From 5452c53e9b336565fe2a1c7fa59d38edc43e0c9f Mon Sep 17 00:00:00 2001
From: Guillaume MM <gm@lyx.org>
Date: Fri, 5 May 2017 23:48:20 +0200
Subject: [PATCH] algorithm2e.module: Add Algorithm style to typeset algorithms

Do not output \begin and \end if there is not environment name. We only need the
nesting feature.
---
 lib/layouts/algorithm2e.module | 14 +++++++++++++-
 src/output_latex.cpp           |  8 ++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/lib/layouts/algorithm2e.module b/lib/layouts/algorithm2e.module
index 94298175da..2a795ced8a 100644
--- a/lib/layouts/algorithm2e.module
+++ b/lib/layouts/algorithm2e.module
@@ -1,7 +1,8 @@
 #\DeclareLyXModule[algorithm2e.sty]{Algorithm2e}
 #DescriptionBegin
 # Use the algorithm2e package for algorithm floats rather
-# than LyX's home-brewed algorithm floats.
+# than LyX's home-brewed algorithm floats. Use the Algorithm
+# style to enter and indent the algorithm.
 #DescriptionEnd
 #
 #Author: Jürgen Spitzmüller
@@ -26,3 +27,14 @@ Float
 	RefPrefix             alg
 End
 
+Style Algorithm
+  Category              List
+  Margin                Static
+  LatexType             Environment
+  NextNoIndent          1
+  ParbreakIsNewline     1
+  ToggleIndent          Never
+  KeepEmpty             1
+  LeftMargin            MM
+  Align                 Left
+End
diff --git a/src/output_latex.cpp b/src/output_latex.cpp
index 7db9e7c52b..c8a6bc4ee9 100644
--- a/src/output_latex.cpp
+++ b/src/output_latex.cpp
@@ -258,8 +258,10 @@ static TeXEnvironmentData prepareEnvironment(Buffer const & buf,
 		data.leftindent_open = true;
 	}
 
-	if (style.isEnvironment()) {
+	if (style.isEnvironment())
 		state->nest_level_ += 1;
+
+	if (style.isEnvironment() && !style.latexname().empty()) {
 		os << "\\begin{" << from_ascii(style.latexname()) << '}';
 		if (!style.latexargs().empty()) {
 			OutputParams rp = runparams;
@@ -324,7 +326,9 @@ static void finishEnvironment(otexstream & os, OutputParams const & runparams,
 			}
 		}
 		state->nest_level_ -= 1;
-		os << "\\end{" << from_ascii(data.style->latexname()) << "}\n";
+		string const & name = data.style->latexname();
+		if (!name.empty())
+			os << "\\end{" << from_ascii(name) << "}\n";
 		state->prev_env_language_ = data.par_language;
 		if (runparams.encoding != data.prev_encoding) {
 			runparams.encoding = data.prev_encoding;
-- 
2.39.2