;; A configuration is a single SEXP starting with the keyword
;; :source-registry followed by a list of directives.
CONFIGURATION := (:source-registry DIRECTIVE ...)

;; A directive is one of the following:
DIRECTIVE :=
    ;; INHERITANCE DIRECTIVE:
    ;; Your configuration expression MUST contain
    ;; exactly one of the following:
    :inherit-configuration |
    ;; splices inherited configuration (often specified last) or
    :ignore-inherited-configuration |
    ;; drop inherited configuration (specified anywhere)

    ;; forward compatibility directive (since ASDF 2.011.4), useful when
    ;; you want to use new configuration features but have to bootstrap
    ;; the newer required ASDF from an older release that doesn't
    ;; support said features:
    :ignore-invalid-entries |

    ;; add a single directory to be scanned (no recursion)
    (:directory DIRECTORY-PATHNAME-DESIGNATOR) |

    ;; add a directory hierarchy, recursing but
    ;; excluding specified patterns
    (:tree DIRECTORY-PATHNAME-DESIGNATOR) |

    ;; override the defaults for exclusion patterns
    (:exclude EXCLUSION-PATTERN ...) |
    ;; augment the defaults for exclusion patterns
    (:also-exclude EXCLUSION-PATTERN ...) |
    ;; Note that the scope of a an exclude pattern specification is
    ;; the rest of the current configuration expression or file.

    ;; splice the parsed contents of another config file
    (:include REGULAR-FILE-PATHNAME-DESIGNATOR) |

    ;; This directive specifies that some default must be spliced.
    :default-registry

REGULAR-FILE-PATHNAME-DESIGNATOR
    := PATHNAME-DESIGNATOR ; interpreted as a file
DIRECTORY-PATHNAME-DESIGNATOR
    := PATHNAME-DESIGNATOR ; interpreted as a directory

PATHNAME-DESIGNATOR :=
    NIL | ;; Special: skip this entry.
    ABSOLUTE-COMPONENT-DESIGNATOR ;; see pathname DSL

EXCLUSION-PATTERN := a string without wildcards, that will be matched
    exactly against the name of a any subdirectory in the directory
    component of a path. e.g. "_darcs" will match
    #p"/foo/bar/_darcs/src/bar.asd"

ABSOLUTE-COMPONENT-DESIGNATOR :=
    (ABSOLUTE-COMPONENT-DESIGNATOR RELATIVE-COMPONENT-DESIGNATOR ...) |
    STRING |
    ;; namestring (better be absolute or bust, directory assumed where
    ;; applicable).  In output-translations, directory is assumed and
    ;; **/*.*.* added if it's last.  On MCL, a MacOSX-style POSIX
    ;; namestring (for MacOS9 style, use #p"..."); Note that none of the
    ;; above applies to strings used in *central-registry*, which
    ;; doesn't use this DSL: they are processed as normal namestrings.
    ;; however, you can compute what you put in the *central-registry*
    ;; based on the results of say
    ;; (asdf::resolve-location "/Users/fare/cl/cl-foo/")
    PATHNAME |
    ;; pathname (better be an absolute path, or bust)
    ;; In output-translations, unless followed by relative components,
    ;; it better have appropriate wildcards, as in **/*.*.*
    :HOME | ; designates the user-homedir-pathname ~/
    :USER-CACHE | ; designates the default location for the user cache
    :HERE |
    ;; designates the location of the configuration file
    ;; (or *default-pathname-defaults*, if invoked interactively)
    :ROOT
    ;; magic, for output-translations source only: paths that are relative
    ;; to the root of the source host and device

They keyword :SYSTEM-CACHE is not accepted in ASDF 3.1 and beyond: it
was a security hazard.

RELATIVE-COMPONENT-DESIGNATOR :=
    (RELATIVE-COMPONENT-DESIGNATOR RELATIVE-COMPONENT-DESIGNATOR ...) |
    STRING |
      ;; relative directory pathname as interpreted by
      ;; parse-unix-namestring.
      ;; In output translations, if last component, **/*.*.* is added
    PATHNAME | ; pathname; unless last component, directory is assumed.
    :IMPLEMENTATION |
       ;; directory based on implementation, e.g. sbcl-1.0.45-linux-x64
    :IMPLEMENTATION-TYPE |
       ;; a directory based on lisp-implementation-type only, e.g. sbcl
    :DEFAULT-DIRECTORY |
       ;; a relativized version of the default directory
    :*/ | ;; any direct subdirectory (since ASDF 2.011.4)
    :**/ | ;; any recursively inferior subdirectory (since ASDF 2.011.4)
    :*.*.* | ;; any file (since ASDF 2.011.4)

The keywords :UID and :USERNAME are no longer supported.

(:source-registry
  (:tree (:home "cl")) ;; will expand to e.g. "/home/joeluser/cl/"
  :inherit-configuration)