Updated documentation and examples.

README.md

@@ -21,16 +21,14 @@ How to use
 This is a simple calculator sample. It shows how to define grammar, associate samantic actions to the grammar and handle semantic values.
 
 ```c++
-#include <assert.h>
-
 // (1) Include the header file
 #include <peglib.h>
+#include <assert.h>
 
 using namespace peglib;
 using namespace std;
 
 int main(void) {
-
     // (2) Make a parser
     auto syntax = R"(
         # Grammar for Calculator...
@@ -42,22 +40,20 @@ int main(void) {
 
     peg parser(syntax);
 
-    parser.packrat_parsing(true); // Enable packrat parsing
-
     // (3) Setup an action
     parser["Additive"] = {
-        nullptr,                                                // Default action
+        nullptr,                                        // Default action
         [](const SemanticValues& sv) {
-            return sv[0].get<int>() + sv[1].get<int>(); // 1st choice
+            return sv[0].get<int>() + sv[1].get<int>(); // "Multitive '+' Additive"
         },
-        [](const SemanticValues& sv) { return sv[0]; }          // 2nd choice
+        [](const SemanticValues& sv) { return sv[0]; }  // "Multitive"
     };
 
     parser["Multitive"] = [](const SemanticValues& sv) {
         switch (sv.choice) {
-        case 0:  // 1st choice
+        case 0:  // "Multitive '+' Additive"
             return sv[0].get<int>() * sv[1].get<int>();
-        default: // 2nd choice
+        default: // "Multitive"
             return sv[0].get<int>();
         }
     };
@@ -67,6 +63,8 @@ int main(void) {
     };
 
     // (4) Parse
+    parser.packrat_parsing(true); // Enable packrat parsing.
+
     int val;
     parser.parse("(1+2)*3", val);
 

example/calc.cc

@@ -12,17 +12,6 @@
 using namespace peglib;
 using namespace std;
 
-//
-//  PEG syntax:
-//
-//      EXPRESSION       <-  _ TERM (TERM_OPERATOR TERM)*
-//      TERM             <-  FACTOR (FACTOR_OPERATOR FACTOR)*
-//      FACTOR           <-  NUMBER / '(' _ EXPRESSION ')' _
-//      TERM_OPERATOR    <-  < [-+] > _
-//      FACTOR_OPERATOR  <-  < [/*] > _
-//      NUMBER           <-  < [0-9]+ > _
-//      ~_               <-  [ \t\r\n]*
-//
 int main(int argc, const char** argv)
 {
     if (argc < 2 || string("--help") == argv[1]) {
@@ -30,8 +19,6 @@ int main(int argc, const char** argv)
         return 1;
     }
 
-    const char* s = argv[1];
-
     auto reduce = [](const SemanticValues& sv) -> long {
         auto result = sv[0].get<long>();
         for (auto i = 1u; i < sv.size(); i += 2) {
@@ -47,7 +34,7 @@ int main(int argc, const char** argv)
         return result;
     };
 
-    const char* syntax =
+    peg parser(
         "  EXPRESSION       <-  _ TERM (TERM_OPERATOR TERM)*      "
         "  TERM             <-  FACTOR (FACTOR_OPERATOR FACTOR)*  "
         "  FACTOR           <-  NUMBER / '(' _ EXPRESSION ')' _   "
@@ -55,9 +42,7 @@ int main(int argc, const char** argv)
         "  FACTOR_OPERATOR  <-  < [/*] > _                        "
         "  NUMBER           <-  < [0-9]+ > _                      "
         "  ~_               <-  [ \t\r\n]*                        "
-        ;
+        );
-
-    peg parser(syntax);
 
     parser["EXPRESSION"]      = reduce;
     parser["TERM"]            = reduce;
@@ -65,9 +50,10 @@ int main(int argc, const char** argv)
     parser["FACTOR_OPERATOR"] = [](const char* s, size_t n) { return (char)*s; };
     parser["NUMBER"]          = [](const char* s, size_t n) { return atol(s); };
 
+    auto expr = argv[1];
     long val = 0;
-    if (parser.parse(s, val)) {
+    if (parser.parse(expr, val)) {
-        cout << s << " = " << val << endl;
+        cout << expr << " = " << val << endl;
         return 0;
     }
 

example/calc2.cc

@@ -29,8 +29,6 @@ int main(int argc, const char** argv)
         return 1;
     }
 
-    const char* s = argv[1];
-
     auto reduce = [](const SemanticValues& sv) -> long {
         auto result = sv[0].get<long>();
         for (auto i = 1u; i < sv.size(); i += 2) {
@@ -55,9 +53,10 @@ int main(int argc, const char** argv)
     FACTOR_OPERATOR <= cls("*/"),                                        [](const char* s, size_t n) { return (char)*s; };
     NUMBER          <= oom(cls("0-9")),                                  [](const char* s, size_t n) { return atol(s); };
 
+    auto expr = argv[1];
     long val = 0;
-    if (EXPRESSION.parse_and_get_value(s, val).ret) {
+    if (EXPRESSION.parse_and_get_value(expr, val).ret) {
-        cout << s << " = " << val << endl;
+        cout << expr << " = " << val << endl;
         return 0;
     }
 

example/calc3.cc

@@ -12,24 +12,12 @@
 using namespace peglib;
 using namespace std;
 
-//
-//  PEG syntax:
-//
-//      EXPRESSION       <-  _ TERM (TERM_OPERATOR TERM)*
-//      TERM             <-  FACTOR (FACTOR_OPERATOR FACTOR)*
-//      FACTOR           <-  NUMBER / '(' _ EXPRESSION ')' _
-//      TERM_OPERATOR    <-  < [-+] > _
-//      FACTOR_OPERATOR  <-  < [/*] > _
-//      NUMBER           <-  < [0-9]+ > _
-//      ~_               <-  [ \t\r\n]*
-//
-
 template <typename T, typename U, typename F>
 static U reduce(T i, T end, U val, F f) {
     if (i == end) {
         return val;
     }
-    std::tie(val, i) = f(val, i);
+    tie(val, i) = f(val, i);
     return reduce(i, end, val, f);
 };
 
@@ -96,9 +84,7 @@ int main(int argc, const char** argv)
         return 1;
     }
 
-    const char* s = argv[1];
+    peg parser(
-
-    const char* syntax =
         "  EXPRESSION       <-  _ TERM (TERM_OPERATOR TERM)*      "
         "  TERM             <-  FACTOR (FACTOR_OPERATOR FACTOR)*  "
         "  FACTOR           <-  NUMBER / '(' _ EXPRESSION ')' _   "
@@ -106,9 +92,7 @@ int main(int argc, const char** argv)
         "  FACTOR_OPERATOR  <-  < [/*] > _                        "
         "  NUMBER           <-  < [0-9]+ > _                      "
         "  ~_               <-  [ \t\r\n]*                        "
-        ;
+        );
-
-    peg parser(syntax);
 
     parser["EXPRESSION"]      = ast_ope::create;
     parser["TERM"]            = ast_ope::create;
@@ -116,9 +100,10 @@ int main(int argc, const char** argv)
     parser["FACTOR_OPERATOR"] = [](const char* s, size_t n) { return *s; };
     parser["NUMBER"]          = ast_num::create;
 
+    auto expr = argv[1];
     shared_ptr<ast_node> ast;
-    if (parser.parse(s, ast)) {
+    if (parser.parse(expr, ast)) {
-        cout << s << " = " << ast->eval() << endl;
+        cout << expr << " = " << ast->eval() << endl;
         return 0;
     }