#!/bin/sh

# This script is a template for a self modifiying script

# License: LGPLv2

# Change the following to whatever
# method updates your script, for e.g.
#     svn update $0
proc update_method {
    return
}
# Note the exec must be read from disk
# before updated_method is called, hence
# why update_this_script is in a function.
proc update_this_script {
    global old_md5 := $[md5sum $0 | cut -d' ' -f1]
    update_method
    global new_md5 := $[md5sum $0 | cut -d' ' -f1]
    if test $old_md5 != $new_md5 {
        exec $0 @Argv
    }
}
update_this_script

echo "rest of script here"
(CommandList
  children: [
    (FuncDef
      name: update_method
      body: (BraceGroup children:[(ControlFlow token:<ControlFlow_Return return>)] spids:[25])
      spids: [21 24]
    )
    (FuncDef
      name: update_this_script
      body: 
        (BraceGroup
          children: [
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:old_md5)
                  op: Equal
                  rhs: 
                    {
                      (CommandSubPart
                        command_list: 
                          (CommandList
                            children: [
                              (Pipeline
                                children: [
                                  (C {(md5sum)} {($ VSub_Number "$0")})
                                  (C {(cut)} {(-d) (SQ <" ">)} {(-f1)})
                                ]
                                negated: False
                              )
                            ]
                          )
                        left_token: <Left_Backtick "`">
                        spids: [49 64]
                      )
                    }
                  spids: [48]
                )
              ]
              spids: [48]
            )
            (C {(update_method)})
            (Assignment
              keyword: Assign_None
              pairs: [
                (assign_pair
                  lhs: (LhsName name:new_md5)
                  op: Equal
                  rhs: 
                    {
                      (CommandSubPart
                        command_list: 
                          (CommandList
                            children: [
                              (Pipeline
                                children: [
                                  (C {(md5sum)} {($ VSub_Number "$0")})
                                  (C {(cut)} {(-d) (SQ <" ">)} {(-f1)})
                                ]
                                negated: False
                              )
                            ]
                          )
                        left_token: <Left_Backtick "`">
                        spids: [71 86]
                      )
                    }
                  spids: [70]
                )
              ]
              spids: [70]
            )
            (If
              arms: [
                (if_arm
                  cond: [
                    (Sentence
                      child: 
                        (C {(Lit_Other "[")} {(DQ ($ VSub_Name "$old_md5"))} 
                          {(KW_Bang "!") (Lit_Other "=")} {(DQ ($ VSub_Name "$new_md5"))} {(Lit_Other "]")}
                        )
                      terminator: <Op_Semi ";">
                    )
                  ]
                  action: [(C {(exec)} {($ VSub_Number "$0")} {(DQ ($ VSub_At "$@"))})]
                  spids: [-1 107]
                )
              ]
              spids: [-1 119]
            )
          ]
          spids: [45]
        )
      spids: [41 44]
    )
    (C {(update_this_script)})
    (C {(echo)} {(DQ ("rest of script here"))})
  ]
)