62 lines
2 KiB
C++
62 lines
2 KiB
C++
/* file parserstatemachine.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 "envframestack.hpp"
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namespace xo {
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namespace scm {
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/** @class parserstatemachine
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* @brief public parser state.
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*
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* Schematica parser state; sent to subsidiary single-feature state machines.
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* For example entry points for the lambda feature (@ref lambda_xs)
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* will accept a non-const parserstatemachine pointer argument
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**/
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class parserstatemachine {
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public:
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using Expression = xo::ast::Expression;
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using Variable = xo::ast::Variable;
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public:
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parserstatemachine(exprstatestack * p_stack,
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envframestack * p_env_stack,
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rp<Expression> * p_emit_expr)
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: p_stack_{p_stack},
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p_env_stack_{p_env_stack},
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p_emit_expr_{p_emit_expr} {}
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std::unique_ptr<exprstate> pop_exprstate();
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exprstate & top_exprstate();
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void push_exprstate(std::unique_ptr<exprstate> x);
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/** lookup variable name in lexical context represented by
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* this psm. nullptr if not found
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**/
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rp<Variable> lookup_var(const std::string & x) const;
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void push_envframe(envframe x);
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void pop_envframe();
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public:
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/** stack of incomplete parser work.
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* generally speaking, push when to start new work for nested content;
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* pop when work complete
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**/
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exprstatestack * p_stack_;
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/** stack of environment frames, one for each enclosing lambda **/
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envframestack * p_env_stack_;
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/** if non-null, store next non-nested complete expressions in
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* *p_emit_expr
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**/
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rp<Expression> * p_emit_expr_;
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};
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} /*namespace scm*/
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} /*namespace xo*/
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/* end parserstatemachine.hpp */
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