Error when declarations are printed without ruleset

Makefile.conf

@@ -4,6 +4,7 @@ SOURCES = \
 	ast.cpp \
 	base64vlq.cpp \
 	bind.cpp \
+	check_nesting.cpp \
 	color_maps.cpp \
 	constants.cpp \
 	context.cpp \

src/check_nesting.cpp

@@ -0,0 +1,60 @@
+#include "sass.hpp"
+#include <vector>
+
+#include "check_nesting.hpp"
+#include "context.hpp"
+// #include "debugger.hpp"
+
+namespace Sass {
+
+  CheckNesting::CheckNesting(Context& ctx)
+  : ctx(ctx),
+    parent_stack(std::vector<AST_Node*>())
+  { }
+
+  AST_Node* CheckNesting::parent()
+  {
+    if (parent_stack.size() > 0)
+      return parent_stack.back();
+    return 0;
+  }
+
+  Statement* CheckNesting::operator()(Block* b)
+  {
+    parent_stack.push_back(b);
+
+    for (auto n : *b) {
+      n->perform(this);
+    }
+
+    parent_stack.pop_back();
+    return b;
+  }
+
+  Statement* CheckNesting::operator()(Declaration* d)
+  {
+    if (!is_valid_prop_parent(parent())) {
+      throw Exception::InvalidSass(d->pstate(), "Properties are only allowed "
+        "within rules, directives, mixin includes, or other properties.");
+    }
+    return static_cast<Statement*>(d);
+  }
+
+  Statement* CheckNesting::fallback_impl(AST_Node* n)
+  {
+    return static_cast<Statement*>(n);
+  }
+
+  bool CheckNesting::is_valid_prop_parent(AST_Node* p) 
+  {
+    if (Definition* def = dynamic_cast<Definition*>(p)) {
+      return def->type() == Definition::MIXIN;
+    }
+
+    return dynamic_cast<Ruleset*>(p) ||
+           dynamic_cast<Keyframe_Rule*>(p) ||
+           dynamic_cast<Propset*>(p) ||
+           dynamic_cast<Directive*>(p) ||
+           dynamic_cast<Mixin_Call*>(p);
+  }
+}

src/check_nesting.hpp

@@ -0,0 +1,37 @@
+#ifndef SASS_CHECK_NESTING_H
+#define SASS_CHECK_NESTING_H
+
+#include "ast.hpp"
+#include "context.hpp"
+#include "operation.hpp"
+
+namespace Sass {
+
+  typedef Environment<AST_Node*> Env;
+
+  class CheckNesting : public Operation_CRTP<Statement*, CheckNesting> {
+
+    Context&                 ctx;
+    std::vector<Block*>      block_stack;
+    std::vector<AST_Node*>   parent_stack;
+
+    AST_Node* parent();
+
+    Statement* fallback_impl(AST_Node* n);
+
+  public:
+    CheckNesting(Context&);
+    ~CheckNesting() { }
+
+    Statement* operator()(Block*);
+    Statement* operator()(Declaration*);
+
+    template <typename U>
+    Statement* fallback(U x) { return fallback_impl(x); }
+
+    bool is_valid_prop_parent(AST_Node*);
+  };
+
+}
+
+#endif

src/context.cpp

@@ -18,6 +18,7 @@
 #include "output.hpp"
 #include "expand.hpp"
 #include "eval.hpp"
+#include "check_nesting.hpp"
 #include "cssize.hpp"
 #include "listize.hpp"
 #include "extend.hpp"
@@ -648,8 +649,13 @@ namespace Sass {
     // create crtp visitor objects
     Expand expand(*this, &global, &backtrace);
     Cssize cssize(*this, &backtrace);
+    CheckNesting check_nesting(*this);
+    // check nesting
+    root = root->perform(&check_nesting)->block();
     // expand and eval the tree
     root = root->perform(&expand)->block();
+    // check nesting
+    root = root->perform(&check_nesting)->block();
     // merge and bubble certain rules
     root = root->perform(&cssize)->block();
     // should we extend something?

win/libsass.targets

@@ -18,6 +18,7 @@
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\base64vlq.hpp" />
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\bind.hpp" />
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\b64\cencode.h" />
+    <ClInclude Include="$(LIBSASS_HEADERS_DIR)\check_nesting.hpp" />
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\color_maps.hpp" />
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\constants.hpp" />
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\context.hpp" />
@@ -71,6 +72,7 @@
     <ClCompile Include="$(LIBSASS_SRC_DIR)\bind.cpp" />
     <ClCompile Condition="$(VisualStudioVersion) &lt; 14.0" Include="$(LIBSASS_SRC_DIR)\c99func.c" />
     <ClCompile Include="$(LIBSASS_SRC_DIR)\cencode.c" />
+    <ClCompile Include="$(LIBSASS_SRC_DIR)\check_nesting.cpp" />
     <ClCompile Include="$(LIBSASS_SRC_DIR)\color_maps.cpp" />
     <ClCompile Include="$(LIBSASS_SRC_DIR)\constants.cpp" />
     <ClCompile Include="$(LIBSASS_SRC_DIR)\context.cpp" />

win/libsass.vcxproj.filters

@@ -66,6 +66,9 @@
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\bind.hpp">
       <Filter>Headers</Filter>
     </ClInclude>
+    <ClInclude Include="$(LIBSASS_HEADERS_DIR)\check_nesting.hpp">
+      <Filter>Headers</Filter>
+    </ClInclude>
     <ClInclude Include="$(LIBSASS_HEADERS_DIR)\color_maps.hpp">
       <Filter>Headers</Filter>
     </ClInclude>
@@ -224,6 +227,9 @@
     <ClCompile Include="$(LIBSASS_SRC_DIR)\cencode.c">
       <Filter>Sources</Filter>
     </ClCompile>
+    <ClCompile Include="$(LIBSASS_SRC_DIR)\check_nesting.cpp">
+      <Filter>Sources</Filter>
+    </ClCompile>
     <ClCompile Include="$(LIBSASS_SRC_DIR)\color_maps.cpp">
       <Filter>Sources</Filter>
     </ClCompile>