;;; nix-shebang.el --- Handle nix shebang header -*- lexical-binding: t -*-
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;; Author: Matthew Bauer <mjbauer95@gmail.com>
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;; Homepage: https://github.com/NixOS/nix-mode
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;; Version: 1.2.1
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;; Keywords: nix, languages, tools, unix
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;; Package-Requires: ((emacs "24.3"))
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;; This file is NOT part of GNU Emacs.
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;;; Commentary:
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;; This detects file headers that look like:
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;; #!/usr/bin/env nix-shell
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;; #!nix-shell -i bash
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;; and correctly detects their file modes.
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;;; Code:
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(require 'files)
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(defvar nix-shebang-interpreter-regexp "#!\s*nix-shell -i \\([^ \t\n]+\\)"
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"Regexp for nix-shell -i header.")
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(defun nix-shebang-get-interpreter ()
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"Get interpreter string from nix-shell -i file."
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(save-excursion
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(goto-char (point-min))
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(forward-line 1)
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(when (looking-at nix-shebang-interpreter-regexp)
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(match-string 1))))
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(defun nix-shebang-mode ()
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"Detect and run file’s interpreter mode."
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(let ((mode (nix-shebang-get-interpreter)))
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(when mode
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(funcall (assoc-default mode
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(mapcar (lambda (e)
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(cons
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(format "\\`%s\\'" (car e))
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(cdr e)))
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interpreter-mode-alist)
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#'string-match-p)))))
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(provide 'nix-shebang)
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;;; nix-shebang.el ends here
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