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gracjangracjan
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Merge pull request #688 from geraldus/ac-improvements
Completion mechanics haskell-completions-grab-prefix implementation
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‎haskell-completions.el

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;; This package provides completions related functionality for
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;; Haskell Mode such grab completion prefix at point, and etc..
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;; Some description
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;; ================
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;;
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;; For major use function `haskell-completions-grab-prefix' is supposed, and
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;; other prefix grabbing functions are used internally by it. So, only this
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;; funciton have prefix minimal length functionality and invokes predicate
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;; function `haskell-completions-can-grab-prefix'.
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;;; Code:
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(require 'haskell-mode)
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(defun haskell-completions-can-grab-prefix ()
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"Check if the case is appropriate for grabbing completion prefix.
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Returns t if point is either at whitespace character, or at
@@ -42,5 +53,146 @@ whitespace or new line, otherwise returns nil.
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(backward-char)
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(not (looking-at (rx (| space line-end)))))))))
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(defun haskell-completions-grab-pragma-prefix ()
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"Grab completion prefix for pragma completions.
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Returns a list of form '(prefix-start-position
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prefix-end-position prefix-value prefix-type) for pramga names
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such as WARNING, DEPRECATED, LANGUAGE and etc. Also returns
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completion prefixes for options in case OPTIONS_GHC pragma, or
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language extensions in case of LANGUAGE pragma. Obsolete OPTIONS
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pragma is supported also."
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(when (nth 4 (syntax-ppss))
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;; We're inside comment
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(let ((p (point))
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(comment-start (nth 8 (syntax-ppss)))
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(case-fold-search nil)
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prefix-start
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prefix-end
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prefix-type
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prefix-value)
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(save-excursion
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(goto-char comment-start)
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(when (looking-at (rx "{-#" (1+ (| space "\n"))))
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(let ((pragma-start (match-end 0)))
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(when (> p pragma-start)
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;; point stands after `{-#`
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(goto-char pragma-start)
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(when (looking-at (rx (1+ (| upper "_"))))
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;; found suitable sequence for pragma name
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(let ((pragma-end (match-end 0))
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(pragma-value (match-string-no-properties 0)))
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(if (eq p pragma-end)
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;; point is at the end of (in)complete pragma name
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;; prepare resulting values
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(progn
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(setq prefix-start pragma-start)
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(setq prefix-end pragma-end)
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(setq prefix-value pragma-value)
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(setq prefix-type
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'haskell-completions-pragma-name-prefix))
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(when (and (> p pragma-end)
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(or (equal "OPTIONS_GHC" pragma-value)
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(equal "OPTIONS" pragma-value)
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(equal "LANGUAGE" pragma-value)))
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;; point is after pragma name, so we need to check
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;; special cases of `OPTIONS_GHC` and `LANGUAGE` pragmas
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;; and provide a completion prefix for possible ghc
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;; option or language extension.
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(goto-char pragma-end)
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(when (re-search-forward
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(rx (* anything)
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(1+ (regexp "\\S-")))
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p
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t)
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(let* ((str (match-string-no-properties 0))
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(split (split-string str (rx (| space "\n")) t))
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(val (car (last split)))
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(end (point)))
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(when (and (equal p end)
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(not (string-match-p "#" val)))
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(setq prefix-value val)
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(backward-char (length val))
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(setq prefix-start (point))
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(setq prefix-end end)
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(setq
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prefix-type
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(if (not (equal "LANGUAGE" pragma-value))
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'haskell-completions-ghc-option-prefix
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'haskell-completions-language-extension-prefix
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)))))))))))))
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(when prefix-value
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(list prefix-start prefix-end prefix-value prefix-type)))))
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(defun haskell-completions-grab-identifier-prefix ()
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"Grab completion prefix for identifier at point.
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Returns a list of form '(prefix-start-position
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prefix-end-position prefix-value prefix-type) for haskell
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identifier at point depending on result of function
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`haskell-ident-pos-at-point'."
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(let ((pos-at-point (haskell-ident-pos-at-point))
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(p (point)))
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(when pos-at-point
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(let* ((start (car pos-at-point))
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(end (cdr pos-at-point))
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(type 'haskell-completions-identifier-prefix)
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(case-fold-search nil)
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value)
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;; we need end position of result, becase of
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;; `haskell-ident-pos-at-point' ignores trailing whitespace, e.g. the
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;; result will be same for `map|` and `map |` invocations.
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(when (<= p end)
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(setq end p)
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(setq value (buffer-substring-no-properties start end))
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(when (string-match-p (rx bos upper) value)
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;; we need to check if found identifier is a module name
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(save-excursion
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(goto-char (line-beginning-position))
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(when (re-search-forward
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(rx "import"
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(? (1+ space) "qualified")
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(1+ space)
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upper
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(1+ (| alnum ".")))
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p ;; bound
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t) ;; no-error
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(if (equal p (point))
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(setq type 'haskell-completions-module-name-prefix)
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(when (re-search-forward
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(rx (| " as " "("))
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start
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t)
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;; but uppercase ident could occur after `as` keyword, or in
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;; module imports after opening parenthesis, in this case
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;; restore identifier type again, it's neccessary to
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;; distinguish the means of completions retrieval
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(setq type 'haskell-completions-identifier-prefix))))))
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(when (nth 8 (syntax-ppss))
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;; eighth element of syntax-ppss result is string or comment start,
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;; so when it's not nil word at point is inside string or comment,
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;; return special literal prefix type
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(setq type 'haskell-completions-general-prefix))
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;; finally take in account minlen if given and return the result
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(when value (list start end value type)))))))
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(defun haskell-completions-grab-prefix (&optional minlen)
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"Grab prefix at point for possible completion.
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Returns a list of form '(prefix-start-position
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prefix-end-position prefix-value prefix-type) depending on
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situation, e.g. is it needed to complete pragma, module name,
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arbitrary identifier, and etc. Rerurns nil in case it is
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impossible to grab prefix.
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If provided optional MINLEN parameter this function will return
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result only if prefix length is not less than MINLEN."
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(when (haskell-completions-can-grab-prefix)
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(let ((prefix (cond
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((haskell-completions-grab-pragma-prefix))
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((haskell-completions-grab-identifier-prefix)))))
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(cond ((and minlen prefix)
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(when (>= (length (nth 2 prefix)) minlen)
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prefix))
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(prefix prefix)))))
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(provide 'haskell-completions)
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;;; haskell-completions.el ends here

‎haskell.el

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(end (match-end 1)))
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(list start end
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(haskell-process-get-repl-completions process text))))
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;; Complete OPTIONS using :complete repl ":set ..."
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;; Complete OPTIONS, a completion list comes from variable
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;; `haskell-ghc-supported-options'
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((and (nth 4 (syntax-ppss))
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(save-excursion
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(let ((p (point)))
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(rx symbol-start "-" (* (char alnum ?-)))
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(line-beginning-position)))
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(list (match-beginning 0) (match-end 0) haskell-ghc-supported-options))
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;; Complete LANGUAGE :complete repl ":set -X..."
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;; Complete LANGUAGE, a list of completions comes from variable
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;; `haskell-ghc-supported-options'
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((and (nth 4 (syntax-ppss))
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(save-excursion
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(let ((p (point)))

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