1.1 --- a/src/Pure/General/alist.ML	Wed Oct 05 14:01:32 2005 +0200
     1.2 +++ b/src/Pure/General/alist.ML	Wed Oct 05 18:38:28 2005 +0200
     1.3 @@ -9,6 +9,7 @@
     1.4  
     1.5  signature ALIST =
     1.6  sig
     1.7 +  exception DUP
     1.8    val lookup: ('a * 'b -> bool) -> ('b * 'c) list -> 'a -> 'c option
     1.9    val defined: ('a * 'b -> bool) -> ('b * 'c) list -> 'a -> bool
    1.10    val update: ('a * 'a -> bool) -> ('a * 'b)
    1.11 @@ -20,12 +21,23 @@
    1.12    val map_entry: ('a * 'b -> bool) -> 'a -> ('c -> 'c)
    1.13      -> ('b * 'c) list -> ('b * 'c) list
    1.14    val make: ('a -> 'b) -> 'a list -> ('a * 'b) list
    1.15 +  val merge: ('a * 'a -> bool) -> ('b * 'b -> bool)
    1.16 +    -> ('a * 'b) list * ('a * 'b) list -> ('a * 'b) list (*exception DUP*)
    1.17    val find: ('a * 'b -> bool) -> ('c * 'b) list -> 'a -> 'c list
    1.18  end;
    1.19  
    1.20  structure AList: ALIST =
    1.21  struct
    1.22  
    1.23 +fun find_index eq xs key =
    1.24 +  let
    1.25 +    fun find [] _ = 0
    1.26 +      | find ((key', value)::xs) i =
    1.27 +          if eq (key, key')
    1.28 +          then i
    1.29 +          else find xs (i+1);
    1.30 +  in find xs 1 end;
    1.31 +
    1.32  fun lookup _ [] _ = NONE
    1.33    | lookup eq ((key, value)::xs) key' =
    1.34        if eq (key', key) then SOME value
    1.35 @@ -35,30 +47,44 @@
    1.36    | defined eq ((key, value)::xs) key' =
    1.37        eq (key', key) orelse defined eq xs key';
    1.38  
    1.39 -fun update eq (key, value) xs =
    1.40 +fun update eq (x as (key, value)) xs =
    1.41    let
    1.42 -    fun upd ((x as (key', _))::xs) =
    1.43 -      if eq (key, key')
    1.44 -      then (key, value)::xs
    1.45 -      else x :: upd xs
    1.46 -  in if defined eq xs key then upd xs else (key, value)::xs end;
    1.47 +    val i = find_index eq xs key;
    1.48 +    fun upd 1 (_::xs) = (x::xs)
    1.49 +      | upd i (x::xs) = x :: upd (i-1) xs;
    1.50 +  in if i = 0 then x::xs else upd i xs end;
    1.51  
    1.52  fun default eq (key, value) xs =
    1.53    if defined eq xs key then xs else (key, value)::xs;
    1.54  
    1.55  fun delete eq key xs =
    1.56    let
    1.57 -    fun del ((x as (key', _))::xs) =
    1.58 -      if eq (key, key') then xs
    1.59 -      else x :: del xs;
    1.60 -  in if defined eq xs key then del xs else xs end;
    1.61 +    val i = find_index eq xs key;
    1.62 +    fun del 1 (_::xs) = xs
    1.63 +      | del i (x::xs) = x :: del (i-1) xs;
    1.64 +  in if i = 0 then xs else del i xs end;
    1.65  
    1.66 -fun map_entry eq key' f xs =
    1.67 +fun map_entry eq key f xs =
    1.68    let
    1.69 -    fun mapp ((x as (key, value))::xs) =
    1.70 -      if eq (key', key) then (key, f value)::xs
    1.71 -      else x :: mapp xs
    1.72 -  in if defined eq xs key' then mapp xs else xs end;
    1.73 +    val i = find_index eq xs key;
    1.74 +    fun mapp 1 ((x as (key, value))::xs) = (key, f value) :: xs
    1.75 +      | mapp i (x::xs) = x :: mapp (i-1) xs;
    1.76 +  in if i = 0 then xs else mapp i xs end;
    1.77 +
    1.78 +exception DUP;
    1.79 +
    1.80 +fun merge eq_key eq_val (xs, ys) =
    1.81 +  let
    1.82 +    fun add (x as (key, value)) ys =
    1.83 +      case lookup eq_key ys key
    1.84 +       of NONE => update eq_key x ys
    1.85 +        | SOME value' =>
    1.86 +            if eq_val (value, value')
    1.87 +            then ys
    1.88 +            else raise DUP;
    1.89 +  in
    1.90 +    fold_rev add xs ys
    1.91 +  end;
    1.92  
    1.93  fun make keyfun =
    1.94    let fun keypair x = (x, keyfun x)
    1.95 @@ -67,7 +93,7 @@
    1.96  fun find eq [] _ = []
    1.97    | find eq ((key, value) :: xs) value' =
    1.98        let
    1.99 -        val values = find eq xs value'
   1.100 +        val values = find eq xs value';
   1.101        in if eq (value', value) then key :: values else values end;
   1.102  
   1.103  end;