[WebSocketExtensionParser] Have Consume.* methods return bool instead of using has_error()

net/websockets/websocket_extension_parser.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/websockets/websocket_extension_parser.h"
 
 #include "base/strings/string_util.h"
 
 namespace net {
 
 WebSocketExtensionParser::WebSocketExtensionParser() {}
 
 WebSocketExtensionParser::~WebSocketExtensionParser() {}
 
-void WebSocketExtensionParser::Parse(const char* data, size_t size) {
+bool WebSocketExtensionParser::Parse(const char* data, size_t size) {
   current_ = data;
   end_ = data + size;
-  has_error_ = false;
   extensions_.clear();
 
+  bool failed = false;
+
   while (true) {
     WebSocketExtension extension;
-    ConsumeExtension(&extension);
-    if (has_error_)
+    if (!ConsumeExtension(&extension)) {
+      failed = true;
       break;
+    }
     extensions_.push_back(extension);
 
     ConsumeSpaces();
-    DCHECK(!has_error_);
 
     if (!ConsumeIfMatch(',')) {
       break;
     }
   }
 
-  has_error_ = has_error_ || current_ != end_;
-  if (has_error_)
-    extensions_.clear();
+  if (!failed && current_ == end_)
+    return true;
+
+  extensions_.clear();
+  return false;
 }
 
-void WebSocketExtensionParser::Consume(char c) {
-  DCHECK(!has_error_);
+bool WebSocketExtensionParser::Consume(char c) {
   ConsumeSpaces();
-  DCHECK(!has_error_);
   if (current_ == end_ || c != current_[0]) {
-    has_error_ = true;
-    return;
+    return false;
   }
   ++current_;
+  return true;
 }
 
-void WebSocketExtensionParser::ConsumeExtension(WebSocketExtension* extension) {
-  DCHECK(!has_error_);
+bool WebSocketExtensionParser::ConsumeExtension(WebSocketExtension* extension) {
   base::StringPiece name;
-  ConsumeToken(&name);
-  if (has_error_) return;
+  if (!ConsumeToken(&name))
+    return false;
   *extension = WebSocketExtension(name.as_string());
 
   while (ConsumeIfMatch(';')) {
     WebSocketExtension::Parameter parameter((std::string()));
-    ConsumeExtensionParameter(&parameter);
-    if (has_error_) return;
+    if (!ConsumeExtensionParameter(&parameter))
+      return false;
     extension->Add(parameter);
   }
+
+  return true;
 }
 
-void WebSocketExtensionParser::ConsumeExtensionParameter(
+bool WebSocketExtensionParser::ConsumeExtensionParameter(
     WebSocketExtension::Parameter* parameter) {
-  DCHECK(!has_error_);
   base::StringPiece name, value;
   std::string value_string;
 
-  ConsumeToken(&name);
-  if (has_error_) return;
+  if (!ConsumeToken(&name))
+    return false;
+
   if (!ConsumeIfMatch('=')) {
     *parameter = WebSocketExtension::Parameter(name.as_string());
-    return;
+    return true;
   }
 
   if (Lookahead('\"')) {
-    ConsumeQuotedToken(&value_string);
+    if (!ConsumeQuotedToken(&value_string))
+      return false;
   } else {
-    ConsumeToken(&value);
+    if (!ConsumeToken(&value))
+      return false;
     value_string = value.as_string();

[eroman, 2015/04/06 19:07:52]

FYI: Before value.as_string() was called unconditionally even if ConsumeToken()
failed. I think the new behavior is correct, but just wanted to raise this
difference.

[tyoshino (SeeGerritForStatus), 2015/04/13 14:11:59]

Thanks. value_string is not used when has_error_ is set. If ConsumeToken()
fails, it set has_error_. So, it's fine.

   }
-  if (has_error_) return;
   *parameter = WebSocketExtension::Parameter(name.as_string(), value_string);
+  return true;
 }
 
-void WebSocketExtensionParser::ConsumeToken(base::StringPiece* token) {
-  DCHECK(!has_error_);
+bool WebSocketExtensionParser::ConsumeToken(base::StringPiece* token) {
   ConsumeSpaces();
-  DCHECK(!has_error_);
   const char* head = current_;
   while (current_ < end_ &&
          !IsControl(current_[0]) && !IsSeparator(current_[0]))
     ++current_;
   if (current_ == head) {
-    has_error_ = true;
-    return;
+    return false;
   }
   *token = base::StringPiece(head, current_ - head);
+  return true;
 }
 
-void WebSocketExtensionParser::ConsumeQuotedToken(std::string* token) {
-  DCHECK(!has_error_);
-  Consume('"');
-  if (has_error_) return;
+bool WebSocketExtensionParser::ConsumeQuotedToken(std::string* token) {
+  if (!Consume('"'))
+    return false;
+
   *token = "";
   while (current_ < end_ && !IsControl(current_[0])) {
     if (UnconsumedBytes() >= 2 && current_[0] == '\\') {
       char next = current_[1];
       if (IsControl(next) || IsSeparator(next)) break;
       *token += next;
       current_ += 2;
     } else if (IsSeparator(current_[0])) {
       break;
     } else {
       *token += current_[0];
       ++current_;
     }
   }
   // We can't use Consume here because we don't want to consume spaces.
   if (current_ < end_ && current_[0] == '"')
     ++current_;
   else
-    has_error_ = true;
-  has_error_ = has_error_ || token->empty();
+    return false;

[eroman, 2015/04/06 19:07:52]

optional: You might inverse the test above to do:

 if (....)
   return false;

 ++current_;

[tyoshino (SeeGerritForStatus), 2015/04/13 14:11:59]

Done.

+
+  if (token->empty())

[eroman, 2015/04/06 19:07:52]

optinal:

  return !token->empty();

[tyoshino (SeeGerritForStatus), 2015/04/13 14:11:59]

Done.

+    return false;
+
+  return true;
 }
 
 void WebSocketExtensionParser::ConsumeSpaces() {
-  DCHECK(!has_error_);
   while (current_ < end_ && (current_[0] == ' ' || current_[0] == '\t'))
     ++current_;
   return;
 }
 
 bool WebSocketExtensionParser::Lookahead(char c) {
-  DCHECK(!has_error_);
   const char* head = current_;
-
-  Consume(c);
-  bool result = !has_error_;
+  bool result = Consume(c);
   current_ = head;
-  has_error_ = false;
   return result;
 }
 
 bool WebSocketExtensionParser::ConsumeIfMatch(char c) {
-  DCHECK(!has_error_);
   const char* head = current_;
+  if (Consume(c))

[eroman, 2015/04/06 19:07:52]

optional: I find the opposite more readable:

if (!Consume(c)) {
  ....
  return false;
}

return true;

[tyoshino (SeeGerritForStatus), 2015/04/13 14:11:59]

Done.

+    return true;
 
-  Consume(c);
-  if (has_error_) {
-    current_ = head;
-    has_error_ = false;
-    return false;
-  }
-  return true;
+  current_ = head;
+  return false;
 }
 
 // static
 bool WebSocketExtensionParser::IsControl(char c) {
   return (0 <= c && c <= 31) || c == 127;
 }
 
 // static
 bool WebSocketExtensionParser::IsSeparator(char c) {
   const char separators[] = "()<>@,;:\\\"/[]?={} \t";
   return strchr(separators, c) != NULL;
 }
 
 }  // namespace net