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https://github.com/yhirose/cpp-peglib.git
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Added left recursice detection.
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yhirose
parent
4dc334e481
commit
67de659288
163
peglib.h
163
peglib.h
@ -18,6 +18,7 @@
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#include <map>
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#include <memory>
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#include <mutex>
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#include <set>
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#include <string>
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#include <unordered_map>
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#include <vector>
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@ -973,9 +974,10 @@ class DefinitionReference : public Ope
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{
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public:
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DefinitionReference(
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const std::unordered_map<std::string, Definition>& grammar, const std::string& name)
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const std::unordered_map<std::string, Definition>& grammar, const std::string& name, const char* s)
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: grammar_(grammar)
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, name_(name) {}
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, name_(name)
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, s_(s) {}
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size_t parse(const char* s, size_t n, SemanticValues& sv, Context& c, any& dt) const override;
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@ -983,9 +985,10 @@ public:
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std::shared_ptr<Ope> get_rule() const;
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private:
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//private:
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const std::unordered_map<std::string, Definition>& grammar_;
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const std::string name_;
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const char* s_;
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mutable std::once_flag init_;
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mutable std::shared_ptr<Ope> rule_;
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};
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@ -1018,13 +1021,13 @@ struct Ope::Visitor
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struct AssignIDToDefinition : public Ope::Visitor
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{
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void visit(Sequence& ope) override {
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for (auto op: ope.opes_) {
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op->accept(*this);
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for (auto ope: ope.opes_) {
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ope->accept(*this);
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}
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}
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void visit(PrioritizedChoice& ope) override {
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for (auto op: ope.opes_) {
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op->accept(*this);
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for (auto ope: ope.opes_) {
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ope->accept(*this);
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}
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}
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void visit(ZeroOrMore& ope) override { ope.ope_->accept(*this); }
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@ -1047,13 +1050,13 @@ struct IsToken : public Ope::Visitor
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IsToken() : has_anchor(false), has_rule(false) {}
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void visit(Sequence& ope) override {
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for (auto op: ope.opes_) {
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op->accept(*this);
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for (auto ope: ope.opes_) {
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ope->accept(*this);
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}
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}
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void visit(PrioritizedChoice& ope) override {
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for (auto op: ope.opes_) {
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op->accept(*this);
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for (auto ope: ope.opes_) {
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ope->accept(*this);
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}
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}
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void visit(ZeroOrMore& ope) override { ope.ope_->accept(*this); }
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@ -1438,8 +1441,8 @@ inline std::shared_ptr<Ope> usr(std::function<size_t (const char* s, size_t n, S
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return std::make_shared<User>(fn);
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}
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inline std::shared_ptr<Ope> ref(const std::unordered_map<std::string, Definition>& grammar, const std::string& name) {
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return std::make_shared<DefinitionReference>(grammar, name);
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inline std::shared_ptr<Ope> ref(const std::unordered_map<std::string, Definition>& grammar, const std::string& name, const char* s) {
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return std::make_shared<DefinitionReference>(grammar, name, s);
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}
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/*-----------------------------------------------------------------------------
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@ -1523,6 +1526,100 @@ private:
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{}
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};
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struct DetectLeftRecursion : public Ope::Visitor {
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DetectLeftRecursion(const std::string& name)
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: s_(nullptr), name_(name), done_(false) {}
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void visit(Sequence& ope) override {
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for (auto ope: ope.opes_) {
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ope->accept(*this);
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if (done_) {
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break;
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} else if (s_) {
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done_ = true;
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break;
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}
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}
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}
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void visit(PrioritizedChoice& ope) override {
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for (auto ope: ope.opes_) {
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ope->accept(*this);
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if (s_) {
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done_ = true;
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break;
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}
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}
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}
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void visit(ZeroOrMore& ope) override {
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ope.ope_->accept(*this);
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done_ = false;
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}
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void visit(OneOrMore& ope) override {
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ope.ope_->accept(*this);
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done_ = true;
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}
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void visit(Option& ope) override {
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ope.ope_->accept(*this);
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done_ = false;
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}
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void visit(AndPredicate& ope) override {
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ope.ope_->accept(*this);
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done_ = false;
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}
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void visit(NotPredicate& ope) override {
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ope.ope_->accept(*this);
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done_ = false;
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}
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void visit(LiteralString& ope) override {
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done_ = !ope.lit_.empty();
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}
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void visit(CharacterClass& ope) override {
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done_ = true;
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}
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void visit(Character& ope) override {
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done_ = true;
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}
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void visit(AnyCharacter& ope) override {
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done_ = true;
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}
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void visit(Capture& ope) override {
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ope.ope_->accept(*this);
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}
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void visit(Anchor& ope) override {
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ope.ope_->accept(*this);
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}
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void visit(Ignore& ope) override {
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ope.ope_->accept(*this);
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}
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void visit(User& ope) override {
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done_ = true;
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}
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void visit(WeakHolder& ope) override {
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ope.weak_.lock()->accept(*this);
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}
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void visit(Holder& ope) override {
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ope.ope_->accept(*this);
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}
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void visit(DefinitionReference& ope) override {
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if (ope.name_ == name_) {
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s_ = ope.s_;
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} else if (refs_.find(ope.name_) != refs_.end()) {
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;
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} else {
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refs_.insert(ope.name_);
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ope.get_rule()->accept(*this);
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}
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done_ = true;
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}
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const char* s_;
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private:
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std::string name_;
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std::set<std::string> refs_;
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bool done_;
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};
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void make_grammar() {
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// Setup PEG syntax parser
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g["Grammar"] <= seq(g["Spacing"], oom(g["Definition"]), g["EndOfFile"]);
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@ -1679,12 +1776,15 @@ private:
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auto baseId = ignore ? 1 : 0;
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const auto& ident = sv[baseId].val.get<std::string>();
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data.references[ident] = sv.s; // for error handling
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if (data.references.find(ident) == data.references.end()) {
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data.references[ident] = sv.s; // for error handling
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}
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if (ignore) {
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return ign(ref(*data.grammar, ident));
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return ign(ref(*data.grammar, ident, sv.s));
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} else {
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return ref(*data.grammar, ident);
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return ref(*data.grammar, ident, sv.s);
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}
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},
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// (Expression)
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@ -1769,6 +1869,8 @@ private:
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}
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// Check missing definitions
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bool ret = true;
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for (const auto& x : data.references) {
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const auto& name = x.first;
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auto ptr = x.second;
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@ -1777,10 +1879,37 @@ private:
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auto line = line_info(s, ptr);
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log(line.first, line.second, "'" + name + "' is not defined.");
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}
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return nullptr;
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ret = false;
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}
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}
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if (!ret) {
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return nullptr;
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}
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// Check left recursion
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ret = true;
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for (auto& x: grammar) {
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const auto& name = x.first;
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auto& rule = x.second;
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DetectLeftRecursion lr(name);
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rule.accept(lr);
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if (lr.s_) {
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if (log) {
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auto line = line_info(s, lr.s_);
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log(line.first, line.second, "'" + name + "' is left recursive.");
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}
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ret = false;;
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}
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}
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if (!ret) {
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return nullptr;
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}
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// Set root definition
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start = data.start;
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return data.grammar;
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38
test/test.cc
38
test/test.cc
@ -565,6 +565,44 @@ TEST_CASE("Ignore semantic value of 'and' predicate test", "[general]")
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REQUIRE(ast->nodes[0]->name == "HELLO_WORLD");
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}
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TEST_CASE("Left recursive test", "[left recursive]")
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{
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peg parser(
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" A <- A 'a'"
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" B <- A 'a'"
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);
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REQUIRE(parser == false);
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}
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TEST_CASE("Left recursive with option test", "[left recursive]")
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{
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peg parser(
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" A <- 'a' / 'b'? B 'c' "
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" B <- A "
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);
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REQUIRE(parser == false);
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}
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TEST_CASE("Left recursive with zom test", "[left recursive]")
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{
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peg parser(
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" A <- 'a'* A* "
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);
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REQUIRE(parser == false);
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}
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TEST_CASE("Left recursive with empty string test", "[left recursive]")
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{
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peg parser(
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" A <- '' A"
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);
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REQUIRE(parser == false);
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}
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bool exact(Grammar& g, const char* d, const char* s) {
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auto n = strlen(s);
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auto r = g[d].parse(s, n);
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