93 lines
3.2 KiB
C++
93 lines
3.2 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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using LocalEnv = xo::ast::LocalEnv;
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using token_type = token<char>;
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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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bp<Variable> lookup_var(const std::string & x) const;
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/** update/replace binding for variable @p x in lexical context
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* represented by this psm. Always acts on innermost frame.
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**/
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void upsert_var(bp<Variable> x);
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bp<LocalEnv> top_envframe() const;
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void push_envframe(const rp<LocalEnv> & x);
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rp<LocalEnv> pop_envframe();
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size_t env_stack_size() const { return p_env_stack_->size(); }
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// ----- parsing outputs -----
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void on_expr(bp<Expression> expr);
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void on_expr_with_semicolon(bp<Expression> expr);
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void on_symbol(const std::string & symbol);
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// ---- parsing inputs -----
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void on_semicolon_token(const token_type & tk);
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void on_operator_token(const token_type & tk);
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void on_leftbrace_token(const token_type & tk);
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void on_rightbrace_token(const token_type & tk);
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/** write human-readable representation on @p os **/
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void print(std::ostream & os) const;
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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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inline std::ostream &
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operator<<(std::ostream & os, const parserstatemachine & x) {
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x.print(os);
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return os;
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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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