diff --git a/include/compiler/treeifier/ast.hh b/include/compiler/treeifier/ast.hh
index ba6eb11..f779f38 100644
--- a/include/compiler/treeifier/ast.hh
+++ b/include/compiler/treeifier/ast.hh
@@ -1,43 +1,84 @@
 #pragma once
 
 #include <string>
-#include <list>
+#include <set>
 #include <unordered_map>
 #include <memory>
 #include "compiler/treeifier/tokenizer.hh"
 #include "utils/data.hh"
-#include "utils/slice.hh"
 #include "lang/common.hh"
 
 using namespace std::string_literals;
 using namespace ppc;
+using namespace ppc::messages;
 
 namespace ppc::comp::tree::ast {
-    class constr_parser_t {
-    private:
-        std::string name;
-    public:
-        const std::string &name() { return name; }
-        virtual bool parse(messages::msg_stack_t &messages, vec_slice_t<tok::token_t> &tokens, data::map_t &out) = 0;
-    };
+    class parser_t;
+    class group_parser_t;
 
-    class group_parser_t : constr_parser_t {
+    struct ast_ctx_t {
     private:
-        struct named_parser {
-            constr_parser_t *parser;
-            std::string name;
+        using named_parser_t = std::pair<std::string, parser_t*>;
+
+        struct parser_proxy_t {
+        private:
+            ast_ctx_t &parent;
+        public:
+            parser_t &operator[](const std::string &name) const;
+            parser_proxy_t(ast_ctx_t &parent): parent(parent) { }
         };
-        std::list<constr_parser_t*> parsers;
-        std::unordered_map<std::string, constr_parser_t*> insertion_points;
+
+        struct group_proxy_t {
+        private:
+            ast_ctx_t &parent;
+        public:
+            group_parser_t &operator[](const std::string &name) const;
+            group_proxy_t(ast_ctx_t &parent): parent(parent) { }
+        };
+
+        std::unordered_map<std::string, parser_t*> parsers;
+        std::set<parser_t*> groups;
+
     public:
-        void add_insertion_point(constr_parser_t &parser, const std::string &name);
-        void add(constr_parser_t &parser);
-        void add(const std::string &ins_point, constr_parser_t &parser);
+        msg_stack_t &messages;
+        std::vector<tok::token_t> &tokens;
 
-        bool parse(messages::msg_stack_t &messages, data::map_t &out);
+        void add_parser(std::string name, parser_t &parser);
+        void add_parser(std::string name, group_parser_t &parser);
 
-        group_parser_t();
+        const parser_proxy_t parser;
+        const group_proxy_t group;
+
+        ast_ctx_t(msg_stack_t &messages, std::vector<tok::token_t> tokens):
+            messages(messages),
+            tokens(tokens),
+            parser(*this),
+            group(*this) { }
     };
 
-    extern const constr_parser_t &glob_parser;
+    class parser_t {
+    private:
+        std::string _name;
+    public:
+        const std::string &name() { return _name; }
+        virtual bool parse(ast_ctx_t &ctx, size_t &res_i, data::map_t &out) const = 0;
+        bool operator()(ast_ctx_t &ctx, size_t &i, data::map_t &out) const {
+            return parse(ctx, i, out);
+        }
+    };
+
+    class group_parser_t : public parser_t {
+    private:
+        std::vector<std::pair<lang::namespace_name_t, parser_t*>> named_parsers;
+        std::vector<parser_t*> parsers;
+    public:
+        group_parser_t &add(parser_t &parser);
+        group_parser_t &add(parser_t &parser, const lang::namespace_name_t &name);
+
+        bool parse(ast_ctx_t &ctx, size_t &i, data::map_t &out) const;
+    };
+
+    extern const parser_t &glob_parser;
+
+    const group_parser_t &get_group(std::string name);
 }
\ No newline at end of file
diff --git a/include/compiler/treeifier/ast/helper.hh b/include/compiler/treeifier/ast/helper.hh
new file mode 100644
index 0000000..9d64d7e
--- /dev/null
+++ b/include/compiler/treeifier/ast/helper.hh
@@ -0,0 +1,75 @@
+#include "compiler/treeifier/ast.hh"
+
+namespace ppc::comp::tree::ast {
+    struct tree_helper_t {
+    private:
+        ast_ctx_t &ctx;
+        size_t &res_i;
+        size_t i;
+    public:
+        void submit() {
+            res_i = i;
+        }
+
+        bool ended() {
+            return i == ctx.tokens.size();
+        }
+
+        tok::token_t &curr() { return ctx.tokens[i]; }
+
+        location_t next_loc(size_t n = 1) {
+            location_t res = loc();
+            res.start += res.length;
+            res.code_start += res.length;
+            res.length = n;
+            return res;
+        }
+        location_t loc() {
+            if (ended()) {
+                if (i == 0) return location_t::NONE;
+
+                location_t loc = ctx.tokens[i - 1].location;
+
+                loc.start += loc.length;
+                loc.code_start += loc.length;
+                loc.length = 1;
+
+                return loc;
+            }
+            else return curr().location;
+        }
+
+        bool try_parse(const parser_t &parser, data::map_t &out, messages::msg_stack_t &messages) {
+            try {
+                return parser(ctx, i, out);
+            }
+            catch (messages::message_t msg) {
+                messages.push(msg);
+                return false;
+            }
+        }
+        bool try_parse(const parser_t &parser, data::map_t &out) {
+            try {
+                return parser(ctx, i, out);
+            }
+            catch (messages::message_t msg) {
+                return false;
+            }
+        }
+
+        bool try_advance() {
+            if (ended()) return false;
+            i++;
+            return !ended();
+        }
+        bool advance() {
+            if (ended()) throw messages::message_t(message_t::ERROR, "Unexpected end.", loc());
+            i++;
+            if (ended()) throw messages::message_t(message_t::ERROR, "Unexpected end.", loc());
+        }
+
+        tree_helper_t(ast_ctx_t &ctx, size_t &i): ctx(ctx), res_i(i) {
+            this->i = i;
+        }
+    };
+}
\ No newline at end of file
diff --git a/include/lang/common.hh b/include/lang/common.hh
index 5e2fba2..75d7801 100644
--- a/include/lang/common.hh
+++ b/include/lang/common.hh
@@ -4,11 +4,31 @@
 #include "utils/location.hh"
 
 namespace ppc::lang {
+    template <class T>
+    struct located_t : T {
+        location_t location;
+
+        template <class ...Args>
+        located_t(location_t loc, Args ...args): T(args...), location(loc) { }
+        template <class ...Args>
+        located_t(Args ...args): T(args...), location(location_t::NONE) { }
+    };
+
     struct namespace_name_t {
         std::vector<std::string> segments;
-        ppc::location_t location;
 
-        bool operator ==(const namespace_name_t &other);
+        bool is_empty() const { return segments.empty(); }
+
+        auto begin() { return segments.begin(); }
+        auto end() { return segments.end(); }
+
+        bool operator ==(const namespace_name_t &other)  const;
+        const std::string &operator[](size_t i) const { return segments[i]; }
+
+        std::string to_string() const;
+
+        namespace_name_t() { }
+        namespace_name_t(std::initializer_list<std::string> segments): segments(segments.begin(), segments.end()) { }
     };
 
     bool is_identifier_valid(messages::msg_stack_t &msg_stack, ppc::location_t location, const std::string &name);
diff --git a/include/utils/message.hh b/include/utils/message.hh
index 60f7657..4223d3a 100644
--- a/include/utils/message.hh
+++ b/include/utils/message.hh
@@ -14,8 +14,8 @@ namespace ppc::messages {
             WARNING,
             ERROR,
         } level;
-        location_t location;
         std::string content;
+        location_t location;
 
         message_t(level_t level, std::string content, location_t loc = location_t::NONE) :
             level(level),
diff --git a/include/utils/slice.hh b/include/utils/slice.hh
deleted file mode 100644
index 7a9fa33..0000000
--- a/include/utils/slice.hh
+++ /dev/null
@@ -1,54 +0,0 @@
-#include <vector>
-
-namespace ppc {
-    template <class T>
-    class slice_t {
-    private:
-        T *iterable;
-        std::size_t start;
-        std::size_t n;
-    public:
-        auto begin() const { return iterable->begin() + start; }
-        auto end() const { return iterable->end() + start + n; }
-
-        auto size() const { return n; }
-        auto &operator[](std::size_t i) const { return (iterable*)[start + i]; }
-
-        slice_t(T &iterable, std::size_t start, std::size_t n) {
-            this->iterable = &iterable;
-            this->start = start;
-            this->n = n;
-            if (n == -1u) this->n = iterable.size() - start;
-        }
-    };
-
-    template <class T>
-    using vec_slice_t = slice_t<std::vector<T>>;
-
-
-    template <class T>
-    inline slice_t<T> slice(slice_t<T> &sl) {
-        return slice_t<T>(sl.iterable, sl.start, sl.n);
-    }
-    template <class T>
-    inline slice_t<T> slice(slice_t<T> &sl, std::size_t start) {
-        return slice_t<T>(sl.iterable, sl.start + start, sl.n);
-    }
-    template <class T>
-    inline slice_t<T> slice(slice_t<T> &sl, std::size_t start, std::size_t n) {
-        return slice_t<T>(sl.iterable, sl.start + start, n);
-    }
-
-    template <class T>
-    inline slice_t<T> slice(T &vec) {
-        return slice_t<T>(vec, 0, vec.size());
-    }
-    template <class T>
-    inline slice_t<T> slice(T &vec, std::size_t start) {
-        return slice_t<T>(vec, start, vec.size());
-    }
-    template <class T>
-    inline slice_t<T> slice(T &vec, std::size_t start, std::size_t n) {
-        return slice_t<T>(vec, start, n);
-    }
-}
\ No newline at end of file
diff --git a/src/compiler/treeifier/ast.cc b/src/compiler/treeifier/ast.cc
index 04e224d..1805400 100644
--- a/src/compiler/treeifier/ast.cc
+++ b/src/compiler/treeifier/ast.cc
@@ -1 +1,27 @@
 #include "compiler/treeifier/ast.hh"
+
+namespace ppc::comp::tree::ast {
+    std::unordered_map<std::string, group_parser_t> parsers;
+
+    parser_t &ast_ctx_t::parser_proxy_t::operator[](const std::string &name) const {
+        auto it = parent.parsers.find(name);
+        if (it == parent.parsers.end()) throw "The parser '" + name + "' doesn't exist.";
+        return *it->second;
+    }
+    group_parser_t &ast_ctx_t::group_proxy_t::operator[](const std::string &name) const {
+        parser_t *p = &parent.parser[name];
+        if (parent.groups.find(p) == parent.groups.end()) throw "A parser '" + name + "' exists, but isn't a group.";
+        return *(group_parser_t*)p;
+    }
+
+    void ast_ctx_t::add_parser(std::string name, parser_t &parser) {
+        if (parsers.find(name) != parsers.end()) throw "The parser '" + name + "' already exists.";
+        parsers[name] = &parser;
+    }
+    void ast_ctx_t::add_parser(std::string name, group_parser_t &parser) {
+        if (parsers.find(name) != parsers.end()) throw "The parser '" + name + "' already exists.";
+        parsers[name] = &parser;
+        groups.emplace(&parser);
+    }
+}
+
diff --git a/src/compiler/treeifier/parsers/glob.cc b/src/compiler/treeifier/parsers/glob.cc
index bd30023..a4627b8 100644
--- a/src/compiler/treeifier/parsers/glob.cc
+++ b/src/compiler/treeifier/parsers/glob.cc
@@ -1,11 +1,11 @@
 #include "compiler/treeifier/ast.hh"
 
 namespace ppc::comp::tree::ast {
-    class glob_parser_t : public constr_parser_t {
-        bool parse(messages::msg_stack_t &messages, vec_slice_t<tok::token_t> &tokens, data::map_t &out) {
-            
+    class glob_parser_t : public parser_t {
+        bool parse(ast_ctx_t &ctx, size_t &res_i, data::map_t &out) const {
+            return false;
         }
     };
 
-    const constr_parser_t &glob_parser = glob_parser_t();
+    const parser_t &glob_parser = glob_parser_t();
 }
diff --git a/src/compiler/treeifier/parsers/group.cc b/src/compiler/treeifier/parsers/group.cc
new file mode 100644
index 0000000..3471c78
--- /dev/null
+++ b/src/compiler/treeifier/parsers/group.cc
@@ -0,0 +1,20 @@
+#include "compiler/treeifier/ast.hh"
+#include <algorithm>
+
+using namespace ppc::comp::tree::ast;
+using namespace std::string_literals;
+
+group_parser_t &group_parser_t::add(parser_t &parser) {
+    parsers.push_back(&parser);
+    return *this;
+}
+group_parser_t &group_parser_t::add(parser_t &parser, const lang::namespace_name_t &name) {
+    if (name.is_empty()) throw "Name can't be empty."s;
+    if (std::find(parsers.begin(), parsers.end(), &parser) != parsers.end()) {
+        throw "Parser '" + name.to_string() + "' already in group.";
+    }
+
+    named_parsers.push_back({ name, &parser });
+
+    return *this;
+}
diff --git a/src/lang/common.cc b/src/lang/common.cc
new file mode 100644
index 0000000..7b6c9f5
--- /dev/null
+++ b/src/lang/common.cc
@@ -0,0 +1,27 @@
+
+#include <sstream>
+#include "lang/common.hh"
+
+namespace ppc::lang {
+    std::string namespace_name_t::to_string() const {
+        std::stringstream res;
+
+        for (size_t i = 0; i < segments.size(); i++) {
+            if (i != 0) res << "::";
+            res << segments[i];
+        }
+
+        return res.str();
+    }
+
+    bool namespace_name_t::operator==(const namespace_name_t &other) const {
+        if (other.segments.size() != segments.size()) return false;
+
+        for (size_t i = 0; i < segments.size(); i++) {
+            if (other[i] != segments[i]) return false;
+        }
+
+        return true;
+    }
+}
+