Add Code complete support (#62)

Fixes #3

Author: alexander-penev

src/xinterpreter.cpp

@@ -248,12 +248,21 @@ __get_cxx_version ()
         return kernel_res;
     }
 
-    nl::json interpreter::complete_request_impl(const std::string& /*code*/, int cursor_pos)
+    nl::json interpreter::complete_request_impl(const std::string& code, int cursor_pos)
     {
-        return xeus::create_complete_reply(
-            nl::json::array(), /*matches*/
-            cursor_pos,        /*cursor_start*/
-            cursor_pos         /*cursor_end*/
+        std::vector<std::string> results;
+
+        // split the input to have only the word in the back of the cursor
+        std::string delims = " \t\n`!@#$^&*()=+[{]}\\|;:\'\",<>?.";
+        std::size_t _cursor_pos = cursor_pos;
+        auto text = split_line(code, delims, _cursor_pos);
+        std::string to_complete = text.back().c_str();
+
+        Cpp::CodeComplete(results, code.c_str(), 1, _cursor_pos + 1);
+
+        return xeus::create_complete_reply(results /*matches*/,
+            cursor_pos - to_complete.length() /*cursor_start*/,
+            cursor_pos /*cursor_end*/
         );
     }
 

src/xparser.cpp

@@ -10,7 +10,10 @@
 #include "xparser.hpp"
 
 #include <cstddef>
+#include <regex>
+#include <sstream>
 #include <string>
+#include <vector>
 
 namespace xcpp
 {
@@ -26,4 +29,29 @@ namespace xcpp
         std::size_t last = str.find_last_not_of(' ');
         return str.substr(first, last - first + 1);
     }
+
+    std::vector<std::string>
+    split_line(const std::string& input, const std::string& delims, std::size_t cursor_pos)
+    {
+        // passing -1 as the submatch index parameter performs splitting
+        std::vector<std::string> result;
+        std::stringstream ss;
+
+        ss << "[";
+        for (auto c : delims)
+        {
+            ss << "\\" << c;
+        }
+        ss << "]";
+
+        std::regex re(ss.str());
+
+        std::copy(
+            std::sregex_token_iterator(input.begin(), input.begin() + cursor_pos + 1, re, -1),
+            std::sregex_token_iterator(),
+            std::back_inserter(result)
+        );
+
+        return result;
+    }
 }

src/xparser.hpp

@@ -13,10 +13,14 @@
 #include "xeus-cpp/xeus_cpp_config.hpp"
 
 #include <string>
+#include <vector>
 
 namespace xcpp
-{   
+{
     XEUS_CPP_API
     std::string trim(const std::string& str);
+
+    XEUS_CPP_API std::vector<std::string>
+    split_line(const std::string& input, const std::string& delims, std::size_t cursor_pos);
 }
 #endif