Remove global dispatchers

2 files changed, 117 insertions, 120 deletions

diff --git a/README.org b/README.org
index a880ea0..f5fb5b0 100644
--- a/README.org
+++ b/README.org
@@ -10,8 +10,8 @@ any one of several ways: literally, as a regexp, as an initialism, in
 the flex style, or as multiple word prefixes. By default, regexp and
 initialism matches are enabled.
 
-A completion style is a backend for completion and is used from a
-frontend that provides a completion UI. Any completion style can be
+A completion style is a back-end for completion and is used from a
+front-end that provides a completion UI. Any completion style can be
 used with the default Emacs completion UI (sometimes called minibuffer
 tab completion) or with the built-in Icomplete package (which is
 similar to the more well-known Ido Mode). To use a completion style in
@@ -145,23 +145,15 @@ string.
 
  For more fine-grained control on which matching styles to use for
  each component of the input string, you can add use /style
- dispatchers/. These are specificied in the
+ dispatchers/. These are also specified in the variable
  =orderless-component-matching-styles= whose full syntax is:
 
- =(= /matching-styles/...
-   =:global-dispatchers= /global-dispatchers/...
-   =:component-dispatchers= /component-dispatchers/... =)=
+ =(= /matching-styles/... =:dispatchers= /style-dispatchers/... =)=
 
- There are two types of style dispatchers:
-
- - /global style dispatchers/, which are functions that take the entire
-   input string and are used to determine which matching styles to use
-   by default for each component; and
-
- - /component style dispatchers/, which take a component, its index in
-   the list of components (starting from 0), and the total number of
-   components, and are used to determine the matching styles used for
-   that specific component, overriding the default matching styles.
+ Style dispatchers are functions which take a component, its index in
+ the list of components (starting from 0), and the total number of
+ components, and are used to determine the matching styles used for
+ that specific component, overriding the default matching styles.
 
  A style dispatcher can either decline to handle the input string or
  component, or it can return which matching styles to use. It can
@@ -172,9 +164,6 @@ string.
  As an example, say you wanted the following setup:
 
  - you normally want components to match as regexps,
- - but if you end the string with =!= you want the default to be that
-   components (of the string left removing the final =!=) match
-   literally,
  - except for the first component, which should always match as an
    initialism ---this is pretty useful for, say,
    =execute-extended-command= (=M-x=) or =describe-function= (=C-h f=),
@@ -188,20 +177,11 @@ string.
      (when (string-suffix-p "~" pattern)
        `(orderless-flex . ,(substring pattern 0 -1))))
 
-   (defun literal-if-bang (pattern)
-     (when (string-suffix-p "!" pattern)
-       `(orderless-literal . ,(substring pattern 0 -1))))
-
    (defun first-initialism (pattern index _total)
      (if (= index 0) 'orderless-initialism))
 
    (setq orderless-component-matching-styles
-         '(orderless-regexp orderless-initialism orderless-prefixes))
-
-   (setq orderless-component-matching-styles
-         '(orderless-regexp
-           :global-dispatchers literal-if-bang
-           :component-dispatchers first-initialism flex-if-twiddle))
+         '(orderless-regexp :dispatchers first-initialism flex-if-twiddle))
  #+end_src
 
 ** Component separator regexp
@@ -242,12 +222,16 @@ completion is the one that ends up being used, of course.
 
 ** Pattern compiler
 
-The default machanism for turning an input string into a list of
+The default mechanism for turning an input string into a list of
 regexps to match against, configured using
 =orderless-component-matching-styles=, is probably flexible enough for
 the vast majority of users. But if you want to completely change the
 mechanism, customize the =orderless-pattern-compiler=. It's value should
-be a function from string to lists of regexps.
+be a function from string to lists of regexps. You might find it
+convenient to use =orderless-default-pattern-compiler= as a subroutine
+in your own pattern compiler, it conveniently accepts an optional
+second argument that specifies a list to use instead of
+=orderless-component-matching-styles=.
 
 ** Interactively changing the configuration
 
@@ -284,7 +268,8 @@ components match literally. You could use the following configuration:
   (defun my/match-components-literally ()
     "Components match literally for the rest of the session."
     (interactive)
-    (setq orderless-transient-matching-styles '(orderless-literal)))
+    (setq orderless-transient-matching-styles
+          '(orderless-literal :dispatchers)))
 
   (add-hook 'minibuffer-exit-hook
             #'orderless-remove-transient-configuration)
@@ -293,6 +278,13 @@ components match literally. You could use the following configuration:
     #'my/match-components-literally)
 #+end_src
 
+Note there is nothing after =:dispatchers= in the above code. This is
+different from not including =:dispatchers= at all in the value of
+=orderless-transient-matching-styles=: omitting it all together means
+inherit the dispatchers from =orderless-component-matching-styles=;
+while including =:dispatchers= overrides the list of dispatchers ---in
+the example above, setting it to the empty list.
+
 * Related packages
 
 ** Ivy and Helm
diff --git a/orderless.el b/orderless.el
index f3bca28..4b42c7b 100644
--- a/orderless.el
+++ b/orderless.el
@@ -125,36 +125,31 @@ function `orderless-remove-transient-configuration' to the
 (defcustom orderless-component-matching-styles
   '(orderless-regexp orderless-initialism)
   "Component matching style configuration.
-This should be a list of functions optionally with the symbols
-`:global-dispatchers' and `:component-dispatcher' used to delimit
-portions:
+This should be a list of matching styles or a list of the form:
 
-\(matching-styles...
- :global-dispatchers global-dispatchers...
- :component-dispatcher component-dispatchers...)
+\(matching-styles... :dispatchers dispatchers...)
 
-Here matching-styles... denotes a sequence of matching style
-functions, and each of the *-dispatcher... denotes a sequence of
-style dispatcher functions.  The `:global-dispatchers' and
-`:component-dispatcher' sections are both optional and can occur
-in either order.
+containing matching styles, the symbol `:dispatchers', and style
+dispatchers.
 
 If this variable is nil, regexp matching is assumed.
 
 A matching style is simply a function from strings to strings
 that takes a component to a regexp to match against.  If the
 resulting regexp has no capturing groups, the entire match is
-highlighted, otherwise just the captured groups are.
-
-The list of matching styles at the beginning provides the default
-matching styles for components when the global style dispatchers
-decline to compute a list of default matching styles.  (Even if
-those dispatchers do compute a list of matching styles, it is
-only the default used for components, and can be overridden for
-individual components by the component style dispatchers).
-
-For information on how the lists of dispatchers are used, see
-`orderless-dispatch'."
+highlighted, otherwise just the captured groups are.  Several are
+provided with this package: try customizing this variable to see
+a list of them.
+
+The style dispatchers, if present, are used to override to the
+matching styles based on the actual component and its place in
+the list of components.  For example, a style dispatcher could
+arrange for the first component to match as an initialism and
+subsequent components to match as literals.  As another example,
+a style dispatcher could arrange for a component starting with
+`?' to match the rest of the component in the `orderless-flex'
+style.  For more information on how this variable is used see
+`orderless-default-pattern-compiler'."
   :type '(set
           (const :tag "Regexp" orderless-regexp)
           (const :tag "Literal" orderless-literal)
@@ -166,23 +161,29 @@ For information on how the lists of dispatchers are used, see
             orderless-strict-full-initialism)
           (const :tag "Flex" orderless-flex)
           (const :tag "Prefixes" orderless-prefixes)
-          (const :tag "Global dispatchers" :global-dispatchers)
-          (const :tag "Component dispatchers" :component-dispatchers)
+          (const :tag "Start dispatchers" :dispatchers)
           (function :tag "Custom function"))
   :group 'orderless)
 
 (defcustom orderless-transient-matching-styles nil
   "Component matching style configuration override.
-This variable has the format and meaning as
-`orderless-component-matching-styles' and overrides it when this
-one is non-nil.  It is meant to be set by commands that
-interactively change the matching style configuration.  No such
-commands are provided with this package, but this variable is
-meant to make writing them simple.  If you do use this variable
-you are likely to want to reset it to nil after every completion
-session, which can be achieved by adding the function
-`orderless-remove-transient-configuration' to the
-`minibuffer-exit-hook'."
+This has the format as `orderless-component-matching-styles' and
+overrides it when this one is non-nil.  It is meant to be set by
+commands that interactively change the matching style
+configuration.  No such commands are provided with this package,
+but this variable is meant to make writing them simple.  If you
+do use this variable you are likely to want to reset it to nil
+after every completion session, which can be achieved by adding
+the function `orderless-remove-transient-configuration' to the
+`minibuffer-exit-hook'.
+
+If this variable doesn't not include a `:dispatchers' section,
+then the dispatchers in `orderless-component-matching-styles' are
+used instead.  To indicate you want to use no style dispatchers
+at all, include an empty dispatchers section, for example:
+
+\(setq `orderless-transient-matching-styles'
+       '(orderless-literal :dispatchers))"
   :type 'sexp
   :group 'orderless)
 
@@ -323,32 +324,22 @@ Meant to be added to `exit-minibuffer-hook'."
   (setq orderless-transient-matching-styles nil
         orderless-transient-component-separator nil))
 
-(defun orderless--parse-matching-styles (configuration)
+(defun orderless--styles+dispatchers (configuration)
   "Parse a matching styles CONFIGURATION.
-The CONFIGURATION argument should be a list of functions
-optionally with the symbols `:global-dispatchers' and
-`:component-dispatcher' used to delimit portions:
-
-\(matching-styles...
- :global-dispatchers global-dispatchers...
- :component-dispatcher component-dispatchers...)
-
-Here matching-styles... denotes a sequence of matching style
-functions, and each of the *-dispatcher... denotes a sequence of
-style dispatcher functions.  The `:global-dispatchers' and
-`:component-dispatcher' sections are both optional and can occur
-in either order.
-
-This function returns a 3-element lists of lists: the styles, the
-global dispatchers and the component dispatchers."
-  (let ((result (vector (list) (list) (list)))
-        (type 0))
-    (dolist (elt configuration)
-      (pcase elt
-        (:global-dispatchers (setq type 1))
-        (:component-dispatchers (setq type 2))
-        (_ (push elt (aref result type)))))
-    (mapcar #'nreverse result)))
+The CONFIGURATION should be a list of matching styles or a list
+of the form:
+
+\(matching-styles... :dispatchers dispatchers...)
+
+containing matching styles, the symbol `:dispatchers', and style
+dispatchers.
+
+This function returns a `cons' whose `car' is the list of
+matching styles, and whose `cdr' is the list of style
+dispatchers."
+  (cons
+   (cl-loop for x in configuration until (eq x :dispatchers) collect x)
+   (cdr (memq :dispatchers configuration))))
 
 (defun orderless-dispatch (dispatchers default string &rest args)
   "Run DISPATCHERS to compute matching styles for STRING.
@@ -393,42 +384,56 @@ DEFAULT as the list of styles."
            when result return (cons result string)
            finally (return (cons default string))))
 
-(defun orderless-default-pattern-compiler (pattern)
+(defun orderless-inherit-defaults (config)
+  "Combine CONFIG with `orderless-component-matching-styles'.
+If CONFIG is nil, return `orderless-component-matching-styles'.
+If CONFIG is non-nil, but does not include `:dispatchers',
+inherit them from `orderless-component-matching-styles'.
+Otherwise return CONFIG."
+  (cond
+   ((null config)
+    (or orderless-component-matching-styles 'orderless-regexp))
+   ((memq :dispatchers config)
+    config)
+   (t (append config
+              (memq :dispatchers orderless-component-matching-styles)))))
+
+(defun orderless-default-pattern-compiler (pattern &optional config)
   "Build regexps to match the components of PATTERN.
 
 Split PATTERN on `orderless-component-separator' and compute
-matching styles for each component.  The matching styles are
-computed according to `orderless-component-matching-styles',
-unless the variable `orderless-transient-matching-styles' is
-non-nil, in which case it is used instead.  Whichever variable is
-used is split into a list of default matching styles, a list of
-global dispatchers and a list of component dispatchers.  For each
-component of the PATTERN, the component dispatchers are run to
-determine the matching styles to be used for that component.  If
-the component dispatchers decline to handle the component, then
-the global dispatchers are run on the PATTERN to determine
-matching styles.  Finally, if the global dispatchers decline to
-handle the PATTERN, the list of default matching styles is used.
-
-See `orderless-dispatch' for details on how the lists of
-dispatchers are used.
-
-This is the default value of `orderless-pattern-compiler'."
+matching styles for each component. The matching styles are
+computed according to CONFIG (more precisely, by the result of
+applying `orderless-inherit-defaults' to CONFIG), which is split
+into a list of default matching styles, and a list of style
+dispatchers. For each component of the PATTERN, the style
+dispatchers are run to determine the matching styles to be used
+for that component, they are called with arguments the component,
+the 0-based index of the component and the total number of
+components. If the component dispatchers decline to handle the
+component, then the list of default matching styles is used. See
+`orderless-dispatch' for details on dispatchers.
+
+The CONFIG defaults to `orderless-component-matching-styles',
+unless overriden by `orderless-transient-matching-styles'.  More
+precisely, it defaults to:
+
+\(orderless-inherit-defaults `orderless-transient-matching-styles').
+
+This function is the default for `orderless-pattern-compiler' and
+might come in handy as a subroutine to implement other pattern
+compilers."
+  (unless config (setq config orderless-transient-matching-styles))
+  (setq config (orderless-inherit-defaults config))
   (cl-loop
-   with (matching-styles global-dispatchers component-dispatchers) =
-     (orderless--parse-matching-styles
-      (or orderless-transient-matching-styles
-          orderless-component-matching-styles))
-   with (default . newpat) = (orderless-dispatch
-                              global-dispatchers
-                              (or matching-styles 'orderless-regexp)
-                              pattern)
-   with components = (split-string newpat orderless-component-separator)
+   with (matching-styles . style-dispatchers) =
+     (orderless--styles+dispatchers config)
+   with components = (split-string pattern orderless-component-separator)
    with total = (length components)
    for component in components and index from 0
    for (styles . newcomp) = (orderless-dispatch
-                             component-dispatchers
-                             default component index total)
+                             style-dispatchers matching-styles
+                             component index total)
    collect
    (if (functionp styles)
        (funcall styles newcomp)