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+-- Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
+-- All rights reserved.
+-- Copyright (C) 2007, Gabriel Dos Reis.
+-- All rights reserved.
+--
+-- Redistribution and use in source and binary forms, with or without
+-- modification, are permitted provided that the following conditions are
+-- met:
+--
+--     - Redistributions of source code must retain the above copyright
+--       notice, this list of conditions and the following disclaimer.
+--
+--     - Redistributions in binary form must reproduce the above copyright
+--       notice, this list of conditions and the following disclaimer in
+--       the documentation and/or other materials provided with the
+--       distribution.
+--
+--     - Neither the name of The Numerical ALgorithms Group Ltd. nor the
+--       names of its contributors may be used to endorse or promote products
+--       derived from this software without specific prior written permission.
+--
+-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+-- IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+-- TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+-- PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+-- OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+-- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+-- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+-- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+-- LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+-- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+-- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+import '"g-util"
+)package "BOOT"
+
+--% ITERATORS
+ 
+compReduce(form,m,e) ==
+ compReduce1(form,m,e,$formalArgList)
+
+compReduce1(form is ["REDUCE",op,.,collectForm],m,e,$formalArgList) ==
+  [collectOp,:itl,body]:= collectForm
+  if STRINGP op then op:= INTERN op
+  ^MEMQ(collectOp,'(COLLECT COLLECTV COLLECTVEC)) =>
+        systemError ["illegal reduction form:",form]
+  $sideEffectsList: local
+  $until: local
+  $initList: local
+  $endTestList: local
+  $e:= e
+  itl:= [([.,$e]:= compIterator(x,$e) or return "failed").(0) for x in itl]
+  itl="failed" => return nil
+  e:= $e
+  acc:= GENSYM()
+  afterFirst:= GENSYM()
+  bodyVal:= GENSYM()
+  [part1,m,e]:= comp(["LET",bodyVal,body],m,e) or return nil
+  [part2,.,e]:= comp(["LET",acc,bodyVal],m,e) or return nil
+  [part3,.,e]:= comp(["LET",acc,parseTran [op,acc,bodyVal]],m,e) or return nil
+  identityCode:=
+    id:= getIdentity(op,e) => u.expr where u() == comp(id,m,e) or return nil
+    ["IdentityError",MKQ op]
+  finalCode:=
+    ["PROGN",
+      ["LET",afterFirst,nil],
+       ["REPEAT",:itl,
+        ["PROGN",part1,
+          ["IF", afterFirst,part3,
+                   ["PROGN",part2,["LET",afterFirst,MKQ true]]]]],
+                    ["IF",afterFirst,acc,identityCode]]
+  if $until then
+    [untilCode,.,e]:= comp($until,$Boolean,e)
+    finalCode:= substitute(["UNTIL",untilCode],'$until,finalCode)
+  [finalCode,m,e]
+ 
+getIdentity(x,e) ==
+  GETL(x,"THETA") is [y] => y
+ 
+numberize x ==
+  x=$Zero => 0
+  x=$One => 1
+  atom x => x
+  [numberize first x,:numberize rest x]
+ 
+compRepeatOrCollect(form,m,e) ==
+  fn(form,[m,:$exitModeStack],[#$exitModeStack,:$leaveLevelStack],$formalArgList
+    ,e) where
+      fn(form,$exitModeStack,$leaveLevelStack,$formalArgList,e) ==
+        $until: local
+        [repeatOrCollect,:itl,body]:= form
+        itl':=
+          [([x',e]:= compIterator(x,e) or return "failed"; x') for x in itl]
+        itl'="failed" => nil
+        targetMode:= first $exitModeStack
+        bodyMode:=
+          repeatOrCollect="COLLECT" =>
+            targetMode = '$EmptyMode => '$EmptyMode
+            (u:=modeIsAggregateOf('List,targetMode,e)) =>
+              CADR u
+            (u:=modeIsAggregateOf('PrimitiveArray,targetMode,e)) =>
+              repeatOrCollect:='COLLECTV
+              CADR u
+            (u:=modeIsAggregateOf('Vector,targetMode,e)) =>
+              repeatOrCollect:='COLLECTVEC
+              CADR u
+            stackMessage('"Invalid collect bodytype")
+            return nil
+            -- If we're doing a collect, and the type isn't conformable
+            -- then we've boobed. JHD 26.July.1990
+          $NoValueMode
+        [body',m',e']:=
+          -- (m1:= listOrVectorElementMode targetMode) and comp(body,m1,e) or
+            compOrCroak(body,bodyMode,e) or return nil
+        if $until then
+          [untilCode,.,e']:= comp($until,$Boolean,e')
+          itl':= substitute(["UNTIL",untilCode],'$until,itl')
+        form':= [repeatOrCollect,:itl',body']
+        m'':=
+          repeatOrCollect="COLLECT" =>
+            (u:=modeIsAggregateOf('List,targetMode,e)) => CAR u
+            ["List",m']
+          repeatOrCollect="COLLECTV" =>
+            (u:=modeIsAggregateOf('PrimitiveArray,targetMode,e)) => CAR u
+            ["PrimitiveArray",m']
+          repeatOrCollect="COLLECTVEC" =>
+            (u:=modeIsAggregateOf('Vector,targetMode,e)) => CAR u
+            ["Vector",m']
+          m'
+        coerceExit([form',m'',e'],targetMode)
+ 
+--constructByModemap([x,source,e],target) ==
+--  u:=
+--    [cexpr
+--      for (modemap:= [map,cexpr]) in getModemapList("construct",1,e) | map is [
+--        .,t,s] and modeEqual(t,target) and modeEqual(s,source)] or return nil
+--  fn:= (or/[selfn for [cond,selfn] in u | cond=true]) or return nil
+--  [["call",fn,x],target,e]
+ 
+listOrVectorElementMode x ==
+  x is [a,b,:.] and member(a,'(PrimitiveArray Vector List)) => b
+ 
+compIterator(it,e) ==
+  it is ["IN",x,y] =>
+    --these two lines must be in this order, to get "for f in list f"
+    --to give  an error message if f is undefined
+    [y',m,e]:= comp(y,$EmptyMode,e) or return nil
+    $formalArgList:= [x,:$formalArgList]
+    [mOver,mUnder]:=
+      modeIsAggregateOf("List",m,e) or return
+         stackMessage ["mode: ",m," must be a list of some mode"]
+    if null get(x,"mode",e) then [.,.,e]:=
+      compMakeDeclaration([":",x,mUnder],$EmptyMode,e) or return nil
+    e:= put(x,"value",[genSomeVariable(),mUnder,e],e)
+    [y'',m'',e] := coerce([y',m,e], mOver) or return nil
+    [["IN",x,y''],e]
+  it is ["ON",x,y] =>
+    $formalArgList:= [x,:$formalArgList]
+    [y',m,e]:= comp(y,$EmptyMode,e) or return nil
+    [mOver,mUnder]:=
+      modeIsAggregateOf("List",m,e) or return
+        stackMessage ["mode: ",m," must be a list of other modes"]
+    if null get(x,"mode",e) then [.,.,e]:=
+      compMakeDeclaration([":",x,m],$EmptyMode,e) or return nil
+    e:= put(x,"value",[genSomeVariable(),m,e],e)
+    [y'',m'',e] := coerce([y',m,e], mOver) or return nil
+    [["ON",x,y''],e]
+  it is ["STEP",index,start,inc,:optFinal] =>
+    $formalArgList:= [index,:$formalArgList]
+    --if all start/inc/end compile as small integers, then loop
+    --is compiled as a small integer loop
+    final':= nil
+    (start':= comp(start,$SmallInteger,e)) and
+      (inc':= comp(inc,$NonNegativeInteger,start'.env)) and
+        (not (optFinal is [final]) or
+          (final':= comp(final,$SmallInteger,inc'.env))) =>
+            indexmode:=
+              comp(start,$NonNegativeInteger,e) =>
+                      $NonNegativeInteger
+              $SmallInteger
+            if null get(index,"mode",e) then [.,.,e]:=
+              compMakeDeclaration([":",index,indexmode],$EmptyMode,
+                (final' => final'.env; inc'.env)) or return nil
+            e:= put(index,"value",[genSomeVariable(),indexmode,e],e)
+            if final' then optFinal:= [final'.expr]
+            [["ISTEP",index,start'.expr,inc'.expr,:optFinal],e]
+    [start,.,e]:=
+      comp(start,$Integer,e) or return
+        stackMessage ["start value of index: ",start," must be an integer"]
+    [inc,.,e]:=
+      comp(inc,$Integer,e) or return
+        stackMessage ["index increment:",inc," must be an integer"]
+    if optFinal is [final] then
+      [final,.,e]:=
+        comp(final,$Integer,e) or return
+          stackMessage ["final value of index: ",final," must be an integer"]
+      optFinal:= [final]
+    indexmode:=
+      comp(CADDR it,$NonNegativeInteger,e) => $NonNegativeInteger
+      $Integer
+    if null get(index,"mode",e) then [.,.,e]:=
+      compMakeDeclaration([":",index,indexmode],$EmptyMode,e) or return nil
+    e:= put(index,"value",[genSomeVariable(),indexmode,e],e)
+    [["STEP",index,start,inc,:optFinal],e]
+  it is ["WHILE",p] =>
+    [p',m,e]:=
+      comp(p,$Boolean,e) or return
+        stackMessage ["WHILE operand: ",p," is not Boolean valued"]
+    [["WHILE",p'],e]
+  it is ["UNTIL",p] => ($until:= p; ['$until,e])
+  it is ["|",x] =>
+    u:=
+      comp(x,$Boolean,e) or return
+        stackMessage ["SUCHTHAT operand: ",x," is not Boolean value"]
+    [["|",u.expr],u.env]
+  nil
+ 
+--isAggregateMode(m,e) ==
+--  m is [c,R] and MEMQ(c,'(Vector List)) => R
+--  name:=
+--    m is [fn,:.] => fn
+--    m="$" => "Rep"
+--    m
+--  get(name,"value",e) is [c,R] and MEMQ(c,'(Vector List)) => R
+ 
+modeIsAggregateOf(ListOrVector,m,e) ==
+  m is [ =ListOrVector,R] => [m,R]
+--m = '$EmptyMode => [m,m] I don't think this is correct, breaks POLY +
+  m is ["Union",:l] =>
+    mList:= [pair for m' in l | (pair:= modeIsAggregateOf(ListOrVector,m',e))]
+    1=#mList => first mList
+  name:=
+    m is [fn,:.] => fn
+    m="$" => "Rep"
+    m
+  get(name,"value",e) is [[ =ListOrVector,R],:.] => [m,R]
+ 
+--% VECTOR ITERATORS
+ 
+--the following 4 functions are not currently used
+ 
+--compCollectV(form,m,e) ==
+--  fn(form,[m,:$exitModeStack],[#$exitModeStack,:$leaveLevelStack],e) where
+--    fn(form,$exitModeStack,$leaveLevelStack,e) ==
+--      [repeatOrCollect,it,body]:= form
+--      [it',e]:= compIteratorV(it,e) or return nil
+--      m:= first $exitModeStack
+--      [mOver,mUnder]:= modeIsAggregateOf("Vector",m,e) or $EmptyMode
+--      [body',m',e']:= compOrCroak(body,mUnder,e) or return nil
+--      form':= ["COLLECTV",it',body']
+--     {n:=
+--        it' is ("STEP",.,s,i,f) or it' is ("ISTEP",.,s,i,f) =>
+--              computeMaxIndex(s,f,i);
+--        return nil}
+--      coerce([form',mOver,e'],m)
+--
+--compIteratorV(it,e) ==
+--  it is ["STEP",index,start,inc,final] =>
+--    (start':= comp(start,$Integer,e)) and
+--      (inc':= comp(inc,$NonNegativeInteger,start'.env)) and
+--       (final':= comp(final,$Integer,inc'.env)) =>
+--        indexmode:=
+--          comp(start,$NonNegativeInteger,e) => $NonNegativeInteger
+--          $Integer
+--        if null get(index,"mode",e) then [.,.,e]:=
+--          compMakeDeclaration([":",index,indexmode],$EmptyMode,final'.env) or
+--            return nil
+--        e:= put(index,"value",[genSomeVariable(),indexmode,e],e)
+--        [["ISTEP",index,start'.expr,inc'.expr,final'.expr],e]
+--    [start,.,e]:=
+--      comp(start,$Integer,e) or return
+--        stackMessage ["start value of index: ",start," is not an integer"]
+--    [inc,.,e]:=
+--      comp(inc,$NonNegativeInteger,e) or return
+--        stackMessage ["index increment: ",inc," must be a non-negative integer"]
+--    [final,.,e]:=
+--      comp(final,$Integer,e) or return
+--        stackMessage ["final value of index: ",final," is not an integer"]
+--    indexmode:=
+--      comp(CADDR it,$NonNegativeInteger,e) => $NonNegativeInteger
+--      $Integer
+--    if null get(index,"mode",e) then [.,.,e]:=
+--      compMakeDeclaration([":",index,indexmode],$EmptyMode,e) or return nil
+--    e:= put(index,"value",[genSomeVariable(),indexmode,e],e)
+--    [["STEP",index,start,inc,final],e]
+--  nil
+--
+--computeMaxIndex(s,f,i) ==
+--  i^=1 => cannotDo()
+--  s=1 => f
+--  exprDifference(f,exprDifference(s,1))
+--
+--exprDifference(x,y) ==
+--  y=0 => x
+--  FIXP x and FIXP y => DIFFERENCE(x,y)
+--  ["DIFFERENCE",x,y]
+