argv-parser/arg-parser.js

#!/usr/bin/env node

const test = require('node:test');

// WIP

// Example
/*
let cpuArguments = {
  help: '', // TODO
  args: [
    { flags: { short: 'f' },
      name: 'Filename',
      requiresValue: true, },
    { name: 'Clock speed',
      flags: { short: 'c', long: 'clock' },
      requiresValue: true,
      optional: true },
    { name: 'Pretty-print display',
      flags: { short: 'p', long: 'pretty' },
      optional: true, },
    { name: 'Single-step',
      flags: { short: 's', long: 'step' },
      optional: true, },
    { 'name': 'Debug',
      flags: { short: 'd', long: 'debug' },
      optional: true,
    }
  ]
};
*/


// Constructors

function Arguments(argumentsObject=[], helpText='') {
  this.help = helpText;
  this.args = argumentsObject;
  Arguments.prototype.add = (...a) => a.forEach((x) => argumentsObject.push(x));
};

function Arg({
  name = 'Flag',
  shortFlag = null,
  longFlag = null,
  requiresValue=false,
  optional=false
}) {
  this.name = name;
  this.flags = { short: shortFlag, long: longFlag };
  this.requiresValue = requiresValue;
  this.optional = optional;
};

// Test constructors

let cpuArguments = new Arguments();
cpuArguments.add(
  new Arg({name: 'Filename', shortFlag: 'f', requiresValue: true}),
  new Arg({name: 'Clock speed', shortFlag: 'c', longFlag: 'clock', requiresValue: true, optional: true}),
  new Arg({name: 'Debug', shortFlag: 'd', longFlag: 'debug', optional: true}),
  new Arg({name: 'Pretty-print display', shortFlag: 'p', longFlag: 'pretty', optional: true}),
  new Arg({name: 'Single-step', shortFlag: 's', longFlag: 'step', optional: true}));

///console.log(cpuArguments);
///console.log('flags', cpuArguments.args[0].flags);


// MODULE:

// TODO:
// - building a structured output
// - testing
// - exporting as object

const argsRequiringValues = cpuArguments.args.filter((a) => a.requiresValue);
const requiredArgs = cpuArguments.args.filter((a) => !a.optional);

let argv = process.argv.slice(2);

// Split up grouped short flags
let argvSplit = [].concat(...argv.map((x) => {
  if (x.startsWith('-') && !x.startsWith('--')) { // short flags
    let arr = x.substring(1).split('');
    arr = arr.map((y) => '-' + y);
    return arr;
  }
  return x;
}));


// Check if all the required flags have been included
requiredArgs.forEach((a) => {
  if (!argvSplit.includes('-'+a.flags.short) && !argvSplit.includes('-'+a.flags.long)) {
    let long = (a.flags.long) ? `--${a.flags.long}, ` : '';
    throw new Error(`${a.name} flag (-${a.flags.short}${long}) is required`);
  }
});

// Validate...
argvSplit.forEach((currentArg, index) => {
  console.log('checking', currentArg);
  // Check for attempts to use --flags that don't exist
  if (currentArg.startsWith('--')) {
    console.log('--');
    let valid = cpuArguments.args.filter((a) => { return A.flags.long === currentArg.substring(2)}).length > 0;
    console.log('valid', valid);
    if (!valid) { throw new Error(`There is no ${currentArg} option`); }
  } else if (currentArg.startsWith('-')) {
    console.log(currentArg.substring(1));
    let valid = cpuArguments.args.filter((a) => { console.log(a); return a.flags.short === currentArg.substring(1)}).length > 0;
    if (!valid) { throw new Error(`There is no ${currentArg} option`); }
  }
  ///console.log('  it\'s a valid argument');

  ///console.log('  argsrequiringvalues', argsRequiringValues);
  ///console.log('  currentarg', currentArg);

  // Check if it requires a value...
  // and if it does, do a cursory check to see if one is likely to be there
  let shouldCheckValue = argsRequiringValues.filter((a) => {
    /// console.log('a', a);
    let noDash = currentArg.substring(1);
    return (a.flags.short === noDash || a.flags.long === noDash);
  }).length > 0;
  /// console.log('  requires a value?', shouldCheckValue);
  /// console.log('  split', argvSplit);

  if (shouldCheckValue) {
    ///console.log(currentArg);
    let errorMessage = `Value required for ${currentArg}`;
    // If there's nothing after this flag, error;
    // Or if the next item is a flag... error:
    /// console.log('idx', index, argvSplit[index]);
    if (typeof argvSplit[index + 1] === 'undefined') { throw new Error(errorMessage); }
    else if (argvSplit[index + 1].startsWith('-')) { throw new Error(errorMessage); };
  }
});