106 lines
4 KiB
C++
106 lines
4 KiB
C++
/* file expect_expr_xs.hpp
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*
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* author: Roland Conybeare, Aug 2024
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*/
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#pragma once
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#include "exprstate.hpp"
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namespace xo {
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namespace scm {
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/** @class expect_expr_xs
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* @brief state machine to expect + capture an expression
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*
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* Examples:
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* @text
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* add (1, 2) ;
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* def x : i64 = 5 ; // with allow_defs
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* lambda (f : x64) { ... } ;
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* if (prime(x)) { ... } ;
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* 5 + x ;
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* @endtext
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*
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* top exprstate when expect_expr_xs::start() invoked
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* will receive parsed expression via
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* exprstate::on_expr() or exprstate::on_expr_with_semicolon().
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**/
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class expect_expr_xs : public exprstate {
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public:
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explicit expect_expr_xs(bool allow_defs,
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bool cxl_on_rightbrace);
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static void start(parserstatemachine * p_psm);
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static void start(bool allow_defs,
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bool cxl_on_rightbrace,
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parserstatemachine * p_psm);
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virtual const char * get_expect_str() const override;
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virtual void on_lambda_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_if_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_def_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_leftparen_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_leftbrace_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_rightbrace_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_symbol_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_bool_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_i64_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_f64_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_string_token(const token_type & tk,
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parserstatemachine * p_psm) final override;
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/** update exprstate in response to a successfully-parsed subexpression **/
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virtual void on_expr(bp<Expression> expr,
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parserstatemachine * p_psm) override;
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/** update exprstate in response to a successfully-parsed subexpression
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* that's terminated by semicolon ';'
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**/
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virtual void on_expr_with_semicolon(bp<Expression> expr,
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parserstatemachine * p_psm) override;
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virtual void print(std::ostream & os) const override;
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virtual bool pretty_print(const xo::print::ppindentinfo & ppii) const override;
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private:
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static std::unique_ptr<expect_expr_xs> make(bool allow_defs,
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bool cxl_on_rightbrace);
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private:
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/** if true: allow a define-expression here **/
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bool allow_defs_ = false;
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/** if true: expecting either:
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* - expression
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* - right brace '}', in which case no expression
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* if false: expecting
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* - expression
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**/
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bool cxl_on_rightbrace_ = false;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end expect_expr_xs.hpp */
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