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, 91 insertions, 0 deletions

diff --git a/src/source-error-handler.h b/src/source-error-handler.h
new file mode 100644
index 00000000..eaa50300
--- /dev/null
+++ b/src/source-error-handler.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef WABT_SOURCE_ERROR_HANDLER_H_
+#define WABT_SOURCE_ERROR_HANDLER_H_
+
+#include <string>
+
+#include "common.h"
+
+namespace wabt {
+
+class SourceErrorHandler {
+ public:
+  virtual ~SourceErrorHandler() {}
+
+  // Returns true if the error was handled.
+  virtual bool OnError(const Location*,
+                       const std::string& error,
+                       const std::string& source_line,
+                       size_t source_line_column_offset) = 0;
+
+  // OnError will be called with with source_line trimmed to this length.
+  virtual size_t source_line_max_length() const = 0;
+
+  std::string DefaultErrorMessage(const Location*,
+                                  const std::string& error,
+                                  const std::string& source_line,
+                                  size_t source_line_column_offset);
+};
+
+class SourceErrorHandlerNop : public SourceErrorHandler {
+ public:
+  bool OnError(const Location*,
+               const std::string& error,
+               const std::string& source_line,
+               size_t source_line_column_offset) override {
+    return false;
+  }
+
+  size_t source_line_max_length() const override { return 80; }
+};
+
+class SourceErrorHandlerFile : public SourceErrorHandler {
+ public:
+  enum class PrintHeader {
+    Never,
+    Once,
+    Always,
+  };
+
+  SourceErrorHandlerFile(FILE* file = stderr,
+                         const std::string& header = std::string(),
+                         PrintHeader print_header = PrintHeader::Never,
+                         size_t source_line_max_length = 80);
+
+  bool OnError(const Location*,
+               const std::string& error,
+               const std::string& source_line,
+               size_t source_line_column_offset) override;
+
+  size_t source_line_max_length() const override {
+    return source_line_max_length_;
+  }
+
+ private:
+  void PrintErrorHeader();
+  void PrintSourceError();
+
+  FILE* file_;
+  std::string header_;
+  PrintHeader print_header_;
+  size_t source_line_max_length_;
+};
+
+}  // namespace wabt
+
+#endif // WABT_SOURCE_ERROR_HANDLER_H_