riot的expression

var.js

var   re_vars = /(['"\/]).*?[^\\]\1|\.\w*|\w*:|\b(?:(?:new|typeof|in|instanceof) |(?:this|true|false|null|undefined)\b|function *\()|([a-z_]\w*)/gi
              // [ 1               ][ 2  ][ 3 ][ 4                                                                                  ][ 5       ]
              // find variable names:
              // 1. skip quoted strings and regexps: "a b", 'a b', 'a \'b\'', /a b/
              // 2. skip object properties: .name
              // 3. skip object literals: name:
              // 4. skip javascript keywords
              // 5. match var name
function wrap(s, nonull) {
    s = s.trim()
    return !s ? 'void 0' : '(function(v){try{\n v='

        // prefix vars (name => data.name)
        + (s.replace(re_vars, function(s, _, v) { return v ? 'd.'+ v : s })

          // break the expression if its empty (resulting in undefined value)
          || 'x')

      + '\n}finally{\nreturn '

        // default to empty string for falsy values except zero
        + (nonull ? '!v&&v!==0?"":v' : 'v')

      + '\n}}).call(d)'
  }

var f = new Function('d', 'return ' + wrap('a+b'));



console.log(
  f,
  f({
    a: 1,
    b: 2
  })
 );