let the makefile choose the correct sed

Author: Muri Nicanor

doc/Makefile

@@ -1,4 +1,5 @@
 SRCDIR = ../src
+SED:=$(shell command -v sed || gsed)
 
 all: doxygen
 
@@ -52,10 +53,10 @@ clean:
 # create Doxygen documentation
 doxygen: create_output create_links
 	doxygen
-	gsed -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberFloatType, AllocatorType >@@g' html/*.html
-	gsed -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberFloatType, AllocatorType >@@g' html/*.html
-	gsed -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType >@@g' html/*.html
-	gsed -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType >@@g' html/*.html
+	$(SED) -i 's@&lt; ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberFloatType, AllocatorType &gt;@@g' html/*.html
+	$(SED) -i 's@&lt;&#160;ObjectType,&#160;ArrayType,&#160;StringType,&#160;BooleanType,&#160;NumberIntegerType,&#160;NumberFloatType,&#160;AllocatorType&#160;&gt;@@g' html/*.html
+	$(SED) -i 's@&lt; ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType &gt;@@g' html/*.html
+	$(SED) -i 's@< ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberUnsignedType, NumberFloatType, AllocatorType >@@g' html/*.html
 
 upload: clean doxygen check_output
 	cd html ; ../scripts/git-update-ghpages nlohmann/json
@@ -70,14 +71,14 @@ upload: clean doxygen check_output
 # create docset for Dash
 docset: create_output
 	cp Doxyfile Doxyfile_docset
-	gsed -i 's/DISABLE_INDEX          = NO/DISABLE_INDEX          = YES/' Doxyfile_docset
-	gsed -i 's/SEARCHENGINE           = YES/SEARCHENGINE           = NO/' Doxyfile_docset
-	gsed -i 's@HTML_EXTRA_STYLESHEET  = css/mylayout.css@HTML_EXTRA_STYLESHEET  = css/mylayout_docset.css@' Doxyfile_docset
+	$(SED) -i 's/DISABLE_INDEX          = NO/DISABLE_INDEX          = YES/' Doxyfile_docset
+	$(SED) -i 's/SEARCHENGINE           = YES/SEARCHENGINE           = NO/' Doxyfile_docset
+	$(SED) -i 's@HTML_EXTRA_STYLESHEET  = css/mylayout.css@HTML_EXTRA_STYLESHEET  = css/mylayout_docset.css@' Doxyfile_docset
 	rm -fr html *.docset
 	doxygen Doxyfile_docset
-	gsed -i 's@&lt; ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberFloatType, AllocatorType &gt;@@g' html/*.html
-	gsed -i 's@&lt;&#160;ObjectType,&#160;ArrayType,&#160;StringType,&#160;BooleanType,&#160;NumberIntegerType,&#160;NumberFloatType,&#160;AllocatorType&#160;&gt;@@g' html/*.html
+	$(SED) -i 's@&lt; ObjectType, ArrayType, StringType, BooleanType, NumberIntegerType, NumberFloatType, AllocatorType &gt;@@g' html/*.html
+	$(SED) -i 's@&lt;&#160;ObjectType,&#160;ArrayType,&#160;StringType,&#160;BooleanType,&#160;NumberIntegerType,&#160;NumberFloatType,&#160;AllocatorType&#160;&gt;@@g' html/*.html
 	make -C html
 	mv html/*.docset .
-	gsed -i 's@<string>doxygen</string>@<string>json</string>@' me.nlohmann.json.docset/Contents/Info.plist
+	$(SED) -i 's@<string>doxygen</string>@<string>json</string>@' me.nlohmann.json.docset/Contents/Info.plist
 	rm -fr Doxyfile_docset html