
<<DummyTreePack.mesa>>
<<Last edited by Satterthwaite on January 11, 1983 10:05 am>>

DIRECTORY
Alloc: TYPE USING [Handle, Notifier, AddNotify, DropNotify],
Tree: TYPE USING [Base, Index, Link, Scan, Null, NullIndex, treeType],
TreeOps: TYPE USING [];

TreePack: PROGRAM
IMPORTS Alloc 
EXPORTS TreeOps = { 

<<TreeOps>>

endIndex: Tree.Index = Tree.Index.LAST;
endMark: Tree.Link = [subtree[index: endIndex]];

tb: PRIVATE Tree.Base;        -- tree base

UpdateBase: Alloc.Notifier = {tb _ base[Tree.treeType]};

Initialize: PUBLIC PROC [Alloc.Handle, UNCOUNTED ZONE] = {
Alloc.AddNotify[NIL, UpdateBase]};

Finalize: PUBLIC PROC = {Alloc.DropNotify[NIL, UpdateBase]};

ScanSons: PUBLIC PROC [root: Tree.Link, action: Tree.Scan] = {
IF root # Tree.Null THEN
WITH root SELECT FROM
subtree => {
node: Tree.Index = index;
FOR i: CARDINAL IN [1 .. SonCount[node]] DO
action[tb[node].son[i]] ENDLOOP};
ENDCASE;
RETURN};

SonCount: PROC [node: Tree.Index] RETURNS [CARDINAL] = {
RETURN [SELECT node FROM
Tree.NullIndex, endIndex => 0,
ENDCASE => IF tb[node].name = $list AND tb[node].nSons = 0
THEN ListLength[[subtree[index: node]]] + 1
ELSE tb[node].nSons]};

ListLength: PUBLIC PROC [t: Tree.Link] RETURNS [CARDINAL] = {
IF t = Tree.Null THEN RETURN [0];
WITH t SELECT FROM
subtree => {
node: Tree.Index = index;
n: CARDINAL;
IF tb[node].name # $list THEN RETURN [1];
n _ tb[node].nSons;
IF n # 0 THEN RETURN [n];
FOR i: CARDINAL _ 1, i+1 UNTIL tb[node].son[i] = endMark DO
n _ n+1 ENDLOOP;
RETURN [n]};
ENDCASE => RETURN [1]};

GetNode: PUBLIC PROC [t: Tree.Link] RETURNS [Tree.Index] = {
RETURN [NARROW[t, Tree.Link.subtree].index]};

}.