66 lines
2.3 KiB
C++
66 lines
2.3 KiB
C++
/* file let1_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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#include "xo/expression/LocalSymtab.hpp"
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namespace xo {
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namespace scm {
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class let1_xs : public exprstate {
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public:
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using LocalEnv = xo::scm::LocalSymtab;
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public:
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/** given local definition equivalent to
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* def lhs_name = rhs;
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* rest...
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* parse sequence of incoming expressions rest... (until '}')
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*
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* Result expression creates and inits @p lhs_name,
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* then evaluates expressions that follow definition
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* up to same-level '}'
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**/
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static void start(const std::string & lhs_name,
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const rp<Expression> & rhs,
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parserstatemachine * p_psm);
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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 on_rightbrace_token(const token_type & tk,
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parserstatemachine * p_psm) override;
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private:
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let1_xs(std::string lhs_name,
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rp<LocalEnv> local_env,
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rp<Expression> rhs);
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/** named ctor idiom **/
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static std::unique_ptr<let1_xs> make(std::string lhs_name,
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rp<LocalEnv> local_env,
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rp<Expression> rhs);
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private:
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/** name for new local variable **/
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std::string lhs_name_;
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/** environment. contains just @ref lhs_name_ **/
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rp<LocalEnv> local_env_;
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/** set initial value for @ref lhs_name_ from value of this expression **/
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rp<Expression> rhs_;
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/** evaluate expressions in this sequence, in order, in environment
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* with variable @ref lhs_name_ defined
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**/
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std::vector<rp<Expression>> expr_v_;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end let1_xs.hpp */
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