gecko-dev/xpfe/bootstrap/appleevents/patricia.c

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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* The Original Code is Mozilla Communicator client code.
*
* The Initial Developer of the Original Code is
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* Portions created by the Initial Developer are Copyright (C) 1998
* the Initial Developer. All Rights Reserved.
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* Contributor(s):
* Simon Fraser <sfraser@netscape.com>
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/*---------------------------------------------------------------------
Patricia
D.R. Morrison's "Practical Algorithm To Retrieve Information
Coded in Alphanumeric"
This implementation geared towards the storage of data that
is indexed through arbitrary-length binary keys (e.g. sequence
data). It also only deals with the case where every key is unique;
duplicate keys are not entered into the tree, although you may
do some processing on duplicates in the ReplaceFunction passed
to PatriciaInsert.
There is no function to remove nodes from the tree at present.
The implementation is modular, in the sense that all tree data structures
are declared in this file, and are not intended to be accessed externally.
You should only use the functions prototyped in patricia.h, all of which
start with 'Patricia', and should consider the tree as an opaque data
structure.
Ref: Donald R. Morrison. PATRICIA -- practical algorithm to retrieve
information coded in alphanumeric. Journal of the ACM, 15(4):514-534,
October 1968
See Sedgewick, R. Algorithms, 2nd Ed. (1988) for implemenation details.
-----------------------------------------------------------------------*/
#include <string.h>
#include <stdlib.h>
//#include "utils.h"
#include "patricia.h"
#include "nsAEDefs.h" // for AE_ASSERT
/* Uncomment to print verbose logging on tree activity */
//#define VERBOSE
/* Data structures */
typedef struct TNodeTag {
unsigned char *key; /* The node's key value in an array of chars */
short bit; /* The bit that is examined at this node */
long nodeID; /* Unique ID for each node, used for debugging */
struct TNodeTag *left; /* Pointer to left child node */
struct TNodeTag *right; /* Pointer to right child node */
void *data; /* Pointer to user-defined data structure */
} TNode;
typedef struct {
TNode* headNode; /* Pointer to dummy head node */
long numKeyBits; /* Size of keys, in bits */
long keySize; /* Size of keys, in chars (assumed to be 8 bits each) */
long numNodes; /* Number of nodes in tree */
} TPatriciaTree;
/* These macros assume that key is a *[unsigned] char, and that a char is 8 bits big */
#define TestKeyBit(key, bit) ( (key[bit >> 3] & (1 << (bit & 7))) != 0 )
#define CompareKeyBits(key1, key2, bit) ( (key1[bit >> 3] & (1 << (bit & 7))) == (key2[bit >> 3] & (1 << (bit & 7))) )
/*---------------------------------------------------------------------
MakeNewNode
Allocates a new node as an object on the heap, and initializes
the key and bit values to those supplied.
Entry: key binary key data
bit bit value
nodeData user data for this node, if any.
Exit: return value pointer to the new node, or NULL on error
-----------------------------------------------------------------------*/
static TNode *MakeNewNode(TPatriciaTree *tree, const unsigned char *key, short bit, void *nodeData)
{
static long nodeID = 0;
TNode *newNode;
newNode = (TNode *)calloc(1, sizeof(TNode));
if (newNode == NULL) return NULL;
newNode->key = (unsigned char *)calloc(tree->keySize + 1, 1); //last bit must be zero
if (newNode->key == NULL) {
free(newNode);
return NULL;
}
memcpy(newNode->key, key, tree->keySize);
newNode->bit = bit;
newNode->data = nodeData;
newNode->nodeID = nodeID;
nodeID ++;
return newNode;
}
/*---------------------------------------------------------------------
MakeHeadNode
Allocates the dummy head node of the tree, which is initialized to
key field = 000000...
bits = numKeyBits
left & right = point to self
data = NULL
Exit: return value pointer to the new node, or NULL on error
-----------------------------------------------------------------------*/
static TNode *MakeHeadNode(TPatriciaTree *tree)
{
TNode *newNode;
newNode = (TNode *)calloc(1, sizeof(TNode));
if (newNode == NULL) return NULL;
newNode->key = (unsigned char *)calloc(tree->keySize + 1, 1); //last bit must be zero
if (newNode->key == NULL) {
free(newNode);
return NULL;
}
memset(newNode->key, 0, tree->keySize);
newNode->bit = tree->numKeyBits;
newNode->data = NULL;
newNode->nodeID = -1;
/* Both self-pointers for the head node */
newNode->left = newNode;
newNode->right = newNode;
return newNode;
}
/*---------------------------------------------------------------------
InternalSearch
Search the tree for a node with the given key, starting at
startNode.
Entry: tree pointer to a tree
key binary key data
startNode node to start the search (must NOT be NULL)
Exit: return value: pointer to found node, or node with upward
link. The caller must verify whether this
is the node wanted by comparing keys.
-----------------------------------------------------------------------*/
static TNode *InternalSearch(TPatriciaTree *tree, TNode *x, const unsigned char *key)
{
TNode *p;
AE_ASSERT(x, "No node");
do {
p = x;
if (TestKeyBit(key, x->bit))
x = x->right;
else
x = x->left;
} while (p->bit > x->bit);
return x;
}
/*---------------------------------------------------------------------
InternalTraverse
A traverse routine used internally.
Entry: tree pointer to a tree
key binary key data
x node to start the search (must NOT be NULL)
traverseFunc function called on each node, like this:
(*traverseFunc)(x->data, x->key, arg1, arg2);
Exit: return value: 0 if everything OK
Non-zero value on error
-----------------------------------------------------------------------*/
static int InternalTraverse(TPatriciaTree *tree, TNode *x, NodeTraverseFunction traverseFunc, void *arg1, void *arg2)
{
TNode *p;
int err = 0;
AE_ASSERT(x, "No node");
AE_ASSERT(x->left && x->right, "Left or right child missing");
#ifdef VERBOSE
printf("Visiting node %ld with left %ld and right %ld\n", x->nodeID, x->left->nodeID, x->right->nodeID);
#endif
if (x != tree->headNode) {
err = (*traverseFunc)(x->data, x->key, arg1, arg2);
if (err != 0) return err;
}
p = x->left;
if (p->bit < x->bit)
err = InternalTraverse(tree, p, traverseFunc, arg1, arg2);
if (err != 0) return err;
p = x->right;
if (p->bit < x->bit)
err = InternalTraverse(tree, p, traverseFunc, arg1, arg2);
return err;
}
/*---------------------------------------------------------------------
TraverseAndFree
A traverse routine used internall.
Entry: tree pointer to a tree
key binary key data
x node to start the search (must NOT be NULL)
traverseFunc function called on each node, like this:
(*traverseFunc)(x->data, x->key, arg1, arg2);
Exit: return value: 0 if everything OK
Non-zero value on error
-----------------------------------------------------------------------*/
static int TraverseAndFree(TPatriciaTree *tree, TNode *x, NodeFreeFunction freeFunc, void *refCon)
{
TNode *p;
int err = 0;
AE_ASSERT(x, "No node");
AE_ASSERT(x->left && x->right, "Left or right child missing");
p = x->left;
if (p->bit < x->bit) {
err = TraverseAndFree(tree, p, freeFunc, refCon);
if (err != 0) return err;
}
p = x->right;
if (p->bit < x->bit) {
err = TraverseAndFree(tree, p, freeFunc, refCon);
if (err != 0) return err;
}
err = (*freeFunc)(x->data, x->key, refCon);
#ifdef VERBOSE
printf("Freeing node %ld\n", x->nodeID);
#endif
free(x->key);
free(x);
return err;
}
#pragma mark -
/*---------------------------------------------------------------------
InitPatriciaTree
Allocate and initialize a new, empty PatriciaTree.
Entry: keySize length of the keys, in bits
Exit: return value A reference to the created PatriciaTree,
or NULL on error.
-----------------------------------------------------------------------*/
PatriciaTreeRef PatriciaInitTree(long numKeyBits)
{
TPatriciaTree *tree = NULL;
tree = (TPatriciaTree *)calloc(1, sizeof(TPatriciaTree));
if (tree == NULL) return NULL;
tree->numKeyBits = numKeyBits;
tree->keySize = (numKeyBits >> 3) + ((numKeyBits & 7) != 0);
tree->numNodes = 0;
tree->headNode = MakeHeadNode(tree);
if (tree->headNode == NULL) {
free(tree);
return NULL;
}
return (PatriciaTreeRef)tree;
}
/*---------------------------------------------------------------------
PatriciaFreeTree
Free a Patricia tree and all associate data structures. freeFunc is
called on each node's node->data. If no freeFunc is supplied, then
the node->data will NOT be freed.
Entry: treeRef reference to a previously allocated PatriciaTree
freeFunc a function that is called on each node->data
arg pointer to data that is also passed to the free function.
The free function is called like this: (*freeFunc)(node->data, node->key, arg)
-----------------------------------------------------------------------*/
void PatriciaFreeTree(PatriciaTreeRef treeRef, NodeFreeFunction freeFunc, void *refCon)
{
TPatriciaTree *tree = (TPatriciaTree *)treeRef;
if (tree == NULL) return;
/* Traverse the tree and free the data */
TraverseAndFree(tree, tree->headNode, freeFunc, refCon);
free(tree);
}
/*---------------------------------------------------------------------
PatriciaSearch
Search the tree for the node with the given key.
Entry: key pointer to binary key data
data pointer to placeholder for returned data
If you pass NULL in this argument, no value
will be returned (i.e. I don't deference 0).
Exit: return value 1 if key found (data returned in *data)
0 if key not found (NULL returned in *data)
-----------------------------------------------------------------------*/
int PatriciaSearch(PatriciaTreeRef treeRef, const unsigned char *key, void **data)
{
TPatriciaTree *tree = (TPatriciaTree *)treeRef;
TNode *foundNode;
AE_ASSERT(tree, "Where is my tree?");
foundNode = InternalSearch(tree, tree->headNode, key);
AE_ASSERT(foundNode, "Should have found node");
if (memcmp(foundNode->key, key, tree->keySize) == 0) {
if (data != NULL)
*data = foundNode->data;
return 1;
} else
return 0;
}
/*---------------------------------------------------------------------
PatriciaInsert
Insert a node into the tree with the given key and data.
Entry: key pointer to binary key data
replaceFunc function executed when a node with the key we
are inserting is found in the tree.
data pointer to node data structure
Exit: return value 0 if insertion successful
1 if key already exists
-1 if some other error
-----------------------------------------------------------------------*/
int PatriciaInsert(PatriciaTreeRef treeRef, NodeReplaceFunction replaceFunc, const unsigned char *key, void *data, void *refCon)
{
TPatriciaTree *tree = (TPatriciaTree *)treeRef;
TNode *x, *t, *p;
short i;
x = tree->headNode;
t = InternalSearch(tree, x, key);
AE_ASSERT(t, "Should have found node");
if (memcmp(t->key, key, tree->keySize) == 0) {
if (replaceFunc) (*replaceFunc)(&t->data, t->key, data, refCon);
return 1; /* It's already there */
}
i = tree->numKeyBits - 1;
while (CompareKeyBits(key, t->key, i))
i --;
do {
p = x;
x = (TestKeyBit(key, x->bit)) ? x->right : x->left;
} while (x->bit > i && p->bit > x->bit);
t = MakeNewNode(tree, key, i, data);
if (t == NULL) return -1;
if (TestKeyBit(key, t->bit)) {
t->right = t;
t->left = x;
} else {
t->right = x;
t->left = t;
}
if (TestKeyBit(key, p->bit))
p->right = t;
else
p->left = t;
#ifdef VERBOSE
printf("Inserted node %ld with left %ld and right %ld\n", t->nodeID, t->left->nodeID, t->right->nodeID);
#endif
tree->numNodes ++;
return 0;
}
/*---------------------------------------------------------------------
PatriciaTraverse
Traverse the tree, executing traverseFunc for each node. It's called like
this:
(*traverseFunc)(node->data, node->key, arg1, arg2);
traverseFunc should return 0 if it completes successfully, or any other
value if there is an error. In this case, the traverse is abruptly terminated.
Entry: treeRef reference to a Patricia tree
traverseFunc function to be called on each node
arg1, arg2 arguments passed to traverseFunc
Exit: return value 0 if traverse competed successfully
-1 if something caused the traverse to
terminate.
-----------------------------------------------------------------------*/
int PatriciaTraverse(PatriciaTreeRef treeRef, NodeTraverseFunction traverseFunc, void *arg, void *refCon)
{
TPatriciaTree *tree = (TPatriciaTree *)treeRef;
return InternalTraverse(tree, tree->headNode, traverseFunc, arg, refCon);
}
/*---------------------------------------------------------------------
PatriciaGetNumNodes
Return the number of nodes in the tree
-----------------------------------------------------------------------*/
long PatriciaGetNumNodes(PatriciaTreeRef treeRef)
{
return ((TPatriciaTree *)treeRef)->numNodes;
}