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Algo.cpp
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Algo.cpp
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#include "Algo.h"
bool Algo::Check(Grammar grammar, const std::string& word) {
grammar_ = grammar;
word_ = word;
situation_lists_.clear();
situation_lists_.resize(word.size() + 1);
Situation fake_start_situation = GetFakeStartSituation();
situation_lists_[0].insert(fake_start_situation);
for (size_t position = 0; position <= word.size(); ++position) {
Scan(position);
size_t old_situation_list_size = 0;
do {
old_situation_list_size = situation_lists_[position].size();
Complete(position);
Predict(position);
} while (situation_lists_[position].size() != old_situation_list_size);
}
Situation final_situation = fake_start_situation.MovePointRight();
const std::set<Situation>& last_situation_list = situation_lists_[word.size()];
return (std::find(last_situation_list.begin(),
last_situation_list.end(), final_situation) != last_situation_list.end());
}
Situation Algo::GetFakeStartSituation() {
std::string fake_rule_raw_format = std::string(1, Grammar::start_symbol) + "->" + Grammar::start_symbol;
GrammarRule fake_rule(fake_rule_raw_format);
fake_rule.left_part_.symbol_ = fake_start_symbol;
grammar_.AddRule(fake_rule);
return Situation(fake_rule, 0, 0);
}
void Algo::Scan(size_t position) {
if (position == 0) {
return;
}
for (const Situation& situation : situation_lists_[position - 1]) {
if (situation.CheckNextSymbolIsTerminal() && situation.GetNextSymbol() == word_[position - 1]) {
situation_lists_[position].insert(situation.MovePointRight());
}
}
}
void Algo::Predict(size_t position) {
for (Situation situation : situation_lists_[position]) {
if (!situation.CheckRuleCompleted() && !situation.CheckNextSymbolIsTerminal()) {
for (const GrammarRule& rule : grammar_.rules_) {
if (situation.GetNextSymbol() == rule.left_part_.symbol_) {
situation_lists_[position].emplace(rule, position, 0);
}
}
}
}
}
void Algo::Complete(size_t position) {
for (const Situation& situation : situation_lists_[position]) {
if (situation.CheckRuleCompleted()) {
for (const Situation& upper_situation : situation_lists_[situation.previous_level_position_]) {
if (!upper_situation.CheckRuleCompleted() && upper_situation.GetNextSymbol() == situation.rule_.left_part_.symbol_) {
situation_lists_[position].insert(upper_situation.MovePointRight());
}
}
}
}
}