107 lines
3.4 KiB
C++
107 lines
3.4 KiB
C++
/** @file if_else_xs.hpp
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*
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* author: Roland Conybeare, Jul 2025
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**/
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#pragma once
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#include "xo/expression/IfExpr.hpp"
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#include "exprstate.hpp"
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#include "xo/indentlog/print/ppdetail_atomic.hpp"
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namespace xo {
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namespace scm {
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/**
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* if test-expr then then-expr else else-expr ;
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* ^ ^ ^ ^ ^ ^ ^
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* | | | | | | |
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* | if_1 if_2 if_3 if_4 if_5 if_6
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* if_0
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*
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* if_0 --on_if_token()--> if_1
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* if_1 --on_expr()--> if_2
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* if_2 --on_then_token()--> if_3
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* if_3 --on_expr()--> if_4
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* if_4 --on_else_token()--> if_5
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* --on_semicolon_token()--> (done)
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* if_5 --on_expr()-->if_6
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* if_6 --on_semicolon_token()--> (done)
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**/
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enum class ifexprstatetype {
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invalid = -1,
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if_0,
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if_1,
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if_2,
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if_3,
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if_4,
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if_5,
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if_6,
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n_ifexprstatetype,
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};
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extern const char * ifexprstatetype_descr(ifexprstatetype x);
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std::ostream &
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operator<<(std::ostream & os, ifexprstatetype x);
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/** @class if_else_xs
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* @brief state to provide parsing of a conditional expression
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**/
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class if_else_xs : public exprstate {
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public:
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using IfExprAccess = xo::ast::IfExprAccess;
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public:
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if_else_xs(rp<IfExprAccess> if_expr);
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virtual ~if_else_xs() = default;
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static const if_else_xs * from(const exprstate * x) { return dynamic_cast<const if_else_xs *>(x); }
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static void start(parserstatemachine * p_psm);
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// ----- inherited from exprstate -----
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virtual const char * get_expect_str() const 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_then_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_else_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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virtual void on_semicolon_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_expr(bp<Expression> expr,
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parserstatemachine * p_psm) override;
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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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private:
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static std::unique_ptr<if_else_xs> make();
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/** exit this exprstate,
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* and deliver @ref if_expr_ to parent exprstate
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**/
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void finish_and_continue(parserstatemachine * p_psm);
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private:
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ifexprstatetype ifxs_type_;
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/** scaffold output expression here **/
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rp<IfExprAccess> if_expr_;
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};
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} /*namespace scm*/
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namespace print {
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PPDETAIL_ATOMIC(xo::scm::ifexprstatetype);
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}
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} /*namespace xo*/
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/* end if_else_xs.hpp */
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