expressions working

Signed-off-by: Casey Lee <cplee@nektos.com>

vendor/github.com/robertkrimen/otto/file/README.markdown

@@ -0,0 +1,110 @@
+# file
+--
+    import "github.com/robertkrimen/otto/file"
+
+Package file encapsulates the file abstractions used by the ast & parser.
+
+## Usage
+
+#### type File
+
+```go
+type File struct {
+}
+```
+
+
+#### func  NewFile
+
+```go
+func NewFile(filename, src string, base int) *File
+```
+
+#### func (*File) Base
+
+```go
+func (fl *File) Base() int
+```
+
+#### func (*File) Name
+
+```go
+func (fl *File) Name() string
+```
+
+#### func (*File) Source
+
+```go
+func (fl *File) Source() string
+```
+
+#### type FileSet
+
+```go
+type FileSet struct {
+}
+```
+
+A FileSet represents a set of source files.
+
+#### func (*FileSet) AddFile
+
+```go
+func (self *FileSet) AddFile(filename, src string) int
+```
+AddFile adds a new file with the given filename and src.
+
+This an internal method, but exported for cross-package use.
+
+#### func (*FileSet) File
+
+```go
+func (self *FileSet) File(idx Idx) *File
+```
+
+#### func (*FileSet) Position
+
+```go
+func (self *FileSet) Position(idx Idx) *Position
+```
+Position converts an Idx in the FileSet into a Position.
+
+#### type Idx
+
+```go
+type Idx int
+```
+
+Idx is a compact encoding of a source position within a file set. It can be
+converted into a Position for a more convenient, but much larger,
+representation.
+
+#### type Position
+
+```go
+type Position struct {
+	Filename string // The filename where the error occurred, if any
+	Offset   int    // The src offset
+	Line     int    // The line number, starting at 1
+	Column   int    // The column number, starting at 1 (The character count)
+
+}
+```
+
+Position describes an arbitrary source position including the filename, line,
+and column location.
+
+#### func (*Position) String
+
+```go
+func (self *Position) String() string
+```
+String returns a string in one of several forms:
+
+    file:line:column    A valid position with filename
+    line:column         A valid position without filename
+    file                An invalid position with filename
+    -                   An invalid position without filename
+
+--
+**godocdown** http://github.com/robertkrimen/godocdown