#!/bin/sh
# Alternative to build1 that tries to avoid redoing redundant work.
# Also splits compilation into multiple .cc files (see 'cleave' below).
# Faster than build1 for recompiling after small changes.
#
# For details on the basic form of this script, see https://notabug.org/akkartik/basic-build.

set -e  # stop immediately on error

# Some environment variables that can be passed in. For example, to turn off
# optimization:
#   $ CFLAGS=-g ./build2
test "$CXX" || export CXX=c++
test "$CC" || export CC=cc
test "$CFLAGS" || export CFLAGS="-g -O2"
export CFLAGS="$CFLAGS -Wall -Wextra -ftrapv -fno-strict-aliasing"

# Outline:
# [0-9]*.cc -> mu.cc -> .build/*.cc -> .build/*.o -> .build/mu_bin
# (layers)   |        |              |             |
#          tangle  cleave          $CXX          $CXX

# can also be called with a layer to only build until
#   $ ./build2 --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

# 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
    # auto-generate various lists (ending in '_list' by convention) {
    # list of types
    {
      grep -h "^struct .* {" [0-9]*.cc  |sed 's/\(struct *[^ ]*\).*/\1;/'
      grep -h "^typedef " [0-9]*.cc
    }  |update type_list
    # list of function declarations, so I can define them in any order
    grep -h "^[^ #].*) {" [0-9]*.cc  |sed 's/ {.*/;/'  |update function_list
    # list of code files to compile
    ls [0-9]*.cc  |grep -v "\.test\.cc$"  |sed 's/.*/#include "&"/'  |update file_list
    # list of test files to compile
    ls [0-9]*.test.cc  |sed 's/.*/#include "&"/'  |update test_file_list
    # list of tests to run
    grep -h "^[[:space:]]*void test_" [0-9]*.cc  |sed 's/^\s*void \(.*\)() {$/\1,/'  |update test_list
    grep -h "^\s*void test_" [0-9]*.cc  |sed 's/^\s*void \(.*\)() {.*/"\1",/'  |update test_name_list
    # }
    # Now that we have all the _lists, compile 'tangle'
    $CXX $CFLAGS boot.cc -o tangle
    ./tangle test
  noisy_cd ..  # no effect; just to show us returning to the parent directory
}

LAYERS=$(./enumerate/enumerate --until $UNTIL_LAYER  |grep '\.cc$')
older_than mu.cc $LAYERS enumerate/enumerate tangle/tangle && {
  # no update here; rely on 'update' calls downstream
  ./tangle/tangle $LAYERS  > mu.cc
}

older_than cleave/cleave cleave/cleave.cc && {
  $CXX $CFLAGS cleave/cleave.cc -o cleave/cleave
  rm -rf .build
}

mkdir -p .build
# auto-generate function declarations, so I can define them in any order
# functions start out unindented, have all args on the same line, and end in ') {'
#
#    <style>pre { line-height: 125%; }
td.linenos .normal { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
span.linenos { color: inherit; background-color: transparent; padding-left: 5px; padding-right: 5px; }
td.linenos .special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
span.linenos.special { color: #000000; background-color: #ffffc0; padding-left: 5px; padding-right: 5px; }
.highlight .hll { background-color: #ffffcc }
.highlight .c { color: #888888 } /* Comment */
.highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */
.highlight .k { color: #008800; font-weight: bold } /* Keyword */
.highlight .ch { color: #888888 } /* Comment.Hashbang */
.highlight .cm { color: #888888 } /* Comment.Multiline */
.highlight .cp { color: #cc0000; font-weight: bold } /* Comment.Preproc */
.highlight .cpf { color: #888888 } /* Comment.PreprocFile */
.highlight .c1 { color: #888888 } /* Comment.Single */
.highlight .cs { color: #cc0000; font-weight: bold; background-color: #fff0f0 } /* Comment.Special */
.highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */
.highlight .ge { font-style: italic } /* Generic.Emph */
.highlight .ges { font-weight: bold; font-style: italic } /* Generic.EmphStrong */
.highlight .gr { color: #aa0000 } /* Generic.Error */
.highlight .gh { color: #333333 } /* Generic.Heading */
.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
.highlight .go { color: #888888 } /* Generic.Output */
.highlight .gp { color: #555555 } /* Generic.Prompt */
.highlight .gs { font-weight: bold } /* Generic.Strong */
.highlight .gu { color: #666666 } /* Generic.Subheading */
.highlight .gt { color: #aa0000 } /* Generic.Traceback */
.highlight .kc { color: #008800; font-weight: bold } /* Keyword.Constant */
.highlight .kd { color: #008800; font-weight: bold } /* Keyword.Declaratio