DESTDIR ?=
JAR_DIR ?= /usr/share/java

FAIL    = exit 1
FIND    = find
INSTALL = install
JAR     = jar
JAVAC   = javac
MKDIRS  = mkdir -p
RM      = rm -f
TOUCH   = touch

dep_dir = $1 $(shell $(FIND) $1 2>/dev/null)

all: PHONY java_cup.jar

java_cup.jar: classes
	$(JAR) cfe $@ java_cup.Main -C $< .
	$(TOUCH) $<

classes: . $(wildcard *.java) $(call dep_dir,runtime simple_calc)
	$(RM) -r $@
	$(MKDIRS) $@
	$(JAVAC) -d $@ $(filter %.java,$^) || { $(RM) -r $@; $(FAIL); }
	$(TOUCH) $@
	$(TOUCH) .

install: PHONY $(DESTDIR)$(JAR_DIR)/java_cup.jar

$(DESTDIR)$(JAR_DIR)/%.jar: %.jar
	$(INSTALL) -Dm644 $< $@

clean: PHONY
	$(RM) -r -- build *.jar

.PHONY: PHONY
.DELETE_ON_ERROR:
.SECONDARY: