128 lines
5.2 KiB
EmacsLisp
128 lines
5.2 KiB
EmacsLisp
(require 'subr-x)
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(defvar simpc-mode-syntax-table
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(let ((table (make-syntax-table)))
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;; C/C++ style comments
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(modify-syntax-entry ?/ ". 124b" table)
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(modify-syntax-entry ?* ". 23" table)
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(modify-syntax-entry ?\n "> b" table)
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;; Preprocessor stuff?
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(modify-syntax-entry ?# "." table)
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;; Chars are the same as strings
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(modify-syntax-entry ?' "\"" table)
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;; Treat <> as punctuation (needed to highlight C++ keywords
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;; properly in template syntax)
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(modify-syntax-entry ?< "." table)
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(modify-syntax-entry ?> "." table)
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(modify-syntax-entry ?& "." table)
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(modify-syntax-entry ?% "." table)
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table))
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(defun simpc-types ()
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'("char" "int" "long" "short" "void" "bool" "float" "double" "signed" "unsigned"
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"char16_t" "char32_t" "char8_t"
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"int8_t" "uint8_t" "int16_t" "uint16_t" "int32_t" "uint32_t" "int64_t" "uint64_t"
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"uintptr_t"
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"size_t"
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"va_list"))
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(defun simpc-keywords ()
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'("auto" "break" "case" "const" "continue" "default" "do"
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"else" "enum" "extern" "for" "goto" "if" "register"
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"return" "sizeof" "static" "struct" "switch" "typedef"
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"union" "volatile" "while" "alignas" "alignof" "and"
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"and_eq" "asm" "atomic_cancel" "atomic_commit" "atomic_noexcept" "bitand"
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"bitor" "catch" "class" "co_await"
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"co_return" "co_yield" "compl" "concept" "const_cast" "consteval" "constexpr"
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"constinit" "decltype" "delete" "dynamic_cast" "explicit" "export" "false"
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"friend" "inline" "mutable" "namespace" "new" "noexcept" "not" "not_eq"
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"nullptr" "operator" "or" "or_eq" "private" "protected" "public" "reflexpr"
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"reinterpret_cast" "requires" "static_assert" "static_cast" "synchronized"
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"template" "this" "thread_local" "throw" "true" "try" "typeid" "typename"
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"using" "virtual" "wchar_t" "xor" "xor_eq"))
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(defun simpc-font-lock-keywords ()
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(list
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`("# *\\(warn\\|error\\)" . font-lock-warning-face)
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`("# *[#a-zA-Z0-9_]+" . font-lock-preprocessor-face)
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`("# *include\\(?:_next\\)?\\s-+\\(\\(<\\|\"\\).*\\(>\\|\"\\)\\)" . (1 font-lock-string-face))
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`("\\(?:enum\\|struct\\)\\s-+\\([a-zA-Z0-9_]+\\)" . (1 font-lock-type-face))
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`(,(regexp-opt (simpc-keywords) 'symbols) . font-lock-keyword-face)
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`(,(regexp-opt (simpc-types) 'symbols) . font-lock-type-face)))
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(defun simpc--previous-non-empty-line ()
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"Returns either NIL when there is no such line or a pair (line . indentation)"
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(save-excursion
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;; If you are on the first line, but not at the beginning of buffer (BOB) the `(bobp)`
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;; function does not return `t`. So we have to move to the beginning of the line first.
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;; TODO: feel free to suggest a better approach for checking BOB here.
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(move-beginning-of-line nil)
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(if (bobp)
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;; If you are standing at the BOB, you by definition don't have a previous non-empty line.
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nil
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;; Moving one line backwards because the current line is by definition is not
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;; the previous non-empty line.
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(forward-line -1)
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;; Keep moving backwards until we hit BOB or a non-empty line.
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(while (and (not (bobp))
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(string-empty-p
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(string-trim-right
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(thing-at-point 'line t))))
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(forward-line -1))
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(if (string-empty-p
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(string-trim-right
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(thing-at-point 'line t)))
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;; If after moving backwards for this long we still look at an empty
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;; line we by definition didn't find the previous non-empty line.
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nil
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;; We found the previous non-empty line!
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(cons (thing-at-point 'line t)
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(current-indentation))))))
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(defun simpc--desired-indentation ()
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(let ((prev (simpc--previous-non-empty-line)))
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(if (not prev)
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(current-indentation)
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(let ((indent-len 4)
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(cur-line (string-trim-right (thing-at-point 'line t)))
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(prev-line (string-trim-right (car prev)))
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(prev-indent (cdr prev)))
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(cond
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((string-match-p "^\\s-*switch\\s-*(.+)" prev-line)
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prev-indent)
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((and (string-suffix-p "{" prev-line)
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(string-prefix-p "}" (string-trim-left cur-line)))
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prev-indent)
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((string-suffix-p "{" prev-line)
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(+ prev-indent indent-len))
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((string-prefix-p "}" (string-trim-left cur-line))
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(max (- prev-indent indent-len) 0))
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((string-suffix-p ":" prev-line)
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(if (string-suffix-p ":" cur-line)
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prev-indent
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(+ prev-indent indent-len)))
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((string-suffix-p ":" cur-line)
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(max (- prev-indent indent-len) 0))
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(t prev-indent))))))
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;;; TODO: customizable indentation (amount of spaces, tabs, etc)
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(defun simpc-indent-line ()
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(interactive)
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(when (not (bobp))
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(let* ((desired-indentation
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(simpc--desired-indentation))
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(n (max (- (current-column) (current-indentation)) 0)))
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(indent-line-to desired-indentation)
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(forward-char n))))
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(define-derived-mode simpc-mode prog-mode "Simple C"
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"Simple major mode for editing C files."
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:syntax-table simpc-mode-syntax-table
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(setq-local font-lock-defaults '(simpc-font-lock-keywords))
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(setq-local indent-line-function 'simpc-indent-line)
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(setq-local comment-start "// "))
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(provide 'simpc-mode)
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