diff --git a/src/analyse/analyse.cc b/src/analyse/analyse.cc
index 9fd6d49..96629bd 100644
--- a/src/analyse/analyse.cc
+++ b/src/analyse/analyse.cc
@@ -26,43 +26,84 @@ void Analyse::build(uint64_t code) {
 
     std::queue<analyse_t*>{}.swap(cache);
 
+    cache.emplace(&cases.emplace(code, analyse_t {
+        .code = code,
+        .mask = 0,
+        .step = 0,
+        .src = std::list<analyse_t*>{},
+    }).first->second);
+
+    while (!cache.empty()) {
+        core.next_cases(cache.front()->code, cache.front()->mask);
+        cache.pop();
+    }
+
+    std::cout << "size: " << cases.size() << std::endl;
+
+}
+
+std::vector<uint64_t> Analyse::build_until(uint64_t code, const Analyse::match_t &match) {
+
+    auto core = init();
+
+    cases.clear();
+    cases.reserve(65536);
+
+    std::queue<analyse_t*>{}.swap(cache);
 
     cache.emplace(&cases.emplace(code, analyse_t {
         .code = code,
         .mask = 0,
         .step = 0,
-            .src = std::list<analyse_t*>{},
-//            .src = std::vector<analyse_t*>{},
-//            .src = std::set<analyse_t*>{},
-//            .src = std::unordered_set<analyse_t*>{},
+        .src = std::list<analyse_t*>{},
     }).first->second);
 
+
+    auto layer_end = cache.back();
+    std::vector<uint64_t> matched; // matched list
+
+
     while (!cache.empty()) {
+        if (match(cache.front()->code)) { // match target
+            matched.emplace_back(cache.front()->code);
+        }
+
         core.next_cases(cache.front()->code, cache.front()->mask);
+
+        if (cache.front() == layer_end) { // reach layer ending
+            if (!matched.empty()) {
+
+                std::cout << "size: " << cases.size() << std::endl;
+
+                return matched; // stop at first matched layer
+            }
+            layer_end = cache.back(); // reset layer ending
+        }
+
         cache.pop();
     }
 
     std::cout << "size: " << cases.size() << std::endl;
 
+    return std::vector<uint64_t>{}; // no target found
+
 }
 
+
 void Analyse::new_case(uint64_t code, uint64_t mask) {
     auto current = cases.find(code);
     if (current != cases.end()) { // new case already exist
         if (current->second.step == cache.front()->step + 1) { // new case at next layer
             current->second.mask |= mask; // update mask info
             current->second.src.emplace_back(cache.front()); // link more parent case
-//            current->second.src.emplace(cache.front()); // link more parent case
         }
     } else { // new case not exist
         cache.emplace(&cases.emplace(code, analyse_t { // record new case
             .code = code,
             .mask = mask,
             .step = cache.front()->step + 1,
-                .src = std::list<analyse_t*>{cache.front()}, // link parent case
-//                .src = std::vector<analyse_t*>{cache.front()}, // link parent case
-//                .src = std::set<analyse_t*>{cache.front()}, // link parent case
-//                .src = std::unordered_set<analyse_t*>{cache.front()}, // link parent case
+            .src = std::list<analyse_t*>{cache.front()}, // link parent case
         }).first->second);
     }
 }
+
diff --git a/src/analyse/analyse.h b/src/analyse/analyse.h
index c993765..93e8400 100644
--- a/src/analyse/analyse.h
+++ b/src/analyse/analyse.h
@@ -37,8 +37,12 @@ public:
 //    void backtrack(uint64_t code);
 //    void backtrack(const std::vector<uint64_t> &raw_code_list);
 
+    typedef std::function<bool(uint64_t)> match_t;
+
     void build(uint64_t code);
 
+    std::vector<uint64_t> build_until(uint64_t code, const match_t &match);
+
 //    inline Core init(uint64_t code);
     inline Core init();
 
diff --git a/src/fast_cal/fast_cal.h b/src/fast_cal/fast_cal.h
index 5b8ff1b..1835aed 100644
--- a/src/fast_cal/fast_cal.h
+++ b/src/fast_cal/fast_cal.h
@@ -19,6 +19,8 @@ public:
     int step_num(const RawCode &code);
     std::vector<RawCode> backtrack(const RawCode &code);
 
+    // TODO: should we using code as class member
+
     /// BFS search functions
     void build(const RawCode &code);
     RawCode solve(const RawCode &code);
diff --git a/src/main.cc b/src/main.cc
index 4552d89..71aa55b 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -59,7 +59,13 @@ int main() {
 
 
     auto a = Analyse();
-    a.build((uint64_t)RawCode::from_common_code("1a9bf0c"));
+//    a.build((uint64_t)RawCode::from_common_code("1a9bf0c"));
+    auto ret = a.build_until((uint64_t)RawCode::from_common_code("1a9bf0c"), [](uint64_t code) {
+        return ((code >> (3 * 0xD)) & 0b111) == B_2x2;
+    });
+    for (const auto &r : ret) {
+        std::cout << RawCode(r) << std::endl;
+    }
 
 //    auto raw_code = CommonCode("A5D3AF0").to_raw_code().unwrap();