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RT = { EMPTY_ARRAY: [] };
function APersistentVector( _meta ) {
this._meta = _meta;
}
APersistentVector.prototype.meta = function() {
return this._meta;
};
APersistentVector.prototype.peek = function() {
if( this.count() > 0 ) {
return this.nth( this.count() - 1 );
}
return null;
};
function PersistentVector( _meta, cnt, shift, root, tail ) {
APersistentVector.call( this, _meta );
this._meta = _meta;
this.cnt = cnt;
this.shift = shift;
this.root = root;
this.tail = tail;
}
PersistentVector.prototype = new APersistentVector( null );
PersistentVector.contraction = PersistentVector;
PersistentVector.prototype.tailoff = function() {
return this.cnt - this.tail.length;
};
PersistentVector.prototype.nth = function( i ) {
if( i >= 0 && i < this.cnt ) {
if( i >= this.tailoff() ) {
return this.tail[ i & 0x01f ];
}
var arr = this.root;
for( var level = this.shift; level > 0; level -= 5 ) {
arr = arr[ (i >>> level) & 0x01f ];
}
return arr[ i & 0x01f ];
}
throw "IndexOutOfBoundsException";
};
PersistentVector.prototype.assocN = function( i, val ) {
if( i >= 0 && i < this.cnt ) {
if( i >= this.tailoff() ) {
var newTail = this.tail.slice( 0 );
newTail[ i & 0x01f ] = val;
return new PersistentVector(
this.meta(), this.cnt, this.shift, this.root, newTail );
}
return new PersistentVector(
this.meta(), this.cnt, this.shift,
this.doAssoc( this.shift, this.root, i, val), this.tail );
}
if( i == this.cnt ) {
return this.cons( val );
}
throw "IndexOutOfBoundsException";
};
PersistentVector.prototype.doAssoc = function( level, arr, i, val ) {
var ret = arr.slice( 0 );
if( level == 0 ) {
ret[ i & 0x01f ] = val;
}
else {
var subidx = (i >>> level) & 0x01f;
ret[ subidx ] = this.doAssoc( level - 5, arr[ subidx ], i, val );
}
return ret;
};
PersistentVector.prototype.count = function() {
return this.cnt;
};
PersistentVector.prototype.withMeta = function( _meta ) {
return new PersistentVector(
_meta, this.cnt, this.shift, this.root, this.tail );
};
PersistentVector.prototype.cons = function( val ) {
if( this.tail.length < 32 ) {
var newTail = this.tail.concat( [val] );
return new PersistentVector(
this.meta(), this.cnt + 1, this.shift, this.root, newTail );
}
var expansion = [null];
var newroot = this.pushTail( this.shift - 5, this.root, this.tail, expansion);
var newshift = this.shift;
if( expansion[0] != null ) {
newroot = [newroot, expansion[0]];
newshift += 5;
}
return new PersistentVector(
this.meta(), this.cnt+1, newshift, newroot, [val] );
};
PersistentVector.prototype.empty = function() {
return PersistentVector.EMPTY.withMeta( this.meta() );
};
PersistentVector.prototype.pushTail = function( level, arr, tailNode, expansion)
{
var newchild;
if( level == 0 ) {
newchild = tailNode;
}
else {
newchild = this.pushTail(
level - 5, arr[arr.length - 1], tailNode, expansion);
if( expansion[0] == null ) {
var ret = arr.slice( 0 );
ret[ arr.length - 1 ] = newchild;
return ret;
}
else {
newchild = expansion[0];
}
}
//expansion
if( arr.length == 32 ) {
expansion[0] = [newchild];
return arr;
}
expansion[0] = null;
return arr.concat([newchild]);
};
PersistentVector.prototype.pop = function() {
if( this.cnt == 0 ) {
throw "IllegalStateException: Can't pop empty vector";
}
if( this.cnt == 1 ) {
return PersistentVector.EMPTY.withMeta( this.meta() );
}
if( this.tail.length > 1 ) {
var newTail = this.tail.slice( 0, this.tail.length - 1 );
return new PersistentVector(
this.meta(), this.cnt - 1, this.shift, this.root, newTail );
}
var ptail = [null];
var newroot = this.popTail( this.shift - 5, this.root, ptail );
var newshift = this.shift;
if( newroot == null ) {
newroot = RT.EMPTY_ARRAY;
}
if( this.shift > 5 && newroot.length == 1 ) {
newroot = newroot[0];
newshift -= 5;
}
return new PersistentVector(
this.meta(), this.cnt - 1, newshift, newroot, ptail[0] );
};
PersistentVector.prototype.popTail = function( shift, arr, ptail ) {
if( shift > 0 ) {
var newchild = this.popTail( shift - 5, arr[ arr.length - 1 ], ptail );
if( newchild != null ) {
var ret = arr.slice( 0 );
ret[ arr.length - 1 ] = newchild;
return ret;
}
}
if( shift == 0 ) {
ptail[0] = arr[ arr.length - 1 ];
}
//contraction
if( arr.length == 1 ) {
return null;
}
return arr.slice( 0, arr.length - 1 );
};
PersistentVector.EMPTY = new PersistentVector(
{}, 0, 5, RT.EMPTY_ARRAY, RT.EMPTY_ARRAY );
PersistentVector.create = function( items ) {
var ret = PersistentVector.EMPTY;
for( var i = 0; i < items.length; ++i ) {
ret = ret.cons( items[ i ] );
}
return ret;
}
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