withGetopt: init

krebs/5pkgs/simple/withGetopt.nix

@@ -0,0 +1,106 @@
+with import <stockholm/lib>;
+{ utillinux, writeDash }:
+
+opt-spec: cmd-spec: let
+
+  cmd = cmd-spec opts;
+
+  cmd-script =
+    if typeOf cmd == "set"
+      then "exec ${cmd}"
+      else cmd;
+
+  opts = mapAttrs (name: value: value // rec {
+    long = value.long or (replaceStrings ["_"] ["-"] name);
+    ref = value.ref or "\"\$${varname}\"";
+    switch = value.switch or false;
+    varname = value.varname or (replaceStrings ["-"] ["_"] name);
+  }) opt-spec;
+
+  # true if b requires a to define its default value
+  opts-before = a: b:
+    test ".*[$]${stringAsChars (c: "[${c}]") a.varname}\\>.*" (b.default or "");
+
+  opts-list = let
+    sort-out = toposort opts-before (attrValues opts);
+  in
+    if sort-out ? result
+      then sort-out.result
+      else throw "toposort output: ${toJSON sort-out}";
+
+  wrapper-name =
+    if typeOf cmd == "set" && cmd ? name
+      then "${cmd.name}-getopt"
+      else "getopt-wrapper";
+
+in writeDash wrapper-name ''
+  set -efu
+
+  wrapper_name=${shell.escape wrapper-name}
+
+  ${concatStringsSep "\n" (mapAttrsToList (name: opt: /* sh */ ''
+    unset ${opt.varname}
+  '') opts)}
+
+  args=$(${utillinux}/bin/getopt \
+      -n "$wrapper_name" \
+      -o "" \
+      -l ${concatMapStringsSep ","
+            (opt: opt.long + optionalString (!opt.switch) ":")
+            (attrValues opts)} \
+      -s sh \
+      -- "$@")
+  if \test $? != 0; then exit 1; fi
+  eval set -- "$args"
+
+  while :; do
+    case $1 in
+    ${concatStringsSep "\n" (mapAttrsToList (name: opt: /* sh */ ''
+      --${opt.long})
+        ${if opt.switch then /* sh */ ''
+          ${opt.varname}=true
+          shift
+        '' else /* sh */ ''
+          ${opt.varname}=$2
+          shift 2
+        ''}
+      ;;
+    '') opts)}
+    --)
+      shift
+      break
+    esac
+  done
+
+  ${concatMapStringsSep "\n"
+    (opt: /* sh */ ''
+      if \test "''${${opt.varname}+1}" != 1; then
+        printf '%s: missing mandatory option '--%s'\n' \
+            "$wrapper_name" \
+            ${shell.escape opt.long}
+        error=1
+      fi
+    '')
+    (filter
+      (x: ! hasAttr "default" x)
+      (attrValues opts))}
+  if test "''${error+1}" = 1; then
+    exit 1
+  fi
+
+  ${concatMapStringsSep "\n"
+    (opt: /* sh */ ''
+      if \test "''${${opt.varname}+1}" != 1; then
+        ${opt.varname}=${opt.default}
+      fi
+    '')
+    (filter
+      (hasAttr "default")
+      opts-list)}
+
+  ${concatStringsSep "\n" (mapAttrsToList (name: opt: /* sh */ ''
+    export ${opt.varname}
+  '') opts)}
+
+  ${cmd-script}
+''