text: // sass.hpp must go before all system headers to get the
  // __EXTENSIONS__ fix on Solaris.
  #include "sass.hpp"
  #include "ast.hpp"
  
  #include "remove_placeholders.hpp"
  #include "sass_functions.hpp"
  #include "check_nesting.hpp"
  #include "fn_selectors.hpp"
  #include "fn_strings.hpp"
  #include "fn_numbers.hpp"
  #include "fn_colors.hpp"
  #include "fn_miscs.hpp"
  #include "fn_lists.hpp"
  #include "fn_maps.hpp"
  #include "context.hpp"
  #include "expand.hpp"
  #include "parser.hpp"
  #include "cssize.hpp"
  
  namespace Sass {
    using namespace Constants;
    using namespace File;
    using namespace Sass;
  
    inline bool sort_importers (const Sass_Importer_Entry& i, const Sass_Importer_Entry& j)
    { return sass_importer_get_priority(i) > sass_importer_get_priority(j); }
  
    static std::string safe_input(const char* in_path)
    {
      if (in_path == nullptr || in_path[0] == '\0') return "stdin";
      return in_path;
    }
  
    static std::string safe_output(const char* out_path, std::string input_path)
    {
      if (out_path == nullptr || out_path[0] == '\0') {
        if (input_path.empty()) return "stdout";
        return input_path.substr(0, input_path.find_last_of(".")) + ".css";
      }
      return out_path;
    }
  
    Context::Context(struct Sass_Context& c_ctx)
    : CWD(File::get_cwd()),
      c_options(c_ctx),
      entry_path(""),
      head_imports(0),
      plugins(),
      emitter(c_options),
  
      ast_gc(),
      strings(),
      resources(),
      sheets(),
      import_stack(),
      callee_stack(),
      traces(),
      extender(Extender::NORMAL, traces),
      c_compiler(NULL),
  
      c_headers               (std::vector<Sass_Importer_Entry>()),
      c_importers             (std::vector<Sass_Importer_Entry>()),
      c_functions             (std::vector<Sass_Function_Entry>()),
  
      indent                  (safe_str(c_options.indent, "  ")),
      linefeed                (safe_str(c_options.linefeed, "\n")),
  
      input_path              (make_canonical_path(safe_input(c_options.input_path))),
      output_path             (make_canonical_path(safe_output(c_options.output_path, input_path))),
      source_map_file         (make_canonical_path(safe_str(c_options.source_map_file, ""))),
      source_map_root         (make_canonical_path(safe_str(c_options.source_map_root, "")))
  
    {
  
      // Sass 3.4: The current working directory will no longer be placed onto the Sass load path by default.
      // If you need the current working directory to be available, set SASS_PATH=. in your shell's environment.
      // include_paths.push_back(CWD);
  
      // collect more paths from different options
      collect_include_paths(c_options.include_path);
      collect_include_paths(c_options.include_paths);
      collect_plugin_paths(c_options.plugin_path);
      collect_plugin_paths(c_options.plugin_paths);
  
      // load plugins and register custom behaviors
      for(auto plug : plugin_paths) plugins.load_plugins(plug);
      for(auto fn : plugins.get_headers()) c_headers.push_back(fn);
      for(auto fn : plugins.get_importers()) c_importers.push_back(fn);
      for(auto fn : plugins.get_functions()) c_functions.push_back(fn);
  
      // sort the items by priority (lowest first)
      sort (c_headers.begin(), c_headers.end(), sort_importers);
      sort (c_importers.begin(), c_importers.end(), sort_importers);
  
      emitter.set_filename(abs2rel(output_path, source_map_file, CWD));
  
    }
  
    void Context::add_c_function(Sass_Function_Entry function)
    {
      c_functions.push_back(function);
    }
    void Context::add_c_header(Sass_Importer_Entry header)
    {
      c_headers.push_back(header);
      // need to sort the array afterwards (no big deal)
      sort (c_headers.begin(), c_headers.end(), sort_importers);
    }
    void Context::add_c_importer(Sass_Importer_Entry importer)
    {
      c_importers.push_back(importer);
      // need to sort the array afterwards (no big deal)
      sort (c_importers.begin(), c_importers.end(), sort_importers);
    }
  
    Context::~Context()
    {
      // resources were allocated by malloc
      for (size_t i = 0; i < resources.size(); ++i) {
        free(resources[i].contents);
        free(resources[i].srcmap);
      }
      // free all strings we kept alive during compiler execution
      for (size_t n = 0; n < strings.size(); ++n) free(strings[n]);
      // everything that gets put into sources will be freed by us
      // this shouldn't have anything in it anyway!?
      for (size_t m = 0; m < import_stack.size(); ++m) {
        sass_import_take_source(import_stack[m]);
        sass_import_take_srcmap(import_stack[m]);
        sass_delete_import(import_stack[m]);
      }
      // clear inner structures (vectors) and input source
      resources.clear(); import_stack.clear();
      sheets.clear();
    }
  
    Data_Context::~Data_Context()
    {
      // --> this will be freed by resources
      // make sure we free the source even if not processed!
      // if (resources.size() == 0 && source_c_str) free(source_c_str);
      // if (resources.size() == 0 && srcmap_c_str) free(srcmap_c_str);
      // source_c_str = 0; srcmap_c_str = 0;
    }
  
    File_Context::~File_Context()
    {
    }
  
    void Context::collect_include_paths(const char* paths_str)
    {
      if (paths_str) {
        const char* beg = paths_str;
        const char* end = Prelexer::find_first<PATH_SEP>(beg);
  
        while (end) {
          std::string path(beg, end - beg);
          if (!path.empty()) {
            if (*path.rbegin() != '/') path += '/';
            include_paths.push_back(path);
          }
          beg = end + 1;
          end = Prelexer::find_first<PATH_SEP>(beg);
        }
  
        std::string path(beg);
        if (!path.empty()) {
          if (*path.rbegin() != '/') path += '/';
          include_paths.push_back(path);
        }
      }
    }
  
    void Context::collect_include_paths(string_list* paths_array)
    {
      while (paths_array)
      {
        collect_include_paths(paths_array->string);
        paths_array = paths_array->next;
      }
    }
  
    void Context::collect_plugin_paths(const char* paths_str)
    {
      if (paths_str) {
        const char* beg = paths_str;
        const char* end = Prelexer::find_first<PATH_SEP>(beg);
  
        while (end) {
          std::string path(beg, end - beg);
          if (!path.empty()) {
            if (*path.rbegin() != '/') path += '/';
            plugin_paths.push_back(path);
          }
          beg = end + 1;
          end = Prelexer::find_first<PATH_SEP>(beg);
        }
  
        std::string path(beg);
        if (!path.empty()) {
          if (*path.rbegin() != '/') path += '/';
          plugin_paths.push_back(path);
        }
      }
    }
  
    void Context::collect_plugin_paths(string_list* paths_array)
    {
      while (paths_array)
      {
        collect_plugin_paths(paths_array->string);
        paths_array = paths_array->next;
      }
    }
  
    // resolve the imp_path in base_path or include_paths
    // looks for alternatives and returns a list from one directory
    std::vector<Include> Context::find_includes(const Importer& import)
    {
      // make sure we resolve against an absolute path
      std::string base_path(rel2abs(import.base_path));
      // first try to resolve the load path relative to the base path
      std::vector<Include> vec(resolve_includes(base_path, import.imp_path));
      // then search in every include path (but only if nothing found yet)
      for (size_t i = 0, S = include_paths.size(); vec.size() == 0 && i < S; ++i)
      {
        // call resolve_includes and individual base path and append all results
        std::vector<Include> resolved(resolve_includes(include_paths[i], import.imp_path));
        if (resolved.size()) vec.insert(vec.end(), resolved.begin(), resolved.end());
      }
      // return vector
      return vec;
    }
  
    // register include with resolved path and its content
    // memory of the resources will be freed by us on exit
    void Context::register_resource(const Include& inc, const Resource& res)
    {
  
      // do not parse same resource twice
      // maybe raise an error in this case
      // if (sheets.count(inc.abs_path)) {
      //   free(res.contents); free(res.srcmap);
      //   throw std::runtime_error("duplicate resource registered");
      //   return;
      // }
  
      // get index for this resource
      size_t idx = resources.size();
  
      // tell emitter about new resource
      emitter.add_source_index(idx);
  
      // put resources under our control
      // the memory will be freed later
      resources.push_back(res);
  
      // add a relative link to the working directory
      included_files.push_back(inc.abs_path);
      // add a relative link  to the source map output file
      srcmap_links.push_back(abs2rel(inc.abs_path, source_map_file, CWD));
  
      // get pointer to the loaded content
      Sass_Import_Entry import = sass_make_import(
        inc.imp_path.c_str(),
        inc.abs_path.c_str(),
        res.contents,
        res.srcmap
      );
      // add the entry to the stack
      import_stack.push_back(import);
  
      // get pointer to the loaded content
      const char* contents = resources[idx].contents;
      // keep a copy of the path around (for parserstates)
      // ToDo: we clean it, but still not very elegant!?
      strings.push_back(sass_copy_c_string(inc.abs_path.c_str()));
      // create the initial parser state from resource
      ParserState pstate(strings.back(), contents, idx);
  
      // check existing import stack for possible recursion
      for (size_t i = 0; i < import_stack.size() - 2; ++i) {
        auto parent = import_stack[i];
        if (std::strcmp(parent->abs_path, import->abs_path) == 0) {
          std::string cwd(File::get_cwd());
          // make path relative to the current directory
          std::string stack("An @import loop has been found:");
          for (size_t n = 1; n < i + 2; ++n) {
            stack += "\n    " + std::string(File::abs2rel(import_stack[n]->abs_path, cwd, cwd)) +
              " imports " + std::string(File::abs2rel(import_stack[n+1]->abs_path, cwd, cwd));
          }
          // implement error throw directly until we
          // decided how to handle full stack traces
          throw Exception::InvalidSyntax(pstate, traces, stack);
          // error(stack, prstate ? *prstate : pstate, import_stack);
        }
      }
  
      // create a parser instance from the given c_str buffer
      Parser p(Parser::from_c_str(contents, *this, traces, pstate));
      // do not yet dispose these buffers
      sass_import_take_source(import);
      sass_import_take_srcmap(import);
      // then parse the root block
      Block_Obj root = p.parse();
      // delete memory of current stack frame
      sass_delete_import(import_stack.back());
      // remove current stack frame
      import_stack.pop_back();
      // create key/value pair for ast node
      std::pair<const std::string, StyleSheet>
        ast_pair(inc.abs_path, { res, root });
      // register resulting resource
      sheets.insert(ast_pair);
    }
  
    // register include with resolved path and its content
    // memory of the resources will be freed by us on exit
    void Context::register_resource(const Include& inc, const Resource& res, ParserState& prstate)
    {
      traces.push_back(Backtrace(prstate));
      register_resource(inc, res);
      traces.pop_back();
    }
  
    // Add a new import to the context (called from `import_url`)
    Include Context::load_import(const Importer& imp, ParserState pstate)
    {
  
      // search for valid imports (ie. partials) on the filesystem
      // this may return more than one valid result (ambiguous imp_path)
      const std::vector<Include> resolved(find_includes(imp));
  
      // error nicely on ambiguous imp_path
      if (resolved.size() > 1) {
        std::stringstream msg_stream;
        msg_stream << "It's not clear which file to import for ";
        msg_stream << "'@import \"" << imp.imp_path << "\"'." << "\n";
        msg_stream << "Candidates:" << "\n";
        for (size_t i = 0, L = resolved.size(); i < L; ++i)
        { msg_stream << "  " << resolved[i].imp_path << "\n"; }
        msg_stream << "Please delete or rename all but one of these files." << "\n";
        error(msg_stream.str(), pstate, traces);
      }
  
      // process the resolved entry
      else if (resolved.size() == 1) {
        bool use_cache = c_importers.size() == 0;
        // use cache for the resource loading
        if (use_cache && sheets.count(resolved[0].abs_path)) return resolved[0];
        // try to read the content of the resolved file entry
        // the memory buffer returned must be freed by us!
        if (char* contents = read_file(resolved[0].abs_path)) {
          // register the newly resolved file resource
          register_resource(resolved[0], { contents, 0 }, pstate);
          // return resolved entry
          return resolved[0];
        }
      }
  
      // nothing found
      return { imp, "" };
  
    }
  
    void Context::import_url (Import* imp, std::string load_path, const std::string& ctx_path) {
  
      ParserState pstate(imp->pstate());
      std::string imp_path(unquote(load_path));
      std::string protocol("file");
  
      using namespace Prelexer;
      if (const char* proto = sequence< identifier, exactly<':'>, exactly<'/'>, exactly<'/'> >(imp_path.c_str())) {
  
        protocol = std::string(imp_path.c_str(), proto - 3);
        // if (protocol.compare("file") && true) { }
      }
  
      // add urls (protocol other than file) and urls without protocol to `urls` member
      // ToDo: if ctx_path is already a file resource, we should not add it here?
      if (imp->import_queries() || protocol != "file" || imp_path.substr(0, 2) == "//") {
        imp->urls().push_back(SASS_MEMORY_NEW(String_Quoted, imp->pstate(), load_path));
      }
      else if (imp_path.length() > 4 && imp_path.substr(imp_path.length() - 4, 4) == ".css") {
        String_Constant* loc = SASS_MEMORY_NEW(String_Constant, pstate, unquote(load_path));
        Argument_Obj loc_arg = SASS_MEMORY_NEW(Argument, pstate, loc);
        Arguments_Obj loc_args = SASS_MEMORY_NEW(Arguments, pstate);
        loc_args->append(loc_arg);
        Function_Call* new_url = SASS_MEMORY_NEW(Function_Call, pstate, std::string("url"), loc_args);
        imp->urls().push_back(new_url);
      }
      else {
        const Importer importer(imp_path, ctx_path);
        Include include(load_import(importer, pstate));
        if (include.abs_path.empty()) {
          error("File to import not found or unreadable: " + imp_path + ".", pstate, traces);
        }
        imp->incs().push_back(include);
      }
  
    }
  
  
    // call custom importers on the given (unquoted) load_path and eventually parse the resulting style_sheet
    bool Context::call_loader(const std::string& load_path, const char* ctx_path, ParserState& pstate, Import* imp, std::vector<Sass_Importer_Entry> importers, bool only_one)
    {
      // unique counter
      size_t count = 0;
      // need one correct import
      bool has_import = false;
      // process all custom importers (or custom headers)
      for (Sass_Importer_Entry& importer_ent : importers) {
        // int priority = sass_importer_get_priority(importer);
        Sass_Importer_Fn fn = sass_importer_get_function(importer_ent);
        // skip importer if it returns NULL
        if (Sass_Import_List includes =
            fn(load_path.c_str(), importer_ent, c_compiler)
        ) {
          // get c pointer copy to iterate over
          Sass_Import_List it_includes = includes;
          while (*it_includes) { ++count;
            // create unique path to use as key
            std::string uniq_path = load_path;
            if (!only_one && count) {
              std::stringstream path_strm;
              path_strm << uniq_path << ":" << count;
              uniq_path = path_strm.str();
            }
            // create the importer struct
            Importer importer(uniq_path, ctx_path);
            // query data from the current include
            Sass_Import_Entry include_ent = *it_includes;
            char* source = sass_import_take_source(include_ent);
            char* srcmap = sass_import_take_srcmap(include_ent);
            size_t line = sass_import_get_error_line(include_ent);
            size_t column = sass_import_get_error_column(include_ent);
            const char *abs_path = sass_import_get_abs_path(include_ent);
            // handle error message passed back from custom importer
            // it may (or may not) override the line and column info
            if (const char* err_message = sass_import_get_error_message(include_ent)) {
              if (source || srcmap) register_resource({ importer, uniq_path }, { source, srcmap }, pstate);
              if (line == std::string::npos && column == std::string::npos) error(err_message, pstate, traces);
              else error(err_message, ParserState(ctx_path, source, Position(line, column)), traces);
            }
            // content for import was set
            else if (source) {
              // resolved abs_path should be set by custom importer
              // use the created uniq_path as fallback (maybe enforce)
              std::string path_key(abs_path ? abs_path : uniq_path);
              // create the importer struct
              Include include(importer, path_key);
              // attach information to AST node
              imp->incs().push_back(include);
              // register the resource buffers
              register_resource(include, { source, srcmap }, pstate);
            }
            // only a path was retuned
            // try to load it like normal
            else if(abs_path) {
              // checks some urls to preserve
              // `http://`, `https://` and `//`
              // or dispatchs to `import_file`
              // which will check for a `.css` extension
              // or resolves the file on the filesystem
              // added and resolved via `add_file`
              // finally stores everything on `imp`
              import_url(imp, abs_path, ctx_path);
            }
            // move to next
            ++it_includes;
          }
          // deallocate the returned memory
          sass_delete_import_list(includes);
          // set success flag
          has_import = true;
          // break out of loop
          if (only_one) break;
        }
      }
      // return result
      return has_import;
    }
  
    void register_function(Context&, Signature sig, Native_Function f, Env* env);
    void register_function(Context&, Signature sig, Native_Function f, size_t arity, Env* env);
    void register_overload_stub(Context&, std::string name, Env* env);
    void register_built_in_functions(Context&, Env* env);
    void register_c_functions(Context&, Env* env, Sass_Function_List);
    void register_c_function(Context&, Env* env, Sass_Function_Entry);
  
    char* Context::render(Block_Obj root)
    {
      // check for valid block
      if (!root) return 0;
      // start the render process
      root->perform(&emitter);
      // finish emitter stream
      emitter.finalize();
      // get the resulting buffer from stream
      OutputBuffer emitted = emitter.get_buffer();
      // should we append a source map url?
      if (!c_options.omit_source_map_url) {
        // generate an embedded source map
        if (c_options.source_map_embed) {
          emitted.buffer += linefeed;
          emitted.buffer += format_embedded_source_map();
        }
        // or just link the generated one
        else if (source_map_file != "") {
          emitted.buffer += linefeed;
          emitted.buffer += format_source_mapping_url(source_map_file);
        }
      }
      // create a copy of the resulting buffer string
      // this must be freed or taken over by implementor
      return sass_copy_c_string(emitted.buffer.c_str());
    }
  
    void Context::apply_custom_headers(Block_Obj root, const char* ctx_path, ParserState pstate)
    {
      // create a custom import to resolve headers
      Import_Obj imp = SASS_MEMORY_NEW(Import, pstate);
      // dispatch headers which will add custom functions
      // custom headers are added to the import instance
      call_headers(entry_path, ctx_path, pstate, imp);
      // increase head count to skip later
      head_imports += resources.size() - 1;
      // add the statement if we have urls
      if (!imp->urls().empty()) root->append(imp);
      // process all other resources (add Import_Stub nodes)
      for (size_t i = 0, S = imp->incs().size(); i < S; ++i) {
        root->append(SASS_MEMORY_NEW(Import_Stub, pstate, imp->incs()[i]));
      }
    }
  
    Block_Obj File_Context::parse()
    {
  
      // check if entry file is given
      if (input_path.empty()) return {};
  
      // create absolute path from input filename
      // ToDo: this should be resolved via custom importers
      std::string abs_path(rel2abs(input_path, CWD));
  
      // try to load the entry file
      char* contents = read_file(abs_path);
  
      // alternatively also look inside each include path folder
      // I think this differs from ruby sass (IMO too late to remove)
      for (size_t i = 0, S = include_paths.size(); contents == 0 && i < S; ++i) {
        // build absolute path for this include path entry
        abs_path = rel2abs(input_path, include_paths[i]);
        // try to load the resulting path
        contents = read_file(abs_path);
      }
  
      // abort early if no content could be loaded (various reasons)
      if (!contents) throw std::runtime_error("File to read not found or unreadable: " + input_path);
  
      // store entry path
      entry_path = abs_path;
  
      // create entry only for import stack
      Sass_Import_Entry import = sass_make_import(
        input_path.c_str(),
        entry_path.c_str(),
        contents,
        0
      );
      // add the entry to the stack
      import_stack.push_back(import);
  
      // create the source entry for file entry
      register_resource({{ input_path, "." }, abs_path }, { contents, 0 });
  
      // create root ast tree node
      return compile();
  
    }
  
    Block_Obj Data_Context::parse()
    {
  
      // check if source string is given
      if (!source_c_str) return {};
  
      // convert indented sass syntax
      if(c_options.is_indented_syntax_src) {
        // call sass2scss to convert the string
        char * converted = sass2scss(source_c_str,
          // preserve the structure as much as possible
          SASS2SCSS_PRETTIFY_1 | SASS2SCSS_KEEP_COMMENT);
        // replace old source_c_str with converted
        free(source_c_str); source_c_str = converted;
      }
  
      // remember entry path (defaults to stdin for string)
      entry_path = input_path.empty() ? "stdin" : input_path;
  
      // ToDo: this may be resolved via custom importers
      std::string abs_path(rel2abs(entry_path));
      char* abs_path_c_str = sass_copy_c_string(abs_path.c_str());
      strings.push_back(abs_path_c_str);
  
      // create entry only for the import stack
      Sass_Import_Entry import = sass_make_import(
        entry_path.c_str(),
        abs_path_c_str,
        source_c_str,
        srcmap_c_str
      );
      // add the entry to the stack
      import_stack.push_back(import);
  
      // register a synthetic resource (path does not really exist, skip in includes)
      register_resource({{ input_path, "." }, input_path }, { source_c_str, srcmap_c_str });
  
      // create root ast tree node
      return compile();
    }
  
    // parse root block from includes
    Block_Obj Context::compile()
    {
      // abort if there is no data
      if (resources.size() == 0) return {};
      // get root block from the first style sheet
      Block_Obj root = sheets.at(entry_path).root;
      // abort on invalid root
      if (root.isNull()) return {};
      Env global; // create root environment
      // register built-in functions on env
      register_built_in_functions(*this, &global);
      // register custom functions (defined via C-API)
      for (size_t i = 0, S = c_functions.size(); i < S; ++i)
      { register_c_function(*this, &global, c_functions[i]); }
      // create initial backtrace entry
      // create crtp visitor objects
      Expand expand(*this, &global);
      Cssize cssize(*this);
      CheckNesting check_nesting;
      // check nesting in all files
      for (auto sheet : sheets) {
        auto styles = sheet.second;
        check_nesting(styles.root);
      }
      // expand and eval the tree
      root = expand(root);
  
      Extension unsatisfied;
      // check that all extends were used
      if (extender.checkForUnsatisfiedExtends(unsatisfied)) {
        throw Exception::UnsatisfiedExtend(traces, unsatisfied);
      }
  
      // check nesting
      check_nesting(root);
      // merge and bubble certain rules
      root = cssize(root);
  
      // clean up by removing empty placeholders
      // ToDo: maybe we can do this somewhere else?
      Remove_Placeholders remove_placeholders;
      root->perform(&remove_placeholders);
  
      // return processed tree
      return root;
    }
    // EO compile
  
    std::string Context::format_embedded_source_map()
    {
      std::string map = emitter.render_srcmap(*this);
      std::istringstream is( map );
      std::ostringstream buffer;
      base64::encoder E;
      E.encode(is, buffer);
      std::string url = "data:application/json;base64," + buffer.str();
      url.erase(url.size() - 1);
      return "/*# sourceMappingURL=" + url + " */";
    }
  
    std::string Context::format_source_mapping_url(const std::string& file)
    {
      std::string url = abs2rel(file, output_path, CWD);
      return "/*# sourceMappingURL=" + url + " */";
    }
  
    char* Context::render_srcmap()
    {
      if (source_map_file == "") return 0;
      std::string map = emitter.render_srcmap(*this);
      return sass_copy_c_string(map.c_str());
    }
  
  
    // for data context we want to start after "stdin"
    // we probably always want to skip the header includes?
    std::vector<std::string> Context::get_included_files(bool skip, size_t headers)
    {
        // create a copy of the vector for manipulations
        std::vector<std::string> includes = included_files;
        if (includes.size() == 0) return includes;
        if (skip) { includes.erase( includes.begin(), includes.begin() + 1 + headers); }
        else { includes.erase( includes.begin() + 1, includes.begin() + 1 + headers); }
        includes.erase( std::unique( includes.begin(), includes.end() ), includes.end() );
        std::sort( includes.begin() + (skip ? 0 : 1), includes.end() );
        return includes;
    }
  
    void register_function(Context& ctx, Signature sig, Native_Function f, Env* env)
    {
      Definition* def = make_native_function(sig, f, ctx);
      def->environment(env);
      (*env)[def->name() + "[f]"] = def;
    }
  
    void register_function(Context& ctx, Signature sig, Native_Function f, size_t arity, Env* env)
    {
      Definition* def = make_native_function(sig, f, ctx);
      std::stringstream ss;
      ss << def->name() << "[f]" << arity;
      def->environment(env);
      (*env)[ss.str()] = def;
    }
  
    void register_overload_stub(Context& ctx, std::string name, Env* env)
    {
      Definition* stub = SASS_MEMORY_NEW(Definition,
                                         ParserState("[built-in function]"),
                                         0,
                                         name,
                                         {},
                                         0,
                                         true);
      (*env)[name + "[f]"] = stub;
    }
  
  
    void register_built_in_functions(Context& ctx, Env* env)
    {
      using namespace Functions;
      // RGB Functions
      register_function(ctx, rgb_sig, rgb, env);
      register_overload_stub(ctx, "rgba", env);
      register_function(ctx, rgba_4_sig, rgba_4, 4, env);
      register_function(ctx, rgba_2_sig, rgba_2, 2, env);
      register_function(ctx, red_sig, red, env);
      register_function(ctx, green_sig, green, env);
      register_function(ctx, blue_sig, blue, env);
      register_function(ctx, mix_sig, mix, env);
      // HSL Functions
      register_function(ctx, hsl_sig, hsl, env);
      register_function(ctx, hsla_sig, hsla, env);
      register_function(ctx, hue_sig, hue, env);
      register_function(ctx, saturation_sig, saturation, env);
      register_function(ctx, lightness_sig, lightness, env);
      register_function(ctx, adjust_hue_sig, adjust_hue, env);
      register_function(ctx, lighten_sig, lighten, env);
      register_function(ctx, darken_sig, darken, env);
      register_function(ctx, saturate_sig, saturate, env);
      register_function(ctx, desaturate_sig, desaturate, env);
      register_function(ctx, grayscale_sig, grayscale, env);
      register_function(ctx, complement_sig, complement, env);
      register_function(ctx, invert_sig, invert, env);
      // Opacity Functions
      register_function(ctx, alpha_sig, alpha, env);
      register_function(ctx, opacity_sig, alpha, env);
      register_function(ctx, opacify_sig, opacify, env);
      register_function(ctx, fade_in_sig, opacify, env);
      register_function(ctx, transparentize_sig, transparentize, env);
      register_function(ctx, fade_out_sig, transparentize, env);
      // Other Color Functions
      register_function(ctx, adjust_color_sig, adjust_color, env);
      register_function(ctx, scale_color_sig, scale_color, env);
      register_function(ctx, change_color_sig, change_color, env);
      register_function(ctx, ie_hex_str_sig, ie_hex_str, env);
      // String Functions
      register_function(ctx, unquote_sig, sass_unquote, env);
      register_function(ctx, quote_sig, sass_quote, env);
      register_function(ctx, str_length_sig, str_length, env);
      register_function(ctx, str_insert_sig, str_insert, env);
      register_function(ctx, str_index_sig, str_index, env);
      register_function(ctx, str_slice_sig, str_slice, env);
      register_function(ctx, to_upper_case_sig, to_upper_case, env);
      register_function(ctx, to_lower_case_sig, to_lower_case, env);
      // Number Functions
      register_function(ctx, percentage_sig, percentage, env);
      register_function(ctx, round_sig, round, env);
      register_function(ctx, ceil_sig, ceil, env);
      register_function(ctx, floor_sig, floor, env);
      register_function(ctx, abs_sig, abs, env);
      register_function(ctx, min_sig, min, env);
      register_function(ctx, max_sig, max, env);
      register_function(ctx, random_sig, random, env);
      // List Functions
      register_function(ctx, length_sig, length, env);
      register_function(ctx, nth_sig, nth, env);
      register_function(ctx, set_nth_sig, set_nth, env);
      register_function(ctx, index_sig, index, env);
      register_function(ctx, join_sig, join, env);
      register_function(ctx, append_sig, append, env);
      register_function(ctx, zip_sig, zip, env);
      register_function(ctx, list_separator_sig, list_separator, env);
      register_function(ctx, is_bracketed_sig, is_bracketed, env);
      // Map Functions
      register_function(ctx, map_get_sig, map_get, env);
      register_function(ctx, map_merge_sig, map_merge, env);
      register_function(ctx, map_remove_sig, map_remove, env);
      register_function(ctx, map_keys_sig, map_keys, env);
      register_function(ctx, map_values_sig, map_values, env);
      register_function(ctx, map_has_key_sig, map_has_key, env);
      register_function(ctx, keywords_sig, keywords, env);
      // Introspection Functions
      register_function(ctx, type_of_sig, type_of, env);
      register_function(ctx, unit_sig, unit, env);
      register_function(ctx, unitless_sig, unitless, env);
      register_function(ctx, comparable_sig, comparable, env);
      register_function(ctx, variable_exists_sig, variable_exists, env);
      register_function(ctx, global_variable_exists_sig, global_variable_exists, env);
      register_function(ctx, function_exists_sig, function_exists, env);
      register_function(ctx, mixin_exists_sig, mixin_exists, env);
      register_function(ctx, feature_exists_sig, feature_exists, env);
      register_function(ctx, call_sig, call, env);
      register_function(ctx, content_exists_sig, content_exists, env);
      register_function(ctx, get_function_sig, get_function, env);
      // Boolean Functions
      register_function(ctx, not_sig, sass_not, env);
      register_function(ctx, if_sig, sass_if, env);
      // Misc Functions
      register_function(ctx, inspect_sig, inspect, env);
      register_function(ctx, unique_id_sig, unique_id, env);
      // Selector functions
      register_function(ctx, selector_nest_sig, selector_nest, env);
      register_function(ctx, selector_append_sig, selector_append, env);
      register_function(ctx, selector_extend_sig, selector_extend, env);
      register_function(ctx, selector_replace_sig, selector_replace, env);
      register_function(ctx, selector_unify_sig, selector_unify, env);
      register_function(ctx, is_superselector_sig, is_superselector, env);
      register_function(ctx, simple_selectors_sig, simple_selectors, env);
      register_function(ctx, selector_parse_sig, selector_parse, env);
    }
  
    void register_c_functions(Context& ctx, Env* env, Sass_Function_List descrs)
    {
      while (descrs && *descrs) {
        register_c_function(ctx, env, *descrs);
        ++descrs;
      }
    }
    void register_c_function(Context& ctx, Env* env, Sass_Function_Entry descr)
    {
      Definition* def = make_c_function(descr, ctx);
      def->environment(env);
      (*env)[def->name() + "[f]"] = def;
    }
  
  }
  