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org.apache.xmlbeans.impl.common.XPath Maven / Gradle / Ivy
/* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.xmlbeans.impl.common;
import javax.xml.namespace.QName;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.HashMap;
import org.apache.xmlbeans.XmlError;
import org.apache.xmlbeans.XmlException;
import org.apache.xmlbeans.impl.common.XMLChar;
public class XPath
{
public static class XPathCompileException extends XmlException
{
XPathCompileException ( XmlError err )
{
super( err.toString(), null, err );
}
}
//
//
//
public static class ExecutionContext
{
public ExecutionContext ( )
{
_stack = new ArrayList();
}
public static final int HIT = 0x1;
public static final int DESCEND = 0x2;
public static final int ATTRS = 0x4;
public final void init ( XPath xpath )
{
if (_xpath != xpath)
{
_xpath = xpath;
_paths = new PathContext [ xpath._selector._paths.length ];
for ( int i = 0 ; i < _paths.length ; i++ )
_paths[ i ] = new PathContext();
}
_stack.clear();
for ( int i = 0 ; i < _paths.length ; i++ )
_paths[ i ].init( xpath._selector._paths[ i ] );
}
public final int start ( )
{
int result = 0;
for ( int i = 0 ; i < _paths.length ; i++ )
result |= _paths[ i ].start();
return result;
}
public final int element ( QName name )
{
assert name != null;
_stack.add( name );
int result = 0;
for ( int i = 0 ; i < _paths.length ; i++ )
result |= _paths[ i ].element( name );
return result;
}
public final boolean attr ( QName name )
{
boolean hit = false;
for ( int i = 0 ; i < _paths.length ; i++ )
hit = hit | _paths[ i ].attr( name );
return hit;
}
public final void end ( )
{
_stack.remove( _stack.size() - 1 );
for ( int i = 0 ; i < _paths.length ; i++ )
_paths[ i ].end();
}
private final class PathContext
{
PathContext ( )
{
_prev = new ArrayList();
}
void init ( Step steps )
{
_curr = steps;
_prev.clear();
}
private QName top ( int i )
{
return (QName) ExecutionContext.this._stack.get( _stack.size() - 1 - i );
}
// goes back to the begining of the sequence since last // wildcard
private void backtrack ( )
{
assert _curr != null;
if (_curr._hasBacktrack)
{ // _backtrack seems to be a pointer to the step that follows a // wildcard
// ex: for .//b/c/d steps c and d should backtrack to b in case there isn't a match
_curr = _curr._backtrack;
return;
}
assert !_curr._deep;
_curr = _curr._prev;
search: for ( ; !_curr._deep ; _curr = _curr._prev )
{
int t = 0;
for ( Step s = _curr ; !s._deep ; s = s._prev )
{
if (!s.match( top( t++ )))
continue search;
}
break;
}
}
int start ( )
{
assert _curr != null;
assert _curr._prev == null;
if (_curr._name != null)
return _curr._flags;
// If the steps consist on only a terminator, then the path can
// only be '.'. In this case, we get a hit, but there is
// nothing else to match. No need to backtrack.
_curr = null;
return HIT;
}
int element ( QName name )
{
//System.out.println(" Path.element: " + name);
_prev.add( _curr );
if (_curr == null)
return 0;
assert _curr._name != null;
if (!_curr._attr && _curr.match( name ))
{
if ((_curr = _curr._next)._name != null)
return _curr._flags;
backtrack();
//System.out.println(" element - HIT " + _curr._flags);
return _curr == null ? HIT : HIT | _curr._flags;
}
for ( ; ; )
{
backtrack();
if (_curr == null)
return 0;
if (_curr.match( name ))
{
_curr = _curr._next;
break;
}
if (_curr._deep)
break;
}
return _curr._flags;
}
boolean attr ( QName name )
{
return _curr != null && _curr._attr && _curr.match( name );
}
void end ( )
{
//System.out.println(" Path.end ");
_curr = (Step) _prev.remove( _prev.size() - 1 );
}
private Step _curr;
private List _prev;
}
private XPath _xpath;
private ArrayList _stack;
private PathContext[] _paths;
}
//
//
//
public static XPath compileXPath ( String xpath )
throws XPathCompileException
{
return compileXPath( xpath, "$this", null );
}
public static XPath compileXPath ( String xpath, String currentNodeVar )
throws XPathCompileException
{
return compileXPath( xpath, currentNodeVar, null );
}
public static XPath compileXPath ( String xpath, Map namespaces )
throws XPathCompileException
{
return compileXPath( xpath, "$this", namespaces );
}
public static XPath compileXPath (
String xpath, String currentNodeVar, Map namespaces )
throws XPathCompileException
{
return
new CompilationContext( namespaces, currentNodeVar ).
compile( xpath );
}
private static class CompilationContext
{
CompilationContext ( Map namespaces, String currentNodeVar )
{
assert
_currentNodeVar == null ||
_currentNodeVar.startsWith( "$" );
if (currentNodeVar == null)
_currentNodeVar = "$this";
else
_currentNodeVar = currentNodeVar;
_namespaces = new HashMap();
_externalNamespaces =
namespaces == null ? new HashMap() : namespaces;
}
XPath compile ( String expr ) throws XPathCompileException
{
_offset = 0;
_line = 1;
_column = 1;
_expr = expr;
return tokenizeXPath();
}
int currChar ( )
{
return currChar( 0 );
}
int currChar ( int offset )
{
return
_offset + offset >= _expr.length()
? -1
: _expr.charAt( _offset + offset );
}
void advance ( )
{
if (_offset < _expr.length())
{
char ch = _expr.charAt( _offset );
_offset++;
_column++;
if (ch == '\r' || ch == '\n')
{
_line++;
_column = 1;
if (_offset + 1 < _expr.length())
{
char nextCh = _expr.charAt( _offset + 1 );
if ((nextCh == '\r' || nextCh == '\n') && ch != nextCh)
_offset++;
}
}
}
}
void advance ( int count )
{
assert count >= 0;
while ( count-- > 0 )
advance();
}
boolean isWhitespace ( )
{
return isWhitespace( 0 );
}
boolean isWhitespace ( int offset )
{
int ch = currChar( offset );
return ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r';
}
boolean isNCNameStart ( )
{
return
currChar() == -1
? false :
XMLChar.isNCNameStart( currChar() );
}
boolean isNCName ( )
{
return
currChar() == -1
? false :
XMLChar.isNCName( currChar() );
}
boolean startsWith ( String s )
{
return startsWith( s, 0 );
}
boolean startsWith ( String s, int offset )
{
if (_offset + offset >= _expr.length())
return false;
return _expr.startsWith( s, _offset + offset );
}
private XPathCompileException newError ( String msg )
{
XmlError err =
XmlError.forLocation(
msg, XmlError.SEVERITY_ERROR, null,
_line, _column, _offset );
return new XPathCompileException( err );
}
String lookupPrefix ( String prefix ) throws XPathCompileException
{
if (_namespaces.containsKey( prefix ))
return (String) _namespaces.get( prefix );
if (_externalNamespaces.containsKey( prefix ))
return (String) _externalNamespaces.get( prefix );
if (prefix.equals( "xml" ))
return "http://www.w3.org/XML/1998/namespace";
if (prefix.equals( "xs" ))
return "http://www.w3.org/2001/XMLSchema";
if (prefix.equals( "xsi" ))
return "http://www.w3.org/2001/XMLSchema-instance";
if (prefix.equals( "fn" ))
return "http://www.w3.org/2002/11/xquery-functions";
if (prefix.equals( "xdt" ))
return "http://www.w3.org/2003/11/xpath-datatypes";
if (prefix.equals( "local" ))
return "http://www.w3.org/2003/11/xquery-local-functions";
throw newError( "Undefined prefix: " + prefix );
}
private boolean parseWhitespace ( ) throws XPathCompileException
{
boolean sawSpace = false;
while ( isWhitespace() )
{
advance();
sawSpace = true;
}
return sawSpace;
}
//
// Tokenizing will consume whitespace followed by the tokens, separated
// by whitespace. The whitespace following the last token is not
// consumed.
//
private boolean tokenize ( String s )
{
assert s.length() > 0;
int offset = 0;
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s, offset ))
return false;
offset += s.length();
advance( offset );
return true;
}
private boolean tokenize ( String s1, String s2 )
{
assert s1.length() > 0;
assert s2.length() > 0;
int offset = 0;
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s1, offset ))
return false;
offset += s1.length();
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s2, offset ))
return false;
offset += s2.length();
advance( offset );
return true;
}
private boolean tokenize ( String s1, String s2, String s3)
{
assert s1.length() > 0;
assert s2.length() > 0;
assert s3.length() > 0;
int offset = 0;
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s1, offset ))
return false;
offset += s1.length();
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s2, offset ))
return false;
offset += s2.length();
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s3, offset ))
return false;
offset += s3.length();
while ( isWhitespace( offset ) )
offset++;
advance( offset );
return true;
}
private boolean tokenize ( String s1, String s2, String s3,String s4) {
assert s1.length() > 0;
assert s2.length() > 0;
assert s3.length() > 0;
assert s4.length() > 0;
int offset = 0;
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s1, offset ))
return false;
offset += s1.length();
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s2, offset ))
return false;
offset += s2.length();
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s3, offset ))
return false;
offset += s3.length();
while ( isWhitespace( offset ) )
offset++;
if (!startsWith( s4, offset ))
return false;
offset += s4.length();
advance( offset );
return true;
}
private String tokenizeNCName ( ) throws XPathCompileException
{
parseWhitespace();
if (!isNCNameStart())
throw newError( "Expected non-colonized name" );
StringBuffer sb = new StringBuffer();
sb.append( (char) currChar() );
for ( advance() ; isNCName() ; advance() )
sb.append( (char) currChar() );
return sb.toString();
}
private QName getAnyQName ( )
{
return new QName( "", "" );
}
private QName tokenizeQName ( ) throws XPathCompileException
{
if (tokenize( "*" ))
return getAnyQName();
String ncName = tokenizeNCName();
if (!tokenize( ":" ))
return new QName( lookupPrefix( "" ), ncName );
return
new QName(
lookupPrefix( ncName ),
tokenize( "*" ) ? "" : tokenizeNCName() );
}
private String tokenizeQuotedUri ( ) throws XPathCompileException
{
char quote;
if (tokenize( "\"" ))
quote = '"';
else if (tokenize( "'" ))
quote = '\'';
else
throw newError( "Expected quote (\" or ')" );
StringBuffer sb = new StringBuffer();
for ( ; ; )
{
if (currChar() == -1)
throw newError( "Path terminated in URI literal" );
if (currChar() == quote)
{
advance();
if (currChar() != quote)
break;
}
sb.append( (char) currChar() );
advance();
}
return sb.toString();
}
private Step addStep ( boolean deep, boolean attr, QName name, Step steps )
{
Step step = new Step( deep, attr, name );
if (steps == null)
return step;
Step s = steps;
while ( steps._next != null )
steps = steps._next;
steps._next = step;
step._prev = steps;
return s;
}
private Step tokenizeSteps ( ) throws XPathCompileException
{
if (tokenize( "/" ))
throw newError( "Absolute paths unsupported" );
boolean deep;
if (tokenize( "$", _currentNodeVar, "//" ) || tokenize( ".", "//" ))
deep = true;
else if (tokenize( "$", _currentNodeVar, "/" ) || tokenize( ".", "/" ))
deep = false;
else if (tokenize( "$", _currentNodeVar ) || tokenize( "." ))
return addStep( false, false, null, null );
else
deep = false;
Step steps = null;
// Compile the steps removing /. and mergind //. with the next step
boolean deepDot = false;
for ( ; ; )
{
if (tokenize( "attribute", "::" ) || tokenize( "@" ))
{
steps = addStep( deep, true, tokenizeQName(), steps );
break;
}
QName name;
if (tokenize( "." ))
deepDot = deepDot || deep;
else
{
tokenize( "child", "::" );
if ((name = tokenizeQName()) != null)
{
steps = addStep( deep, false, name, steps );
deep = false; // only this step needs to be deep
// other folowing steps will be deep only if they are preceded by // wildcard
}
}
if (tokenize( "//" ))
{
deep = true;
deepDot = false;
}
else if (tokenize( "/" ))
{
if (deepDot)
deep = true;
}
else
break;
}
// If there was a //. at the end of th path, then we need to make
// two paths, one with * at the end and another with @* at the end.
if ((_lastDeepDot = deepDot))
{
_lastDeepDot = true;
steps = addStep( true, false, getAnyQName(), steps );
}
// Add sentinal step (_name == null)
return addStep( false, false, null, steps );
}
private void computeBacktrack ( Step steps )
throws XPathCompileException
{
//
// Compute static backtrack information
//
// Note that I use the fact that _hasBacktrack is initialized to
// false and _backtrack to null in the following code.
//
Step s, t;
for ( s = steps ; s != null ; s = t )
{
// Compute the segment from [ s, t )
for ( t = s._next ; t != null && !t._deep ; )
t = t._next;
// If the segment is NOT rooted at //, then the backtrack is
// null for the entire segment, including possible attr and/or
// sentinal
if (!s._deep)
{
for ( Step u = s ; u != t ; u = u._next )
u._hasBacktrack = true;
continue;
}
// Compute the sequence [ s, u ) of length n which contain no
// wild steps.
int n = 0;
Step u = s;
while ( u != t && u._name != null && !u.isWild() && !u._attr )
{
n++;
u = u._next;
}
// Now, apply KMP to [ s, u ) for fast backtracking
QName [] pattern = new QName [ n + 1 ];
int [] kmp = new int [ n + 1 ];
Step v = s;
for ( int i = 0 ; i < n ; i++ )
{
pattern[ i ] = v._name;
v = v._next;
}
pattern[ n ] = getAnyQName();
int i = 0;
int j = kmp[ 0 ] = -1;
while ( i < n )
{
while ( j > -1 && !pattern[ i ].equals( pattern[ j ] ) )
j = kmp[ j ];
if (pattern[ ++i ].equals( pattern[ ++j ] ))
kmp[ i ] = kmp[ j ];
else
kmp[ i ] = j;
}
i = 0;
for ( v = s ; v != u ; v = v._next )
{
v._hasBacktrack = true;
v._backtrack = s;
for ( j = kmp[ i ] ; j > 0 ; j-- )
v._backtrack = v._backtrack._next;
i++;
}
// Compute the success backtrack and stuff it into an attr and
// sentinal if they exist for this segment
v = s;
if (n > 1)
{
for ( j = kmp[ n - 1 ] ; j > 0 ; j-- )
v = v._next;
}
if (u != t && u._attr)
{
u._hasBacktrack = true;
u._backtrack = v;
u = u._next;
}
if (u != t && u._name == null)
{
u._hasBacktrack = true;
u._backtrack = v;
}
// The first part of a deep segment always backtracks to itself
assert s._deep;
s._hasBacktrack = true;
s._backtrack = s;
}
}
private void tokenizePath ( ArrayList paths )
throws XPathCompileException
{
_lastDeepDot = false;
Step steps = tokenizeSteps();
computeBacktrack( steps );
paths.add( steps );
// If the last path ended in //., that path will match all
// elements, here I make a path which matches all attributes.
if (_lastDeepDot)
{
_sawDeepDot = true;
Step s = null;
for ( Step t = steps ; t != null ; t = t._next )
{
if (t._next != null && t._next._next == null)
s = addStep( t._deep, true, t._name, s );
else
s = addStep( t._deep, t._attr, t._name, s );
}
computeBacktrack( s );
paths.add( s );
}
}
private Selector tokenizeSelector ( ) throws XPathCompileException
{
ArrayList paths = new ArrayList();
tokenizePath( paths );
while ( tokenize( "|" ) )
tokenizePath( paths );
return new Selector( (Step[]) paths.toArray( new Step [ 0 ] ) );
}
private XPath tokenizeXPath ( ) throws XPathCompileException
{
for ( ; ; )
{
if (tokenize( "declare", "namespace" ))
{
if (!parseWhitespace())
throw newError( "Expected prefix after 'declare namespace'" );
String prefix = tokenizeNCName();
if (!tokenize( "=" ))
throw newError( "Expected '='" );
String uri = tokenizeQuotedUri();
if (_namespaces.containsKey( prefix ))
{
throw newError(
"Redefinition of namespace prefix: " + prefix );
}
_namespaces.put( prefix, uri );
//return these to saxon:? Is it an error to pass external NS
//that conflicts? or should we just override it?
if (_externalNamespaces.containsKey( prefix ))
{
throw newError(
"Redefinition of namespace prefix: " + prefix );
}
_externalNamespaces.put( prefix, uri );
if (! tokenize( ";" ))
{
// throw newError(
// "Namespace declaration must end with ;" );
}
_externalNamespaces.put(_NS_BOUNDARY,new Integer(_offset));
continue;
}
if (tokenize( "declare","default", "element", "namespace" ))
{
String uri = tokenizeQuotedUri();
if (_namespaces.containsKey( "" ))
{
throw newError(
"Redefinition of default element namespace" );
}
_namespaces.put( "", uri );
//return these to saxon:? Is it an error to pass external NS
//that conflicts? or should we just override it?
if (_externalNamespaces.containsKey( XPath._DEFAULT_ELT_NS ))
{
throw newError("Redefinition of default element namespace : ");
}
_externalNamespaces.put( XPath._DEFAULT_ELT_NS, uri );
if (! tokenize( ";" ))
throw newError("Default Namespace declaration must end with ;" );
//the boundary is the last ; in the prolog...
_externalNamespaces.put(_NS_BOUNDARY,new Integer(_offset));
continue;
}
break;
}
// Add the default prefix mapping if it has not been redefined
if (!_namespaces.containsKey( "" ))
_namespaces.put( "", "" );
Selector selector = tokenizeSelector();
parseWhitespace();
if (currChar() != -1)
{
throw newError(
"Unexpected char '" + (char) currChar() + "'" );
}
return new XPath( selector, _sawDeepDot );
}
//split of prolog decls that are not standard XPath syntax
//but work in v1
private void processNonXpathDecls(){
}
private String _expr;
private boolean _sawDeepDot; // Saw one overall
private boolean _lastDeepDot;
private String _currentNodeVar;
// private Map _namespaces;
protected Map _namespaces;
private Map _externalNamespaces;
private int _offset;
private int _line;
private int _column;
}
private static final class Step
{
Step ( boolean deep, boolean attr, QName name )
{
_name = name;
_deep = deep;
_attr = attr;
int flags = 0;
if (_deep || !_attr)
flags |= ExecutionContext.DESCEND;
if (_attr)
flags |= ExecutionContext.ATTRS;
_flags = flags;
}
boolean isWild ( )
{
return _name.getLocalPart().length() == 0;
}
boolean match ( QName name )
{
String local = _name.getLocalPart();
String nameLocal = name.getLocalPart();
String uri;
String nameUri;
int localLength = local.length();
int uriLength;
// match any name to _name when _name is empty ""@""
if (localLength==0)
{
uri = _name.getNamespaceURI();
uriLength = uri.length();
if (uriLength==0)
return true;
return uri.equals(name.getNamespaceURI());
}
if (localLength!=nameLocal.length())
return false;
uri = _name.getNamespaceURI();
nameUri = name.getNamespaceURI();
if (uri.length()!=nameUri.length())
return false;
return local.equals(nameLocal) && uri.equals(nameUri);
}
final boolean _attr;
final boolean _deep;
int _flags;
final QName _name;
Step _next, _prev;
boolean _hasBacktrack;
Step _backtrack;
}
private static final class Selector
{
Selector ( Step[] paths )
{
_paths = paths;
}
final Step[] _paths;
}
//
//
//
private XPath ( Selector selector, boolean sawDeepDot )
{
_selector = selector;
_sawDeepDot = sawDeepDot;
}
public boolean sawDeepDot ( )
{
return _sawDeepDot;
}
public static final String _NS_BOUNDARY = "$xmlbeans!ns_boundary";
public static final String _DEFAULT_ELT_NS = "$xmlbeans!default_uri";
private final Selector _selector;
private final boolean _sawDeepDot;
}
