36630: new function zsh_directory_name_generic

1 files changed, 185 insertions, 2 deletions

diff --git a/Doc/Zsh/contrib.yo b/Doc/Zsh/contrib.yo
index b966e781c..330c6f588 100644
--- a/Doc/Zsh/contrib.yo
+++ b/Doc/Zsh/contrib.yo
@@ -12,6 +12,7 @@ such as shell functions, look for comments in the function source files.
 startmenu()
 menu(Utilities)
 menu(Recent Directories)
+menu(Other Directory Functions)
 menu(Version Control Information)
 menu(Prompt Themes)
 menu(ZLE Functions)
@@ -324,7 +325,7 @@ options tt(-Uz) are appropriate.
 )
 enditem()
 
-texinode(Recent Directories)(Version Control Information)(Utilities)(User Contributions)
+texinode(Recent Directories)(Other Directory Functions)(Utilities)(User Contributions)
 cindex(recent directories, maintaining list of)
 cindex(directories, maintaining list of recent)
 findex(cdr)
@@ -585,7 +586,189 @@ avoid side effects if the change to the directory is to be invisible at the
 command line.  See the contents of the function tt(chpwd_recent_dirs) for
 more details.
 
-texinode(Version Control Information)(Prompt Themes)(Recent Directories)(User Contributions)
+texinode(Other Directory Functions)(Version Control Information)(Recent Directories)(User Contributions)
+cindex(directories, named, dynamic, helper function)
+cindex(dynamic directory naming, helper function)
+cindex(named directories, dynamic, helper function)
+findex(zsh_directory_name_generic)
+sect(Abbreviated dynamic references to directories)
+
+The dynamic directory naming system is described in the subsection
+em(Dynamic named directories) of
+ifzman(the section em(Filename Expansion) in zmanref(expn))\
+ifnzman(noderef(Filename Expansion)).  In this, a reference to
+tt(~[)var(...)tt(]) is expanded by a function found by the hooks
+mechanism.
+
+The contributed function tt(zsh_directory_name_generic) provides a
+system allowing the user to refer to directories with only a limited
+amount of new code.  It supports all three of the standard interfaces
+for directory naming: converting from a name to a directory, converting
+in the reverse direction to find a short name, and completion of names.
+
+The main feature of this function is a path-like syntax,
+combining abbreviations at multiple levels separated by ":".
+As an example, ~[g:p:s] might specify:
+startitem()
+item(tt(g))(
+The top level directory for your git area.  This first component
+has to match, or the function will retrun indicating another
+directory name hook function should be tried.
+)
+item(tt(p))(
+The name of a project within your git area.
+)
+item(tt(s))(
+The source area within that project.
+)
+enditem()
+This allows you to collapse references to long hierarchies to a very
+compact form, particularly if the hierarchies are similar across different
+areas of the disk.
+
+Name components may be completed: if a description is shown at the top
+of the list of completions, it includes the path to which previous
+components expand, while the description for an individual completion
+shows the path segment it would add.  No additional configuration is
+needed for this as the completion system is aware of the dynamic
+directory name mechanism.
+
+subsect(Usage)
+
+To use the function, first define a wrapper function for your specific
+case.  We'll assume it's to be autoloaded.  This can have any name but
+we'll refer to it as zdn_mywrapper.  This wrapper function will define
+various variables and then call this function with the same arguments
+that the wrapper function gets.  This configuration is described below.
+
+Then arrange for the wrapper to be run as a zsh_directory_name hook:
+
+example(autoload -Uz add-zsh-hook zsh_diretory_name_generic zdn_mywrapper
+add-zsh-hook -U zsh_directory_name zdn_mywrapper)
+
+subsect(Configuration)
+
+The wrapper function should define a local associative array zdn_top.
+Alternatively, this can be set with a style called tt(mapping).  The
+context for the style is tt(:zdn:)var(wrapper-name) where
+var(wrapper-name) is the function calling zsh_directory_name_generic;
+for example:
+
+example(zstyle :zdn:zdn_mywrapper: mapping zdn_mywrapper_top)
+
+The keys in this associative array correspond to the first component of
+the name.  The values are matching directories.  They may have an
+optional suffix with a slash followed by a colon and the name of a
+variable in the same format to give the next component.  (The slash
+before the colon is to disambiguate the case where a colon is needed in
+the path for a drive.  There is otherwise no syntax for escaping this,
+so path components whose names start with a colon are not supported.)  A
+special component tt(:default:) specifies a variable in the form
+tt(/:)var(var) (the path section is ignored and so is usually empty)
+that will be used for the next component if no variable is given for the
+path.  Variables referred to within tt(zdn_top) have the same format as
+tt(zdn_top) itself, but contain relative paths.
+
+For example,
+
+example(local -A zdn_top=(
+  g   ~/git
+  ga  ~/alternate/git
+  gs  /scratch/$USER/git/:second2
+  :default: /:second1
+))
+
+This specifies the behaviour of a directory referred to as tt(~[g:...])
+or tt(~[ga:...]) or tt(~[gs:...]).  Later path components are optional;
+in that case tt(~[g]) expands to tt(~/git), and so on.  tt(gs) expands
+to tt(/scratch/$USER/git) and uses the associative array tt(second2) to
+match the second component; tt(g) and tt(ga) use the associative array
+tt(second1) to match the second component.
+
+When expanding a name to a directory, if the first component is not tt(g) or
+tt(ga) or tt(gs), it is not an error; the function simply returns 1 so that a
+later hook function can be tried.  However, matching the first component
+commits the function, so if a later component does not match, an error
+is printed (though this still does not stop later hooks from being
+executed).
+
+For components after the first, a relative path is expected, but note that
+multiple levels may still appear.  Here is an example of tt(second1):
+
+example(local -A second1=(
+  p   myproject
+  s   somproject
+  os  otherproject/subproject/:third
+))
+
+The path as found from tt(zdn_top) is extended with the matching
+directory, so tt(~[g:p]) becomes tt(~/git/myproject).  The slash between
+is added automatically (it's not possible to have a later component
+modify the name of a directory already matched).  Only tt(os) specifies
+a variable for a third component, and there's no tt(:default:), so it's
+an error to use a name like tt(~[g:p:x]) or tt(~[ga:s:y]) because
+there's nowhere to look up the tt(x) or tt(y).
+
+The associative arrays need to be visible within this function; the
+generic function therefore uses internal variable names beginning
+tt(_zdn_) in order to avoid clashes.  Note that the variable tt(reply)
+needs to be passed back to the shell, so should not be local in the
+calling function.
+
+The function does not test whether directories assembled by component
+actually exist; this allows the system to work across automounted
+file systems.  The error from the command trying to use a non-existent
+directory should be sufficient to indicate the problem.
+
+subsect(Complete example)
+
+Here is a full fictitious but usable autoloadable definition of the
+example function defined by the code above.  So tt(~[gs:p:s]) expands
+to tt(/scratch/$USER/git/myscratchproject/top/srcdir) (with tt($USER)
+also expanded).
+
+example(local -A zdn_top=(
+  g   ~/git
+  ga  ~/alternate/git
+  gs  /scratch/$USER/git/:second2
+  :default: /:second1
+)
+
+local -A second1=(
+  p   myproject
+  s   somproject
+  os  otherproject/subproject/:third
+)
+
+local -A second2=(
+  p   myscratchproject
+  s   somescratchproject
+)
+
+local -A third=(
+  s   top/srcdir
+  d   top/documentation
+)
+
+# autoload not needed if you did this at initialisation...
+autoload -Uz zsh_directory_name_generic
+zsh_directory_name_generic "$@)
+
+It is also possible to use global associative arrays, suitably named,
+and set the style for the context of your wrapper function to
+refer to this.  Then your set up code would contain the following:
+
+example(typeset -A zdn_mywrapper_top=(...)
+# ... and so on for other associative arrays ...
+zstyle ':zdn:zdn_mywrapper:' mapping zdn_mywrapper_top
+autoload -Uz add-zsh-hook zsh_directory_name_generic zdn_mywrapper
+add-zsh-hook -U zsh_directory_name zdn_mywrapper)
+
+and the function tt(zdn_mywrapper) would contain only the following:
+
+example(zsh_directory_name_generic "$@")
+
+texinode(Version Control Information)(Prompt Themes)(Other Directory Functions)(User Contributions)
 sect(Gathering information from version control systems)
 cindex(version control utility)