Implement passing arguments to @content

See sass/sass#871
Spec sass/sass-spec#1313
Fixes #2723

src/ast.hpp

@@ -994,14 +994,16 @@ namespace Sass {
   class Mixin_Call final : public Has_Block {
     ADD_CONSTREF(std::string, name)
     ADD_PROPERTY(Arguments_Obj, arguments)
+    ADD_PROPERTY(Parameters_Obj, block_parameters)
   public:
-    Mixin_Call(ParserState pstate, std::string n, Arguments_Obj args, Block_Obj b = {})
-    : Has_Block(pstate, b), name_(n), arguments_(args)
+    Mixin_Call(ParserState pstate, std::string n, Arguments_Obj args, Parameters_Obj b_params = {}, Block_Obj b = {})
+    : Has_Block(pstate, b), name_(n), arguments_(args), block_parameters_(b_params)
     { }
     Mixin_Call(const Mixin_Call* ptr)
     : Has_Block(ptr),
       name_(ptr->name_),
-      arguments_(ptr->arguments_)
+      arguments_(ptr->arguments_),
+      block_parameters_(ptr->block_parameters_)
     { }
     ATTACH_AST_OPERATIONS(Mixin_Call)
     ATTACH_CRTP_PERFORM_METHODS()
@@ -1011,15 +1013,15 @@ namespace Sass {
   // The @content directive for mixin content blocks.
   ///////////////////////////////////////////////////
   class Content final : public Statement {
-    ADD_PROPERTY(Media_Block_Ptr, media_block)
+    ADD_PROPERTY(Arguments_Obj, arguments)
   public:
-    Content(ParserState pstate)
+    Content(ParserState pstate, Arguments_Obj args)
     : Statement(pstate),
-      media_block_(NULL)
+      arguments_(args)
     { statement_type(CONTENT); }
     Content(const Content* ptr)
     : Statement(ptr),
-      media_block_(ptr->media_block_)
+      arguments_(ptr->arguments_)
     { statement_type(CONTENT); }
     ATTACH_AST_OPERATIONS(Content)
     ATTACH_CRTP_PERFORM_METHODS()

src/constants.cpp

@@ -125,6 +125,9 @@ namespace Sass {
     extern const char true_kwd[]  = "true";
     extern const char false_kwd[] = "false";
 
+    // definition keywords
+    extern const char using_kwd[]   = "using";
+
     // miscellaneous punctuation and delimiters
     extern const char percent_str[]     = "%";
     extern const char empty_str[]       = "";

src/constants.hpp

@@ -127,6 +127,9 @@ namespace Sass {
     extern const char true_kwd[];
     extern const char false_kwd[];
 
+    // definition keywords
+    extern const char using_kwd[];
+
     // miscellaneous punctuation and delimiters
     extern const char percent_str[];
     extern const char empty_str[];

src/debugger.hpp

@@ -398,8 +398,8 @@ inline void debug_ast(AST_Node_Ptr node, std::string ind, Env* env)
     Content_Ptr block = Cast<Content>(node);
     std::cerr << ind << "Content " << block;
     std::cerr << " (" << pstate_source_position(node) << ")";
-    std::cerr << " [@media:" << block->media_block() << "]";
     std::cerr << " " << block->tabs() << std::endl;
+    debug_ast(block->arguments(), ind + " args: ", env);
   } else if (Cast<Import_Stub>(node)) {
     Import_Stub_Ptr block = Cast<Import_Stub>(node);
     std::cerr << ind << "Import_Stub " << block;
@@ -480,7 +480,8 @@ inline void debug_ast(AST_Node_Ptr node, std::string ind, Env* env)
     std::cerr << " (" << pstate_source_position(block) << ")";
     std::cerr << " [" <<  block->name() << "]";
     std::cerr << " [has_content: " << block->has_content() << "] " << std::endl;
-    debug_ast(block->arguments(), ind + " args: ");
+    debug_ast(block->arguments(), ind + " args: ", env);
+    debug_ast(block->block_parameters(), ind + " block_params: ", env);
     if (block->block()) debug_ast(block->block(), ind + " ", env);
   } else if (Ruleset_Ptr ruleset = Cast<Ruleset>(node)) {
     std::cerr << ind << "Ruleset " << ruleset;
@@ -605,12 +606,6 @@ inline void debug_ast(AST_Node_Ptr node, std::string ind, Env* env)
       " [hash: " << expression->hash() << "] " <<
       std::endl;
     for(const auto& i : expression->elements()) { debug_ast(i, ind + " ", env); }
-  } else if (Cast<Content>(node)) {
-    Content_Ptr expression = Cast<Content>(node);
-    std::cerr << ind << "Content " << expression;
-    std::cerr << " (" << pstate_source_position(node) << ")";
-    std::cerr << " [@media:" << expression->media_block() << "]";
-    std::cerr << " [Statement]" << std::endl;
   } else if (Cast<Boolean>(node)) {
     Boolean_Ptr expression = Cast<Boolean>(node);
     std::cerr << ind << "Boolean " << expression;

src/expand.cpp

@@ -730,11 +730,13 @@ namespace Sass {
     Env new_env(def->environment());
     env_stack.push_back(&new_env);
     if (c->block()) {
+      Parameters_Obj params = c->block_parameters();
+      if (!params) params = SASS_MEMORY_NEW(Parameters, c->pstate());
       // represent mixin content blocks as thunks/closures
       Definition_Obj thunk = SASS_MEMORY_NEW(Definition,
                                           c->pstate(),
                                           "@content",
-                                          SASS_MEMORY_NEW(Parameters, c->pstate()),
+                                          params,
                                           c->block(),
                                           Definition::MIXIN);
       thunk->environment(env);
@@ -779,10 +781,13 @@ namespace Sass {
       selector_stack.push_back({});
     }
 
+    Arguments_Obj args = c->arguments();
+    if (!args) args = SASS_MEMORY_NEW(Arguments, c->pstate());
+
     Mixin_Call_Obj call = SASS_MEMORY_NEW(Mixin_Call,
                                        c->pstate(),
                                        "@content",
-                                       SASS_MEMORY_NEW(Arguments, c->pstate()));
+                                       args);
 
     Trace_Obj trace = Cast<Trace>(call->perform(this));
 

src/parser.cpp

@@ -644,13 +644,27 @@ namespace Sass {
     // normalize underscores to hyphens
     std::string name(Util::normalize_underscores(lexed));
     // create the initial mixin call object
-    Mixin_Call_Obj call = SASS_MEMORY_NEW(Mixin_Call, pstate, name, {}, {});
+    Mixin_Call_Obj call = SASS_MEMORY_NEW(Mixin_Call, pstate, name, {}, {}, {});
     // parse mandatory arguments
     call->arguments(parse_arguments());
+    // parse using and optional block parameters
+    bool has_parameters = lex< kwd_using >();
+
+    if (has_parameters) {
+      if (!peek< exactly<'('> >()) css_error("Invalid CSS", " after ", ": expected \"(\", was ");
+    } else {
+      if (peek< exactly<'('> >()) css_error("Invalid CSS", " after ", ": expected \";\", was ");
+    }
+
+    if (has_parameters) call->block_parameters(parse_parameters());
+
     // parse optional block
     if (peek < exactly <'{'> >()) {
       call->block(parse_block());
     }
+    else if (has_parameters)  {
+      css_error("Invalid CSS", " after ", ": expected \"{\", was ");
+    }
     // return ast node
     return call.detach();
   }
@@ -2202,7 +2216,10 @@ namespace Sass {
 
   Content_Obj Parser::parse_content_directive()
   {
-    return SASS_MEMORY_NEW(Content, pstate);
+    ParserState call_pos = pstate;
+    Arguments_Obj args = parse_arguments();
+
+    return SASS_MEMORY_NEW(Content, call_pos, args);
   }
 
   If_Obj Parser::parse_if_directive(bool else_if)

src/prelexer.cpp

@@ -1260,6 +1260,9 @@ namespace Sass {
     const char* kwd_lte(const char* src) {
       return exactly<lte>(src);
     }
+    const char* kwd_using(const char* src) {
+      return keyword<using_kwd>(src);
+    }
 
     // match specific IE syntax
     const char* ie_progid(const char* src) {

src/prelexer.hpp

@@ -25,6 +25,7 @@ namespace Sass {
     const char* kwd_gte(const char* src);
     const char* kwd_lt(const char* src);
     const char* kwd_lte(const char* src);
+    const char* kwd_using(const char* src);
 
     // Match standard control chars
     const char* kwd_at(const char* src);