227 lines
8.2 KiB
C++
227 lines
8.2 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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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 parenthesized expression
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* see @ref paren_xs
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**/
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parenexpr,
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expect_rhs_expression,
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expect_symbol,
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expect_type,
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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 exprstatestack;
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class define_xs;
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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 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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#ifdef RELOCATED
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static std::unique_ptr<exprstate> expect_rhs_expression() {
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return std::make_unique<exprstate>(exprstate(exprstatetype::expect_rhs_expression));
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}
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#endif
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static std::unique_ptr<exprstate> expect_symbol() {
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return std::make_unique<exprstate>(exprstate(exprstatetype::expect_symbol));
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}
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static std::unique_ptr<exprstate> expect_type() {
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return std::make_unique<exprstate>(exprstate(exprstatetype::expect_type));
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}
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exprstatetype exs_type() const { return exs_type_; }
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/** true iff this parsing state admits a symbol as next token **/
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virtual bool admits_symbol() const;
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/** true iff this parsing state admits a colon as next token **/
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virtual bool admits_colon() const;
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/** true iff this parsing state admits a semicolon as next token **/
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virtual bool admits_semicolon() const;
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/** true iff this parsing state admits a singleassign '=' as next token **/
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virtual bool admits_singleassign() const;
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/** true iff this parsing state admits a leftparen '(' as next token **/
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virtual bool admits_leftparen() const;
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/** truee iff this parsing state admits a rightparen ')' as next token **/
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virtual bool admits_rightparen() const;
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#ifdef OBSOLETE
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/** true iff this parsing state admits a 64-bit floating point literal token **/
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virtual bool admits_f64() const;
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#endif
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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, exprstatestack * p_stack, rp<Expression> * p_emit_expr);
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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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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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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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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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/** update exprstate when expeccting a typedescr **/
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virtual void on_typedescr(TypeDescr td,
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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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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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exprstatestack * p_stack);
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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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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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/** handle incoming ':' token **/
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virtual void on_colon_token(const token_type & tk,
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exprstatestack * p_stack);
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/** handle incoming ';' token **/
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virtual void on_semicolon_token(const token_type & tk,
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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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/** handle incoming '=' token **/
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virtual void on_singleassign_token(const token_type & tk,
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exprstatestack * p_stack);
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/** handle incoming '(' token **/
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virtual void on_leftparen_token(const token_type & tk,
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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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/** handle incoming ')' token **/
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virtual void on_rightparen_token(const token_type & tk,
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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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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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exprstatestack * p_stack,
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rp<Expression> * p_emit_expr);
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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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/** @class exprstatestack
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* @brief A stack of exprstate objects
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**/
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class exprstatestack {
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public:
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exprstatestack() {}
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bool empty() const { return stack_.empty(); }
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std::size_t size() const { return stack_.size(); }
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exprstate & top_exprstate();
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void push_exprstate(std::unique_ptr<exprstate> exs);
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std::unique_ptr<exprstate> pop_exprstate();
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/** relative to top-of-stack.
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* 0 -> top (last in), z-1 -> bottom (first in)
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**/
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std::unique_ptr<exprstate> & operator[](std::size_t i) {
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std::size_t z = stack_.size();
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assert(i < z);
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return stack_[z - i - 1];
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}
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const std::unique_ptr<exprstate> & operator[](std::size_t i) const {
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std::size_t z = stack_.size();
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assert(i < z);
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return stack_[z - i - 1];
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}
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void print (std::ostream & os) const;
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private:
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std::vector<std::unique_ptr<exprstate>> stack_;
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};
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inline std::ostream &
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operator<< (std::ostream & os, const exprstatestack & 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 exprstatestack * 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 exprstate.hpp **/
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