1 files changed, 91 insertions, 0 deletions
diff --git a/mk/build.mk b/mk/build.mk
new file mode 100644
index 0000000..40b2b9e
--- /dev/null
+++ b/mk/build.mk
@@ -0,0 +1,91 @@
+O := build
+src := $(abspath .)
+
+obj = $(O)/$(rule_top)/$(rule_target)-$(build_id)
+build_id = $(call per_target,build_id)
+
+build_vars = $(foreach var,$(1),$(call add_build_var,$(var))$(newline))
+add_build_var = \
+  $(call target_var,build_id_text) += $$(let val,$$($(1)),$$(if $$(val),$(1)="$$(strip $$(val))"))
+
+build_makefiles := $(wildcard mk/*.mk)
+$(build_makefiles):
+
+build_makefiles += Makefile
+build_stack :=
+
+define enter_build
+  build_stack += $$(rule_target);$$(rule_top)
+
+  rule_top := $(1)
+  rule_target := $(if $(2),$(2),$(target))
+  $$(call target_var,build_id_text) =
+endef
+
+define exit_build
+  last_build := $$(lastword $$(build_stack))
+  build_stack := $$(filter-out $$(last_build),$$(build_stack))
+  last_build := $$(subst ;,$(space),$$(last_build))
+
+  rule_top := $$(lastword $$(last_build))
+  rule_target := $$(firstword $$(last_build))
+endef
+
+define setup_obj
+  export build_id_text := $$(strip $$(call per_target,build_id_text))
+  $$(call target_var,build_id) := $$(shell echo -n "$$$$build_id_text" | sha1sum | head -c8)
+  unexport build_id_text
+
+  $$(obj): export CONTENTS := $$(build_id_text)
+  $$(obj):
+	@mkdir -p $$@ && echo -n "$$$$CONTENTS" >$$@/build-vars
+endef
+
+define find_command_lazy
+  $(2)_cmdline := $$($(2))
+  override $(call defer,$(2),$$(call find_command,$(1),$(2)))
+endef
+
+define find_command
+  override $(2) := $$($(2)_cmdline)
+  ifeq (,$$($(2)))
+    override $(2) := $(1)
+  endif
+
+  which_out := $$(shell which $$($(2)) 2>/dev/null)
+
+  ifneq (0,$$(.SHELLSTATUS))
+    which_out :=
+  endif
+
+  ifeq (,$$(which_out))
+    $$(error $(1) ($$($2)) not found)
+  endif
+endef
+
+shell_defer = $(call defer,$(1),$(1) := $$(call shell_checked,$(2)))
+shell_checked = $(shell $(1))$(if $(filter-out 0,$(.SHELLSTATUS)),$(error Command failed: $(1)))
+
+define find_with_pkgconfig
+  pkgs := $(strip $(1))
+
+  ifneq (,$$(pkgs))
+    ifeq (undefined,$$(origin pkgconfig_cflags/$$(pkgs)))
+      $$(eval $$(run_pkgconfig))
+    endif
+
+    $(2) += $$(pkgconfig_cflags/$$(pkgs))
+    $(3) += $$(pkgconfig_libs/$$(pkgs))
+  endif
+endef
+
+define run_pkgconfig
+  pkgconfig_cflags/$$(pkgs) := $$(shell $$(PKG_CONFIG) --cflags $$(pkgs))
+  ifeq (0,$$(.SHELLSTATUS))
+    pkgconfig_libs/$$(pkgs) := $$(shell $$(PKG_CONFIG) --libs $$(pkgs))
+  endif
+
+  ifneq (0,$$(.SHELLSTATUS))
+    $$(error pkg-config failed for package list: $$(pkgs))
+  endif
+endef