Add a basic build system

build

@@ -0,0 +1,83 @@
+#!/usr/bin/env bash
+
+run() {
+  printf '%s==>%s %s\n' "$(tput setaf 2)" "$(tput sgr0)" "$*"
+  "$@"
+
+  if (( $? )); then
+    exit
+  fi
+}
+
+compile-all() {
+  mkdir -p bin
+
+  for src in src/*.cpp; do
+    bin=bin/${src#src/} bin=${bin%.cpp}.o
+
+    if [[ ! -v CHECK_COMPILE ]] || "$CHECK_COMPILE" "$src" "$bin"; then
+      run c++ "${CXXFLAGS[@]}" -c -o "$bin" "$src"
+    fi
+  done
+
+  run c++ "${LDFLAGS[@]}" -o bin/chimney bin/*.o
+}
+
+set-default-flags() {
+  CXXFLAGS=(-std=c++2a -Wall -Wextra -pedantic -O1 -I include)
+  LDFLAGS=(-O1)
+}
+
+is-newer() {
+  [[ $1 -nt "$2" ]]
+}
+
+cmd-make() {
+  local {CXX,LD}FLAGS
+  set-default-flags
+  CHECK_COMPILE=is-newer compile-all
+}
+
+cmd-fresh() {
+  local {CXX,LD}FLAGS
+  set-default-flags
+  compile-all
+}
+
+cmd-clean() {
+  run rm -rf bin
+}
+
+declare -A opts
+
+while (( $# )); do
+  if [[ $1 = -- ]]; then
+    shift
+    break
+  elif [[ $1 = -no-* ]]; then
+    opts[${1#-no-}]=no
+  elif [[ $1 = -*=* ]]; then
+    key=${1#-} key=${key%%=*}
+    opts[$key]=${1#*=}
+  elif [[ $1 = -?* ]]; then
+    opts[${1#-}]=yes
+  else
+    break
+  fi
+
+  shift
+done
+
+cmd=make
+
+if (( $# )); then
+  cmd=$1
+  shift
+fi
+
+if ! hash cmd-"$cmd" 2>/dev/null; then
+  printf 'Unknown command %s%s%s\n' "$(tput setaf 1)" "$cmd" "$(tput sgr0)" >&2
+  exit
+fi
+
+cmd-"$cmd" "$@"