Provide wrapped version of diff3

Issue: #78

simple-shell/diff3-1.success

@@ -0,0 +1,5 @@
+====3
+1:0a
+2:0a
+3:1c
+  a

simple-shell/diff3-2-stdin1.success

@@ -0,0 +1,7 @@
+====
+1:1,2c
+  a
+  b
+2:0a
+3:1c
+  b

simple-shell/diff3-2-stdin2.success

@@ -0,0 +1,6 @@
+====2
+1:1c
+3:1c
+  b
+2:1c
+  a

simple-shell/diff3-2.success

@@ -0,0 +1,6 @@
+====2
+1:1c
+3:1c
+  b
+2:1c
+  a

simple-shell/diff3-3.success

@@ -0,0 +1,8 @@
+====
+1:1,2c
+  a
+  c
+2:1c
+  b
+3:1c
+  c

unix-tools/.gitignore

@@ -3,6 +3,7 @@ cat
 cmp
 coreutils/*
 diff
+diff3
 etc/*
 gawk/*
 gnulib/*

unix-tools/Makefile

@@ -90,7 +90,7 @@ make:
 	$(MAKE) -C coreutils
 	$(MAKE) -C grep
 
-build-install: cat cmp diff tee make
+build-install: cat cmp diff diff3 tee make
 	mkdir -p ../build/libexec/dgsh ../build/bin
 	cp bash/bash ../build/libexec/dgsh/
 	rm -f ../build/bin/dgsh
@@ -103,11 +103,11 @@ build-install: cat cmp diff tee make
 	cp grep/src/grep ../build/libexec/dgsh/
 	cp grep/src/egrep ../build/libexec/dgsh/
 	cp grep/src/fgrep ../build/libexec/dgsh/
-	chmod 755 cat cmp diff tee
-	cp -p cat cmp diff tee ../build/libexec/dgsh/
+	chmod 755 cat cmp diff diff3 tee
+	cp -p cat cmp diff diff3 tee ../build/libexec/dgsh/
 	./install-wrapped.sh $$(cd .. ; pwd)/build
 
-install: cat cmp diff tee make
+install: cat cmp diff diff3 tee make
 	$(MAKE) -C bash install
 	rm -f $(DESTDIR)$(PREFIX)/bin/dgsh
 	ln $(DESTDIR)$(DGSHPATH)/bash $(DESTDIR)$(PREFIX)/bin/dgsh || install $(DESTDIR)$(DGSHPATH)/bash $(DESTDIR)$(PREFIX)/bin/dgsh
@@ -117,6 +117,7 @@ install: cat cmp diff tee make
 	install cat $(DESTDIR)$(DGSHPATH)
 	install cmp $(DESTDIR)$(DGSHPATH)
 	install diff $(DESTDIR)$(DGSHPATH)
+	install diff3 $(DESTDIR)$(DGSHPATH)
 	install tee $(DESTDIR)$(DGSHPATH)
 	./install-wrapped.sh
 	rm -rf $(DESTDIR)$(MANDUMPDIR)
@@ -130,6 +131,9 @@ cmp: cmp.sh
 diff: diff.sh
 	install $? $@
 
+diff3: diff3.sh
+	install $? $@
+
 tee: tee.sh
 	install $? $@
 

unix-tools/diff3.sh

@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+#!dgsh
+#
+# Dgsh-compatible wrapping of the GNU diff3 command
+# Depending on the arguments, the command can accept 0-3 inputs
+#
+
+
+# For the parsing of long options see
+# https://stackoverflow.com/questions/402377/using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options/7680682#7680682
+optspec=":AeE3xXimaTL:v-:"
+while getopts "$optspec" optchar; do
+  case "${optchar}" in
+    -)
+      case "${OPTARG}" in
+	# Long options with mandatory arguments. In these the argument
+	# can appear separated from the option name, and must be removed.
+	diff-program|label)
+	  OPTIND=$(($OPTIND + 1))
+	  ;;
+      esac
+      ;;
+  esac
+done
+
+# Examine the number of remaining (non-option) arguments
+case $(($# - $OPTIND + 1)) in
+  0)
+    # Exactly three inputs are required
+    exec dgsh-wrap /usr/bin/diff3 "$@" '<|' '<|' '<|'
+    ;;
+  1)
+    if [[ "${!OPTIND}" = '-' ]] ; then
+      # Two inputs (excluding stdin) are required
+      exec dgsh-wrap -I /usr/bin/diff3 "$@" '<|' '<|'
+    else
+      # Two inputs (including stdin) are required
+      exec dgsh-wrap /usr/bin/diff3 "$@" '<|' '<|'
+    fi
+    ;;
+  2)
+    ARG2=$((OPTIND + 1))
+    if [[ "${!OPTIND}" = '-' ]] || [[ "${!ARG2}" = '-' ]] ; then
+      # One (non-stdin) input is required
+      exec dgsh-wrap -I /usr/bin/diff3 "$@" '<|'
+    else
+      # One (stdin) input is required
+      exec dgsh-wrap /usr/bin/diff3 "$@" -
+    fi
+    ;;
+  *)
+    ARG2=$((OPTIND + 1))
+    ARG3=$((OPTIND + 2))
+    if [[ "${!OPTIND}" = '-' ]] || [[ "${!ARG2}" = '-' ]] || [[ "${!ARG3}" = '-' ]] ; then
+      # One (stdin) input is required
+      exec dgsh-wrap /usr/bin/diff3 "$@"
+    else
+      # No input is required
+      exec dgsh-wrap -i 0 /usr/bin/diff3 "$@"
+    fi
+    ;;
+esac

unix-tools/run_all_simple_tests.sh

@@ -170,3 +170,11 @@ there" |
 ./run_simple_test.sh $PSDIR cmp1-same1 'echo -n | cmp - /dev/null'
 ./run_simple_test.sh $PSDIR cmp1-same2 'echo -n | cmp /dev/null -'
 ./run_simple_test.sh $PSDIR cmp0 'cmp /dev/null /dev/null'
+
+# Wrapped diff3
+./run_simple_test.sh $PSDIR diff3-3 '{{ echo a ; echo b ; echo c; }} | diff3'
+./run_simple_test.sh $PSDIR diff3-2 '{{ echo a ; echo b ; }} | diff3 /dev/null'
+./run_simple_test.sh $PSDIR diff3-2-stdin1 '{{ echo a ; echo b ; }} | diff3 - /dev/null'
+./run_simple_test.sh $PSDIR diff3-2-stdin2 '{{ echo a ; echo b ; }} | diff3 /dev/null -'
+./run_simple_test.sh $PSDIR diff3-1 '{{ echo a ; }} | diff3 /dev/null /dev/null'
+./run_simple_test.sh $PSDIR diff3-0 'diff3 /dev/null /dev/null /dev/null'

web/index.html

@@ -277,6 +277,12 @@ <h2>Adapted tools</h2>
 		<td>1</td>
 		<td>Typically two inputs. Compare an arbitrary number of input streams with the <code>--from-file</code> or <code>--to-file</code> options</td>
 	</tr>
+	<tr>
+		<td>diff3</td>
+		<td>0&mdash;3</td>
+		<td>1</td>
+		<td></td>
+	</tr>
 	<tr>
 		<td>grep</td>
 		<td>0&mdash;2</td>