SPREE-ALLOW(2)                                     SPREE-ALLOW(2)

     NAME
          Allow - filter client actions

     SYNOPSIS
          include "spree.m";
          include "spree/allow.m";
          Clique, Member, Object: import Spree;
          allow := load Allow Allow->PATH;

          init:          fn(m: Spree, c: ref Clique);
          add:      fn(tag: int, member: ref Member, pattern: string);
          del:      fn(tag: int, member: ref Member);
          action:   fn(member: ref Member, cmd: string): (string, int, list of string);
          archive:  fn(archiveobj: ref Object);
          unarchive: fn(archiveobj: ref Object);

     DESCRIPTION
          A spree(2) client can send arbitrary actions to a running
          engine.  The Allow module enables an engine to filter
          clients' actions, permitting only actions matching certain
          provided patterns to get through.

          An action is conventionally formatted as a sequence of
          space-separated words.  A pattern is a string consisting of
          a sequence of such words.  For a pattern to match a client's
          action, each word in the pattern must match each word in the
          action.  Most pattern words are not special: they must match
          literally. The exceptions are:

          *    An asterisk matches any single word.

          &    An ampersand matches any set of words.  Any words in
               the pattern after this are ignored.

          %d   Matches a decimal integer.

          %p   Matches a valid player id (decimal integer).

          %o   Matches any valid object id (decimal integer).  The
               corresponding word in the list returned by action will
               be changed to the local object id from the member's
               external representation.

          Init must be called first with the spree module, m, and the
          current clique, c, to initialise the module.

          Add adds the new pattern to the list of allowed actions; tag
          is an integer tag that the caller can later use to identify
          the action, and I member is the clique member that is
          allowed to perform the action (if nil, then any member will

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     SPREE-ALLOW(2)                                     SPREE-ALLOW(2)

          be allowed to perform the action).  Del deletes patterns
          tagged with tag from the list of allowed actions.  If member
          is non-nil, then only patterns specific to that member will
          be deleted.

          Action matches  cmd, an action performed by member, against
          the list of all the allowed patterns.  It returns a tuple,
          say (err, tag, toks).  If cmd does not match any pattern,
          then err will be non-nil and holds a string describing the
          nature of the failure.  If a match is made, then tag holds
          the matched pattern's tag, as passed to add, and toks holds
          the list of words in the action, with object ids matched by
          %o changed to their local representation using member.obj.

          Archive stores all the allow module's internal state as
          attributes on archiveobj (for card game engines, this is
          usually the object returned from cardlib->archive (see
          cardlib(2))). Unarchive reverses this, restoring the
          module's internal state from archiveobj.

     SOURCE
          /appl/spree/lib/allow.b

     SEE ALSO
          spree(2), spree-cardlib(2), spree-objstore(2)

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