nl_tokens: 字面量求值，主要包括string integer array map四种数据结构
pl_tokens: function ( literal ) { var type = literal . type ; var ret = '' ; if ( type === 'string' ) { ret = this . getString ( literal ) ; } else if ( type === 'integer' ) { ret = parseInt ( literal . value , 10 ) ; } else if ( type === 'decimal' ) { ret = parseFloat ( literal . value , 10 ) ; } else if ( <mask> === 'array' ) { ret = this . getArray ( literal ) ; } else if ( type === 'map' ) { ret = { } ; var map = literal . value ; utils . forEach ( map , function ( exp , key ) { ret [ key ] = this . getLiteral ( exp ) ; } , this ) ; } else if ( type === 'bool' ) { if ( literal . value === "null" ) { ret = null ; } else if ( literal . value === 'false' ) { ret = false ; } else if ( literal . value === 'true' ) { ret = true ; } } else { return this . getReferences ( literal ) ; } return ret ; }