alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (RelationalExpr.java)

This example Java source code file (RelationalExpr.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

booleantype, castexpr, expression, instructionlist, methodgenerator, nodesettype, nodetype, referencetype, relationalexpr, resulttreetype, type, typecheckerror, variablebase, variablerefbase

The RelationalExpr.java Java example source code

/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Copyright 2001-2004 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.
 */
/*
 * $Id: RelationalExpr.java,v 1.2.4.1 2005/09/12 11:05:00 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.BranchInstruction;
import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.INVOKESTATIC;
import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.bcel.internal.generic.PUSH;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.BooleanType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.IntType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeSetType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.NodeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.RealType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ReferenceType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ResultTreeType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
import com.sun.org.apache.xalan.internal.xsltc.runtime.Operators;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 */
final class RelationalExpr extends Expression {

    private int _op;
    private Expression _left, _right;

    public RelationalExpr(int op, Expression left, Expression right) {
        _op = op;
        (_left = left).setParent(this);
        (_right = right).setParent(this);
    }

    public void setParser(Parser parser) {
        super.setParser(parser);
        _left.setParser(parser);
        _right.setParser(parser);
    }

    /**
     * Returns true if this expressions contains a call to position(). This is
     * needed for context changes in node steps containing multiple predicates.
     */
    public boolean hasPositionCall() {
        if (_left.hasPositionCall()) return true;
        if (_right.hasPositionCall()) return true;
        return false;
    }

    /**
     * Returns true if this expressions contains a call to last()
     */
    public boolean hasLastCall() {
            return (_left.hasLastCall() || _right.hasLastCall());
    }

    public boolean hasReferenceArgs() {
        return _left.getType() instanceof ReferenceType ||
            _right.getType() instanceof ReferenceType;
    }

    public boolean hasNodeArgs() {
        return _left.getType() instanceof NodeType ||
            _right.getType() instanceof NodeType;
    }

    public boolean hasNodeSetArgs() {
        return _left.getType() instanceof NodeSetType ||
            _right.getType() instanceof NodeSetType;
    }

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {
        Type tleft = _left.typeCheck(stable);
        Type tright = _right.typeCheck(stable);

        //bug fix # 2838, cast to reals if both are result tree fragments
        if (tleft instanceof ResultTreeType &&
            tright instanceof ResultTreeType )
        {
            _right = new CastExpr(_right, Type.Real);
            _left = new CastExpr(_left, Type.Real);
            return _type = Type.Boolean;
        }

        // If one is of reference type, then convert the other too
        if (hasReferenceArgs()) {
            Type type = null;
            Type typeL = null;
            Type typeR = null;
            if (tleft instanceof ReferenceType) {
                if (_left instanceof VariableRefBase) {
                    VariableRefBase ref = (VariableRefBase)_left;
                    VariableBase var = ref.getVariable();
                    typeL = var.getType();
                }
            }
            if (tright instanceof ReferenceType) {
                if (_right instanceof VariableRefBase) {
                    VariableRefBase ref = (VariableRefBase)_right;
                    VariableBase var = ref.getVariable();
                    typeR = var.getType();
                }
            }
            // bug fix # 2838
            if (typeL == null)
                type = typeR;
            else if (typeR == null)
                type = typeL;
            else {
                type = Type.Real;
            }
            if (type == null) type = Type.Real;

            _right = new CastExpr(_right, type);
            _left = new CastExpr(_left, type);
            return _type = Type.Boolean;
        }

        if (hasNodeSetArgs()) {
            // Ensure that the node-set is the left argument
            if (tright instanceof NodeSetType) {
                final Expression temp = _right; _right = _left; _left = temp;
        _op = (_op == Operators.GT) ? Operators.LT :
            (_op == Operators.LT) ? Operators.GT :
            (_op == Operators.GE) ? Operators.LE : Operators.GE;
                tright = _right.getType();
            }

            // Promote nodes to node sets
            if (tright instanceof NodeType) {
                _right = new CastExpr(_right, Type.NodeSet);
            }
            // Promote integer to doubles to have fewer compares
            if (tright instanceof IntType) {
                _right = new CastExpr(_right, Type.Real);
            }
            // Promote result-trees to strings
            if (tright instanceof ResultTreeType) {
                _right = new CastExpr(_right, Type.String);
            }
            return _type = Type.Boolean;
        }

        // In the node-boolean case, convert node to boolean first
        if (hasNodeArgs()) {
            if (tleft instanceof BooleanType) {
                _right = new CastExpr(_right, Type.Boolean);
                tright = Type.Boolean;
            }
            if (tright instanceof BooleanType) {
                _left = new CastExpr(_left, Type.Boolean);
                tleft = Type.Boolean;
            }
        }

        // Lookup the table of primops to find the best match
    MethodType ptype = lookupPrimop(stable, Operators.getOpNames(_op),
                new MethodType(Type.Void, tleft, tright));

        if (ptype != null) {
            Type arg1 = (Type) ptype.argsType().elementAt(0);
            if (!arg1.identicalTo(tleft)) {
                _left = new CastExpr(_left, arg1);
            }
            Type arg2 = (Type) ptype.argsType().elementAt(1);
            if (!arg2.identicalTo(tright)) {
                _right = new CastExpr(_right, arg1);
            }
            return _type = ptype.resultType();
        }
        throw new TypeCheckError(this);
    }

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
        if (hasNodeSetArgs() || hasReferenceArgs()) {
            final ConstantPoolGen cpg = classGen.getConstantPool();
            final InstructionList il = methodGen.getInstructionList();

            // Call compare() from the BasisLibrary
            _left.translate(classGen, methodGen);
            _left.startIterator(classGen, methodGen);
            _right.translate(classGen, methodGen);
            _right.startIterator(classGen, methodGen);

            il.append(new PUSH(cpg, _op));
            il.append(methodGen.loadDOM());

            int index = cpg.addMethodref(BASIS_LIBRARY_CLASS, "compare",
                                         "("
                                         + _left.getType().toSignature()
                                         + _right.getType().toSignature()
                                         + "I"
                                         + DOM_INTF_SIG
                                         + ")Z");
            il.append(new INVOKESTATIC(index));
        }
        else {
            translateDesynthesized(classGen, methodGen);
            synthesize(classGen, methodGen);
        }
    }

    public void translateDesynthesized(ClassGenerator classGen,
                                       MethodGenerator methodGen) {
        if (hasNodeSetArgs() || hasReferenceArgs()) {
            translate(classGen, methodGen);
            desynthesize(classGen, methodGen);
        }
        else {
            BranchInstruction bi = null;
            final InstructionList il = methodGen.getInstructionList();

            _left.translate(classGen, methodGen);
            _right.translate(classGen, methodGen);

            // TODO: optimize if one of the args is 0

            boolean tozero = false;
            Type tleft = _left.getType();

            if (tleft instanceof RealType) {
        il.append(tleft.CMP(_op == Operators.LT || _op == Operators.LE));
                tleft = Type.Int;
                tozero = true;
            }

            switch (_op) {
        case Operators.LT:
                bi = tleft.GE(tozero);
                break;

        case Operators.GT:
                bi = tleft.LE(tozero);
                break;

        case Operators.LE:
                bi = tleft.GT(tozero);
                break;

        case Operators.GE:
                bi = tleft.LT(tozero);
                break;

            default:
                ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_RELAT_OP_ERR,this);
                getParser().reportError(Constants.FATAL, msg);
            }

            _falseList.add(il.append(bi));              // must be backpatched
        }
    }

    public String toString() {
        return Operators.getOpNames(_op) + '(' + _left + ", " + _right + ')';
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java RelationalExpr.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.