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generator: detect LR(0) conflicts

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This commit is contained in:
Matthias Schiffer 2015-04-06 00:22:44 +02:00
parent 696d94d796
commit 6fb60a7201
2 changed files with 35 additions and 4 deletions
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8
src/generator.cpp
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@ -97,9 +97,9 @@ void generator_t::generate_itemsets() {
auto added = add_set(entry.second);
if (entry.first.get_type() == SYMBOL_TYPE_NONTERM)
gotos.emplace(std::make_pair(cur.second, entry.first.get_value()), added.first->second);
add_goto(cur.second, entry.first.get_value(), added.first->second);
else
shifts.emplace(std::make_pair(cur.second, entry.first), added.first->second);
add_shift(cur.second, entry.first, added.first->second);
if (added.second)
queue.push(*added.first);
@ -109,9 +109,9 @@ void generator_t::generate_itemsets() {
auto it = rule_ids.find(item);
if (it != rule_ids.end()) {
if (it->second)
reductions.emplace(cur.second, it->second);
add_reduction(cur.second, it->second);
else
shifts.emplace(std::make_pair(cur.second, symbol_t::make_nonterm("")), 0);
add_shift(cur.second, symbol_t::make_nonterm(""), 0);
}
}
}

31
src/generator.hpp
View file

@ -28,6 +28,7 @@
#include "item.hpp"
#include <stdexcept>
#include <set>
#include <map>
@ -35,6 +36,13 @@
namespace solar {
class generator_t {
public:
class conflict_error : public std::runtime_error {
public:
explicit conflict_error(const std::string& what_arg) : std::runtime_error(what_arg) {}
explicit conflict_error(const char* what_arg) : std::runtime_error(what_arg) {}
};
private:
std::vector<std::pair<item_t, std::string>> rules;
std::map<item_t, size_t> rule_ids;
@ -49,6 +57,8 @@ private:
std::map<size_t, size_t> reductions;
std::map<std::pair<size_t, std::string>, size_t> gotos;
std::set<size_t> shift_conflicts;
void close_set(std::set<item_t> *set);
std::set<item_t> get_set(const std::string &nonterm);
@ -56,6 +66,27 @@ private:
return itemsets.emplace(set, itemsets.size());
}
void add_reduction(size_t from, size_t to) {
if (reductions.count(from))
throw conflict_error("reduce/reduce conflict");
if (shift_conflicts.count(from))
throw conflict_error("shift/reduce conflict");
reductions.emplace(from, to);
}
void add_shift(size_t from, const symbol_t &sym, size_t to) {
if (reductions.count(from))
throw conflict_error("shift/reduce conflict");
shift_conflicts.insert(from);
shifts.emplace(std::make_pair(from, sym), to);
}
void add_goto(size_t from, const std::string &nonterm, size_t to) {
gotos.emplace(std::make_pair(from, nonterm), to);
}
void generate_itemsets();
public: