94 lines
3.5 KiB
C++
94 lines
3.5 KiB
C++
/* file scan_result.hpp
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*
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* author: Roland Conybeare, Jun 2025
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*/
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#pragma once
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#include "token.hpp"
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#include "tokenizer_error.hpp"
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#include "input_state.hpp"
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namespace xo {
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namespace scm {
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/** @class scan_result
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* @brief Represent result of parsing one input token.
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*
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* @code
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* Possible outcomes fall into several categories
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* (with T: @c token_.is_valid(), E: @cerror_.is_error())
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*
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* | T | E | description |
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* |-------+-------+-------------------------------------|
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* | false | false | end of input, including end of line |
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* | true | false | parsed token in T |
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* | false | true | parse error in E |
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*
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* @endcode
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**/
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template <typename CharT>
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class scan_result {
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public:
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using token_type = token<CharT>;
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using span_type = span<const CharT>;
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using error_type = tokenizer_error<CharT>;
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using input_state_type = input_state<CharT>;
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public:
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scan_result(const token_type & token,
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const span_type & consumed,
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const error_type & error = error_type())
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: token_{token}, consumed_{consumed}, error_{error} {}
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static scan_result make_whitespace(const span_type & prefix_input);
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static scan_result make_partial(const span_type & prefix_input);
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static scan_result make_error(const error_type & error,
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input_state_type & input_state_ref);
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bool is_eof_or_ambiguous() const { return token_.is_invalid() && error_.is_not_an_error(); }
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bool is_token() const { return token_.is_valid(); }
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bool is_error() const { return error_.is_error(); }
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const token_type & get_token() const { return token_; }
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const span_type & consumed() const { return consumed_; }
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const error_type & error() const { return error_; }
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public:
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/** Successfully parsed token, whenever tk_type != tokentype::tk_invalid.
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* Will be tokentype::tk_invalid in normal cause of events for valid input,
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* when consuming whitespace
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**/
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token_type token_;
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/** input span represented by .token, on success. Otherwise not defined **/
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span_type consumed_;
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/** error description, whenever .error_.is_error() is true **/
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error_type error_;
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};
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template <typename CharT>
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auto scan_result<CharT>::make_whitespace(const span_type& whitespace_input) -> scan_result
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{
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return scan_result(token_type::invalid(), whitespace_input /*consumed*/);
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}
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template <typename CharT>
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auto scan_result<CharT>::make_partial(const span_type& prefix_input) -> scan_result
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{
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return scan_result(token_type::invalid(), prefix_input /*consumed*/);
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}
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template <typename CharT>
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auto scan_result<CharT>::make_error(const error_type & error,
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input_state_type & input_state_ref) -> scan_result
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{
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/* report+consume entire input line */
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return scan_result(token_type::invalid(),
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input_state_ref.consume_current_line(),
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error);
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}
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} /*namespace scm*/
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} /*namespace xo*/
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/* end scan_result.hpp */
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