Create a new print backend for the updated CUPS APIs

printing/backend/cups_printer.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 PRINTING_BACKEND_CUPS_PRINTER_H_
+#define PRINTING_BACKEND_CUPS_PRINTER_H_
+
+#include <cups/cups.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "printing/backend/cups_deleters.h"
+#include "printing/printing_export.h"
+#include "url/gurl.h"
+
+namespace base {
+class FilePath;
+}
+
+namespace printing {
+
+struct PrinterBasicInfo;
+
+// Provides information regarding cups options.
+class PRINTING_EXPORT CupsOptionProvider {
+ public:
+  virtual ~CupsOptionProvider() = default;
+
+  // Returns the supported ipp attributes for the given |option_name|.
+  // ipp_attribute_t* is owned by CupsOptionProvider.
+  virtual ipp_attribute_t* GetSupportedOptionValues(
+      base::StringPiece option_name) const = 0;
+
+  // Returns supported attribute values for |option_name| where the value can be
+  // convered to a string.
+  virtual std::vector<base::StringPiece> GetSupportedOptionValueStrings(
+      base::StringPiece option_name) const = 0;
+
+  // Returns the default ipp attributes for the given |option_name|.
+  // ipp_attribute_t* is owned by CupsOptionProvider.
+  virtual ipp_attribute_t* GetDefaultOptionValue(
+      base::StringPiece option_name) const = 0;
+
+  // Returns true if the |value| is supported by option |name|.
+  virtual bool CheckOptionSupported(base::StringPiece name,
+                                    base::StringPiece value) const = 0;
+};
+
+// Represents a CUPS printer.
+// Retrieves information from CUPS printer objects as requested.  This class
+// is only valid as long as the CupsConnection which created it exists as they
+// share an http connection which the CupsConnection closes on destruction.
+class PRINTING_EXPORT CupsPrinter : public CupsOptionProvider {
+ public:
+  // This object now owns |dest| and |info|.

[Lei Zhang, 2016/07/21 00:46:20]

No need to explain std::unique_ptr semantics.

[skau, 2016/07/21 20:07:34]

Done.

+  CupsPrinter(http_t* http,
+              std::unique_ptr<cups_dest_t, DestinationDeleter> dest,
+              std::unique_ptr<cups_dinfo_t, DestInfoDeleter> info);
+
+  CupsPrinter(CupsPrinter&& printer);
+
+  ~CupsPrinter() override;
+
+  // Returns true if this is the default printer
+  bool is_default() const;
+
+  ipp_attribute_t* GetSupportedOptionValues(

[Lei Zhang, 2016/07/21 00:46:20]

Bunch up all the overrides:

// CupsOptionProvider:
void Foo() override;
void Bar() override;
...
void Last() override;

[skau, 2016/07/21 20:07:33]

Done.

+      base::StringPiece option_name) const override;
+
+  std::vector<base::StringPiece> GetSupportedOptionValueStrings(
+      base::StringPiece option_name) const override;
+
+  ipp_attribute_t* GetDefaultOptionValue(
+      base::StringPiece option_name) const override;
+
+  bool CheckOptionSupported(base::StringPiece name,
+                            base::StringPiece value) const override;
+
+  // Returns the file name for the PPD retrieved from the print server.
+  base::FilePath GetPPD() const;
+
+  // Returns the name of the printer as configured in CUPS
+  const std::string GetName() const;

[Lei Zhang, 2016/07/21 00:46:20]

If you are returning a copy of the string, there's no need to force const-ness.
Caller should be free to do whatever they want with their copy.

[skau, 2016/07/21 20:07:33]

Done.

+
+  const std::string GetMakeAndModel() const;
+
+  // Returns true if the printer is currently reachable and working.
+  bool IsAvailable() const;
+
+  // Populates |basic_info| with the relevant information about the printer
+  bool ToPrinterInfo(PrinterBasicInfo* basic_info) const;
+
+  ipp_status_t CreateJob(int* job_id,
+                         base::StringPiece job_title,
+                         const std::vector<cups_option_t>& options);
+
+  bool StartDocument(int job_id,
+                     base::StringPiece document_name,
+                     bool last_doc,
+                     const std::vector<cups_option_t>& options);
+
+  bool StreamData(const std::vector<char>& buffer);
+
+  bool FinishDocument();
+
+  ipp_status_t CloseJob(int job_id);
+
+ private:
+  // Lazily initialize dest info as it can require a network call
+  bool InitializeDestInfo() const;
+
+  // http connection owned by the CupsConnection which created this object
+  http_t* cups_http_;

[Lei Zhang, 2016/07/21 00:46:20]

This can be: http_t* const cups_http_; since the pointer itself never changes.

[skau, 2016/07/21 20:07:33]

Done.

+
+  // information to identify a printer
+  std::unique_ptr<cups_dest_t, DestinationDeleter> destination_;
+
+  // opaque object containing printer attributes and options
+  mutable std::unique_ptr<cups_dinfo_t, DestInfoDeleter> dest_info_;
+
+  DISALLOW_COPY_AND_ASSIGN(CupsPrinter);
+};
+
+}  // namespace printing
+
+#endif  // PRINTING_BACKEND_CUPS_PRINTER_H_