How can I copy the contents of an opened TextMate document to the clipboard with AppleScript?

I need to copy the contents of an open TextMate document to the clipboard with AppleScript. Any i开发者_运维知识库deas? Or perhaps an idea for a solution that doesn't use AppleScript but accomplishes the same thing programmatically?

tell application "TextMate" to set x to path of document 1
set the clipboard to x

I thought there'd be an environment variable like TM_CURRENT_LINE for the contents of the current document, but apparently not.