Add makefile rules for regenerating from a local xdrgen (#221)

* Add makefile rules for regenerating from a local xdrgen

* Run bundle install in deployment mode so that gems are installed in the working directory as a cheap hack to reuse them across runs

Co-authored-by: Leigh McCulloch <351529+leighmcculloch@users.noreply.github.com>

Makefile

@@ -31,23 +31,37 @@ generate: src/curr/generated.rs xdr/curr-version src/next/generated.rs xdr/next-
 
 src/curr/generated.rs: $(sort $(wildcard xdr/curr/*.x))
 	> $@
+ifeq ($(LOCAL_XDRGEN),)
 	docker run -i --rm -v $$PWD:/wd -w /wd docker.io/library/ruby:latest /bin/bash -c '\
 		gem install specific_install -v 0.3.7 && \
 		gem specific_install https://github.com/stellar/xdrgen.git -b $(XDRGEN_VERSION) && \
 		xdrgen --language rust --namespace generated --output src/curr $^ \
 		'
+else
+	docker run -i --rm -v $$PWD/../xdrgen:/xdrgen -v $$PWD:/wd -w /wd docker.io/library/ruby:latest /bin/bash -c '\
+		pushd /xdrgen && bundle install --deployment && rake install && popd && \
+		xdrgen --language rust --namespace generated --output src/curr $^ \
+		'
+endif
 	rustfmt $@
 
 xdr/curr-version: $(wildcard .git/modules/xdr/curr/**/*) $(wildcard xdr/curr/*.x)
 	git submodule status -- xdr/curr | sed 's/^ *//g' | cut -f 1 -d " " | tr -d '\n' > xdr/curr-version
 
 src/next/generated.rs: $(sort $(wildcard xdr/next/*.x))
 	> $@
+ifeq ($(LOCAL_XDRGEN),)
 	docker run -i --rm -v $$PWD:/wd -w /wd docker.io/library/ruby:latest /bin/bash -c '\
 		gem install specific_install -v 0.3.7 && \
 		gem specific_install https://github.com/stellar/xdrgen.git -b $(XDRGEN_VERSION) && \
 		xdrgen --language rust --namespace generated --output src/next $^ \
 		'
+else
+	docker run -i --rm -v $$PWD/../xdrgen:/xdrgen -v $$PWD:/wd -w /wd docker.io/library/ruby:latest /bin/bash -c '\
+		pushd /xdrgen && bundle install --deployment && rake install && popd && \
+		xdrgen --language rust --namespace generated --output src/next $^ \
+		'
+endif
 	rustfmt $@
 
 xdr/next-version: $(wildcard .git/modules/xdr/next/**/*) $(wildcard xdr/next/*.x)