Working up parser combinators

CMakeLists.txt

@@ -10,7 +10,7 @@ find_package( Boost 1.36.0 COMPONENTS regex)
 if(Boost_FOUND)
    include_directories(${Boost_INCLUDE_DIRS})
    
-   add_executable(langkit_test langkit/main.cpp langkit/langkit_lexer.cpp)
+   add_executable(langkit_test langkit/main.cpp langkit/langkit_lexer.cpp langkit/langkit_parser.cpp)
    target_link_libraries(langkit_test ${Boost_LIBRARIES})
 
 	 add_executable(typelesscpp_test typelesscpp/test.cpp)

langkit/langkit_parser.cpp

@@ -0,0 +1,61 @@
+// This file is distributed under the BSD License.
+// See LICENSE.TXT for details.
+
+#include "langkit_lexer.hpp"
+#include "langkit_parser.hpp"
+
+Token_Iterator String_Rule(Token_Iterator iter, Token_Iterator end, const std::string &val) {
+    if (iter != end) {
+        if (iter->text == val) {
+            return ++iter;
+        }
+    }
+
+    return iter;
+}
+
+Token_Iterator Type_Rule(Token_Iterator iter, Token_Iterator end, const int val) {
+    if (iter != end) {
+        if (iter->identifier == val) {
+            return ++iter;
+        }
+    }
+
+    return iter;
+}
+
+Token_Iterator Or_Rule(Token_Iterator iter, Token_Iterator end, const Rule &lhs, const Rule &rhs) {
+    Token_Iterator new_iter;
+
+    if (iter != end) {
+        new_iter = lhs.rule(iter, end);
+
+        if (new_iter != iter) {
+            return new_iter;
+        }
+        else {
+            new_iter = rhs.rule(iter, end);
+            if (new_iter != iter) {
+                return new_iter;
+            }
+        }
+    }
+    return iter;
+}
+
+Token_Iterator And_Rule(Token_Iterator iter, Token_Iterator end, const Rule &lhs, const Rule &rhs) {
+    Token_Iterator lhs_iter, rhs_iter;
+
+    if (iter != end) {
+        lhs_iter = lhs.rule(iter, end);
+
+        if (lhs_iter != iter) {
+            rhs_iter = rhs.rule(iter, end);
+            if (rhs_iter != iter) {
+                return rhs_iter;
+            }
+        }
+    }
+
+    return iter;
+}

langkit/langkit_parser.hpp

@@ -0,0 +1,17 @@
+// This file is distributed under the BSD License.
+// See LICENSE.TXT for details.
+
+#ifndef LANGKIT_PARSER_HPP_
+#define LANGKIT_PARSER_HPP_
+
+#include <boost/function.hpp>
+
+#include "langkit_lexer.hpp"
+
+typedef std::vector<Token>::iterator Token_Iterator;
+
+struct Rule {
+    boost::function<Token_Iterator(Token_Iterator iter, Token_Iterator end)> rule;
+};
+
+#endif /* LANGKIT_PARSER_HPP_ */

langkit/main.cpp

@@ -31,8 +31,6 @@ std::string load_file(const char *filename) {
     std::streampos size = infile.tellg();
     infile.seekg(0, std::ios::beg);
 
-    std::cout << "Allocating: " << size << " bytes" << std::endl;
-
     std::vector<char> v(size);
     infile.read(&v[0], size);
 

langkit/tests/roundtrip.gt

@@ -0,0 +1 @@
+def add(x, y) { return x+y }