ob-C.el

;;; ob-C.el --- Babel Functions for C and Similar Languages -*- lexical-binding: t; -*-

;; Copyright (C) 2010-2025 Free Software Foundation, Inc.

;; Author: Eric Schulte
;;      Thierry Banel
;; Maintainer: Thierry Banel <tbanelwebmin@free.fr>
;; Keywords: literate programming, reproducible research
;; URL: https://orgmode.org

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Org-Babel support for evaluating C, C++, D code.
;;
;; very limited implementation:
;; - currently only support :results output
;; - not much in the way of error feedback

;;; Code:

(require 'org-macs)
(org-assert-version)

(require 'cc-mode)
(require 'ob)
(require 'org-macs)

(declare-function org-entry-get "org" (pom property &optional inherit literal-nil))

(defvar org-babel-tangle-lang-exts)
(add-to-list 'org-babel-tangle-lang-exts '("C++" . "cpp"))
(add-to-list 'org-babel-tangle-lang-exts '("D" . "d"))

(defvar org-babel-default-header-args:C '())

(defconst org-babel-header-args:C '((includes . :any)
				    (defines . :any)
				    (main    . :any)
				    (flags   . :any)
				    (cmdline . :any)
				    (libs    . :any))
  "C/C++-specific header arguments.")

(defconst org-babel-header-args:C++
  (append '((namespaces . :any))
	  org-babel-header-args:C)
  "C++-specific header arguments.")

(defcustom org-babel-C-compiler "gcc"
  "Command used to compile a C source code file into an executable.
May be either a command in the path, like gcc
or an absolute path name, like /usr/local/bin/gcc
parameter may be used, like gcc -v"
  :group 'org-babel
  :version "24.3"
  :type 'string)

(defcustom org-babel-C++-compiler "g++"
  "Command used to compile a C++ source code file into an executable.
May be either a command in the path, like g++
or an absolute path name, like /usr/local/bin/g++
parameter may be used, like g++ -v"
  :group 'org-babel
  :version "24.3"
  :type 'string)

(defcustom org-babel-D-compiler "rdmd"
  "Command used to compile and execute a D source code file.
May be either a command in the path, like rdmd
or an absolute path name, like /usr/local/bin/rdmd
parameter may be used, like rdmd --chatty"
  :group 'org-babel
  :version "24.3"
  :type 'string)

(defvar org-babel-c-variant nil
  "Internal variable used to hold which type of C (e.g. C or C++ or D)
is currently being evaluated.")

(defun org-babel-execute:cpp (body params)
  "Execute BODY according to its header arguments PARAMS.
This function calls `org-babel-execute:C++'."
  (org-babel-execute:C++ body params))

(defun org-babel-expand-body:cpp (body params)
  "Expand C++ BODY with org-babel according to its header arguments PARAMS."
  (org-babel-expand-body:C++ body params))

(defun org-babel-execute:C++ (body params)
  "Execute C++ BODY with org-babel according to its header arguments PARAMS.
This function is called by `org-babel-execute-src-block'."
  (let ((org-babel-c-variant 'cpp)) (org-babel-C-execute body params)))

(defun org-babel-expand-body:C++ (body params)
  "Expand C++ BODY with org-babel according to its header arguments PARAMS."
  (let ((org-babel-c-variant 'cpp)) (org-babel-C-expand-C++ body params)))

(defun org-babel-execute:D (body params)
  "Execute D BODY with org-babel according to its header arguments PARAMS.
This function is called by `org-babel-execute-src-block'."
  (let ((org-babel-c-variant 'd)) (org-babel-C-execute body params)))

(defun org-babel-expand-body:D (body params)
  "Expand D BODY with org-babel according to its header arguments PARAMS."
  (let ((org-babel-c-variant 'd)) (org-babel-C-expand-D body params)))

(defun org-babel-execute:C (body params)
  "Execute a C BODY according to its header arguments PARAMS.
This function is called by `org-babel-execute-src-block'."
  (let ((org-babel-c-variant 'c)) (org-babel-C-execute body params)))

(defun org-babel-expand-body:C (body params)
  "Expand C BODY according to its header arguments PARAMS."
  (let ((org-babel-c-variant 'c)) (org-babel-C-expand-C body params)))

(defun org-babel-C-execute (body params)
  "Execute C/C++/D BODY according to its header arguments PARAMS.
This function should only be called by `org-babel-execute:C' or
`org-babel-execute:C++' or `org-babel-execute:D'."
  (let* ((tmp-src-file (org-babel-temp-file
			"C-src-"
			(pcase org-babel-c-variant
			  (`c ".c") (`cpp ".cpp") (`d ".d"))))
	 (tmp-bin-file			;not used for D
	  (org-babel-process-file-name
	   (org-babel-temp-file "C-bin-" org-babel-exeext)))
	 (cmdline (cdr (assq :cmdline params)))
	 (cmdline (if cmdline (concat " " cmdline) ""))
	 (flags (cdr (assq :flags params)))
	 (flags (mapconcat 'identity
			   (if (listp flags) flags (list flags)) " "))
	 (libs (org-babel-read
		(or (cdr (assq :libs params))
		    (org-entry-get nil "libs" t))
		nil))
	 (libs (mapconcat #'identity
			  (if (listp libs) libs (list libs))
			  " "))
	 (full-body
	  (pcase org-babel-c-variant
	    (`c (org-babel-C-expand-C body params))
	    (`cpp (org-babel-C-expand-C++ body params))
	    (`d (org-babel-C-expand-D body params)))))
    (with-temp-file tmp-src-file (insert full-body))
    (pcase org-babel-c-variant
      ((or `c `cpp)
       (org-babel-eval
	(format "%s -o %s %s %s %s"
		(pcase org-babel-c-variant
		  (`c org-babel-C-compiler)
		  (`cpp org-babel-C++-compiler))
		tmp-bin-file
		flags
		(org-babel-process-file-name tmp-src-file)
		libs)
	""))
      (`d nil)) ;; no separate compilation for D
    (let ((results
	   (org-babel-eval
	    (pcase org-babel-c-variant
	      ((or `c `cpp)
	       (concat tmp-bin-file cmdline))
	      (`d
	       (format "%s %s %s %s"
		       org-babel-D-compiler
		       flags
		       (org-babel-process-file-name tmp-src-file)
		       cmdline)))
	    "")))
      (when results
	(setq results (org-remove-indentation results))
	(org-babel-reassemble-table
	 (org-babel-result-cond (cdr (assq :result-params params))
	   results
	   (let ((tmp-file (org-babel-temp-file "c-")))
	     (with-temp-file tmp-file (insert results))
	     (org-babel-import-elisp-from-file tmp-file)))
	 (org-babel-pick-name
	  (cdr (assq :colname-names params)) (cdr (assq :colnames params)))
	 (org-babel-pick-name
	  (cdr (assq :rowname-names params)) (cdr (assq :rownames params)))))
      )))

(defun org-babel-C-expand-C++ (body params)
  "Expand C/C++ BODY with according to its header arguments PARAMS."
  (org-babel-C-expand-C body params))

(defun org-babel-C-expand-C (body params)
  "Expand C/C++ BODY according to its header arguments PARAMS."
  (let ((vars (org-babel--get-vars params))
	(colnames (cdr (assq :colname-names params)))
	(main-p (not (string= (cdr (assq :main params)) "no")))
	(includes (org-babel-read
		   (cdr (assq :includes params))
		   nil))
	(defines (org-babel-read
		  (cdr (assq :defines params))
		  nil))
	(namespaces (org-babel-read
		     (cdr (assq :namespaces params))
		     nil))
        (prologue (cdr (assq :prologue params)))
        (epilogue (cdr (assq :epilogue params))))
    (when (stringp includes)
      (setq includes (split-string includes)))
    (when (stringp namespaces)
      (setq namespaces (split-string namespaces)))
    (when (stringp defines)
      (let ((y nil)
	    (result (list t)))
	(dolist (x (split-string defines))
	  (if (null y)
	      (setq y x)
	    (nconc result (list (concat y " " x)))
	    (setq y nil)))
	(setq defines (cdr result))))
    (setq body
          (concat
           (and prologue (concat prologue "\n"))
           body
           (and epilogue (concat "\n" epilogue "\n"))))
    (mapconcat 'identity
	       (list
		;; includes
		(mapconcat
		 (lambda (inc)
		   ;; :includes '(<foo> <bar>) gives us a list of
		   ;; symbols; convert those to strings.
		   (when (symbolp inc) (setq inc (symbol-name inc)))
		   (if (string-prefix-p "<" inc)
		       (format "#include %s" inc)
		     (format "#include \"%s\"" inc)))
		 includes "\n")
		;; defines
		(mapconcat
		 (lambda (inc) (format "#define %s" inc))
		 (if (listp defines) defines (list defines)) "\n")
		;; namespaces
		(mapconcat
		 (lambda (inc) (format "using namespace %s;" inc))
		 namespaces
		 "\n")
		;; variables
		(mapconcat 'org-babel-C-var-to-C vars "\n")
		;; table sizes
		(mapconcat 'org-babel-C-table-sizes-to-C vars "\n")
		;; tables headers utility
		(when colnames
		  (org-babel-C-utility-header-to-C))
		;; tables headers
		(mapconcat (lambda (head)
                             (let* ((tblnm (car head))
                                    (tbl (cdr (car (let* ((el vars))
                                                     (while (not (or (equal tblnm (caar el)) (not el)))
                                                       (setq el (cdr el)))
                                                     el))))
                                    (type (org-babel-C-val-to-base-type tbl)))
                               (org-babel-C-header-to-C head type))) colnames "\n")
		;; body
		(if main-p
		    (org-babel-C-ensure-main-wrap body)
		  body) "\n") "\n")))

(defun org-babel-C-expand-D (body params)
  "Expand D BODY according to its header arguments PARAMS."
  (let ((vars (org-babel--get-vars params))
	(colnames (cdr (assq :colname-names params)))
	(main-p (not (string= (cdr (assq :main params)) "no")))
	(imports (or (cdr (assq :imports params))
		     (org-babel-read (org-entry-get nil "imports" t)))))
    (when (stringp imports)
      (setq imports (split-string imports)))
    (setq imports (append imports '("std.stdio" "std.conv")))
    (mapconcat 'identity
	       (list
		"module mmm;"
		;; imports
		(mapconcat
		 (lambda (inc) (format "import %s;" inc))
		 imports "\n")
		;; variables
		(mapconcat 'org-babel-C-var-to-C vars "\n")
		;; table sizes
		(mapconcat 'org-babel-C-table-sizes-to-C vars "\n")
		;; tables headers utility
		(when colnames
		  (org-babel-C-utility-header-to-C))
		;; tables headers
		(mapconcat (lambda (head)
                             (let* ((tblnm (car head))
                                    (tbl (cdr (car (let* ((el vars))
                                                     (while (not (or (equal tblnm (caar el)) (not el)))
                                                       (setq el (cdr el)))
                                                     el))))
                                    (type (org-babel-C-val-to-base-type tbl)))
                               (org-babel-C-header-to-C head type))) colnames "\n")
		;; body
		(if main-p
		    (org-babel-C-ensure-main-wrap body)
		  body) "\n") "\n")))

(defun org-babel-C-ensure-main-wrap (body)
  "Wrap BODY in a \"main\" function call if none exists."
  (if (string-match "^[ \t]*[intvod]+[ \t\n\r]*main[ \t]*(.*)" body)
      body
    (format "int main() {\n%s\nreturn 0;\n}\n" body)))

(defun org-babel-prep-session:C (_session _params)
  "Throw and error that sessions are not supported.
This function does nothing as C is a compiled language with no support
for sessions."
  (error "C is a compiled language -- no support for sessions"))

(defun org-babel-load-session:C (_session _body _params)
  "Throw and error that sessions are not supported.
This function does nothing as C is a compiled language with no support
for sessions."
  (error "C is a compiled language -- no support for sessions"))

;; helper functions

(defun org-babel-C-format-val (type val)
  "Handle the FORMAT part of TYPE with the data from VAL."
  (let ((format-data (cadr type)))
    (if (stringp format-data)
	(cons "" (format format-data val))
      (funcall format-data val))))

(defun org-babel-C-val-to-C-type (val)
  "Determine the type of VAL.
Return a list (TYPE-NAME FORMAT).  TYPE-NAME should be the name of the type.
FORMAT can be either a format string or a function which is called with VAL."
  (let* ((basetype (org-babel-C-val-to-base-type val))
	 (type
	  (pcase basetype
	    (`integerp '("int" "%d"))
	    (`floatp '("double" "%s")) ;; %f rounds, use %s to print the float literally
	    (`stringp
	     (list
	      (if (eq org-babel-c-variant 'd) "string" "const char*")
	      "\"%s\""))
            (_ (error "Unknown type %S" basetype)))))
    (cond
     ((integerp val) type) ;; an integer declared in the #+begin_src line
     ((floatp val) type) ;; a numeric declared in the #+begin_src line
     ((and (listp val) (listp (car val))) ;; a table
      `(,(car type)
	(lambda (val)
	  (cons
           (pcase org-babel-c-variant
             ((or `c `cpp) (format "[%d][%d]" (length val) (length (car val))))
             (`d           (format "[%d][%d]" (length (car val)) (length val))))
	   (concat
	    (if (eq org-babel-c-variant 'd) "[\n" "{\n")
	    (mapconcat
	     (lambda (v)
	       (concat
		(if (eq org-babel-c-variant 'd) " [" " {")
		(mapconcat (lambda (w) (format ,(cadr type) w)) v ",")
		(if (eq org-babel-c-variant 'd) "]" "}")))
	     val
	     ",\n")
	    (if (eq org-babel-c-variant 'd) "\n]" "\n}"))))))
     ((or (listp val) (vectorp val)) ;; a list declared in the #+begin_src line
      `(,(car type)
	(lambda (val)
	  (cons
	   (format "[%d]" (length val))
	   (concat
	    (if (eq org-babel-c-variant 'd) "[" "{")
	    (mapconcat (lambda (v) (format ,(cadr type) v)) val ",")
	    (if (eq org-babel-c-variant 'd) "]" "}"))))))
     (t ;; treat unknown types as string
      type))))

(defun org-babel-C-val-to-base-type (val)
  "Determine the base type of VAL.
The type is:
- `integerp' if all base values are integers;
- `floatp' if all base values are either floating points or integers;
- `stringp' otherwise."
  (cond
   ((integerp val) 'integerp)
   ((floatp val) 'floatp)
   ((or (listp val) (vectorp val))
    (let ((type nil))
      (mapc (lambda (v)
	      (pcase (org-babel-C-val-to-base-type v)
		(`stringp (setq type 'stringp))
		(`floatp
		 (when (or (not type) (eq type 'integerp))
		   (setq type 'floatp)))
		(`integerp
		 (unless type (setq type 'integerp)))))
	    val)
      type))
   (t 'stringp)))

(defun org-babel-C-var-to-C (pair)
  "Convert PAIR of (var . val) C variable assignment."
  ;; TODO list support
  (let ((var (car pair))
	(val (cdr pair)))
    (when (symbolp val)
      (setq val (symbol-name val))
      (when (= (length val) 1)
	(setq val (string-to-char val))))
    (let* ((type-data (org-babel-C-val-to-C-type val))
	   (type (car type-data))
	   (formatted (org-babel-C-format-val type-data val))
	   (suffix (car formatted))
	   (data (cdr formatted)))
      (pcase org-babel-c-variant
        ((or `c `cpp)
         (format "%s %s%s = %s;"
	         type
	         var
	         suffix
	         data))
        (`d
         (format "%s%s %s = %s;"
	         type
	         suffix
	         var
	         data))))))

(defun org-babel-C-table-sizes-to-C (pair)
  "Create constants of table dimensions, if PAIR is a table."
  (when (listp (cdr pair))
    (cond
     ((listp (cadr pair)) ;; a table
      (concat
       (format "const int %s_rows = %d;" (car pair) (length (cdr pair)))
       "\n"
       (format "const int %s_cols = %d;" (car pair) (length (cadr pair)))))
     (t ;; a list declared in the #+begin_src line
      (format "const int %s_cols = %d;" (car pair) (length (cdr pair)))))))

(defun org-babel-C-utility-header-to-C ()
  "Generate a utility function to convert a column name into a column number."
  (pcase org-babel-c-variant
    ((or `c `cpp)
     (concat
      "
#ifndef _STRING_H
#include <string.h>
#endif
int get_column_num (int nbcols, const char** header, const char* column)
{
  int c;
  for (c=0; c<nbcols; c++)
    if (strcmp(header[c],column)==0)
      return c;
  return -1;
}
"))
    (`d
     "int get_column_num (string[] header, string column)
{
  foreach (c, h; header)
    if (h==column)
      return to!int(c);
  return -1;
}
")))

(defun org-babel-C-header-to-C (head type)
  "Convert an elisp list of header table into a C or D vector
specifying a variable with the name of the table."
  (let ((table (car head))
        (headers (cdr head))
        (typename (pcase type
                    (`integerp "int")
                    (`floatp "double")
                    (`stringp (pcase org-babel-c-variant
                                ((or `c `cpp) "const char*")
                                (`d "string"))))))
    (concat
     (pcase org-babel-c-variant
       ((or `c `cpp)
        (format "const char* %s_header[%d] = {%s};"
                table
                (length headers)
                (mapconcat (lambda (h) (format "\"%s\"" h)) headers ",")))
       (`d
        (format "string[%d] %s_header = [%s];"
                (length headers)
                table
                (mapconcat (lambda (h) (format "\"%s\"" h)) headers ","))))
     "\n"
     (pcase org-babel-c-variant
       ((or `c `cpp)
	(format
	 "%s %s_h (int row, const char* col) { return %s[row][get_column_num(%d,%s_header,col)]; }"
	 typename table table (length headers) table))
       (`d
	(format
	 "%s %s_h (size_t row, string col) { return %s[row][get_column_num(%s_header,col)]; }"
         typename table table table))))))

(provide 'ob-C)

;;; ob-C.el ends here