[Fetch API] Implement Request.formData and Response.formData.

third_party/WebKit/Source/modules/fetch/MultipartParser.h

+// Copyright 2016 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.
+
+#ifndef MultipartParser_h
+#define MultipartParser_h
+
+#include "modules/ModulesExport.h"
+#include "platform/heap/Handle.h"
+#include "platform/network/ResourceResponse.h"
+#include "wtf/Vector.h"
+
+namespace blink {
+
+class MODULES_EXPORT MultipartParser final : public GarbageCollectedFinalized<MultipartParser> {
+    WTF_MAKE_NONCOPYABLE(MultipartParser);
+
+public:
+    class MODULES_EXPORT Client : public GarbageCollectedMixin {
+    public:
+        virtual ~Client() = default;
+        virtual void partHeaderFieldsInMultipartReceived(const ResourceResponse&) = 0;
+        virtual void partDataInMultipartReceived(const char* bytes, size_t) = 0;
+        virtual void partDataInMultipartFullyReceived() = 0;
+        DEFINE_INLINE_VIRTUAL_TRACE() {}
+    };
+
+    MultipartParser(Vector<char> boundary, Client*);
+    bool appendData(const char* bytes, size_t);
+    void cancel();
+    bool finish();
+
+    bool isCancelled() const { return m_state == Cancelled; }
+
+    DECLARE_TRACE();
+
+private:
+    class Buffer {

[yhirano, 2016/09/20 09:49:53]

This class is used in a two ways:

1. It is a matcher for a fixed pattern (I use the term "fixed" because all
patterns are fixed once a MultipartParser instance is created). 
2. It is a temporary buffer containing a pointer and a size.

They are different concepts and I think they should be separated. Can you rename
this class to something like Matcher? I think we can kill the second usage as
commented in parseDataAndDelimiter.

[e_hakkinen, 2016/09/20 21:59:29]

Done.

+    public:
+        Buffer();
+        Buffer(const char* first, const char* last);
+        Buffer(const char* data, size_t, size_t capacity);
+
+        bool appendIfExpected(char value);
+        bool appendIfExpected(const char* first, const char* last);
+        void clear();
+
+        bool empty() const { return size() == 0u; }
+        const char* data() const { return m_data; }
+        size_t size() const { return m_size; }
+
+    private:
+        size_t m_capacity = 0u;
+        const char* m_data = nullptr;
+        size_t m_size = 0u;
+    };
+
+    Buffer closeDelimiterSuffixBuffer(size_t = 0u) const;

[yhirano, 2016/09/20 09:49:53]

The parameter is never specified.

[e_hakkinen, 2016/09/20 21:59:29]

Done.

+    Buffer delimiterBuffer(size_t = 0u) const;
+    Buffer delimiterSuffixBuffer(size_t = 0u) const;

[yhirano, 2016/09/20 09:49:53]

The parameter is never specified.

[e_hakkinen, 2016/09/20 21:59:29]

Done.

+
+    bool parseDataAndDelimiter(const char** bytesPointer, const char* bytesEnd, Buffer* data);

[yhirano, 2016/09/20 09:49:53]

These three functions are named in the same manner and it looks their return
values have the same meaning but they don't.

parseDataAndDelimiter returns true when it sees the complete delimiter. It
doesn't modify |m_state|. It clears |m_buferredBytes|. parseHeaderFields returns
true when it sees a complete header. It modifies |m_state| when failed. The
caller needs to clear |m_bufferedBytes|. parseTransportPadding returns false
when it sees an error. It doesn't modify |m_state|.

The inconsistency is very hard to understand. Can you make them consistent (more
preferable), or write more comments (less preferable)?

[e_hakkinen, 2016/09/20 21:59:29]

They return true only when they have parsed what they are supposed to parse be
that data and a complete delimiter or a complete header or transport padding.
I preferred to consolidate parsing to these auxiliary functions.
I have now split these functions further, removed most bool returns and split
out some functionality. The latter two resulted in more code duplication. Let's
see if it makes code easier to understand.

+    bool parseHeaderFields(const char** bytesPointer, const char* bytesEnd, WebURLResponse*);
+    bool parseTransportPadding(const char** bytesPointer, const char* bytesEnd) const;
+
+    Buffer m_bufferedBytes;
+    Vector<char> m_bufferedHeaderBytes;
+    Member<Client> m_client;
+    Vector<char> m_delimiter;
+
+    enum State {
+        ParsingPreamble,
+        ParsingDelimiterSuffix,
+        ParsingPartHeaderFields,
+        ParsingPartOctets,
+        ParsingDelimiterOrCloseDelimiterSuffix,
+        ParsingCloseDelimiterSuffix,
+        ParsingEpilogue,
+        Cancelled,
+        Failed,
+        Finished
+    } m_state;
+};
+
+} // namespace blink
+
+#endif // MultipartParser_h