EqualityExpr.java revision 628:2bfaf29cc90b 
1/*
2 * reserved comment block
3 * DO NOT REMOVE OR ALTER!
4 */
5/*
6 * Copyright 2001-2004 The Apache Software Foundation.
7 *
8 * Licensed under the Apache License, Version 2.0 (the "License");
9 * you may not use this file except in compliance with the License.
10 * You may obtain a copy of the License at
11 *
12 *     http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing, software
15 * distributed under the License is distributed on an "AS IS" BASIS,
16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17 * See the License for the specific language governing permissions and
18 * limitations under the License.
19 */
20/*
21 * $Id: EqualityExpr.java,v 1.2.4.1 2005/09/12 10:16:52 pvedula Exp $
22 */
23
24package com.sun.org.apache.xalan.internal.xsltc.compiler;
25
26import com.sun.org.apache.bcel.internal.generic.BranchHandle;
27import com.sun.org.apache.bcel.internal.generic.BranchInstruction;
28import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
29import com.sun.org.apache.bcel.internal.generic.GOTO;
30import com.sun.org.apache.bcel.internal.generic.IFEQ;
31import com.sun.org.apache.bcel.internal.generic.IFNE;
32import com.sun.org.apache.bcel.internal.generic.IF_ICMPEQ;
33import com.sun.org.apache.bcel.internal.generic.IF_ICMPNE;
34import com.sun.org.apache.bcel.internal.generic.INVOKESTATIC;
35import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
36import com.sun.org.apache.bcel.internal.generic.InstructionList;
37import com.sun.org.apache.bcel.internal.generic.PUSH;
38import com.sun.org.apache.xalan.internal.xsltc.compiler.util.BooleanType;
39import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
40import com.sun.org.apache.xalan.internal.xsltc.compiler.util.IntType;
41import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
42import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType;
43import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType;
44import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NumberType;
45import com.sun.org.apache.xalan.internal.xsltc.compiler.util.RealType;
46import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ReferenceType;
47import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ResultTreeType;
48import com.sun.org.apache.xalan.internal.xsltc.compiler.util.StringType;
49import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
50import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
51import com.sun.org.apache.xalan.internal.xsltc.runtime.Operators;
52
53/**
54 * @author Jacek Ambroziak
55 * @author Santiago Pericas-Geertsen
56 * @author Morten Jorgensen
57 * @author Erwin Bolwidt <ejb@klomp.org>
58 */
59final class EqualityExpr extends Expression {
60
61    private final int _op;
62    private Expression _left;
63    private Expression _right;
64
65    public EqualityExpr(int op, Expression left, Expression right) {
66        _op = op;
67        (_left = left).setParent(this);
68        (_right = right).setParent(this);
69    }
70
71    public void setParser(Parser parser) {
72        super.setParser(parser);
73        _left.setParser(parser);
74        _right.setParser(parser);
75    }
76
77    public String toString() {
78        return Operators.getOpNames(_op) + '(' + _left + ", " + _right + ')';
79    }
80
81    public Expression getLeft() {
82        return _left;
83    }
84
85    public Expression getRight() {
86        return _right;
87    }
88
89    public boolean getOp() {
90        return (_op != Operators.NE);
91    }
92
93    /**
94     * Returns true if this expressions contains a call to position(). This is
95     * needed for context changes in node steps containing multiple predicates.
96     */
97    public boolean hasPositionCall() {
98        if (_left.hasPositionCall()) return true;
99        if (_right.hasPositionCall()) return true;
100        return false;
101    }
102
103    public boolean hasLastCall() {
104        if (_left.hasLastCall()) return true;
105        if (_right.hasLastCall()) return true;
106        return false;
107    }
108
109    private void swapArguments() {
110        final Expression temp = _left;
111        _left = _right;
112        _right = temp;
113    }
114
115    /**
116     * Typing rules: see XSLT Reference by M. Kay page 345.
117     */
118    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
119        final Type tleft = _left.typeCheck(stable);
120        final Type tright = _right.typeCheck(stable);
121
122        if (tleft.isSimple() && tright.isSimple()) {
123            if (tleft != tright) {
124                if (tleft instanceof BooleanType) {
125                    _right = new CastExpr(_right, Type.Boolean);
126                }
127                else if (tright instanceof BooleanType) {
128                    _left = new CastExpr(_left, Type.Boolean);
129                }
130                else if (tleft instanceof NumberType ||
131                         tright instanceof NumberType) {
132                    _left = new CastExpr(_left, Type.Real);
133                    _right = new CastExpr(_right, Type.Real);
134                }
135                else {          // both compared as strings
136                    _left = new CastExpr(_left,   Type.String);
137                    _right = new CastExpr(_right, Type.String);
138                }
139            }
140        }
141        else if (tleft instanceof ReferenceType) {
142            _right = new CastExpr(_right, Type.Reference);
143        }
144        else if (tright instanceof ReferenceType) {
145            _left = new CastExpr(_left, Type.Reference);
146        }
147        // the following 2 cases optimize @attr|.|.. = 'string'
148        else if (tleft instanceof NodeType && tright == Type.String) {
149            _left = new CastExpr(_left, Type.String);
150        }
151        else if (tleft == Type.String && tright instanceof NodeType) {
152            _right = new CastExpr(_right, Type.String);
153        }
154        // optimize node/node
155        else if (tleft instanceof NodeType && tright instanceof NodeType) {
156            _left = new CastExpr(_left, Type.String);
157            _right = new CastExpr(_right, Type.String);
158        }
159        else if (tleft instanceof NodeType && tright instanceof NodeSetType) {
160            // compare(Node, NodeSet) will be invoked
161        }
162        else if (tleft instanceof NodeSetType && tright instanceof NodeType) {
163            swapArguments();    // for compare(Node, NodeSet)
164        }
165        else {
166            // At least one argument is of type node, node-set or result-tree
167
168            // Promote an expression of type node to node-set
169            if (tleft instanceof NodeType) {
170                _left = new CastExpr(_left, Type.NodeSet);
171            }
172            if (tright instanceof NodeType) {
173                _right = new CastExpr(_right, Type.NodeSet);
174            }
175
176            // If one arg is a node-set then make it the left one
177            if (tleft.isSimple() ||
178                tleft instanceof ResultTreeType &&
179                tright instanceof NodeSetType) {
180                swapArguments();
181            }
182
183            // Promote integers to doubles to have fewer compares
184            if (_right.getType() instanceof IntType) {
185                _right = new CastExpr(_right, Type.Real);
186            }
187        }
188        return _type = Type.Boolean;
189    }
190
191    public void translateDesynthesized(ClassGenerator classGen,
192                                       MethodGenerator methodGen) {
193        final Type tleft = _left.getType();
194        final InstructionList il = methodGen.getInstructionList();
195
196        if (tleft instanceof BooleanType) {
197            _left.translate(classGen, methodGen);
198            _right.translate(classGen, methodGen);
199        _falseList.add(il.append(_op == Operators.EQ ?
200                                     (BranchInstruction)new IF_ICMPNE(null) :
201                                     (BranchInstruction)new IF_ICMPEQ(null)));
202        }
203        else if (tleft instanceof NumberType) {
204            _left.translate(classGen, methodGen);
205            _right.translate(classGen, methodGen);
206
207            if (tleft instanceof RealType) {
208                il.append(DCMPG);
209        _falseList.add(il.append(_op == Operators.EQ ?
210                                         (BranchInstruction)new IFNE(null) :
211                                         (BranchInstruction)new IFEQ(null)));
212            }
213            else {
214            _falseList.add(il.append(_op == Operators.EQ ?
215                                         (BranchInstruction)new IF_ICMPNE(null) :
216                                         (BranchInstruction)new IF_ICMPEQ(null)));
217            }
218        }
219        else {
220            translate(classGen, methodGen);
221            desynthesize(classGen, methodGen);
222        }
223    }
224
225    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
226        final ConstantPoolGen cpg = classGen.getConstantPool();
227        final InstructionList il = methodGen.getInstructionList();
228
229        final Type tleft = _left.getType();
230        Type tright = _right.getType();
231
232        if (tleft instanceof BooleanType || tleft instanceof NumberType) {
233            translateDesynthesized(classGen, methodGen);
234            synthesize(classGen, methodGen);
235            return;
236        }
237
238        if (tleft instanceof StringType) {
239            final int equals = cpg.addMethodref(STRING_CLASS,
240                                                "equals",
241                                                "(" + OBJECT_SIG +")Z");
242            _left.translate(classGen, methodGen);
243            _right.translate(classGen, methodGen);
244            il.append(new INVOKEVIRTUAL(equals));
245
246        if (_op == Operators.NE) {
247                il.append(ICONST_1);
248                il.append(IXOR);                        // not x <-> x xor 1
249            }
250            return;
251        }
252
253        BranchHandle truec, falsec;
254
255        if (tleft instanceof ResultTreeType) {
256            if (tright instanceof BooleanType) {
257                _right.translate(classGen, methodGen);
258        if (_op == Operators.NE) {
259                    il.append(ICONST_1);
260                    il.append(IXOR); // not x <-> x xor 1
261                }
262                return;
263            }
264
265            if (tright instanceof RealType) {
266                _left.translate(classGen, methodGen);
267                tleft.translateTo(classGen, methodGen, Type.Real);
268                _right.translate(classGen, methodGen);
269
270                il.append(DCMPG);
271        falsec = il.append(_op == Operators.EQ ?
272                                   (BranchInstruction) new IFNE(null) :
273                                   (BranchInstruction) new IFEQ(null));
274                il.append(ICONST_1);
275                truec = il.append(new GOTO(null));
276                falsec.setTarget(il.append(ICONST_0));
277                truec.setTarget(il.append(NOP));
278                return;
279            }
280
281            // Next, result-tree/string and result-tree/result-tree comparisons
282
283            _left.translate(classGen, methodGen);
284            tleft.translateTo(classGen, methodGen, Type.String);
285            _right.translate(classGen, methodGen);
286
287            if (tright instanceof ResultTreeType) {
288                tright.translateTo(classGen, methodGen, Type.String);
289            }
290
291            final int equals = cpg.addMethodref(STRING_CLASS,
292                                                "equals",
293                                                "(" +OBJECT_SIG+ ")Z");
294            il.append(new INVOKEVIRTUAL(equals));
295
296        if (_op == Operators.NE) {
297                il.append(ICONST_1);
298                il.append(IXOR);                        // not x <-> x xor 1
299            }
300            return;
301        }
302
303        if (tleft instanceof NodeSetType && tright instanceof BooleanType) {
304            _left.translate(classGen, methodGen);
305            _left.startIterator(classGen, methodGen);
306            Type.NodeSet.translateTo(classGen, methodGen, Type.Boolean);
307            _right.translate(classGen, methodGen);
308
309            il.append(IXOR); // x != y <-> x xor y
310        if (_op == Operators.EQ) {
311                il.append(ICONST_1);
312                il.append(IXOR); // not x <-> x xor 1
313            }
314            return;
315        }
316
317        if (tleft instanceof NodeSetType && tright instanceof StringType) {
318            _left.translate(classGen, methodGen);
319            _left.startIterator(classGen, methodGen); // needed ?
320            _right.translate(classGen, methodGen);
321            il.append(new PUSH(cpg, _op));
322            il.append(methodGen.loadDOM());
323            final int cmp = cpg.addMethodref(BASIS_LIBRARY_CLASS,
324                                             "compare",
325                                             "("
326                                             + tleft.toSignature()
327                                             + tright.toSignature()
328                                             + "I"
329                                             + DOM_INTF_SIG
330                                             + ")Z");
331            il.append(new INVOKESTATIC(cmp));
332            return;
333        }
334
335        // Next, node-set/t for t in {real, string, node-set, result-tree}
336        _left.translate(classGen, methodGen);
337        _left.startIterator(classGen, methodGen);
338        _right.translate(classGen, methodGen);
339        _right.startIterator(classGen, methodGen);
340
341        // Cast a result tree to a string to use an existing compare
342        if (tright instanceof ResultTreeType) {
343            tright.translateTo(classGen, methodGen, Type.String);
344            tright = Type.String;
345        }
346
347        // Call the appropriate compare() from the BasisLibrary
348        il.append(new PUSH(cpg, _op));
349        il.append(methodGen.loadDOM());
350
351        final int compare = cpg.addMethodref(BASIS_LIBRARY_CLASS,
352                                             "compare",
353                                             "("
354                                             + tleft.toSignature()
355                                             + tright.toSignature()
356                                             + "I"
357                                             + DOM_INTF_SIG
358                                             + ")Z");
359        il.append(new INVOKESTATIC(compare));
360    }
361}
362