46 lines
1.5 KiB
EmacsLisp
46 lines
1.5 KiB
EmacsLisp
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(defun c-macro-expand (beg end)
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"Display the result of expanding all C macros occurring in the region.
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The expansion is entirely correct because it uses the C preprocessor."
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(interactive "r")
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(let ((outbuf (get-buffer-create "*Macroexpansion*"))
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(tempfile "%%macroexpand%%")
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process
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last-needed)
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(save-excursion
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(set-buffer outbuf)
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(erase-buffer))
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(setq process (start-process "macros" outbuf "/lib/cpp"))
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(set-process-sentinel process '(lambda (&rest x)))
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(save-restriction
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(widen)
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(save-excursion
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(goto-char beg)
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(beginning-of-line)
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(setq last-needed (point))
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(if (re-search-backward "^[ \t]*#" nil t)
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(progn
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;; Skip continued lines.
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(while (progn (end-of-line) (= (preceding-char) ?\\))
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(forward-line 1))
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;; Skip the last line of the macro definition we found.
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(forward-line 1)
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(setq last-needed (point)))))
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(write-region (point-min) last-needed tempfile nil 'nomsg)
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(process-send-string process (concat "#include \"" tempfile "\"\n"))
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(process-send-string process "\n")
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(process-send-region process beg end)
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(process-send-string process "\n")
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(process-send-eof process))
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(while (eq (process-status process) 'run)
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(accept-process-output))
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(delete-file tempfile)
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(save-excursion
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(set-buffer outbuf)
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(goto-char (point-max))
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(re-search-backward "\n# [12] \"\"")
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(forward-line 2)
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(while (eolp) (delete-char 1))
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(delete-region (point-min) (point)))
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(display-buffer outbuf)))
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