74 lines
2.7 KiB
C++
74 lines
2.7 KiB
C++
#pragma once
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#ifndef PARSODUS_GRAMMAR_H
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#include "Parsodus/util/firstset.h"
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#include "Parsodus/util/followset.h"
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#include <map>
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#include <memory>
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#include <set>
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#include <string>
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#include <vector>
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namespace pds {
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enum class PrecedenceType {
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LEFT,
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RIGHT,
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NONASSOC
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};
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/**
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* Represents a grammar rule
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* head -> tail[0] tail[1] ... tail[tail.size() - 1]
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*/
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struct Rule {
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std::string head; ///< The replaced variable
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std::vector<std::string> tail; ///< The replacement rule
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const std::string name; ///< An optional name for this rule, if it's empty, there's no name
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std::pair<bool, std::pair<int, PrecedenceType>> precedence; ///< precedence for this rule, the bool indicates whether it's valid (invalid if there is no rightmost terminal and no explicit precedence)
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bool operator<(const Rule& other) const {
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if(head != other.head){
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return head < other.head;
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} else {
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return tail < other.tail;
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}
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}
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Rule() : head(""), tail(), name("") {}
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Rule(const std::string& h, const std::vector<std::string>& t) : head(h), tail(t), name("") {}
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Rule(const std::string& h, const std::vector<std::string>& t, const std::string& name) : head(h), tail(t), name(name) {}
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Rule(const std::string& h, const std::vector<std::string>& t, const std::string& name, std::pair<bool, std::pair<int, PrecedenceType>> precedence) :
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head(h), tail(t), name(name), precedence(precedence) {}
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};
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/**
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* A context free grammar
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* Keeps track of variables, terminals and replacement rules
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*/
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struct Grammar {
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std::string start; ///< the starting variable
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std::set<std::string> variables; ///< the variables
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std::set<std::string> terminals; ///< the terminals
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std::vector<std::shared_ptr<Rule>> rules; ///< the replacement rules
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std::map<std::string, std::pair<int, PrecedenceType> > precedence; ///< lower value -> higher precedence
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std::unique_ptr<util::FirstSet> first;
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std::unique_ptr<util::FollowSet> follow;
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Grammar() : start(""), variables(), terminals(), rules(), first(nullptr), follow(nullptr)
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{}
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Grammar(const Grammar& rhs)
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: start(rhs.start), variables(rhs.variables), terminals(rhs.terminals)
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, rules(rhs.rules), precedence(rhs.precedence), first(nullptr), follow(nullptr) {
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if (rhs.first)
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first = std::make_unique<util::FirstSet>(*rhs.first);
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if (rhs.follow)
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follow = std::make_unique<util::FollowSet>(*rhs.follow);
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}
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};
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}
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#endif //PARSODUS_GRAMMAR_H
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