db/morkreader/nsMorkReader.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is the Mork Reader.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Google Inc.
  19  * Portions created by the Initial Developer are Copyright (C) 2006
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *   Brian Ryner <bryner@brianryner.com> (original author)
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either the GNU General Public License Version 2 or later (the "GPL"), or
  27  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  28  * in which case the provisions of the GPL or the LGPL are applicable instead
  29  * of those above. If you wish to allow use of your version of this file only
  30  * under the terms of either the GPL or the LGPL, and not to allow others to
  31  * use your version of this file under the terms of the MPL, indicate your
  32  * decision by deleting the provisions above and replace them with the notice
  33  * and other provisions required by the GPL or the LGPL. If you do not delete
  34  * the provisions above, a recipient may use your version of this file under
  35  * the terms of any one of the MPL, the GPL or the LGPL.
  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #ifndef nsMorkReader_h_
  40 #define nsMorkReader_h_
  41
  42 #include "nsDataHashtable.h"
  43 #include "nsILineInputStream.h"
  44 #include "nsTArray.h"
  45 #include "nsAutoPtr.h"
  46
  47 // The nsMorkReader object allows a consumer to read in a mork-format
  48 // file and enumerate the rows that it contains.  It does not provide
  49 // any functionality for modifying mork tables.
  50
  51 // References:
  52 //  http://www.mozilla.org/mailnews/arch/mork/primer.txt
  53 //  http://www.mozilla.org/mailnews/arch/mork/grammar.txt
  54 //  http://www.jwz.org/hacks/mork.pl
  55
  56 class NS_STACK_CLASS nsMorkReader
  57 {
  58  public:
  59   // This string type has built-in storage for the hex string representation
  60   // of a 32-bit row id or atom map key, plus the terminating null.
  61   class IDString : public nsFixedCString
  62   {
  63   public:
  64     IDString() : fixed_string_type(mStorage, sizeof(mStorage), 0) {}
  65     IDString(const substring_type &str) :
  66       fixed_string_type(mStorage, sizeof(mStorage), 0)
  67     {
  68       Assign(str);
  69     }
  70
  71   private:
  72     char_type mStorage[9];
  73   };
  74
  75   // Hashtable key type that contains an IDString
  76   class IDKey : public PLDHashEntryHdr
  77   {
  78   public:
  79     typedef const nsCSubstring& KeyType;
  80     typedef const nsCSubstring* KeyTypePointer;
  81
  82     IDKey(KeyTypePointer aStr) : mStr(*aStr) { }
  83     IDKey(const IDKey& toCopy) : mStr(toCopy.mStr) { }
  84     ~IDKey() { }
  85
  86     KeyType GetKey() const { return mStr; }
  87     PRBool KeyEquals(const KeyTypePointer aKey) const
  88     {
  89       return mStr.Equals(*aKey);
  90     }
  91
  92     static KeyTypePointer KeyToPointer(KeyType aKey) { return &aKey; }
  93     static PLDHashNumber HashKey(const KeyTypePointer aKey)
  94     {
  95       return HashString(*aKey);
  96     }
  97     enum { ALLOW_MEMMOVE = PR_FALSE };
  98
  99   private:
 100     const IDString mStr;
 101   };
 102
 103   // A convenience typedef for an IDKey-to-string mapping.
 104   typedef nsDataHashtable<IDKey,nsCString> StringMap;
 105
 106   // A convenience typdef for an IDKey-to-index mapping, used for the
 107   // column index hashtable.
 108   typedef nsDataHashtable<IDKey,PRInt32> IndexMap;
 109
 110   // A MorkColumn represents the data associated with a single table column.
 111   struct MorkColumn
 112   {
 113     MorkColumn(const nsCSubstring &i, const nsCSubstring &n)
 114       : id(i), name(n) {}
 115
 116     IDString id;
 117     nsCString name;
 118   };
 119
 120   // Enumerator callback type for processing table rows.
 121   // A row contains cells.  Each cell specifies a column id, and the value
 122   // for the column for that row.
 123   // rowID is the table-unique row id
 124   // values contains the cell values, in an order which corresponds to
 125   //   the columns returned by GetColumns().
 126   //   You should call NormalizeValue() on any cell value that you plan to use.
 127   // userData is the opaque pointer passed to EnumerateRows()
 128   // The callback can return PL_DHASH_NEXT to continue enumerating,
 129   // or PL_DHASH_STOP to stop.
 130   typedef PLDHashOperator
 131   (* RowEnumerator)(const nsCSubstring &rowID,
 132                     const nsTArray<nsCString> *values,
 133                     void *userData);
 134
 135   // Initialize the importer object's data structures
 136   nsresult Init();
 137
 138   // Read in the given mork file
 139   // Note: currently, only single-table mork files are supported
 140   nsresult Read(nsIFile *aFile);
 141
 142   // Returns the list of columns in the current table.
 143   const nsTArray<MorkColumn>& GetColumns() const { return mColumns; }
 144
 145   // Enumerate the rows in the current table.
 146   void EnumerateRows(RowEnumerator aCallback, void *aUserData) const;
 147
 148   // Get the "meta row" for the table.  Each table has at most one meta row,
 149   // which records information about the table.  Like normal rows, the
 150   // meta row contains columns in the same order as returned by GetColumns().
 151   // Returns null if there is no meta row for this table.
 152   const nsTArray<nsCString>* GetMetaRow() const { return mMetaRow; }
 153
 154   // Normalizes the cell value (resolves references to the value map).
 155   // aValue is modified in-place.
 156   void NormalizeValue(nsCString &aValue) const;
 157
 158   nsMorkReader() {}
 159   ~nsMorkReader();
 160
 161 private:
 162   // Parses a line of the file which contains key/value pairs (either
 163   // the column map or the value map).  Additional lines are read from
 164   // mStream if the line ends mid-entry.  The pairs are added to aMap.
 165   nsresult ParseMap(const nsCSubstring &aLine, StringMap *aMap);
 166
 167   // Parses a line of the file which contains a table or row definition.
 168   // Additional lines are read from mStream of the line ends mid-row.
 169   // An entry is added to mTable using the row ID as the key, which contains
 170   // a column array for the row.  The supplied column hash table maps from
 171   // column id to an index in mColumns.
 172   nsresult ParseTable(const nsCSubstring &aLine, const IndexMap &aColumnMap);
 173
 174   // Reads a single logical line from mStream into aLine.
 175   // Any continuation lines are consumed and appended to the line.
 176   nsresult ReadLine(nsCString &aLine);
 177
 178   // Create a new nsCString array and fill it with the supplied number
 179   // of void strings.  Returns null on out-of-memory.
 180   static nsTArray<nsCString>* NewVoidStringArray(PRInt32 aSize);
 181
 182   nsTArray<MorkColumn> mColumns;
 183   StringMap mValueMap;
 184   nsAutoPtr< nsTArray<nsCString> > mMetaRow;
 185   nsDataHashtable< IDKey,nsTArray<nsCString>* > mTable;
 186   nsCOMPtr<nsILineInputStream> mStream;
 187   nsCString mEmptyString; // note: not EmptyCString() since that's not sharable
 188 };
 189
 190 #endif // nsMorkReader_h_