barg-parser/parser.js

const SPEC = [
  "command;build;Build a dev container",
  "argument;name;type:positional;required;help:Name of the container",
  "argument;image,i;type:option;required;map:image_name;help:Base image",
  "argument;include,I;type:option;repeatable;map:include_paths;help:Include paths",
  "argument;verbose,v;type:flag;repeatable;default:0;help:Increase verbosity (-v, -vv, ...)",
  "argument;quiet,q;type:flag;default:false;help:Suppress all output",
  "argument;cmd;type:rest;map:cmd_rest;help:Command and args to run inside the container",

  "command;stop;Stop a dev container",
  "argument;name;type:positional;required;help:Name of the container",
  "argument;kill,k;type:flag;default:false;help:Force kill the container",
];

const ENTRY = {
  COMMAND: "command",
  ARGUMENT: "argument",
};
const ATTR = {
  REQUIRED: "required",
  HELP: "help",
  DEFAULT: "default",
  MAP: "map",
  TYPE: "type",
  REPEATABLE: "repeatable",
  POSITION: "position",
};
const ATTR_TYPE = {
  POSITIONAL: "positional",
  OPTION: "option",
  FLAG: "flag",
};
const CONTEXT = {
  POS_COUNT: "pos_count",
};
/**
 * Spec = Entry[]
 * Entry = "<element>;...<element>"
 * Entry.type "command": "<entry_type>;<identifiers>;<help_text>"
 * Entry.type "argument": "<entry_type>;<identifiers>;<attribute>;...<attribute>"
 *
 * "arg_end", "arg_rest" are provided without need to specify it in the spec.
 *
 * Attributes:
 * - required
 * - help:<text>
 * - default:<value>
 * - map:<var_name>
 * - type:<"positional"|"option"|"flag">
 * For type.{option,flag}:
 * - repeatable
 *
 */
function parse_spec_entry(raw_entry, context) {
  const elements = raw_entry.split(";");
  const entry = {
    type: elements.shift(),
    aliases: elements.shift().split(","),
  };
  const attributes = {
    [ENTRY.COMMAND]: () => {
      return { help: elements.shift() };
    },
    [ENTRY.ARGUMENT]: () => {
      const attributes = {
        [ATTR.REQUIRED]: false,
        [ATTR.REPEATABLE]: false,
        [ATTR.TYPE]: ATTR_TYPE.POSITIONAL,
        [ATTR.POSITION]: 0,
        [ATTR.MAP]: null,
        [ATTR.DEFAULT]: null,
        [ATTR.HELP]: null,
      };
      elements.forEach((element) => {
        const [attribute, attribute_value = null] = element.split(":");
        ({
          [ATTR.REQUIRED]: (_) => {
            attributes[ATTR.REQUIRED] = true;
          },
          [ATTR.REPEATABLE]: (_) => {
            attributes[ATTR.REPEATABLE] = true;
          },
          [ATTR.TYPE]: (value) => {
            attributes[ATTR.TYPE] = value;
            if (value === ATTR_TYPE.POSITIONAL) {
              attributes[ATTR.POSITION] = context[CONTEXT.POS_COUNT];
              context[CONTEXT.POS_COUNT] += 1;
            }
          },
          [ATTR.MAP]: (value) => {
            attributes[ATTR.MAP] = value;
          },
          [ATTR.DEFAULT]: (value) => {
            attributes[ATTR.DEFAULT] = value;
          },
          [ATTR.HELP]: (value) => {
            attributes[ATTR.HELP] = value;
          },
        })[attribute](attribute_value);
      });
      return attributes;
    },
  }[entry.type]();

  return { ...entry, attr: attributes };
}

function generate_id() {
  let id = 0;
  return () => id++;
}

function parse_spec(spec, command = null) {
  const spec_data = {};
  const spec_aliases = {};

  const get_cmd_id = generate_id();
  const get_arg_id = generate_id();

  let skip_cmd = false;
  let exit_on_next_cmd = false;

  let cmd_id = null;

  const ctx_defaults = { [CONTEXT.POS_COUNT]: 0 };
  const context = {
    ...ctx_defaults,
    reset() {
      Object.assing(this, defaults);
    },
  };
  for (const raw_entry of spec) {
    const entry = parse_spec_entry(raw_entry, context);
    console.log(entry.type);
    const exit = {
      [ENTRY.COMMAND]: () => {
        // Previous command was populated
        if (exit_on_next_cmd) return true;

        // Looking for a single command
        if (command !== null) {
          // Not this one
          if (!entry.aliases.includes(command)) {
            skip_cmd = true;
            return;
          }
          // Populate and exit
          skip_cmd = false;
          exit_on_next_cmd = true;
        }

        entry.id = cmd_id = get_cmd_id();

        spec_data[entry.id] = entry;
        entry.aliases.forEach((alias) => {
          spec_aliases[alias] = entry.id;
        });
      },
      [ENTRY.ARGUMENT]: () => {
        // Do not populate command
        if (skip_cmd) return;

        entry.id = get_arg_id();
        spec_data[`${cmd_id}.${entry.id}`] = entry;
        entry.aliases.forEach((alias) => {
          if (entry.attr.type === ATTR_TYPE.POSITIONAL) {
            spec_aliases[`${cmd_id}.${entry.attr[ATTR.POSITION]}`] = entry.id;
          } else {
            spec_aliases[`${cmd_id}.${alias}`] = entry.id;
          }
        });
      },
    }[entry.type]();
    if (exit) break;
  }

  return { spec_data, spec_aliases };
}

const r = parse_spec(SPEC, "build");
console.log(JSON.stringify(r, null, 2));

/**
 * INPUT: build -i tm0:node mybox
 *
 * spec_aliases[build] -> "0"
 * -i -> option/flag short -> spec_aliases["0.i"] -> "1"
 *
 */