1 files changed, 106 insertions, 0 deletions
diff --git a/subx/build b/subx/build
new file mode 100755
index 00000000..f5ea62c3
--- /dev/null
+++ b/subx/build
@@ -0,0 +1,106 @@
+#!/bin/sh
+# returns 0 on successful build or nothing to build
+# non-zero exit status only on error during building
+set -e  # stop immediately on error
+
+# [0-9]*.cc -> subx.cc -> subx
+# (layers)   |          |
+#          tangle      $CXX
+
+# can also be called with a layer to only build until
+#   $ ./build --until 050
+UNTIL_LAYER=${2:-zzz}
+
+# there's two mechanisms for fast builds here:
+# - if a command is quick to run, always run it but update the result only on any change
+# - otherwise run it only if the output is 'older_than' the inputs
+#
+# avoid combining both mechanisms for a single file
+# otherwise you'll see spurious messages about files being updated
+# risk: a file may unnecessarily update without changes, causing unnecessary work downstream
+
+test "$CXX" || export CXX=c++
+test "$CC" || export CC=cc
+test "$CFLAGS" || export CFLAGS="-g -O3"
+export CFLAGS="$CFLAGS -Wall -Wextra -ftrapv -fno-strict-aliasing"
+
+# return 1 if $1 is older than _any_ of the remaining args
+older_than() {
+  local target=$1
+  shift
+  if [ ! -e $target ]
+  then
+#?     echo "$target doesn't exist"
+    echo "updating $target" >&2
+    return 0  # success
+  fi
+  local f
+  for f in $*
+  do
+    if [ $f -nt $target ]
+    then
+      echo "updating $target" >&2
+      return 0  # success
+    fi
+  done
+  return 1  # failure
+}
+
+# redirect to $1, unless it's already identical
+update() {
+  if [ ! -e $1 ]
+  then
+    cat > $1
+  else
+    cat > $1.tmp
+    diff -q $1 $1.tmp >/dev/null  &&  rm $1.tmp  ||  mv $1.tmp $1
+  fi
+}
+
+update_cp() {
+  if [ ! -e $2/$1 ]
+  then
+    cp $1 $2
+  elif [ $1 -nt $2/$1 ]
+  then
+    cp $1 $2
+  fi
+}
+
+noisy_cd() {
+  cd $1
+  echo "-- `pwd`" >&2
+}
+
+older_than ../enumerate/enumerate ../enumerate/enumerate.cc && {
+  $CXX $CFLAGS ../enumerate/enumerate.cc -o ../enumerate/enumerate
+}
+
+older_than ../tangle/tangle ../tangle/*.cc && {
+  noisy_cd ../tangle
+    {
+      grep -h "^struct .* {" [0-9]*.cc  |sed 's/\(struct *[^ ]*\).*/\1;/'
+      grep -h "^typedef " [0-9]*.cc
+    }  |update type_list
+    grep -h "^[^ #].*) {" [0-9]*.cc  |sed 's/ {.*/;/'  |update function_list
+    ls [0-9]*.cc  |grep -v "\.test\.cc$"  |sed 's/.*/#include "&"/'  |update file_list
+    ls [0-9]*.test.cc  |sed 's/.*/#include "&"/'  |update test_file_list
+    grep -h "^[[:space:]]*void test_" [0-9]*.cc  |sed 's/^\s*void \(.*\)() {$/\1,/'  |update test_list
+    $CXX $CFLAGS boot.cc -o tangle
+  noisy_cd ../subx  # no effect; just to show us returning to the parent directory
+}
+
+LAYERS=$(../enumerate/enumerate --until $UNTIL_LAYER  |grep '.cc$')
+older_than subx.cc $LAYERS ../enumerate/enumerate ../tangle/tangle && {
+  # no update here; rely on 'update' calls downstream
+  ../tangle/tangle $LAYERS  > subx.cc
+}
+
+grep -h "^[^[:space:]#].*) {$" subx.cc  |grep -v ":.*("  |sed 's/ {.*/;/'  |update function_list
+grep -h "^\s*void test_" subx.cc  |sed 's/^\s*void \(.*\)() {.*/\1,/'  |update test_list
+
+older_than subx subx.cc *_list && {
+  $CXX $CFLAGS subx.cc -o subx
+}
+
+exit 0