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token.value
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when Token::BytesT
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finish_token!
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String.new(token.value)
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else
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unexpected_token(token, "StringT or BytesT")
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end
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end
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def read_int
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read_type(Token::IntT) { |token| token.value }
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end
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def read_bytes
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read_type(Token::BytesT) { |token| token.value }
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end
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private def finish_token!
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@current_token = @lexer.next_token
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end
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private macro read_type(type, finish_token = true, &block)
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case token = @current_token
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when {{type}}
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{% if finish_token %}finish_token!{% end %}
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{{ block.body }}
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else
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unexpected_token(token, {{type.stringify.split("::").last}})
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end
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end
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private def unexpected_token(token, expected = nil)
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message = "Unexpected token #{token.class}"
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message += " expected #{expected}" if expected
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raise ParseError.new(message)
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end
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end
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