214 lines
7.6 KiB
C++
214 lines
7.6 KiB
C++
/** @file exprstate.hpp
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*
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* Author: Roland Conybeare
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**/
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#pragma once
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#include "xo/expression/Expression.hpp"
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#include "xo/tokenizer/token.hpp"
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#include <stack>
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//#include <cstdint>
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namespace xo {
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namespace scm {
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/** Identify current state in an expression state machine
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**/
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enum class exprstatetype {
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invalid = -1,
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/** toplevel of some translation unit **/
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expect_toplevel_expression_sequence,
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/** handle define-expression
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* see @ref define_xs
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**/
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defexpr,
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/** handle lambda-expression
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* see @ref lambda_xs
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**/
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lambdaexpr,
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/** handle parenthesized expression
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* see @ref paren_xs
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**/
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parenexpr,
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/** handle sequence expression (aka block)
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* see @ref sequence_xs
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**/
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sequenceexpr,
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/** handle let1 (single local variable)
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* see @ref let1_xs
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**/
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let1expr,
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expect_rhs_expression,
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expect_symbol,
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expect_type,
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/** handle formal argument list
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* see @ref expect_formal_arglist_xs
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**/
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expect_formal_arglist,
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/** handle formal argument
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* see @ref expec_formal_xs
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**/
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expect_formal,
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/** handle expression-in-progress,
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* in case infix operators to follow
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* see @ref progress_xs
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**/
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expr_progress,
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n_exprstatetype
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};
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extern const char *
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exprstatetype_descr(exprstatetype x);
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inline std::ostream &
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operator<< (std::ostream & os, exprstatetype x) {
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os << exprstatetype_descr(x);
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return os;
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}
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class parserstatemachine; /* see parserstatemachine.hpp */
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class exprstatestack;
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class formal_arg;
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/** state associated with a partially-parsed expression.
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**/
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class exprstate {
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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 exprtype = xo::ast::exprtype;
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using token_type = token<char>;
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using TypeDescr = xo::reflect::TypeDescr;
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public:
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exprstate() = default;
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exprstate(exprstatetype exs_type)
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: exs_type_{exs_type}
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{}
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virtual ~exprstate() = default;
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exprstatetype exs_type() const { return exs_type_; }
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/** update exprstate in response to incoming token @p tk,
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* forward instructions to parent parser
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**/
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void on_input(const token_type & tk,
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parserstatemachine * p_psm);
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/** update exprstate in response to a successfully-parsed subexpression **/
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virtual void on_expr(ref::brw<Expression> expr,
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parserstatemachine * p_psm);
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/** update exprstate in response to a successfully-parsed subexpression, that ends with semicolon **/
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virtual void on_expr_with_semicolon(ref::brw<Expression> expr,
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parserstatemachine * p_psm);
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/** update exprstate when expecting a symbol **/
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virtual void on_symbol(const std::string & symbol,
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parserstatemachine * p_psm);
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/** update exprstate when expeccting a typedescr **/
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virtual void on_typedescr(TypeDescr td,
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parserstatemachine * p_psm);
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/** update exprstate when expecting a formal parameter **/
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virtual void on_formal(const rp<Variable> & formal,
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parserstatemachine * p_psm);
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/** update expression when epecting a formal parameter list **/
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virtual void on_formal_arglist(const std::vector<rp<Variable>> & argl,
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parserstatemachine * p_psm);
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/** print human-readable representation on @p os **/
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virtual void print(std::ostream & os) const;
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// ----- input methods -----
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/** handle incoming 'def' token **/
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virtual void on_def_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming 'lambda' token **/
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virtual void on_lambda_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming symbol token **/
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virtual void on_symbol_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming ',' token **/
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virtual void on_comma_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming ':' token **/
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virtual void on_colon_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming ';' token **/
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virtual void on_semicolon_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming '=' token **/
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virtual void on_singleassign_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming '(' token **/
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virtual void on_leftparen_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming ')' token **/
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virtual void on_rightparen_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming '{' token **/
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virtual void on_leftbrace_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming '}' token **/
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virtual void on_rightbrace_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming operator token **/
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virtual void on_operator_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming integer-literal token **/
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virtual void on_i64_token(const token_type & tk,
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parserstatemachine * p_psm);
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/** handle incoming floating-point-literal token **/
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virtual void on_f64_token(const token_type & tk,
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parserstatemachine * p_psm);
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protected:
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/** throw exception when next token is inconsistent with
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* parsing state
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**/
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void illegal_input_error(const char * self_name,
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const token_type & tk) const;
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protected:
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/** explicit subtype: identifies derived class **/
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exprstatetype exs_type_;
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}; /*exprstate*/
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inline std::ostream &
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operator<< (std::ostream & os, const exprstate & x) {
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x.print(os);
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return os;
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}
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inline std::ostream &
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operator<< (std::ostream & os, const exprstate * x) {
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if (x)
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x->print(os);
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else
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os << "nullptr";
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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 exprstate.hpp **/
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