transmogrifer.js

function Transmogrifier (map) {

  var EMPTY  = '',
      SOURCE = 's',
      TARGET = 't',
      DOT    = '.',
      EQUALS = '=',
      OBJECT = '{}',
      BREAK  = ';\n',
      NUMERIC_INDEX_REGEXP = /\.(\d+)/g,
      modifiers = [];

  function makeSource (map /*, root */) {

    var root    = arguments[1] || EMPTY,
        rootDot = (root !== EMPTY) ? root + DOT : EMPTY,
        src     = [],
        prop,
        val,
        i;

    // Open function
    if (root === EMPTY) {
      src.push('var ', TARGET, EQUALS, OBJECT, BREAK);

    // Render nested object
    } else {
      src.push(TARGET, DOT, root, EQUALS, OBJECT, BREAK);
    }

    // Iterate map properties
    for (prop in map) {
      if (map.hasOwnProperty(prop)) {
        val = map[prop];

        // Traverse nested objects
        if (typeof val === 'object') {
          src.push(makeSource(val, prop));

        // Render dot-delimited properties and modifiers
        } else {

          // Render left-hand assignment
          src.push(TARGET, DOT, rootDot, prop, EQUALS);

          // Render modifier
          if (typeof val === 'function') { 
            modifiers[prop] = val;
            src.push('this.modifiers.', prop, '(', SOURCE, ')', BREAK);

          // Render dot-delimited property as gated assignment
          } else {

            val = val.split(DOT);

            for (i = val.length - 1; i >= 0; --i) {
              val[i] = SOURCE + DOT + val.slice(0, i + 1).join(DOT);
            }

            src.push(val.join('&&').replace(NUMERIC_INDEX_REGEXP, '[$1]'), BREAK);
          }
        }
      }
    }

    // Close function
    if (root === EMPTY) {
      src.push('return ', TARGET, BREAK);
    }

    return src.join(EMPTY);
  }

  this.transmogrify = new Function(SOURCE, makeSource(map));
  this.modifiers = modifiers;
}

transmogrifier.min.js

function Transmogrifier(a){var b="",j="s",e="t",g=".",i="=",c="{}",k=";\n",d=/\.(\d+)/g,h=[];function f(o){var m=arguments[1]||b,l=(m!==b)?m+g:b,q=[],r,p,n;if(m===b){q.push("var ",e,i,c,k);}else{q.push(e,g,m,i,c,k);}for(r in o){if(o.hasOwnProperty(r)){p=o[r];if(typeof p==="object"){q.push(f(p,r));}else{q.push(e,g,l,r,i);if(typeof p==="function"){h[r]=p;q.push("this.modifiers.",r,"(",j,")",k);}else{p=p.split(g);for(n=p.length-1;n>=0;--n){p[n]=j+g+p.slice(0,n+1).join(g);}q.push(p.join("&&").replace(d,"[$1]"),k);}}}}if(m===b){q.push("return ",e,k);}return q.join(b);}this.transmogrify=new Function(j,f(a));this.modifiers=h;}

usage.js

var contactMap = {
  firstName:   'invoice.billing.fname',
  lastName:    'invoice.billing.lname',
  billingAddress: {
    undefined:   'foo.bar',
    job:         'invoice.billing.jobs.2.name',
    address: function (obj) {
      var b = obj.invoice.billing; 
      return b.city + ', ' +
             b.state + ' ' +
             b.country;
    }   
  },
  getFullName: function (obj) {
    return function getFullName () {
      return this.firstName + ' ' + this.lastName;
    };
  }      
},

contactTransmogrifier = new Transmogrifier(contactMap),

contact = {
  invoice: {
    billing: {
      fname:   'Dave',
      lname:   'Furfero',
      city:    'Harlem',
      state:   'NY',
      country: 'USA',
      jobs: [
        {name:'Live Nation'},
        {name:'Time, Inc.'},
        {name:'MLB'}
      ]
    }
  }
};

console.group('source');
console.log(contactTransmogrifier.transmogrify.toString());
console.groupEnd('source');

console.group('input');
console.dir(contact);
console.groupEnd('input');

console.group('output');
console.dir(contactTransmogrifier.transmogrify(contact));
console.groupEnd('output');

console.group('time');
var r = stress(function contactTransmogrifierTest() {
  contactTransmogrifier.transmogrify(contact);
}); // stress
console.log(r.each, 'ms');
console.groupEnd('time');

var p = contactTransmogrifier.transmogrify(contact);
console.log(p.getFullName());