add nullptr to perform_search

we need a nullptr at the end, to show where the list ends.

Makefile

@@ -1,4 +1,3 @@
-# Compiler and flags
 CXX = g++
 CC = gcc
 CXXFLAGS = -shared -fPIC
@@ -7,7 +6,7 @@ LDFLAGS = -L. -ltrie_loader -Wl,-rpath=.
 # Paths and files
 LIBRARY_NAME = libtrie_loader.so
 EXECUTABLE_NAME = wrapper_executable
-SRC_CPP = libtrie_loader.hpp
+SRC_CPP = libtrie_loader.cpp
 SRC_C = main.c
 
 # Targets

haskell.hs

@@ -0,0 +1,47 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+
+{-
+ $ ghc -o my_program Haskell.hs -L. -ltrie_loader
+-}
+
+import Foreign
+import Foreign.C
+import Control.Monad (when)
+
+-- Declare the C functions
+foreign import ccall "load_trie" loadTrie :: CString -> IO (Ptr ())
+foreign import ccall "perform_search" performSearch :: Ptr () -> CString -> Ptr CSize -> IO (Ptr (Ptr CChar))
+foreign import ccall "free_trie" freeTrie :: Ptr () -> IO ()
+foreign import ccall "free_search_results" freeSearchResults :: Ptr (Ptr CChar) -> IO ()
+
+main :: IO ()
+main = do
+    -- Just call the functions, do nothing with the result
+
+    putStrLn "Calling load_trie..."
+    -- Load the trie (don't care about the result)
+    dictFile <- newCString "/home/hashirama/.local/share/hakurei/dict.bin"
+    trieHandle <- loadTrie dictFile
+    if trieHandle == nullPtr
+        then putStrLn "Failed to load trie"
+        else putStrLn "Trie loaded successfully"
+
+    putStrLn "Calling perform_search..."
+    -- Perform search (we care about the result here)
+    searchStr <- newCString "電気通信業務取扱規程"
+    resultCount <- malloc :: IO (Ptr CSize)
+    resultsPtr <- performSearch trieHandle searchStr resultCount
+    when (resultsPtr /= nullPtr) $ do
+        -- If results are returned, process them
+        -- Dereference the first result in the results pointer
+        firstResult <- peek resultsPtr >>= peekCString
+        putStrLn $ "First search result: " ++ firstResult
+
+        -- Free the search results (assuming we have a way to handle multiple results)
+        freeSearchResults resultsPtr
+
+    putStrLn "Calling free_trie..."
+    -- Free the trie (again, no checks, just call)
+    freeTrie trieHandle
+
+    putStrLn "Functions were called"

libtrie_loader.cpp

@@ -2,6 +2,7 @@
 #include <string>
 #include <iostream>
 #include <vector>
+#include <string.h> // for strdup 
 
 typedef void* TrieHandle;  // Opaque pointer to represent the trie in C
 
@@ -31,7 +32,6 @@ TrieHandle load_trie_from_cstring(const char* cstr) {
 }
 
 
-// C++ function to perform prefix search and return results as a dynamically allocated array of strings (C-compatible)
 const char** search_prefix(TrieHandle handle, const char* search_str, size_t* result_count) {
     xcdat::trie_15_type* trie = reinterpret_cast<xcdat::trie_15_type*>(handle);
     xcdat::trie_15_type::prefix_iterator itr = trie->make_prefix_iterator(search_str);
@@ -42,18 +42,23 @@ const char** search_prefix(TrieHandle handle, const char* search_str, size_t* re
         results.push_back(std::string(itr.decoded_view()));
     }
 
-    // Allocate memory to store the results
+    // Allocate memory to store the results + 1 for the null terminator
     *result_count = results.size();
-    const char** result_array = new const char*[*result_count];
+    const char** result_array = new const char*[*result_count + 1]; // +1 for null pointer
 
     // Copy the results from the vector to the array
     for (size_t i = 0; i < *result_count; ++i) {
-        result_array[i] = results[i].c_str();  // Store the raw pointer to the string data
+        result_array[i] = strdup(results[i].c_str()); // Dynamically allocate strings
     }
+
+    // Add a null terminator
+    result_array[*result_count] = nullptr;
+
     return result_array;
 }
 
 
+
 // C territory
 
 // Wrapper function to load the trie, for C usage

main.c

@@ -23,7 +23,7 @@ int main() {
 
     size_t result_count = 0;
     // Perform the search using the wrapper function
-    const char** results = perform_search(trie_handle, "真珠湾降", &result_count);
+    const char** results = perform_search(trie_handle, "よくない影響", &result_count);
 
     // Print all the results
     printf("Results found:\n");