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### A.10 Using the mapping API

Org has sophisticated mapping capabilities to find all entries satisfying certain criteria. Internally, this functionality is used to produce agenda views, but there is also an API that can be used to execute arbitrary functions for each or selected entries. The main entry point for this API is:

— Function: org-map-entries func &optional match scope &rest skip

> Call FUNC at each headline selected by MATCH in SCOPE.

> FUNC is a function or a Lisp form. The function will be called without arguments, with the cursor positioned at the beginning of the headline. The return values of all calls to the function will be collected and returned as a list.

> The call to FUNC will be wrapped into a save-excursion form, so FUNC does not need to preserve point. After evaluation, the cursor will be moved to the end of the line (presumably of the headline of the processed entry) and search continues from there. Under some circumstances, this may not produce the wanted results. For example, if you have removed (e.g. archived) the current (sub)tree it could mean that the next entry will be skipped entirely. In such cases, you can specify the position from where search should continue by making FUNC set the variable `org-map-continue-from' to the desired buffer position.

> MATCH is a tags/property/todo match as it is used in the agenda match view. Only headlines that are matched by this query will be considered during the iteration. When MATCH is nil or t, all headlines will be visited by the iteration.

> SCOPE determines the scope of this command. It can be any of:

>               nil     the current buffer, respecting the restriction if any
>               tree    the subtree started with the entry at point
>               file    the current buffer, without restriction
>               file-with-archives
>                       the current buffer, and any archives associated with it
>               agenda  all agenda files
>               agenda-with-archives
>                       all agenda files with any archive files associated with them
>               (file1 file2 ...)
>                       if this is a list, all files in the list will be scanned

> The remaining args are treated as settings for the skipping facilities of the scanner. The following items can be given here:

>               archive   skip trees with the archive tag
>               comment   skip trees with the COMMENT keyword
>               function or Lisp form
>                         will be used as value for org-agenda-skip-function,
>                         so whenever the function returns t, FUNC
>                         will not be called for that entry and search will
>                         continue from the point where the function leaves it

The function given to that mapping routine can really do anything you like. It can use the property API (see Using the property API) to gather more information about the entry, or in order to change metadata in the entry. Here are a couple of functions that might be handy:

— Function: org-todo &optional arg

> Change the TODO state of the entry. See the docstring of the functions for the many possible values for the argument ARG.

— Function: org-priority &optional action

> Change the priority of the entry. See the docstring of this function for the possible values for ACTION.

— Function: org-toggle-tag tag &optional onoff

> Toggle the tag TAG in the current entry. Setting ONOFF to either `on` or `off` will not toggle tag, but ensure that it is either on or off.

— Function: org-promote

> Promote the current entry.

— Function: org-demote

> Demote the current entry.

Here is a simple example that will turn all entries in the current file with a tag `TOMORROW` into TODO entries with the keyword `UPCOMING`. Entries in comment trees and in archive trees will be ignored.

         (org-map-entries
            '(org-todo "UPCOMING")
            "+TOMORROW" 'file 'archive 'comment)

The following example counts the number of entries with TODO keyword `WAITING`, in all agenda files.

         (length (org-map-entries t "/+WAITING" 'agenda))