ham rules to generate Protoc C++

_build.ham

# ProtocToCpp TARGET : input.proto ;
rule ProtocToCpp {
  local genDir = _pb ;
  local input = [ FGristFiles $(2) ] ;
  local cpp = [ FGristFiles [ FDirName $(input:D) $(genDir) $(input:B).pb.cc ] ] ;
  local h = [ FGristFiles [ FDirName $(input:D) $(genDir) $(input:B).pb.h ] ] ;
  local outDir = [ FGetAbsolutePath [ FDirName $(input:D) $(genDir) ] ]  ;
  ProtocRun_ $(cpp) $(h) : $(input) : $(genDir) : $(outDir) ;
  DEPENDS protoc-to-cpp : $(cpp) $(h) ;
  NOTFILE protoc-to-cpp ;
  return [ FDirName $(genDir) $(input:BS=.pb.cc) ] ;
}

# ProtocToRun_ OUTPUTS : INPUT : GEN_DIR : OUT_DIR ;
rule ProtocRun_ {
  DEPENDS $(<) : $(>) ;
  INPUT_PROTO on $(<) = $(2) ;
  GEN_DIR on $(<) = $(3) ;
  OUT_DIR on $(<) = $(4) ;
  return $(1) ;
}
actions ProtocRun_ {
  . "$HAM_HOME/bin/ham-bash-lib.sh"
  mkdir -p "$(OUT_DIR)"
  cd "$(INPUT_PROTO:D)"
  protoc --cpp_out="$(OUT_DIR)" "$(INPUT_PROTO:BS)"

  # Prepend clang-format off & remove trailing whitespace
  echo "// clang-format off" > "_tmp_trimmed.cc"
  sed -E 's/[[:space:]]*$//' "$(OUT_DIR)/$(INPUT_PROTO:BS=).pb.cc" >> "_tmp_trimmed.cc"
  mv "_tmp_trimmed.cc" "$(OUT_DIR)/$(INPUT_PROTO:BS=).pb.cc"

  # Prepend clang-format off & remove trailing whitespace
  echo "// clang-format off" > "_tmp_trimmed.h"
  sed -E 's/[[:space:]]*$//' "$(OUT_DIR)/$(INPUT_PROTO:BS=).pb.h" >> "_tmp_trimmed.h"
  mv "_tmp_trimmed.h" "$(OUT_DIR)/$(INPUT_PROTO:BS=).pb.h"
}