com.ctc.wstx.sr.ElemAttrs Maven / Gradle / Ivy
Show all versions of woodstox-core Show documentation
package com.ctc.wstx.sr;
import javax.xml.namespace.QName;
/**
* Container class that is constructed with enough raw attribute information,
* to be able to lazily construct full attribute objects, to be accessed
* via Iterator, or fully-qualified name.
*
* Implementation note: code for using Map-like structure is unfortunately
* cut'n pasted from {@link AttributeCollector}. Problem
* with refactoring is that it's 90% the same code, but not 100%.
*
* Although instances of this class are constructed by stream readers,
* it is actually used by element event objects.
*/
public final class ElemAttrs
{
//private final static int OFFSET_LOCAL_NAME = 0;
private final static int OFFSET_NS_URI = 1;
//private final static int OFFSET_NS_PREFIX = 2;
//private final static int OFFSET_VALUE = 3;
/**
* Array that contains 4 Strings for each attribute;
* localName, URI, prefix, value. Can be used to lazily construct
* structure(s) needed to return Iterator for accessing all
* attributes.
*/
private final String[] mRawAttrs;
/**
* Raw offset (in mRawAttrs) of the first attribute
* instance that was created through default value expansion.
*/
private final int mDefaultOffset;
/*
//////////////////////////////////////////////////////////////
// Information that defines "Map-like" data structure used for
// quick access to attribute values by fully-qualified name
// (only used for "long" lists)
//////////////////////////////////////////////////////////////
*/
// // // For full explanation, see source for AttributeCollector
private final int[] mAttrMap;
private final int mAttrHashSize;
private final int mAttrSpillEnd;
/**
* Method called to create "short" attribute list; list that has
* only few entries, and can thus be searched for attributes using
* linear search, without using any kind of Map structure.
*
* Currently the limit is 4 attributes; 1, 2 or 3 attribute lists are
* considered short, 4 or more 'long'.
*
* @param rawAttrs Array that contains 4 Strings for each attribute;
* localName, URI, prefix, value. Can be used to lazily construct
* structure(s) needed to return Iterator for accessing all
* attributes.
* @param defOffset Index of the first default attribute, if any;
* number of all attributes if none
*/
public ElemAttrs(String[] rawAttrs, int defOffset)
{
mRawAttrs = rawAttrs;
mAttrMap = null;
mAttrHashSize = 0;
mAttrSpillEnd = 0;
mDefaultOffset = (defOffset << 2);
}
/**
* Method called to create "long" attribute list; list that has
* a few entries, and efficient access by fully-qualified name should
* not be done by linear search.
*
* @param rawAttrs Array that contains 4 Strings for each attribute;
* localName, URI, prefix, value. Can be used to lazily construct
* structure(s) needed to return Iterator for accessing all
* attributes.
*/
public ElemAttrs(String[] rawAttrs, int defOffset,
int[] attrMap, int hashSize, int spillEnd)
{
mRawAttrs = rawAttrs;
mDefaultOffset = (defOffset << 2);
mAttrMap = attrMap;
mAttrHashSize = hashSize;
mAttrSpillEnd = spillEnd;
}
/*
////////////////////////////////////////////////////
// Public API
////////////////////////////////////////////////////
*/
public String[] getRawAttrs() {
return mRawAttrs;
}
public int findIndex(QName name)
{
// Do we have a Map to do lookup against?
if (mAttrMap != null) { // yup
return findMapIndex(name.getNamespaceURI(), name.getLocalPart());
}
// Nope, linear search:
String ln = name.getLocalPart();
String uri = name.getNamespaceURI();
boolean defaultNs = (uri == null || uri.length() == 0);
String[] raw = mRawAttrs;
for (int i = 0, len = raw.length; i < len; i += 4) {
if (!ln.equals(raw[i])) {
continue;
}
String thisUri = raw[i+OFFSET_NS_URI]; // lgtm [java/index-out-of-bounds]
if (defaultNs) {
if (thisUri == null || thisUri.length() == 0) {
return i;
}
} else { // non-default NS
if (thisUri != null &&
(thisUri == uri || thisUri.equals(uri))) {
return i;
}
}
}
return -1;
}
public int getFirstDefaultOffset() {
return mDefaultOffset;
}
public boolean isDefault(int ix) {
return (ix >= mDefaultOffset);
}
/*
////////////////////////////////////////////////////
// Internal methods
////////////////////////////////////////////////////
*/
/**
*
* Note: this method is very similar to
* {@link com.ctc.wstx.sr.AttributeCollector#getAttrValue}; basically
* most of it was cut'n pasted. Would be nice to refactor, but it's
* bit hard to do that since data structures are not 100% identical
* (mostly attribute storage, not Map structure itself).
*/
private final int findMapIndex(String nsURI, String localName)
{
// Primary hit?
int hash = localName.hashCode();
if (nsURI == null) {
nsURI = ""; // just to simplify comparisons -- array contains nulls
} else if (nsURI.length() > 0) {
hash ^= nsURI.hashCode();
}
int ix = mAttrMap[hash & (mAttrHashSize - 1)];
if (ix == 0) { // nothing in here; no spills either
return -1;
}
// Index is "one off" (since 0 indicates 'null), 4 Strings per attr
ix = (ix - 1) << 2;
// Is primary candidate match?
String[] raw = mRawAttrs;
String thisName = raw[ix];
/* Equality first, since although equals() checks that too, it's
* very likely to match (if interning Strings), and we can save
* a method call.
*/
if (thisName == localName || thisName.equals(localName)) {
String thisURI = raw[ix+OFFSET_NS_URI];
if (thisURI == nsURI) {
return ix;
}
if (thisURI == null) {
if (nsURI.length() == 0) {
return ix;
}
} else if (thisURI.equals(nsURI)) {
return ix;
}
}
/* Nope, need to traverse spill list, which has 2 entries for
* each spilled attribute id; first for hash value, second index.
*/
for (int i = mAttrHashSize, len = mAttrSpillEnd; i < len; i += 2) {
if (mAttrMap[i] != hash) {
continue;
}
/* Note: spill indexes are not off-by-one, since there's no need
* to mask 0
*/
ix = mAttrMap[i+1] << 2; // ... but there are 4 Strings for each attr
thisName = raw[ix];
if (thisName == localName || thisName.equals(localName)) {
String thisURI = raw[ix+1];
if (thisURI == nsURI) {
return ix;
}
if (thisURI == null) {
if (nsURI.length() == 0) {
return ix;
}
} else if (thisURI.equals(nsURI)) {
return ix;
}
}
}
return -1;
}
}