;;; clean-aindent-mode.el --- Simple indent and unindent, trims indent white-space
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;; This is free and unencumbered software released into the public domain.
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;; (http://unlicense.org)
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;; Author: peter marinov <efravia@gmail.com>
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;; Created: 2013-08-17
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;; Last: 2015-08-16
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;; Version: 1.5.0
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;; Package-Version: 20171017.2043
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;; License: C0 (public domain)
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;; URL: https://github.com/pmarinov/clean-aindent-mode
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;; Doc URL: http://www.emacswiki.org/emacs/CleanAutoIndent
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;; Keywords: indentation whitespace backspace
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;; This file is not part of GNU Emacs.
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;;; Commentary:
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;; === Description of the features
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;; 1. Extension of 'newline-and-indent' that keeps track of the last
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;; auto-indent operation and, if it is abandoned, would take care to
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;; trim down the unused white space characters.
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;;
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;; 2. Simple indent, if activated, where cursor is aligned with
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;; indent of the lines above.
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;;
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;; 3. Backspace Unindent. Extension of M-backspace.
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;; When cursor is in the indentation space of a line, or at the first
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;; character and you press M-backspace it will move the entire line to
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;; be aligned to the line above or any other that is with indentation
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;; smaller than the current.
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;;
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;; Detailed documentation with example situations and screenshots:
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;; http://www.emacswiki.org/emacs/CleanAutoIndent
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;;
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;; === To activate
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;; 'M-x clean-aindent-mode'
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;; or
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;; add this to your init.el:
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;; (clean-aindent-mode t)
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;;
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;; By default auto-indent is bound to 'C-j'. Bind it to 'RET' for most
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;; convenient use of the features. Add this to your init.el:
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;; (define-key global-map (kbd "RET") 'newline-and-indent)
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;;
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;; In case you installed the extension via MELPA, use this suggested configiration:
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;;
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;; (defun my-pkg-init()
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;; (electric-indent-mode -1) ; no electric indent, auto-indent is sufficient
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;; (clean-aindent-mode t)
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;; (setq clean-aindent-is-simple-indent t)
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;; (define-key global-map (kbd "RET") 'newline-and-indent))
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;; (add-hook 'after-init-hook 'my-pkg-init)
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;;
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;; === Options
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;; M-x customize, search for 'auto indent', toggle to on,
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;; then 'Apply and Save'.
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;; or
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;; add this to your init.el:
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;; (set 'clean-aindent-is-simple-indent t)
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;;
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;;; Change Log:
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;;
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;; 2015-06-18, v1.5.0, pmarinov
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;; - Fix for a compiler warning by justbur
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;; - Extra comments in README
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;;
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;; 2014-06-14, pmarinov, v1.4.0
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;; - Implement as an advice to 'newline-and-indent'
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;;
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;; 2014-06-01, pmarinov, v1.3.0
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;; - Activate via a minor mode
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;; - Further cleanup of the name space
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;;
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;; 2014-05-27, pmarinov, v1.2.0
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;; Changed: Move all function under the same namespace (function prefix)
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;;
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;; 2014-03-07, pmarinov, v1.1.0
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;; Added: Simple auto indent feature. Configurable via M-x customize.
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;;
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;; 2013-08-31, pmarinov, v1.0.0
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;; First implementation.
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;;
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(defgroup clean-aindent nil
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"Settings for 'clean-aindent-mode'"
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:group 'indent)
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(defcustom clean-aindent-is-simple-indent nil
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"Determines if indentation should use the smart language mode or simple mode"
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:tag "Clean auto indent is in simple mode"
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:group 'clean-aindent
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:type 'boolean)
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;;
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;; Implementation of Clean auto indent and simple indent
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;;
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(defun clean-aindent--get-indent-len()
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"Computes the length of the line at 'clean-aindent--last-indent."
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(let ((eol-pos 0))
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(save-excursion
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(goto-char clean-aindent--last-indent)
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(end-of-line)
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(setq eol-pos (point))
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(beginning-of-line)
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;; return ln-len = eol-pos - pos
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(- eol-pos (point)))))
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(defun clean-aindent--abandonedp()
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"Checks if last auto-indent position was abandoned.
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Verifies if cursor moved away and that the indent was left
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unaltered."
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(if (not clean-aindent--last-indent)
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nil
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;; (message "clean-aindent--last-indent %d point %d" clean-aindent--last-indent (point))
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(if (= clean-aindent--last-indent (point))
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nil
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;; Checking for indent length is to detect if something was not
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;; typed to alter it. Altered indent shouldn't be trimmed.
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(if (not (= clean-aindent--last-indent-len (clean-aindent--get-indent-len)))
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nil
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t))))
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(defun clean-aindent--trim-last-point()
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"Deletes the whitespaces inserted at last indentation"
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(save-excursion
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(goto-char clean-aindent--last-indent)
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; Select the entire line
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(let ((s 0)
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(e 0))
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(beginning-of-line)
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(setq s (point))
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(end-of-line)
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(setq e (point))
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(delete-trailing-whitespace s e)
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(end-of-line)
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(message "auto trimmed %d chars" (- e (point))))))
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(defun clean-aindent--check-last-point()
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"Checks if last pos of auto-indent was abandoned and deletes it"
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(if (clean-aindent--abandonedp)
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(clean-aindent--trim-last-point))
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;; Once we leave the position, clean the indent bookmark
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(if
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(and
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clean-aindent--last-indent
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(not (= clean-aindent--last-indent (point))))
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(setq clean-aindent--last-indent nil)))
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(defun clean-aindent--find-indent()
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"Searches lines backward, finds first non-blank. Returns
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indentation value"
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(save-excursion
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;; Walk lines backward, until first non-blank
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(clean-aindent--prev-line)
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;; Return indentation of that line
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(current-indentation)))
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(defun clean-aindent--simple-newline-and-indent()
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"Simple auto indent. Indentation is based only on previous line
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indentation, regardless of language settings."
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;; First remove any trailing spaces from the current line
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(save-excursion
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(let ((s 0)
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(e 0))
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(beginning-of-line)
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(setq s (point))
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(end-of-line)
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(setq e (point))
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(delete-trailing-whitespace s e)
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(end-of-line)))
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;; Insert a new line and indent
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(newline)
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(indent-to (clean-aindent--find-indent) 0))
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(defadvice newline-and-indent (around clean-aindent)
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"Advice for newline-and-indent(), implements clean auto-indent.
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Removes unneeded whitespaces by keeping track of the place of the
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last indentation so that they can be deleted in case the indentation was
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abandoned."
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(clean-aindent--check-last-point) ;; In case of consequtive aindent calls
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(if clean-aindent-is-simple-indent
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(clean-aindent--simple-newline-and-indent) ;; Run our simple indent feature
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(progn
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ad-do-it)) ;; Run 'newline-and-indent' here
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(setq clean-aindent--last-indent nil)
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;; Make local: track on per buffer basis
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(make-local-variable 'clean-aindent--last-indent)
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;; Track position and length of the indentation
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(setq clean-aindent--last-indent (point))
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(setq clean-aindent--last-indent-len (clean-aindent--get-indent-len))
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(make-local-variable 'clean-aindent--last-indent-len))
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;;
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;; Backspace-unindent implementation functions
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;;
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(defun clean-aindent--get-line-len()
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"Computes length of current line"
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(save-excursion
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(beginning-of-line nil)
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(let ((pos (point)))
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(end-of-line nil)
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(- (point) pos))))
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(defun clean-aindent--line-emptyp()
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"Checks if line is empty"
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(save-excursion
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(beginning-of-line nil)
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(if (= (point) 1)
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nil
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(= (clean-aindent--get-line-len) 0))))
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(defun clean-aindent--prev-line()
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"Move cursor to previous line, skip empty lines"
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(let ((c (point)))
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(while
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(and
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(= 0 (forward-line -1))
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(clean-aindent--line-emptyp)))
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;; return 't if we moved, nil if already beginning of buffer
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(not (= c (point)))))
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(defun clean-aindent--find-u-indent(start)
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"Searches lines backward, finds the one that is indented less
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than certain indentation t"
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(save-excursion
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(let (c)
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(while
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(and
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(setq c (current-indentation))
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(> c 0)
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;; Find an indent smaller than _start_
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(<= start c)
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;; Walk lines backward
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(clean-aindent--prev-line)))
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;; _c_ is the computed unindent size
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c)))
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(defun clean-aindent--inside-indentp()
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"Returns true if cursor is in the leading whitespace or first
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non-blank character of a line"
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(save-excursion
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(let ((pos (point)))
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(beginning-of-line nil)
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(skip-chars-forward " \t")
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(if (<= pos (point))
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t
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nil))))
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(defun clean-aindent--line-point()
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"Get (point) at the beginning of the current line"
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(save-excursion
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(beginning-of-line)
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(point)))
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(defun clean-aindent--goto-column(col)
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"Moves the cursor to a certain column position.
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Column position is different from char position because of TABs"
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(beginning-of-line nil)
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(while (< (current-column) col)
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(right-char)))
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(defun clean-aindent--bsunindent(arg)
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"Unindents.
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Bound to `M-backspace' key. Searches lines backward, finds the one that
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is indented less than the current one. Unindents current line to
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align with that smaller indentation"
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(interactive "p")
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(if (not (clean-aindent--inside-indentp))
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(kill-word (- arg)) ;; Original "C-backspace" key function
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;; else: cursor is inside indent space, do unindent
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(let*
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((ln (clean-aindent--line-point))
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(c (current-indentation))
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(n (clean-aindent--find-u-indent c)) ;; compute new indent
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(s (+ ln n))) ;; start of region to delete
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(if (not (= s c))
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(progn
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;; (message "new unindent %d" n)
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;; Delete characters between s to c
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(clean-aindent--goto-column c)
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(backward-delete-char-untabify (- c n)))))))
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;;
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;; Initial setup
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;;
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(defvar clean-aindent--last-indent nil)
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(defvar clean-aindent--last-indent-len 0)
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(defvar clean-aindent-mode--keymap (make-keymap) "clean-aindent-mode keymap.")
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(define-key clean-aindent-mode--keymap [remap backward-kill-word] 'clean-aindent--bsunindent)
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;;;###autoload
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(define-minor-mode clean-aindent-mode
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"Activates clean auto indent for function 'newline-and-indent' and
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back-space unindent for M-DEL (meta-backspace).
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clean-aindent mode is a global minor mode.
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1. Extension of 'newline-and-indent' that keeps track of the last
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auto-indent operation and, if it is abandoned, would take care to
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trim down the unused white space characters.
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2. Simple indent, if activated, where cursor is aligned with
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indent of the lines above.
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3. Backspace Unindent. Extension of M-backspace. When cursor is
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in the indentation space of a line, or at the first character and
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you press M-backspace it will move the entire line to be aligned
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to the line above or any other that is with indentation smaller
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than the current."
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:init-value nil ; The initial value - disabled by default
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:global t ; Global minor mode
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:keymap clean-aindent-mode--keymap
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;; BODY
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(if clean-aindent-mode
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;; Activate
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(progn
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(ad-enable-advice 'newline-and-indent 'around 'clean-aindent)
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(ad-activate 'newline-and-indent)
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(add-hook 'post-command-hook 'clean-aindent--check-last-point))
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;; Deactivate
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(progn
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(ad-disable-advice 'newline-and-indent 'around 'clean-aindent)
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(ad-activate 'newline-and-indent)
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(remove-hook 'post-command-hook 'clean-aindent--check-last-point))))
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(provide 'clean-aindent-mode)
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;;; clean-aindent-mode.el ends here
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