Makefile and docs: add EXCLUDE_PKGS and show*deps* functionality

1 files changed, 60 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index f68e790..daf2b69 100644
--- a/Makefile
+++ b/Makefile
@@ -99,7 +99,7 @@ else
 endif
 
 .PHONY: all
-all: $(PKGS)
+all: all-filtered
 
 .PHONY: check-requirements
 define CHECK_REQUIREMENT
@@ -261,6 +261,65 @@ $(foreach TARGET,$(MXE_TARGETS), \
     $(foreach PKG,$(PKGS), \
         $(eval $(call PKG_RULE,$(PKG),$(call TMP_DIR,$(PKG)),$(TARGET)))))
 
+# convenience set-like functions for unique lists
+SET_APPEND = \
+    $(eval $(1) := $(sort $($(1)) $(2)))
+
+SET_CLEAR = \
+    $(eval $(1) := )
+
+# WALK functions accept a list of pkgs and/or wildcards
+WALK_UPSTREAM = \
+    $(strip \
+        $(foreach PKG,$(filter $(1),$(PKGS)),\
+            $(foreach DEP,$($(PKG)_DEPS) $(foreach TARGET,$(MXE_TARGETS),$($(PKG)_DEPS_$(TARGET))),\
+                $(if $(filter-out $(PKGS_VISITED),$(DEP)),\
+                    $(call SET_APPEND,PKGS_VISITED,$(DEP))\
+                    $(call WALK_UPSTREAM,$(DEP))\
+                    $(DEP)))))
+
+# not really walking downstream - that seems to be quadratic, so take
+# a linear approach and filter the fully expanded upstream for each pkg
+WALK_DOWNSTREAM = \
+    $(strip \
+        $(foreach PKG,$(PKGS),\
+            $(call SET_CLEAR,PKGS_VISITED)\
+            $(eval $(PKG)_DEPS_ALL := $(call WALK_UPSTREAM,$(PKG))))\
+        $(foreach PKG,$(PKGS),\
+            $(if $(filter $(1),$($(PKG)_DEPS_ALL)),$(PKG))))
+
+# EXCLUDE_PKGS can be a list of pkgs and/or wildcards
+RECURSIVELY_EXCLUDED_PKGS = \
+    $(sort \
+        $(filter $(EXCLUDE_PKGS),$(PKGS))\
+        $(call SET_CLEAR,PKGS_VISITED)\
+        $(call WALK_DOWNSTREAM,$(EXCLUDE_PKGS)))
+
+.PHONY: all-filtered
+all-filtered: $(filter-out $(call RECURSIVELY_EXCLUDED_PKGS),$(PKGS))
+
+# print a list of upstream dependencies and downstream dependents
+show-deps-%:
+	$(call SET_CLEAR,PKGS_VISITED)
+	$(info $* upstream dependencies:$(newline)\
+	    $(call WALK_UPSTREAM,$*)\
+	    $(newline)$(newline)$* downstream dependents:$(newline)\
+	    $(call WALK_DOWNSTREAM,$*))
+	@echo
+
+# show upstream dependencies and downstream dependents separately
+# suitable for usage in shell with: `make show-downstream-deps-foo`
+# @echo -n suppresses the "Nothing to be done" without an eol
+show-downstream-deps-%:
+	$(call SET_CLEAR,PKGS_VISITED)
+	$(info $(call WALK_DOWNSTREAM,$*))
+	@echo -n
+
+show-upstream-deps-%:
+	$(call SET_CLEAR,PKGS_VISITED)\
+	$(info $(call WALK_UPSTREAM,$*))
+	@echo -n
+
 .PHONY: clean
 clean:
 	rm -rf $(call TMP_DIR,*) $(PREFIX)/*