Added str() in SemanticValues.

README.md

@@ -60,7 +60,7 @@ int main(void) {
     };
 
     parser["Number"] = [](const SemanticValues& sv) {
-        return stoi(string(sv.s, sv.n), nullptr, 10);
+        return stoi(sv.str(), nullptr, 10);
     };
 
     // (4) Parse
@@ -89,7 +89,7 @@ struct SemanticValue {
     const char* s;    // Token start for the semantic value
     size_t      n;    // Token length for the semantic value
 
-    // Utility method
+    // Cast semantic value
     template <typename T> T& get();
     template <typename T> const T& get() const;
 };
@@ -100,6 +100,9 @@ struct SemanticValues : protected std::vector<SemanticValue>
     size_t      n;      // Token length
     size_t      choice; // Choice number (0 based index)
 
+    // Get token
+    std::string str() const;
+
     // Transform the semantice values vector to another vector
     template <typename F> auto transform(size_t beg, size_t end, F f) const -> vector<typename std::remove_const<decltype(f(SemanticValue()))>::type>;
     template <typename F> auto transform(F f) const -> vector<typename std::remove_const<decltype(f(SemanticValue()))>::type>;
@@ -126,7 +129,7 @@ peg pg(syntax);
 
 pg["TOKEN"] = [](const SemanticValues& sv) {
     // 'token' doesn't include trailing whitespaces
-    auto token = string(sv.s, sv.n);
+    auto token = sv.str();
 };
 
 auto ret = pg.parse(" token1, token2 ");
@@ -164,7 +167,7 @@ peglib::peg parser(
 peglib::peg parser("NUMBER  <-  [0-9]+");
 
 parser["NUMBER"] = [](const SemanticValues& sv) {
-    auto val = stol(string(sv.s, sv.n), nullptr, 10);
+    auto val = stol(sv.str(), nullptr, 10);
     if (val != 100) {
         throw peglib::parse_error("value error!!");
     }
@@ -279,7 +282,7 @@ vector<string> tags;
 Definition ROOT, TAG_NAME, _;
 ROOT     <= seq(_, zom(seq(chr('['), TAG_NAME, chr(']'), _)));
 TAG_NAME <= oom(seq(npd(chr(']')), dot())), [&](const SemanticValues& sv) {
-                tags.push_back(string(sv.s, sv.n));
+                tags.push_back(sv.str());
             };
 _        <= zom(cls(" \t"));
 

peglib.h

@@ -205,6 +205,10 @@ struct SemanticValues : protected std::vector<SemanticValue>
     using std::vector<T>::emplace;
     using std::vector<T>::emplace_back;
 
+    std::string str() const {
+        return std::string(s, n);
+    }
+
     template <typename F>
     auto transform(F f) const -> vector<typename std::remove_const<decltype(f(SemanticValue()))>::type> {
         vector<typename std::remove_const<decltype(f(SemanticValue()))>::type> r;

test/test.cc

@@ -34,7 +34,7 @@ TEST_CASE("String capture test", "[general]")
     std::vector<std::string> tags;
 
     parser["TAG_NAME"] = [&](const peglib::SemanticValues& sv) {
-        tags.push_back(std::string(sv.s, sv.n));
+        tags.push_back(sv.str());
     };
 
     auto ret = parser.parse(" [tag1] [tag:2] [tag-3] ");
@@ -73,7 +73,7 @@ TEST_CASE("String capture test2", "[general]")
     Definition ROOT, TAG, TAG_NAME, WS;
     ROOT     <= seq(WS, zom(TAG));
     TAG      <= seq(chr('['), TAG_NAME, chr(']'), WS);
-    TAG_NAME <= oom(seq(npd(chr(']')), dot())), [&](const SemanticValues& sv) { tags.push_back(string(sv.s, sv.n)); };
+    TAG_NAME <= oom(seq(npd(chr(']')), dot())), [&](const SemanticValues& sv) { tags.push_back(sv.str()); };
     WS       <= zom(cls(" \t"));
 
     auto r = ROOT.parse(" [tag1] [tag:2] [tag-3] ");
@@ -98,7 +98,7 @@ TEST_CASE("String capture test3", "[general]")
    std::vector<std::string> tags;
 
    pg["TOKEN"] = [&](const SemanticValues& sv) {
-       tags.push_back(std::string(sv.s, sv.n));
+       tags.push_back(sv.str());
    };
 
    auto ret = pg.parse(" [tag1] [tag:2] [tag-3] ");
@@ -270,7 +270,7 @@ TEST_CASE("mutable lambda test", "[general]")
 
     // This test makes sure if the following code can be compiled.
     pg["TOKEN"] = [=](const SemanticValues& sv) mutable {
-        vec.push_back(string(sv.s, sv.n));
+        vec.push_back(sv.str());
     };
 }
 
@@ -343,7 +343,7 @@ TEST_CASE("Calculator test", "[general]")
     TERM            = reduce;
     TERM_OPERATOR   = [](const SemanticValues& sv) { return *sv.s; };
     FACTOR_OPERATOR = [](const SemanticValues& sv) { return *sv.s; };
-    NUMBER          = [](const SemanticValues& sv) { return stol(string(sv.s, sv.n), nullptr, 10); };
+    NUMBER          = [](const SemanticValues& sv) { return stol(sv.str(), nullptr, 10); };
 
     // Parse
     long val;
@@ -389,7 +389,7 @@ TEST_CASE("Calculator test2", "[general]")
     g["TERM"]            = reduce;
     g["TERM_OPERATOR"]   = [](const SemanticValues& sv) { return *sv.s; };
     g["FACTOR_OPERATOR"] = [](const SemanticValues& sv) { return *sv.s; };
-    g["NUMBER"]          = [](const SemanticValues& sv) { return stol(string(sv.s, sv.n), nullptr, 10); };
+    g["NUMBER"]          = [](const SemanticValues& sv) { return stol(sv.str(), nullptr, 10); };
 
     // Parse
     long val;
@@ -431,7 +431,7 @@ TEST_CASE("Calculator test3", "[general]")
     parser["TERM"]            = reduce;
     parser["TERM_OPERATOR"]   = [](const SemanticValues& sv) { return (char)*sv.s; };
     parser["FACTOR_OPERATOR"] = [](const SemanticValues& sv) { return (char)*sv.s; };
-    parser["NUMBER"]          = [](const SemanticValues& sv) { return stol(string(sv.s, sv.n), nullptr, 10); };
+    parser["NUMBER"]          = [](const SemanticValues& sv) { return stol(sv.str(), nullptr, 10); };
 
     // Parse
     long val;
@@ -622,7 +622,7 @@ TEST_CASE("Semantic predicate test", "[predicate]")
     peg parser("NUMBER  <-  [0-9]+");
 
     parser["NUMBER"] = [](const SemanticValues& sv) {
-        auto val = stol(string(sv.s, sv.n), nullptr, 10);
+        auto val = stol(sv.str(), nullptr, 10);
         if (val != 100) {
             throw parse_error("value error!!");
         }