Change {Source,Binary}ErrorHandler to C++ (#403)

Added some new classes:

* BinaryErrorHandler: abstract base class
* BinaryErrorHandlerFile: writes errors to a FILE*
* SourceErrorHandler: abstract base class
* SourceErrorHandlerNop: eats all errors
* SourceErrorHandlerFile: writes errors to a FILE*

There are some specific ones as well:

* BinaryErrorHandlerAssert: used in wasm-interp to handle writing out a
  custom header with assertion "failures"; i.e. places where the error
  handler should fire.
* BinaryErrorHandlerModule: used when parsing a .wast, but there's an
  embedded binary file.

1 files changed, 2 insertions, 4 deletions

diff --git a/src/binary-reader-ast.cc b/src/binary-reader-ast.cc
index de0a2a93..2aafc341 100644
--- a/src/binary-reader-ast.cc
+++ b/src/binary-reader-ast.cc
@@ -25,6 +25,7 @@
 #include <vector>
 
 #include "ast.h"
+#include "binary-error-handler.h"
 #include "binary-reader-nop.h"
 #include "common.h"
 
@@ -264,10 +265,7 @@ Result BinaryReaderAST::AppendExpr(Expr* expr) {
 }
 
 bool BinaryReaderAST::HandleError(uint32_t offset, const char* message) {
-  if (error_handler->on_error) {
-    return error_handler->on_error(offset, message, error_handler->user_data);
-  }
-  return false;
+  return error_handler->OnError(offset, message);
 }
 
 bool BinaryReaderAST::OnError(const char* message) {