зеркало из https://github.com/mozilla/gecko-dev.git
94 строки
4.4 KiB
Java
94 строки
4.4 KiB
Java
/* -*- Mode: java; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.0 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS"
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* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
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* the License for the specific language governing rights and limitations
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* under the License.
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*
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* The Original Code is the Grendel mail/news client.
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*
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* The Initial Developer of the Original Code is Netscape Communications
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* Corporation. Portions created by Netscape are Copyright (C) 1997
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* Netscape Communications Corporation. All Rights Reserved.
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*
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* Created: Mauro Botelho <mabotelh@email.com>, 20 Mar 1999.
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*/
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package grendel.storage.mdb;
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/*| nsIMdbBlob: a base class for objects composed mainly of byte sequence state.
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**| (This provides a base class for nsIMdbCell, so that cells themselves can
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**| be used to set state in another cell, without extracting a buffer.)
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|*/
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interface nsIMdbBlob extends nsIMdbObject { // a string with associated charset
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// { ===== begin nsIMdbBlob methods =====
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// { ----- begin attribute methods -----
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public void SetBlob(nsIMdbEnv ev,
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nsIMdbBlob ioBlob); // reads inBlob slots
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// when inBlob is in the same suite, this might be fastest cell-to-cell
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public void ClearBlob( // make empty (so content has zero length)
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nsIMdbEnv ev);
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// clearing a yarn is like SetYarn() with empty yarn instance content
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public int GetBlobFill(nsIMdbEnv ev);
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// size of blob
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// Same value that would be put into mYarn_Fill, if one called GetYarn()
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// with a yarn instance that had mYarn_Buf==nil and mYarn_Size==0.
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public void SetYarn(nsIMdbEnv ev,
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final String inYarn); // reads from yarn slots
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// make this text object contain content from the yarn's buffer
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public String GetYarn(nsIMdbEnv ev);
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// writes some yarn slots
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// copy content into the yarn buffer, and update mYarn_Fill and mYarn_Form
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public String AliasYarn(nsIMdbEnv ev);
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// writes ALL yarn slots
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// AliasYarn() reveals sensitive internal text buffer state to the caller
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// by setting mYarn_Buf to point into the guts of this text implementation.
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//
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// The caller must take great care to avoid writing on this space, and to
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// avoid calling any method that would cause the state of this text object
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// to change (say by directly or indirectly setting the text to hold more
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// content that might grow the size of the buffer and free the old buffer).
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// In particular, callers should scrupulously avoid making calls into the
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// mdb interface to write any content while using the buffer pointer found
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// in the returned yarn instance. Best safe usage involves copying content
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// into some other kind of external content representation beyond mdb.
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//
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// (The original design of this method a week earlier included the concept
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// of very fast and efficient cooperative locking via a pointer to some lock
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// member slot. But let's ignore that complexity in the current design.)
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//
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// AliasYarn() is specifically intended as the first step in transferring
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// content from nsIMdbBlob to a nsString representation, without forcing extra
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// allocations and/or memory copies. (A standard nsIMdbBlob_AsString() utility
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// will use AliasYarn() as the first step in setting a nsString instance.)
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//
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// This is an alternative to the GetYarn() method, which has copy semantics
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// only; AliasYarn() relaxes a robust safety principle only for performance
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// reasons, to accomodate the need for callers to transform text content to
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// some other canonical representation that would necessitate an additional
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// copy and transformation when such is incompatible with the mdbYarn format.
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//
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// The implementation of AliasYarn() should have extremely little overhead
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// besides the public dispatch to the method implementation, and the code
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// necessary to populate all the mdbYarn member slots with internal buffer
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// address and metainformation that describes the buffer content. Note that
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// mYarn_Grow must always be set to nil to indicate no resizing is allowed.
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// } ----- end attribute methods -----
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// } ===== end nsIMdbBlob methods =====
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};
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