first commit

ext/mstch/src/CMakeLists.txt

@@ -0,0 +1,66 @@
+find_package(Boost 1.54 REQUIRED)
+
+set(mstch_INCLUDE_DIR
+      ${PROJECT_SOURCE_DIR}/include CACHE STRING "mstch include directory")
+
+# /home/mwo/crow-monero-test/ext/mstch
+message(${PROJECT_SOURCE_DIR})
+#
+include_directories(
+    ${Boost_INCLUDE_DIR})
+
+set(SRC
+    state/in_section.cpp
+    state/outside_section.cpp
+    state/render_state.hpp
+    visitor/get_token.hpp
+    visitor/has_token.hpp
+    visitor/is_node_empty.hpp
+    visitor/render_node.hpp
+    visitor/render_section.hpp
+    mstch.cpp
+    render_context.cpp
+    template_type.cpp
+    token.cpp
+    utils.cpp)
+
+add_library(mstch STATIC ${SRC})
+#
+set_property(TARGET mstch PROPERTY VERSION ${mstch_VERSION})
+#
+#install(
+#    TARGETS mstch EXPORT mstchTargets
+#    LIBRARY DESTINATION lib
+#    ARCHIVE DESTINATION lib)
+#
+#install(
+#    FILES "${PROJECT_SOURCE_DIR}/include/mstch/mstch.hpp"
+#    DESTINATION include/mstch
+#    COMPONENT Devel)
+#
+#include(CMakePackageConfigHelpers)
+#write_basic_package_version_file(
+#    "${CMAKE_CURRENT_BINARY_DIR}/mstch/mstch-config-version.cmake"
+#    VERSION ${mstch_VERSION}
+#    COMPATIBILITY AnyNewerVersion)
+#
+#export(
+#    EXPORT mstchTargets
+#    FILE "${CMAKE_CURRENT_BINARY_DIR}/mstch/mstch-targets.cmake"
+#    NAMESPACE mstch::)
+#
+#configure_file(
+#    "${PROJECT_SOURCE_DIR}/cmake/mstch-config.cmake"
+#    "${CMAKE_CURRENT_BINARY_DIR}/mstch/mstch-config.cmake")
+#
+#install(
+#    EXPORT mstchTargets
+#    FILE mstch-targets.cmake
+#    NAMESPACE mstch::
+#    DESTINATION lib/cmake/mstch)
+#
+#install(FILES
+#    "${PROJECT_SOURCE_DIR}/cmake/mstch-config.cmake"
+#    "${CMAKE_CURRENT_BINARY_DIR}/mstch/mstch-config-version.cmake"
+#    DESTINATION lib/cmake/mstch
+#    COMPONENT Devel)

ext/mstch/src/mstch.cpp

@@ -0,0 +1,20 @@
+#include <iostream>
+
+#include "mstch/mstch.hpp"
+#include "render_context.hpp"
+
+using namespace mstch;
+
+std::function<std::string(const std::string&)> mstch::config::escape;
+
+std::string mstch::render(
+    const std::string& tmplt,
+    const node& root,
+    const std::map<std::string,std::string>& partials)
+{
+  std::map<std::string, template_type> partial_templates;
+  for (auto& partial: partials)
+    partial_templates.insert({partial.first, {partial.second}});
+
+  return render_context(root, partial_templates).render(tmplt);
+}

ext/mstch/src/render_context.cpp

@@ -0,0 +1,72 @@
+#include "render_context.hpp"
+#include "state/outside_section.hpp"
+#include "visitor/get_token.hpp"
+
+using namespace mstch;
+
+const mstch::node render_context::null_node;
+
+render_context::push::push(render_context& context, const mstch::node& node):
+    m_context(context)
+{
+  context.m_nodes.emplace_front(node);
+  context.m_node_ptrs.emplace_front(&node);
+  context.m_state.push(std::unique_ptr<render_state>(new outside_section));
+}
+
+render_context::push::~push() {
+  m_context.m_nodes.pop_front();
+  m_context.m_node_ptrs.pop_front();
+  m_context.m_state.pop();
+}
+
+std::string render_context::push::render(const template_type& templt) {
+  return m_context.render(templt);
+}
+
+render_context::render_context(
+    const mstch::node& node,
+    const std::map<std::string, template_type>& partials):
+    m_partials(partials), m_nodes(1, node), m_node_ptrs(1, &node)
+{
+  m_state.push(std::unique_ptr<render_state>(new outside_section));
+}
+
+const mstch::node& render_context::find_node(
+    const std::string& token,
+    std::list<node const*> current_nodes)
+{
+  if (token != "." && token.find('.') != std::string::npos)
+    return find_node(token.substr(token.rfind('.') + 1),
+        {&find_node(token.substr(0, token.rfind('.')), current_nodes)});
+  else
+    for (auto& node: current_nodes)
+      if (visit(has_token(token), *node))
+        return visit(get_token(token, *node), *node);
+  return null_node;
+}
+
+const mstch::node& render_context::get_node(const std::string& token) {
+    return find_node(token, m_node_ptrs);
+}
+
+std::string render_context::render(
+    const template_type& templt, const std::string& prefix)
+{
+  std::string output;
+  bool prev_eol = true;
+  for (auto& token: templt) {
+    if (prev_eol && prefix.length() != 0)
+      output += m_state.top()->render(*this, {prefix});
+    output += m_state.top()->render(*this, token);
+    prev_eol = token.eol();
+  }
+  return output;
+}
+
+std::string render_context::render_partial(
+    const std::string& partial_name, const std::string& prefix)
+{
+  return m_partials.count(partial_name) ?
+      render(m_partials.at(partial_name), prefix) : "";
+}

ext/mstch/src/render_context.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <deque>
+#include <list>
+#include <sstream>
+#include <string>
+#include <stack>
+
+#include "mstch/mstch.hpp"
+#include "state/render_state.hpp"
+#include "template_type.hpp"
+
+namespace mstch {
+
+class render_context {
+ public:
+  class push {
+   public:
+    push(render_context& context, const mstch::node& node = {});
+    ~push();
+    std::string render(const template_type& templt);
+   private:
+    render_context& m_context;
+  };
+
+  render_context(
+      const mstch::node& node,
+      const std::map<std::string, template_type>& partials);
+  const mstch::node& get_node(const std::string& token);
+  std::string render(
+      const template_type& templt, const std::string& prefix = "");
+  std::string render_partial(
+      const std::string& partial_name, const std::string& prefix);
+  template<class T, class... Args>
+  void set_state(Args&& ... args) {
+    m_state.top() = std::unique_ptr<render_state>(
+        new T(std::forward<Args>(args)...));
+  }
+
+ private:
+  static const mstch::node null_node;
+  const mstch::node& find_node(
+      const std::string& token,
+      std::list<node const*> current_nodes);
+  std::map<std::string, template_type> m_partials;
+  std::deque<mstch::node> m_nodes;
+  std::list<const mstch::node*> m_node_ptrs;
+  std::stack<std::unique_ptr<render_state>> m_state;
+};
+
+}

ext/mstch/src/state/in_section.cpp

@@ -0,0 +1,34 @@
+#include "in_section.hpp"
+#include "outside_section.hpp"
+#include "visitor/is_node_empty.hpp"
+#include "visitor/render_section.hpp"
+
+using namespace mstch;
+
+in_section::in_section(type type, const token& start_token):
+    m_type(type), m_start_token(start_token), m_skipped_openings(0)
+{
+}
+
+std::string in_section::render(render_context& ctx, const token& token) {
+  if (token.token_type() == token::type::section_close)
+    if (token.name() == m_start_token.name() && m_skipped_openings == 0) {
+      auto& node = ctx.get_node(m_start_token.name());
+      std::string out;
+
+      if (m_type == type::normal && !visit(is_node_empty(), node))
+        out = visit(render_section(ctx, m_section, m_start_token.delims()), node);
+      else if (m_type == type::inverted && visit(is_node_empty(), node))
+        out = render_context::push(ctx).render(m_section);
+
+      ctx.set_state<outside_section>();
+      return out;
+    } else
+      m_skipped_openings--;
+  else if (token.token_type() == token::type::inverted_section_open ||
+      token.token_type() == token::type::section_open)
+    m_skipped_openings++;
+
+  m_section << token;
+  return "";
+}

ext/mstch/src/state/in_section.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <sstream>
+#include <vector>
+
+#include "render_state.hpp"
+#include "template_type.hpp"
+
+namespace mstch {
+
+class in_section: public render_state {
+ public:
+  enum class type { inverted, normal };
+  in_section(type type, const token& start_token);
+  std::string render(render_context& context, const token& token) override;
+
+ private:
+  const type m_type;
+  const token& m_start_token;
+  template_type m_section;
+  int m_skipped_openings;
+};
+
+}

ext/mstch/src/state/outside_section.cpp

@@ -0,0 +1,32 @@
+#include "outside_section.hpp"
+
+#include "visitor/render_node.hpp"
+#include "in_section.hpp"
+#include "render_context.hpp"
+
+using namespace mstch;
+
+std::string outside_section::render(
+    render_context& ctx, const token& token)
+{
+  using flag = render_node::flag;
+  switch (token.token_type()) {
+    case token::type::section_open:
+      ctx.set_state<in_section>(in_section::type::normal, token);
+      break;
+    case token::type::inverted_section_open:
+      ctx.set_state<in_section>(in_section::type::inverted, token);
+      break;
+    case token::type::variable:
+      return visit(render_node(ctx, flag::escape_html), ctx.get_node(token.name()));
+    case token::type::unescaped_variable:
+      return visit(render_node(ctx, flag::none), ctx.get_node(token.name()));
+    case token::type::text:
+      return token.raw();
+    case token::type::partial:
+      return ctx.render_partial(token.name(), token.partial_prefix());
+    default:
+      break;
+  }
+  return "";
+}

ext/mstch/src/state/outside_section.hpp

@@ -0,0 +1,12 @@
+#pragma once
+
+#include "render_state.hpp"
+
+namespace mstch {
+
+class outside_section: public render_state {
+ public:
+  std::string render(render_context& context, const token& token) override;
+};
+
+}

ext/mstch/src/state/render_state.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <memory>
+
+#include "token.hpp"
+
+namespace mstch {
+
+class render_context;
+
+class render_state {
+ public:
+  virtual ~render_state() {}
+  virtual std::string render(render_context& context, const token& token) = 0;
+};
+
+}

ext/mstch/src/template_type.cpp

@@ -0,0 +1,104 @@
+#include "template_type.hpp"
+
+using namespace mstch;
+
+template_type::template_type(const std::string& str, const delim_type& delims):
+    m_open(delims.first), m_close(delims.second)
+{
+  tokenize(str);
+  strip_whitespace();
+}
+
+template_type::template_type(const std::string& str):
+    m_open("{{"), m_close("}}")
+{
+  tokenize(str);
+  strip_whitespace();
+}
+
+void template_type::process_text(citer begin, citer end) {
+  if (begin == end)
+    return;
+  auto start = begin;
+  for (auto it = begin; it != end; ++it)
+    if (*it == '\n' || it == end - 1) {
+      m_tokens.push_back({{start, it + 1}});
+      start = it + 1;
+    }
+}
+
+void template_type::tokenize(const std::string& tmp) {
+  citer beg = tmp.begin();
+  auto npos = std::string::npos;
+
+  for (std::size_t cur_pos = 0; cur_pos < tmp.size();) {
+    auto open_pos = tmp.find(m_open, cur_pos);
+    auto close_pos = tmp.find(
+        m_close, open_pos == npos ? open_pos : open_pos + 1);
+
+    if (close_pos != npos && open_pos != npos) {
+      if (*(beg + open_pos + m_open.size()) == '{' &&
+          *(beg + close_pos + m_close.size()) == '}')
+        ++close_pos;
+
+      process_text(beg + cur_pos, beg + open_pos);
+      cur_pos = close_pos + m_close.size();
+      m_tokens.push_back({{beg + open_pos, beg + close_pos + m_close.size()},
+          m_open.size(), m_close.size()});
+
+      if (cur_pos == tmp.size()) {
+        m_tokens.push_back({{""}});
+        m_tokens.back().eol(true);
+      }
+
+      if (*(beg + open_pos + m_open.size()) == '=' &&
+          *(beg + close_pos - 1) == '=')
+      {
+        auto tok_beg = beg + open_pos + m_open.size() + 1;
+        auto tok_end = beg + close_pos - 1;
+        auto front_skip = first_not_ws(tok_beg, tok_end);
+        auto back_skip = first_not_ws(reverse(tok_end), reverse(tok_beg));
+        m_open = {front_skip, beg + tmp.find(' ', front_skip - beg)};
+        m_close = {beg + tmp.rfind(' ', back_skip - beg) + 1, back_skip + 1};
+      }
+    } else {
+      process_text(beg + cur_pos, tmp.end());
+      cur_pos = close_pos;
+    }
+  }
+}
+
+void template_type::strip_whitespace() {
+  auto line_begin = m_tokens.begin();
+  bool has_tag = false, non_space = false;
+
+  for (auto it = m_tokens.begin(); it != m_tokens.end(); ++it) {
+    auto type = (*it).token_type();
+    if (type != token::type::text && type != token::type::variable &&
+        type != token::type::unescaped_variable)
+      has_tag = true;
+    else if (!(*it).ws_only())
+      non_space = true;
+
+    if ((*it).eol()) {
+      if (has_tag && !non_space) {
+        store_prefixes(line_begin);
+
+        auto c = line_begin;
+        for (bool end = false; !end; (*c).ws_only() ? c = m_tokens.erase(c) : ++c)
+          if ((end = (*c).eol()))
+            it = c - 1;
+      }
+
+      non_space = has_tag = false;
+      line_begin = it + 1;
+    }
+  }
+}
+
+void template_type::store_prefixes(std::vector<token>::iterator beg) {
+  for (auto cur = beg; !(*cur).eol(); ++cur)
+    if ((*cur).token_type() == token::type::partial &&
+        cur != beg && (*(cur - 1)).ws_only())
+      (*cur).partial_prefix((*(cur - 1)).raw());
+}

ext/mstch/src/template_type.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <string>
+#include <vector>
+
+#include "token.hpp"
+#include "utils.hpp"
+
+namespace mstch {
+
+class template_type {
+ public:
+  template_type() = default;
+  template_type(const std::string& str);
+  template_type(const std::string& str, const delim_type& delims);
+  std::vector<token>::const_iterator begin() const { return m_tokens.begin(); }
+  std::vector<token>::const_iterator end() const { return m_tokens.end(); }
+  void operator<<(const token& token) { m_tokens.push_back(token); }
+
+ private:
+  std::vector<token> m_tokens;
+  std::string m_open;
+  std::string m_close;
+  void strip_whitespace();
+  void process_text(citer beg, citer end);
+  void tokenize(const std::string& tmp);
+  void store_prefixes(std::vector<token>::iterator beg);
+};
+
+}

ext/mstch/src/token.cpp

@@ -0,0 +1,42 @@
+#include "token.hpp"
+#include "utils.hpp"
+
+using namespace mstch;
+
+token::type token::token_info(char c) {
+  switch (c) {
+    case '>': return type::partial;
+    case '^': return type::inverted_section_open;
+    case '/': return type::section_close;
+    case '&': return type::unescaped_variable;
+    case '#': return type::section_open;
+    case '!': return type::comment;
+    default: return type::variable;
+  }
+}
+
+token::token(const std::string& str, std::size_t left, std::size_t right):
+    m_raw(str), m_eol(false), m_ws_only(false)
+{
+  if (left != 0 && right != 0) {
+    if (str[left] == '=' && str[str.size() - right - 1] == '=') {
+      m_type = type::delimiter_change;
+    } else if (str[left] == '{' && str[str.size() - right - 1] == '}') {
+      m_type = type::unescaped_variable;
+      m_name = {first_not_ws(str.begin() + left + 1, str.end() - right),
+          first_not_ws(str.rbegin() + 1 + right, str.rend() - left) + 1};
+    } else {
+      auto c = first_not_ws(str.begin() + left, str.end() - right);
+      m_type = token_info(*c);
+      if (m_type != type::variable)
+        c = first_not_ws(c + 1, str.end() - right);
+      m_name = {c, first_not_ws(str.rbegin() + right, str.rend() - left) + 1};
+      m_delims = {{str.begin(), str.begin() + left},
+          {str.end() - right, str.end()}};
+    }
+  } else {
+    m_type = type::text;
+    m_eol = (str.size() > 0 && str[str.size() - 1] == '\n');
+    m_ws_only = (str.find_first_not_of(" \r\n\t") == std::string::npos);
+  }
+}

ext/mstch/src/token.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <string>
+
+namespace mstch {
+
+using delim_type = std::pair<std::string, std::string>;
+
+class token {
+ public:
+  enum class type {
+    text, variable, section_open, section_close, inverted_section_open,
+    unescaped_variable, comment, partial, delimiter_change
+  };
+  token(const std::string& str, std::size_t left = 0, std::size_t right = 0);
+  type token_type() const { return m_type; };
+  const std::string& raw() const { return m_raw; };
+  const std::string& name() const { return m_name; };
+  const std::string& partial_prefix() const { return m_partial_prefix; };
+  const delim_type& delims() const { return m_delims; };
+  void partial_prefix(const std::string& p_partial_prefix) {
+    m_partial_prefix = p_partial_prefix;
+  };
+  bool eol() const { return m_eol; }
+  void eol(bool eol) { m_eol = eol; }
+  bool ws_only() const { return m_ws_only; }
+
+ private:
+  type m_type;
+  std::string m_name;
+  std::string m_raw;
+  std::string m_partial_prefix;
+  delim_type m_delims;
+  bool m_eol;
+  bool m_ws_only;
+  type token_info(char c);
+};
+
+}

ext/mstch/src/utils.cpp

@@ -0,0 +1,44 @@
+#include "utils.hpp"
+#include "mstch/mstch.hpp"
+
+mstch::citer mstch::first_not_ws(mstch::citer begin, mstch::citer end) {
+  for (auto it = begin; it != end; ++it)
+    if (*it != ' ') return it;
+  return end;
+}
+
+mstch::citer mstch::first_not_ws(mstch::criter begin, mstch::criter end) {
+  for (auto rit = begin; rit != end; ++rit)
+    if (*rit != ' ') return --(rit.base());
+  return --(end.base());
+}
+
+mstch::criter mstch::reverse(mstch::citer it) {
+  return std::reverse_iterator<mstch::citer>(it);
+}
+
+std::string mstch::html_escape(const std::string& str) {
+  if (mstch::config::escape)
+    return mstch::config::escape(str);
+  
+  std::string out;
+  citer start = str.begin();
+
+  auto add_escape = [&out, &start](const std::string& escaped, citer& it) {
+    out += std::string{start, it} + escaped;
+    start = it + 1;
+  };
+
+  for (auto it = str.begin(); it != str.end(); ++it)
+    switch (*it) {
+      case '&': add_escape("&amp;", it); break;
+      case '\'': add_escape("&#39;", it); break;
+      case '"': add_escape("&quot;", it); break;
+      case '<': add_escape("&lt;", it); break;
+      case '>': add_escape("&gt;", it); break;
+      case '/': add_escape("&#x2F;", it); break;
+      default: break;
+    }
+
+  return out + std::string{start, str.end()};
+}

ext/mstch/src/utils.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <string>
+#include <boost/variant/apply_visitor.hpp>
+
+namespace mstch {
+
+using citer = std::string::const_iterator;
+using criter = std::string::const_reverse_iterator;
+
+citer first_not_ws(citer begin, citer end);
+citer first_not_ws(criter begin, criter end);
+std::string html_escape(const std::string& str);
+criter reverse(citer it);
+
+template<class... Args>
+auto visit(Args&&... args) -> decltype(boost::apply_visitor(
+    std::forward<Args>(args)...))
+{
+  return boost::apply_visitor(std::forward<Args>(args)...);
+}
+
+}

ext/mstch/src/visitor/get_token.hpp

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <boost/variant/static_visitor.hpp>
+
+#include "mstch/mstch.hpp"
+#include "has_token.hpp"
+
+namespace mstch {
+
+class get_token: public boost::static_visitor<const mstch::node&> {
+ public:
+  get_token(const std::string& token, const mstch::node& node):
+      m_token(token), m_node(node)
+  {
+  }
+
+  template<class T>
+  const mstch::node& operator()(const T&) const {
+    return m_node;
+  }
+
+  const mstch::node& operator()(const map& map) const {
+    return map.at(m_token);
+  }
+
+  const mstch::node& operator()(const std::shared_ptr<object>& object) const {
+    return object->at(m_token);
+  }
+
+ private:
+  const std::string& m_token;
+  const mstch::node& m_node;
+};
+
+}

ext/mstch/src/visitor/has_token.hpp

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <boost/variant/static_visitor.hpp>
+
+#include "mstch/mstch.hpp"
+
+namespace mstch {
+
+class has_token: public boost::static_visitor<bool> {
+ public:
+  has_token(const std::string& token): m_token(token) {
+  }
+
+  template<class T>
+  bool operator()(const T&) const {
+    return m_token == ".";
+  }
+
+  bool operator()(const map& map) const {
+    return map.count(m_token) == 1;
+  }
+
+  bool operator()(const std::shared_ptr<object>& object) const {
+    return object->has(m_token);
+  }
+
+ private:
+  const std::string& m_token;
+};
+
+}

ext/mstch/src/visitor/is_node_empty.hpp

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <boost/variant/static_visitor.hpp>
+
+#include "mstch/mstch.hpp"
+
+namespace mstch {
+
+class is_node_empty: public boost::static_visitor<bool> {
+ public:
+  template<class T>
+  bool operator()(const T&) const {
+    return false;
+  }
+
+  bool operator()(const std::nullptr_t&) const {
+    return true;
+  }
+
+  bool operator()(const int& value) const {
+    return value == 0;
+  }
+
+  bool operator()(const double& value) const {
+    return value == 0;
+  }
+
+  bool operator()(const bool& value) const {
+    return !value;
+  }
+
+  bool operator()(const std::string& value) const {
+    return value == "";
+  }
+
+  bool operator()(const array& array) const {
+    return array.size() == 0;
+  }
+};
+
+}

ext/mstch/src/visitor/render_node.hpp

@@ -0,0 +1,56 @@
+#pragma once
+
+#include <sstream>
+#include <boost/variant/static_visitor.hpp>
+
+#include "render_context.hpp"
+#include "mstch/mstch.hpp"
+#include "utils.hpp"
+
+namespace mstch {
+
+class render_node: public boost::static_visitor<std::string> {
+ public:
+  enum class flag { none, escape_html };
+  render_node(render_context& ctx, flag p_flag = flag::none):
+      m_ctx(ctx), m_flag(p_flag)
+  {
+  }
+
+  template<class T>
+  std::string operator()(const T&) const {
+    return "";
+  }
+
+  std::string operator()(const int& value) const {
+    return std::to_string(value);
+  }
+
+  std::string operator()(const double& value) const {
+    std::stringstream ss;
+    ss << value;
+    return ss.str();
+  }
+
+  std::string operator()(const bool& value) const {
+    return value ? "true" : "false";
+  }
+
+  std::string operator()(const lambda& value) const {
+    template_type interpreted{value([this](const mstch::node& n) {
+      return visit(render_node(m_ctx), n);
+    })};
+    auto rendered = render_context::push(m_ctx).render(interpreted);
+    return (m_flag == flag::escape_html) ? html_escape(rendered) : rendered;
+  }
+
+  std::string operator()(const std::string& value) const {
+    return (m_flag == flag::escape_html) ? html_escape(value) : value;
+  }
+
+ private:
+  render_context& m_ctx;
+  flag m_flag;
+};
+
+}

ext/mstch/src/visitor/render_section.hpp

@@ -0,0 +1,57 @@
+#pragma once
+
+#include <boost/variant/static_visitor.hpp>
+
+#include "render_context.hpp"
+#include "mstch/mstch.hpp"
+#include "utils.hpp"
+#include "render_node.hpp"
+
+namespace mstch {
+
+class render_section: public boost::static_visitor<std::string> {
+ public:
+  enum class flag { none, keep_array };
+  render_section(
+      render_context& ctx,
+      const template_type& section,
+      const delim_type& delims,
+      flag p_flag = flag::none):
+      m_ctx(ctx), m_section(section), m_delims(delims), m_flag(p_flag)
+  {
+  }
+
+  template<class T>
+  std::string operator()(const T& t) const {
+    return render_context::push(m_ctx, t).render(m_section);
+  }
+
+  std::string operator()(const lambda& fun) const {
+    std::string section_str;
+    for (auto& token: m_section)
+      section_str += token.raw();
+    template_type interpreted{fun([this](const mstch::node& n) {
+      return visit(render_node(m_ctx), n);
+    }, section_str), m_delims};
+    return render_context::push(m_ctx).render(interpreted);
+  }
+
+  std::string operator()(const array& array) const {
+    std::string out;
+    if (m_flag == flag::keep_array)
+      return render_context::push(m_ctx, array).render(m_section);
+    else
+      for (auto& item: array)
+        out += visit(render_section(
+            m_ctx, m_section, m_delims, flag::keep_array), item);
+    return out;
+  }
+
+ private:
+  render_context& m_ctx;
+  const template_type& m_section;
+  const delim_type& m_delims;
+  flag m_flag;
+};
+
+}