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philiprbrenanphiliprbrenan
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‎BtreeBan.java‎

Lines changed: 61 additions & 39 deletions
Original file line numberDiff line numberDiff line change
@@ -122,7 +122,7 @@ LayoutBam layoutBtree() //
122122
array("stealFromRight"); // Whether the steal from the right was successful
123123
array("stealFromRight_parent"); // The parent of the branch which wants to steal from the right child
124124
array("stealFromRight_index"); // The index of the child that wants to steal from the right sibling in its parent
125-
array("stealFromRight_parentBranchSize"); // Parent branch size
125+
array("stealFromRight_nP"); // Parent branch size
126126
array("stealFromRight_right"); // Index of sibling on right
127127
array("stealFromRight_l"); // Left child index
128128
array("stealFromRight_lk"); // Left child key
@@ -133,6 +133,13 @@ LayoutBam layoutBtree() //
133133
array("stealFromRight_td"); //
134134
array("stealFromRight_bd"); //
135135

136+
array("mergeRoot_nP"); // Number in root
137+
array("mergeRoot_l"); // Left child of root
138+
array("mergeRoot_r"); // Right child of node
139+
array("mergeRoot_nl"); // Number in left child
140+
array("mergeRoot_nr"); // Number in right child
141+
array("mergeRoot_pkn"); //
142+
136143
array("mergeLeftSibling"); // Whether the merge with the left sibling was successful
137144
array("mergeLeftSibling_parent"); // The parent of the branch which wants to merge with its left sibling
138145
array("mergeLeftSibling_index"); // The index of the child that wants to steal from the child in its parent
@@ -187,6 +194,15 @@ void allocate() //
187194
L.zero("keys", a); L.zero("data", a);
188195
}
189196

197+
void free(String f) // Free a new node to make it available for reuse
198+
{final int n = L.get(f);
199+
if (n == 0) stop("Cannot free root"); // The root is never freed
200+
L.ones("free", f); L.ones("isLeaf", f); L.ones("current_size", f); // Invalidate all control information
201+
L.ones("keys", f); L.ones("data", f);
202+
L.move("free", "freeChainHead", f); // Chain this node in front of the last freed node
203+
L.move("freeChainHead", f); // Freed node becomes head of the free chain
204+
}
205+
190206
void free() // Free a new node to make it available for reuse
191207
{final String f = "free_1"; // Index of node to be freed
192208
final int n = L.get(f);
@@ -438,7 +454,7 @@ void stealFromRight() //
438454
final String $P = "stealFromRight_parent"; // Parent node
439455
final String $index = "stealFromRight_index"; // Index of child stealing from the right sibling
440456
final String $parent = "stealFromRight_parent"; // The parent of the branch which wants to steal from the right child
441-
final String $nP = "stealFromRight_parentBranchSize"; // Parent branch size
457+
final String $nP = "stealFromRight_nP"; // Parent branch size
442458
final String $right = "stealFromRight_right"; // Index of sibling on right
443459
final String $l = "stealFromRight_l"; // Left child index
444460
final String $lk = "stealFromRight_lk"; // Left child key
@@ -488,58 +504,64 @@ void stealFromRight() //
488504
//D2 Merge // Merge two nodes together and free the resulting free node
489505

490506
void mergeRoot() // Merge into the root
491-
{rootIsLeaf();
507+
{final String $nP = "mergeRoot_nP";
508+
final String $l = "mergeRoot_l";
509+
final String $r = "mergeRoot_r";
510+
final String $nl = "mergeRoot_nl";
511+
final String $nr = "mergeRoot_nr";
512+
final String $pkn = "mergeRoot_pkn";
513+
514+
rootIsLeaf();
492515
if (L.get("rootIsLeaf") > 0) return;
493-
L.set(0, "branchSize_1"); branchSize(); final int nP = L.get("branchSize");
494-
if (nP > 1) return;
516+
L.set(0, "branchSize_1"); branchSize(); L.move($nP, "branchSize");
517+
if (L.get($nP) > 1) return;
495518

496-
int P = 0;
497-
setStuck(P);
498-
stuck_firstElement(); int l = getData();
499-
stuck_lastElement (); int r = getData();
519+
setStuck(0);
520+
stuck_firstElement(); getData($l);
521+
stuck_lastElement (); getData($r);
500522

501-
L.set(P, "hasLeavesForChildren_1"); // Children are leaves
523+
L.move("hasLeavesForChildren_1", "root");
502524
hasLeavesForChildren();
503525
if (L.get("hasLeavesForChildren") > 0) // Children are leaves
504-
{L.set(l, "leafSize_1"); leafSize(); final int nl = L.get("leafSize");
505-
L.set(r, "leafSize_1"); leafSize(); final int nr = L.get("leafSize");
526+
{L.move("leafSize_1", $l); leafSize(); L.move($nl, "leafSize");
527+
L.move("leafSize_1", $r); leafSize(); L.move($nr, "leafSize");
506528

507-
if (nl + nr <= maxKeysPerLeaf)
508-
{setStuck(P); stuck_clear();
509-
for (int i = 0; i < nl; ++i)
510-
{setStuck(l); stuck_shift();
511-
setStuck(P); stuck_push();
529+
if (L.get($nl) + L.get($nr) <= maxKeysPerLeaf)
530+
{setStuck("root"); stuck_clear();
531+
for (int i = 0; i < L.get($nl); ++i)
532+
{setStuck($l); stuck_shift();
533+
setStuck("root"); stuck_push();
512534
}
513-
for (int i = 0; i < nr; ++i)
514-
{setStuck(r); stuck_shift();
515-
setStuck(P); stuck_push();
535+
for (int i = 0; i < L.get($nr); ++i)
536+
{setStuck($r); stuck_shift();
537+
setStuck("root"); stuck_push();
516538
}
517-
L.set(P, "setLeaf"); setLeaf();
518-
L.set(l, "free_1"); free();
519-
L.set(r, "free_1"); free();
539+
L.move("setLeaf", "root"); setLeaf();
540+
free($l);
541+
free($r);
520542
}
521543
}
522544
else
523-
{L.set(l, "branchSize_1"); branchSize(); final int nl = L.get("branchSize");
524-
L.set(r, "branchSize_1"); branchSize(); final int nr = L.get("branchSize");
525-
if (nl + 1 + nr > maxKeysPerBranch) return;
526-
setStuck(P); stuck_firstElement(); final int pkn = getKey();
545+
{L.move("branchSize_1", $l); branchSize(); L.move($nl, "branchSize");
546+
L.move("branchSize_1", $r); branchSize(); L.move($nr, "branchSize");
547+
if (L.get($nl) + 1 + L.get($nr) > maxKeysPerBranch) return;
548+
setStuck("root"); stuck_firstElement(); getKey($pkn);
527549
stuck_clear();
528-
for (int i = 0; i < nl; ++i)
529-
{setStuck(l); stuck_shift();
530-
setStuck(P); stuck_push();
550+
for (int i = 0; i < L.get($nl); ++i)
551+
{setStuck($l); stuck_shift();
552+
setStuck("root"); stuck_push();
531553
}
532-
setStuck(l); stuck_lastElement();
533-
setStuck(P); setKey(pkn); stuck_push();
554+
setStuck($l); stuck_lastElement();
555+
setStuck("root"); setKey($pkn); stuck_push();
534556

535-
for (int i = 0; i < nr; ++i)
536-
{setStuck(r); stuck_shift();
537-
setStuck(P); stuck_push();
557+
for (int i = 0; i < L.get($nr); ++i)
558+
{setStuck($r); stuck_shift();
559+
setStuck("root"); stuck_push();
538560
}
539-
setStuck(r); stuck_lastElement(); // Top next
540-
setStuck(P); setKey(0); stuck_push(); // Top so ignored by search ... except last
541-
L.set(l, "free_1"); free();
542-
L.set(r, "free_1"); free();
561+
setStuck($r); stuck_lastElement(); // Top next
562+
setStuck("root"); setKey("root"); stuck_push(); // Top so ignored by search ... except last
563+
free($l);
564+
free($r);
543565
}
544566
}
545567

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