match.js

var assert = require('./assert');
var isFunction = require('./isFunction');
var isType = require('./isType');
var Any = require('./Any');

module.exports = function match(x) {
  var type, guard, f, count;
  for (var i = 1, len = arguments.length; i < len; ) {
    type = arguments[i];
    guard = arguments[i + 1];
    f = arguments[i + 2];

    if (isFunction(f) && !isType(f)) {
      i = i + 3;
    }
    else {
      f = guard;
      guard = Any.is;
      i = i + 2;
    }

    if (process.env.NODE_ENV !== 'production') {
      count = (count || 0) + 1;
      assert(isType(type), function () { return 'Invalid type in clause #' + count; });
      assert(isFunction(guard), function () { return 'Invalid guard in clause #' + count; });
      assert(isFunction(f), function () { return 'Invalid block in clause #' + count; });
    }

    if (type.is(x) && guard(x)) {
      return f(x);
    }
  }
  assert.fail('Match error');
};