swarm.collections.index.protocol.html

set for Swarm2.1是圣菲研究院的开发人员对Swarm的特性及其使用描述的最为完备的指南性文档。从这里可以获得最细致的平台说明。

CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.METHOD.PU.M791"
></A
><P
></P
>- (void)<B
CLASS="FUNCPROTOTYPE"
>setLoc:</B
> (id &lt;Symbol&gt;)<VAR
CLASS="PDPARAM"
>locSymbol</VAR
> <BR> The setLoc: message may be used to reset the current location of an index to either Start or End.  It may be used to reprocess a collection using an existing index after some other location has already been reached.  It may also be used to position an index at the end of all members prior to traversing members in reverse order using prev.<BR> Besides Start and End, setLoc: accepts the special argument values of BetweenAfter and BetweenBefore, which are also defined symbols.  These argument values are only valid if the index is positioned at a current member.  They reposition the index to the special location between the current member and its immediately following or preceding member.<P
></P
></DIV
></LI
><LI
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.METHOD.PU.M443"
></A
><P
></P
>- (int)<B
CLASS="FUNCPROTOTYPE"
>getOffset</B
><BR> Provided there is no major computational cost, an index also maintains the integer offset of its current member within the enumeration sequence of the collection.  These integer offset values have the same definition as in the atOffset: messages of Collection.  The getOffset message returns this current offset value.  If the index is current positioned at the Start or End location, getOffset returns -1.  If the index is positioned at a Between location, getOffset returns the offset of the immediately preceding member.  If the offset is not currently available from the index, getOffset returns the special value UnknownOffset.  This value is defined by a macro as the maximally negative value of a 32-bit, 2's-complement integer.<BR> An offset is always available from an index if its current position has been reached by repeated operations from an initial Start or End position, and there has been no other modification to the underlying collection.  Some forms of direct member access operations supported by some index types, however, may result in an integer offset not being available.  These restrictions are noted with the individual index type.<P
></P
></DIV
></LI
><LI
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.METHOD.PU.M815"
></A
><P
></P
>- <B
CLASS="FUNCPROTOTYPE"
>setOffset:</B
> (unsigned)<VAR
CLASS="PDPARAM"
>offset</VAR
> <BR> Using the setOffset: message, an index may be positioned directly to a member using the offset of the member within its enumeration sequence. The speed of this operation depends on the specific type of the collection, just as noted for the atOffset: message on Collection.  In the worst case, this operation is linear in the magnitude of the offset.<P
></P
></DIV
></LI
><LI
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.METHOD.PU.M198"
></A
><P
></P
>- (int)<B
CLASS="FUNCPROTOTYPE"
>compare:</B
> <VAR
CLASS="PDPARAM"
>anIndex</VAR
> <BR> The compare: message compares the current location of one index with the current location of another index passed as its argument.  If the two indexes have the same location, compare: returns zero.  Otherwise, compare: returns +1 or -1 according to whether the argument index precedes or follows the receiver index in the enumeration sequence of the collection.  If either of the two indexes has an unknown offset, and the location of the other index is anything other than Start or End or an immediately adjacent member, compare: returns the UnknownOffset integer value.<P
></P
></DIV
></LI
></UL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6929"
></A
><H2
>Macros</H2
><P
></P
><UL
><LI
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.MACRO.INDEXENDP"
></A
><P
></P
><P
><CODE
><B
CLASS="FSFUNC"
>INDEXENDP</B
>(<VAR
CLASS="PDPARAM"
>obj</VAR
>)</CODE
></P
><BR> Predicate to test if index is at the end.<P
></P
></DIV
></LI
><LI
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.MACRO.INDEXSTARTP"
></A
><P
></P
><P
><CODE
><B
CLASS="FSFUNC"
>INDEXSTARTP</B
>(<VAR
CLASS="PDPARAM"
>obj</VAR
>)</CODE
></P
><BR> Predicate to test if index is at the start.<P
></P
></DIV
></LI
><LI
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="SWARM.COLLECTIONS.INDEX.MACRO.REMOVEDP"
></A
><P
></P
><P
><CODE
><B
CLASS="FSFUNC"
>REMOVEDP</B
>(<VAR
CLASS="PDPARAM"
>obj</VAR
>)</CODE
></P
><BR> Predicate to test if item at index has been removed.<P
></P
></DIV
></LI
><LI
><P
>UndefinedOffset</P
></LI
></UL
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN6961"
></A
><H2
>Globals</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.START"
>id &lt;Symbol&gt; Start </A
></DT
><DD
><P
> values for index location</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.END"
>id &lt;Symbol&gt; End </A
></DT
><DD
><P
> values for index location</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.BETWEEN"
>id &lt;Symbol&gt; Between </A
></DT
><DD
><P
> values for index location</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.REMOVED"
>id &lt;Symbol&gt; Removed </A
></DT
><DD
><P
> values for index location</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.MEMBER"
>id &lt;Symbol&gt; Member </A
></DT
><DD
><P
> values for index location</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.OFFSETOUTOFRANGE"
>id &lt;Error&gt; OffsetOutOfRange </A
></DT
><DD
><P
> error types for collections</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.NOMEMBERS"
>id &lt;Error&gt; NoMembers </A
></DT
><DD
><P
> error types for collections</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.ALREADYATEND"
>id &lt;Error&gt; AlreadyAtEnd </A
></DT
><DD
><P
> error types for collections</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.ALREADYATSTART"
>id &lt;Error&gt; AlreadyAtStart </A
></DT
><DD
><P
> error types for collections</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.INVALIDINDEXLOC"
>id &lt;Error&gt; InvalidIndexLoc </A
></DT
><DD
><P
> error types for collections</P
></DD
><DT
><A
NAME="SWARM.COLLECTIONS.INDEX.GLOBAL.INVALIDLOCSYMBOL"
>id &lt;Error&gt; InvalidLocSymbol </A
></DT
><DD
><P
> error types for collections</P
></DD
></DL
></DIV
></DIV
><DIV
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