Merge pull request #715 from mgreter/feature/overload-error-fn

Implement @error function

Author: mgreter

ast.hpp

@@ -442,6 +442,18 @@ namespace Sass {
     ATTACH_OPERATIONS();
   };
 
+  ///////////////////////////////
+  // The Sass `@error` directive.
+  ///////////////////////////////
+  class Error : public Statement {
+    ADD_PROPERTY(Expression*, message);
+  public:
+    Error(string path, Position position, Expression* msg)
+    : Statement(path, position), message_(msg)
+    { }
+    ATTACH_OPERATIONS();
+  };
+
   ///////////////////////////////////////////
   // CSS comments. These may be interpolated.
   ///////////////////////////////////////////

ast_factory.hpp

@@ -24,6 +24,7 @@ namespace Sass {
     Import<Function_Call*>* new_CSS_Import(string p, size_t l, Function_Call* loc);
     Import<String*>* new_SASS_Import(string p, size_t l, String* loc);
     Warning* new_Warning(string p, size_t l, Expression* msg);
+    Error* new_Error(string p, size_t l, Expression* msg);
     Comment* new_Comment(string p, size_t l, String* txt);
     If* new_If(string p, size_t l, Expression* pred, Block* con, Block* alt = 0);
     For* new_For(string p, size_t l, string var, Expression* lo, Expression* hi, Block* b, bool inc);

ast_fwd_decl.hpp

@@ -17,6 +17,7 @@ namespace Sass {
   class Import;
   class Import_Stub;
   class Warning;
+  class Error;
   class Comment;
   class If;
   class For;

constants.cpp

@@ -26,6 +26,7 @@ namespace Sass {
     extern const char in_kwd[]            = "in";
     extern const char while_kwd[]         = "@while";
     extern const char warn_kwd[]          = "@warn";
+    extern const char error_kwd[]         = "@error";
     extern const char default_kwd[]       = "default";
     extern const char global_kwd[]        = "global";
     extern const char null_kwd[]          = "null";

constants.hpp

@@ -26,6 +26,7 @@ namespace Sass {
     extern const char in_kwd[];
     extern const char while_kwd[];
     extern const char warn_kwd[];
+    extern const char error_kwd[];
     extern const char default_kwd[];
     extern const char global_kwd[];
     extern const char null_kwd[];

error_handling.cpp

@@ -7,12 +7,12 @@
 
 namespace Sass {
 
-  Error::Error(Type type, string path, Position position, string message)
+  Sass_Error::Sass_Error(Type type, string path, Position position, string message)
   : type(type), path(path), position(position), message(message)
   { }
 
   void error(string msg, string path, Position position)
-  { throw Error(Error::syntax, path, position, msg); }
+  { throw Sass_Error(Sass_Error::syntax, path, position, msg); }
 
   void error(string msg, string path, Position position, Backtrace* bt)
   {
@@ -22,7 +22,7 @@ namespace Sass {
     Backtrace top(bt, path, position, "");
     msg += top.to_string();
 
-    throw Error(Error::syntax, path, position, msg);
+    throw Sass_Error(Sass_Error::syntax, path, position, msg);
   }
 
 }

error_handling.hpp

@@ -10,15 +10,15 @@ namespace Sass {
 
   struct Backtrace;
 
-  struct Error {
+  struct Sass_Error {
     enum Type { read, write, syntax, evaluation };
 
     Type type;
     string path;
     Position position;
     string message;
 
-    Error(Type type, string path, Position position, string message);
+    Sass_Error(Type type, string path, Position position, string message);
 
   };
 

eval.cpp

@@ -218,6 +218,38 @@ namespace Sass {
     return 0;
   }
 
+  Expression* Eval::operator()(Error* e)
+  {
+    Expression* message = e->message()->perform(this);
+    To_String to_string;
+
+    // try to use generic function
+    if (env->has("@error[f]")) {
+
+      Definition* def = static_cast<Definition*>((*env)["@error[f]"]);
+      // Block*          body   = def->block();
+      // Native_Function func   = def->native_function();
+      Sass_C_Function c_func = def->c_function();
+
+      To_C to_c;
+      union Sass_Value* c_args = sass_make_list(1, SASS_COMMA);
+      sass_list_set_value(c_args, 0, message->perform(&to_c));
+      Sass_Value* c_val = c_func(c_args, def->cookie());
+      sass_delete_value(c_args);
+      sass_delete_value(c_val);
+      return 0;
+
+    }
+
+    string prefix("Error: ");
+    string result(unquote(message->perform(&to_string)));
+    cerr << prefix << result;
+    Backtrace top(backtrace, e->path(), e->position(), "");
+    cerr << top.to_string(true);
+    cerr << endl << endl;
+    return 0;
+  }
+
   Expression* Eval::operator()(List* l)
   {
     if (l->is_expanded()) return l;
@@ -450,6 +482,8 @@ namespace Sass {
       Sass_Value* c_val = c_func(c_args, def->cookie());
       if (sass_value_get_tag(c_val) == SASS_ERROR) {
         error("error in C function " + c->name() + ": " + sass_error_get_message(c_val), c->path(), c->position(), backtrace);
+      } else if (sass_value_get_tag(c_val) == SASS_WARNING) {
+        error("warning in C function " + c->name() + ": " + sass_warning_get_message(c_val), c->path(), c->position(), backtrace);
       }
       result = cval_to_astnode(c_val, ctx, backtrace, c->path(), c->position());
 
@@ -1037,7 +1071,10 @@ namespace Sass {
         e = new (ctx.mem) Null(path, position);
       } break;
       case SASS_ERROR: {
-        error("error in C function: " + string(sass_error_get_message(v)), path, position, backtrace);
+        error("Error in C function: " + string(sass_error_get_message(v)), path, position, backtrace);
+      } break;
+      case SASS_WARNING: {
+        error("Warning in C function: " + string(sass_warning_get_message(v)), path, position, backtrace);
       } break;
     }
     return e;

eval.hpp

@@ -46,6 +46,7 @@ namespace Sass {
     Expression* operator()(While*);
     Expression* operator()(Return*);
     Expression* operator()(Warning*);
+    Expression* operator()(Error*);
 
     Expression* operator()(List*);
     Expression* operator()(Map*);

expand.cpp

@@ -174,6 +174,13 @@ namespace Sass {
     return 0;
   }
 
+  Statement* Expand::operator()(Error* e)
+  {
+    // eval handles this too, because errors may occur in functions
+    e->perform(eval->with(env, backtrace));
+    return 0;
+  }
+
   Statement* Expand::operator()(Comment* c)
   {
     // TODO: eval the text, once we're parsing/storing it as a String_Schema