ob-eshell.el: Add Eshell support for Babel

* lisp/ob-eshell.el (org-babel-execute:eshell): Execute Eshell code in Babel.
(org-babel-prep-session:eshell):
(ob-eshell-session-live-p):
(org-babel-eshell-initiate-session):
(org-babel-variable-assignments:eshell):
(org-babel-load-session:eshell):

* testing/test-ob-eshell.el: Write test for ob-eshell.

* doc/org-manual.org (Languages): Add Babel language eshell identity.

3 files changed, 201 insertions, 23 deletions

diff --git a/doc/org-manual.org b/doc/org-manual.org
index 27131c8..535aa9d 100644
--- a/doc/org-manual.org
+++ b/doc/org-manual.org
@@ -17600,29 +17600,29 @@ code block header arguments:
 Code blocks in the following languages are supported.
 
 #+attr_texinfo: :columns 0.20 0.35 0.20 0.20
-| Language   | Identifier    | Language      | Identifier   |
-|------------+---------------+---------------+--------------|
-| Asymptote  | =asymptote=   | Lua           | =lua=        |
-| Awk        | =awk=         | MATLAB        | =matlab=     |
-| C          | =C=           | Mscgen        | =mscgen=     |
-| C++        | =C++=[fn:139] | OCaml         | =ocaml=      |
-| Clojure    | =clojure=     | Octave        | =octave=     |
-| CSS        | =css=         | Org mode      | =org=        |
-| D          | =D=[fn:140]   | Oz            | =oz=         |
-| ditaa      | =ditaa=       | Perl          | =perl=       |
-| Emacs Calc | =calc=        | Plantuml      | =plantuml=   |
-| Emacs Lisp | =emacs-lisp=  | Processing.js | =processing= |
-| Fortran    | =fortran=     | Python        | =python=     |
-| Gnuplot    | =gnuplot=     | R             | =R=          |
-| GNU Screen | =screen=      | Ruby          | =ruby=       |
-| Graphviz   | =dot=         | Sass          | =sass=       |
-| Haskell    | =haskell=     | Scheme        | =scheme=     |
-| Java       | =java=        | Sed           | =sed=        |
-| Javascript | =js=          | shell         | =sh=         |
-| LaTeX      | =latex=       | SQL           | =sql=        |
-| Ledger     | =ledger=      | SQLite        | =sqlite=     |
-| Lilypond   | =lilypond=    | Vala          | =vala=       |
-| Lisp       | =lisp=        |               |              |
+| Language   | Identifier    | Language       | Identifier   |
+|------------+---------------+----------------+--------------|
+| Asymptote  | =asymptote=   | Lisp           | =lisp=       |
+| Awk        | =awk=         | Lua            | =lua=        |
+| C          | =C=           | MATLAB         | =matlab=     |
+| C++        | =C++=[fn:135] | Mscgen         | =mscgen=     |
+| Clojure    | =clojure=     | Objective Caml | =ocaml=      |
+| CSS        | =css=         | Octave         | =octave=     |
+| D          | =D=[fn:136]   | Org mode       | =org=        |
+| ditaa      | =ditaa=       | Oz             | =oz=         |
+| Emacs Calc | =calc=        | Perl           | =perl=       |
+| Emacs Lisp | =emacs-lisp=  | Plantuml       | =plantuml=   |
+| Eshell     | =eshell=      | Processing.js  | =processing= |
+| Fortran    | =fortran=     | Python         | =python=     |
+| Gnuplot    | =gnuplot=     | R              | =R=          |
+| GNU Screen | =screen=      | Ruby           | =ruby=       |
+| Graphviz   | =dot=         | Sass           | =sass=       |
+| Haskell    | =haskell=     | Scheme         | =scheme=     |
+| Java       | =java=        | Sed            | =sed=        |
+| Javascript | =js=          | shell          | =sh=         |
+| LaTeX      | =latex=       | SQL            | =sql=        |
+| Ledger     | =ledger=      | SQLite         | =sqlite=     |
+| Lilypond   | =lilypond=    | Vala           | =vala=       |
 
 Additional documentation for some languages is at
 https://orgmode.org/worg/org-contrib/babel/languages.html.
diff --git a/lisp/ob-eshell.el b/lisp/ob-eshell.el
new file mode 100644
index 0000000..45eb338
--- /dev/null
+++ b/lisp/ob-eshell.el
@@ -0,0 +1,105 @@
+;;; ob-eshell.el --- Babel Functions for Eshell      -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2018 Free Software Foundation, Inc.
+
+;; Author: stardiviner <numbchild@gmail.com>
+;; Keywords: literate programming, reproducible research
+;; Homepage: 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 Eshell source code.
+
+;;; Code:
+(require 'ob)
+(require 'eshell)
+
+(defvar org-babel-default-header-args:eshell '())
+
+(defun org-babel-execute:eshell (body params)
+  "Execute a block of Eshell code BODY with PARAMS.
+This function is called by `org-babel-execute-src-block'.
+
+The BODY can be any code which allowed executed in Eshell.
+Eshell allow to execute normal shell command and Elisp code.
+More details please reference Eshell Info.
+
+The PARAMS are variables assignments."
+  (let* ((session (org-babel-eshell-initiate-session
+		   (cdr (assq :session params))))
+	 (full-body (org-babel-expand-body:generic
+		     body params (org-babel-variable-assignments:eshell params))))
+    (if session
+	(progn
+	  (with-current-buffer session
+	    (dolist (line (split-string full-body "\n"))
+	      (goto-char eshell-last-output-end)
+	      (insert line)
+	      (eshell-send-input))
+	    ;; get output of last input
+	    ;; TODO: collect all output instead of last command's output.
+	    (goto-char eshell-last-input-end)
+	    (buffer-substring-no-properties (point) eshell-last-output-start)))
+      (with-temp-buffer
+	(eshell-command full-body t)
+	(buffer-string)))))
+
+(defun org-babel-prep-session:eshell (session params)
+  "Prepare SESSION according to the header arguments specified in PARAMS."
+  (let* ((session (org-babel-eshell-initiate-session session))
+	 ;; Eshell session buffer is read from variable `eshell-buffer-name'.
+	 (eshell-buffer-name session)
+	 (var-lines (org-babel-variable-assignments:eshell params)))
+    (call-interactively #'eshell)
+    (mapc #'eshell-command var-lines)
+    session))
+
+(defun ob-eshell-session-live-p (session)
+  "Non-nil if Eshell SESSION exists."
+  (get-buffer session))
+
+(defun org-babel-eshell-initiate-session (&optional session params)
+  "Initiate a session named SESSION according to PARAMS."
+  (when (and session (not (string= session "none")))
+    (save-window-excursion
+      (or (ob-eshell-session-live-p session)
+	  (progn
+	    (let ((eshell-buffer-name session))
+	      (eshell))
+	    (get-buffer (current-buffer)))))
+    session))
+
+(defun org-babel-variable-assignments:eshell (params)
+  "Convert ob-eshell :var specified variables into Eshell variables assignments."
+  (mapcar
+   (lambda (pair)
+     (format "(setq %s %S)" (car pair) (cdr pair)))
+   (org-babel--get-vars params)))
+
+(defun org-babel-load-session:eshell (session body params)
+  "Load BODY into SESSION with PARAMS."
+  (save-window-excursion
+    (let ((buffer (org-babel-prep-session:eshell session params)))
+      (with-current-buffer buffer
+	(goto-char (point-max))
+	(insert (org-babel-chomp body)))
+      buffer)))
+
+(provide 'ob-eshell)
+
+;;; ob-eshell.el ends here
diff --git a/testing/lisp/test-ob-eshell.el b/testing/lisp/test-ob-eshell.el
new file mode 100644
index 0000000..5b0eb27
--- /dev/null
+++ b/testing/lisp/test-ob-eshell.el
@@ -0,0 +1,73 @@
+;;; test-ob-eshell.el
+
+;; Copyright (c) 2018 stardiviner
+;; Authors: stardiviner
+
+;; This file is not part of GNU Emacs.
+
+;; This program 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.
+
+;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Comment:
+
+;; Template test file for Org tests
+
+;;; Code:
+(unless (featurep 'ob-eshell)
+  (signal 'missing-test-dependency "Support for Eshell code blocks"))
+
+(ert-deftest ob-eshell/execute ()
+  "Test ob-eshell execute."
+  (should
+   (string=
+    (org-test-with-temp-text
+	"#+begin_src eshell
+echo 2
+#+end_src"
+      (org-babel-execute-src-block))
+    ": 2")))
+
+(ert-deftest ob-eshell/variables-assignment ()
+  "Test ob-eshell variables assignment."
+  (should
+   (string=
+    (org-test-with-temp-text
+	"#+begin_src eshell :var hi=\"hello, world\"
+echo $hi
+#+end_src"
+      (org-babel-execute-src-block))
+    ": hello, world")))
+
+(ert-deftest ob-eshell/session ()
+  "Test ob-eshell session."
+  (should
+   (string=
+    (org-test-with-temp-text
+	"#+begin_src eshell :session
+(setq hi \"hello, world\")
+#+end_src
+
+#+begin_src eshell :session
+echo $hi
+#+end_src"
+      (org-babel-execute-src-block)
+      (org-babel-next-src-block)
+      (org-babel-execute-src-block)
+      (goto-char (org-babel-where-is-src-block-result))
+      (forward-line)
+      (buffer-substring-no-properties (point) (line-end-position)))
+    ": hello, world")))
+
+(provide 'test-ob-eshell)
+
+;;; test-ob-eshell.el ends here