doc: an introductory example for C++

Suggested by Victor Khomenko.
http://lists.gnu.org/archive/html/bug-bison/2018-08/msg00037.html

* doc/bison.texi (A Simple C++ Example): New.
* examples/c++/local.mk, examples/c++/simple.test: New.
Extract, check, and install this new example.
* examples/local.mk: Adjust.
* examples/test: Adjust to the case where the dirname differs
from the test name.

examples/c++/local.mk

@@ -0,0 +1,45 @@
+## Copyright (C) 2018 Free Software Foundation, Inc.
+##
+## 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/>.
+
+## -------------------- ##
+## Building & testing.  ##
+## -------------------- ##
+
+BUILT_SOURCES += $(simple_sources)
+CLEANFILES +=  %D%/simple.[ch] %D%/simple.output
+CLEANDIRS += %D%/*.dSYM
+
+simple_extracted = %D%/simple.yy
+simple_sources = $(simple_extracted)
+extracted += $(simple_extracted)
+
+if ENABLE_CXX14
+  check_PROGRAMS += %D%/simple
+  nodist_%C%_simple_SOURCES = $(simple_sources)
+
+  %C%_simple_CXXFLAGS = $(CXX11_CXXFLAGS)
+  # Don't use gnulib's system headers.
+  %C%_simple_CPPFLAGS = -I$(top_builddir)
+  dist_TESTS += %D%/simple.test
+  %D%/simple.cc: $(BISON_IN) $(dist_pkgdata_DATA)
+endif
+
+
+## ------------ ##
+## Installing.  ##
+## ------------ ##
+
+cxxdir = $(docdir)/examples/c++
+cxx_DATA = $(simple_extracted)

examples/c++/simple.test

@@ -0,0 +1,4 @@
+#! /bin/sh
+
+: >input
+run 0 "{I have three numbers for you., 1, 2, 3, And that's all!}"

examples/calc++/local.mk

@@ -69,6 +69,7 @@ check_PROGRAMS += %D%/calc++
 nodist_%C%_calc___SOURCES =                     \
   $(calcxx_sources)
 
+# Don't use gnulib's system headers.
 %C%_calc___CPPFLAGS = -I$(top_builddir)/%D%
 %C%_calc___CXXFLAGS = $(AM_CXXFLAGS) $(FLEX_SCANNER_CXXFLAGS)
 dist_TESTS += %D%/calc++.test

examples/local.mk

@@ -69,5 +69,6 @@ CLEANFILES += %D%/variant.output %D%/variant-11.output
 CLEANDIRS += %D%/*.dSYM
 
 include %D%/calc++/local.mk
+include %D%/c++/local.mk
 include %D%/mfcalc/local.mk
 include %D%/rpcalc/local.mk

examples/mfcalc/local.mk

@@ -28,6 +28,7 @@ extracted += $(mfcalc_extracted)
 
 check_PROGRAMS += %D%/mfcalc
 nodist_%C%_mfcalc_SOURCES = $(mfcalc_sources)
+# Don't use gnulib's system headers.
 %C%_mfcalc_CPPFLAGS = -I$(top_builddir)/%D%
 %C%_mfcalc_LDADD = -lm
 

examples/rpcalc/local.mk

@@ -28,6 +28,7 @@ extracted += $(rpcalc_extracted)
 
 check_PROGRAMS += %D%/rpcalc
 nodist_%C%_rpcalc_SOURCES = $(rpcalc_sources)
+# Don't use gnulib's system headers.
 %C%_rpcalc_CPPFLAGS = -I$(top_builddir)/%D%
 %C%_rpcalc_LDADD = -lm
 

examples/test

@@ -15,7 +15,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-me=`basename $1 .test`
+me=$(basename "$1" .test)
+medir=$(basename "$(dirname "$1")")
 
 # Number of the current test.
 number=1
@@ -27,7 +28,7 @@ exit=true
 cwd=`pwd`
 
 # The exercised program.
-for p in $cwd/examples/$me/$me $cwd/examples/$me
+for p in "$cwd/examples/$medir/$me" "$cwd/examples/$me"
 do
     if test -x "$p"; then
         prog=$p