/*
 * Copyright (c) 2018, Google LLC. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.tools.javac.comp;

import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.tree.JCTree;
import com.sun.tools.javac.tree.JCTree.JCAnnotatedType;
import com.sun.tools.javac.tree.JCTree.JCAnnotation;
import com.sun.tools.javac.tree.JCTree.JCArrayAccess;
import com.sun.tools.javac.tree.JCTree.JCArrayTypeTree;
import com.sun.tools.javac.tree.JCTree.JCAssert;
import com.sun.tools.javac.tree.JCTree.JCAssign;
import com.sun.tools.javac.tree.JCTree.JCAssignOp;
import com.sun.tools.javac.tree.JCTree.JCBinary;
import com.sun.tools.javac.tree.JCTree.JCBlock;
import com.sun.tools.javac.tree.JCTree.JCBreak;
import com.sun.tools.javac.tree.JCTree.JCCase;
import com.sun.tools.javac.tree.JCTree.JCCatch;
import com.sun.tools.javac.tree.JCTree.JCClassDecl;
import com.sun.tools.javac.tree.JCTree.JCCompilationUnit;
import com.sun.tools.javac.tree.JCTree.JCConditional;
import com.sun.tools.javac.tree.JCTree.JCContinue;
import com.sun.tools.javac.tree.JCTree.JCDoWhileLoop;
import com.sun.tools.javac.tree.JCTree.JCEnhancedForLoop;
import com.sun.tools.javac.tree.JCTree.JCErroneous;
import com.sun.tools.javac.tree.JCTree.JCExports;
import com.sun.tools.javac.tree.JCTree.JCExpressionStatement;
import com.sun.tools.javac.tree.JCTree.JCFieldAccess;
import com.sun.tools.javac.tree.JCTree.JCForLoop;
import com.sun.tools.javac.tree.JCTree.JCIdent;
import com.sun.tools.javac.tree.JCTree.JCIf;
import com.sun.tools.javac.tree.JCTree.JCImport;
import com.sun.tools.javac.tree.JCTree.JCInstanceOf;
import com.sun.tools.javac.tree.JCTree.JCLabeledStatement;
import com.sun.tools.javac.tree.JCTree.JCLambda;
import com.sun.tools.javac.tree.JCTree.JCLiteral;
import com.sun.tools.javac.tree.JCTree.JCMemberReference;
import com.sun.tools.javac.tree.JCTree.JCMethodDecl;
import com.sun.tools.javac.tree.JCTree.JCMethodInvocation;
import com.sun.tools.javac.tree.JCTree.JCModifiers;
import com.sun.tools.javac.tree.JCTree.JCModuleDecl;
import com.sun.tools.javac.tree.JCTree.JCNewArray;
import com.sun.tools.javac.tree.JCTree.JCNewClass;
import com.sun.tools.javac.tree.JCTree.JCOpens;
import com.sun.tools.javac.tree.JCTree.JCPackageDecl;
import com.sun.tools.javac.tree.JCTree.JCPrimitiveTypeTree;
import com.sun.tools.javac.tree.JCTree.JCProvides;
import com.sun.tools.javac.tree.JCTree.JCRequires;
import com.sun.tools.javac.tree.JCTree.JCReturn;
import com.sun.tools.javac.tree.JCTree.JCSwitch;
import com.sun.tools.javac.tree.JCTree.JCSynchronized;
import com.sun.tools.javac.tree.JCTree.JCThrow;
import com.sun.tools.javac.tree.JCTree.JCTry;
import com.sun.tools.javac.tree.JCTree.JCTypeApply;
import com.sun.tools.javac.tree.JCTree.JCTypeCast;
import com.sun.tools.javac.tree.JCTree.JCTypeIntersection;
import com.sun.tools.javac.tree.JCTree.JCTypeParameter;
import com.sun.tools.javac.tree.JCTree.JCTypeUnion;
import com.sun.tools.javac.tree.JCTree.JCUnary;
import com.sun.tools.javac.tree.JCTree.JCUses;
import com.sun.tools.javac.tree.JCTree.JCVariableDecl;
import com.sun.tools.javac.tree.JCTree.JCWhileLoop;
import com.sun.tools.javac.tree.JCTree.JCWildcard;
import com.sun.tools.javac.tree.JCTree.LetExpr;
import com.sun.tools.javac.tree.JCTree.TypeBoundKind;
import com.sun.tools.javac.tree.TreeInfo;
import com.sun.tools.javac.tree.TreeScanner;
import com.sun.tools.javac.util.List;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Objects;

A visitor that compares two lambda bodies for structural equality.
/** A visitor that compares two lambda bodies for structural equality. */
public class TreeDiffer extends TreeScanner { public TreeDiffer( Collection<? extends Symbol> symbols, Collection<? extends Symbol> otherSymbols) { this.equiv = equiv(symbols, otherSymbols); } private static Map<Symbol, Symbol> equiv( Collection<? extends Symbol> symbols, Collection<? extends Symbol> otherSymbols) { Map<Symbol, Symbol> result = new HashMap<>(); Iterator<? extends Symbol> it = otherSymbols.iterator(); for (Symbol symbol : symbols) { if (!it.hasNext()) break; result.put(symbol, it.next()); } return result; } private JCTree parameter; private boolean result; private Map<Symbol, Symbol> equiv = new HashMap<>(); public boolean scan(JCTree tree, JCTree parameter) { if (tree == null || parameter == null) { return tree == null && parameter == null; } tree = TreeInfo.skipParens(tree); parameter = TreeInfo.skipParens(parameter); if (tree.type != null && tree.type.constValue() != null && parameter.type != null && parameter.type.constValue() != null) { return Objects.equals(tree.type.constValue(), parameter.type.constValue()); } if (tree.getTag() != parameter.getTag()) { return false; } JCTree prevParameter = this.parameter; boolean prevResult = this.result; try { this.parameter = parameter; tree.accept(this); return result; } finally { this.parameter = prevParameter; this.result = prevResult; } } private boolean scan(Iterable<? extends JCTree> xs, Iterable<? extends JCTree> ys) { if (xs == null || ys == null) { return xs == null && ys == null; } Iterator<? extends JCTree> x = xs.iterator(); Iterator<? extends JCTree> y = ys.iterator(); while (x.hasNext() && y.hasNext()) { if (!scan(x.next(), y.next())) { return false; } } return !x.hasNext() && !y.hasNext(); } private boolean scanDimAnnotations(List<List<JCAnnotation>> xs, List<List<JCAnnotation>> ys) { if (xs == null || ys == null) { return xs == null && ys == null; } Iterator<List<JCAnnotation>> x = xs.iterator(); Iterator<List<JCAnnotation>> y = ys.iterator(); while (x.hasNext() && y.hasNext()) { if (!scan(x.next(), y.next())) { return false; } } return !x.hasNext() && !y.hasNext(); } @Override public void visitIdent(JCIdent tree) { JCIdent that = (JCIdent) parameter; // Identifiers are a special case: we want to ensure the identifiers correspond to the // same symbols (rather than just having the same name), but also consider lambdas // equal if they differ only in the names of the parameters. Symbol symbol = tree.sym; Symbol otherSymbol = that.sym; if (symbol != null && otherSymbol != null) { if (Objects.equals(equiv.get(symbol), otherSymbol)) { result = true; return; } } result = tree.sym == that.sym; } @Override public void visitSelect(JCFieldAccess tree) { JCFieldAccess that = (JCFieldAccess) parameter; result = scan(tree.selected, that.selected) && tree.sym == that.sym; } @Override public void visitAnnotatedType(JCAnnotatedType tree) { JCAnnotatedType that = (JCAnnotatedType) parameter; result = scan(tree.annotations, that.annotations) && scan(tree.underlyingType, that.underlyingType); } @Override public void visitAnnotation(JCAnnotation tree) { JCAnnotation that = (JCAnnotation) parameter; result = scan(tree.annotationType, that.annotationType) && scan(tree.args, that.args); } @Override public void visitApply(JCMethodInvocation tree) { JCMethodInvocation that = (JCMethodInvocation) parameter; result = scan(tree.typeargs, that.typeargs) && scan(tree.meth, that.meth) && scan(tree.args, that.args) && tree.polyKind == that.polyKind; } @Override public void visitAssert(JCAssert tree) { JCAssert that = (JCAssert) parameter; result = scan(tree.cond, that.cond) && scan(tree.detail, that.detail); } @Override public void visitAssign(JCAssign tree) { JCAssign that = (JCAssign) parameter; result = scan(tree.lhs, that.lhs) && scan(tree.rhs, that.rhs); } @Override public void visitAssignop(JCAssignOp tree) { JCAssignOp that = (JCAssignOp) parameter; result = scan(tree.lhs, that.lhs) && scan(tree.rhs, that.rhs) && tree.operator == that.operator; } @Override public void visitBinary(JCBinary tree) { JCBinary that = (JCBinary) parameter; result = scan(tree.lhs, that.lhs) && scan(tree.rhs, that.rhs) && tree.operator == that.operator; } @Override public void visitBlock(JCBlock tree) { JCBlock that = (JCBlock) parameter; result = tree.flags == that.flags && scan(tree.stats, that.stats); } @Override public void visitBreak(JCBreak tree) { JCBreak that = (JCBreak) parameter; result = scan(tree.value, that.value); } @Override public void visitCase(JCCase tree) { JCCase that = (JCCase) parameter; result = scan(tree.pats, that.pats) && scan(tree.stats, that.stats); } @Override public void visitCatch(JCCatch tree) { JCCatch that = (JCCatch) parameter; result = scan(tree.param, that.param) && scan(tree.body, that.body); } @Override public void visitClassDef(JCClassDecl tree) { JCClassDecl that = (JCClassDecl) parameter; result = scan(tree.mods, that.mods) && tree.name == that.name && scan(tree.typarams, that.typarams) && scan(tree.extending, that.extending) && scan(tree.implementing, that.implementing) && scan(tree.defs, that.defs); } @Override public void visitConditional(JCConditional tree) { JCConditional that = (JCConditional) parameter; result = scan(tree.cond, that.cond) && scan(tree.truepart, that.truepart) && scan(tree.falsepart, that.falsepart); } @Override public void visitContinue(JCContinue tree) { JCContinue that = (JCContinue) parameter; result = tree.label == that.label; } @Override public void visitDoLoop(JCDoWhileLoop tree) { JCDoWhileLoop that = (JCDoWhileLoop) parameter; result = scan(tree.body, that.body) && scan(tree.cond, that.cond); } @Override public void visitErroneous(JCErroneous tree) { JCErroneous that = (JCErroneous) parameter; result = scan(tree.errs, that.errs); } @Override public void visitExec(JCExpressionStatement tree) { JCExpressionStatement that = (JCExpressionStatement) parameter; result = scan(tree.expr, that.expr); } @Override public void visitExports(JCExports tree) { JCExports that = (JCExports) parameter; result = scan(tree.qualid, that.qualid) && scan(tree.moduleNames, that.moduleNames); } @Override public void visitForLoop(JCForLoop tree) { JCForLoop that = (JCForLoop) parameter; result = scan(tree.init, that.init) && scan(tree.cond, that.cond) && scan(tree.step, that.step) && scan(tree.body, that.body); } @Override public void visitForeachLoop(JCEnhancedForLoop tree) { JCEnhancedForLoop that = (JCEnhancedForLoop) parameter; result = scan(tree.var, that.var) && scan(tree.expr, that.expr) && scan(tree.body, that.body); } @Override public void visitIf(JCIf tree) { JCIf that = (JCIf) parameter; result = scan(tree.cond, that.cond) && scan(tree.thenpart, that.thenpart) && scan(tree.elsepart, that.elsepart); } @Override public void visitImport(JCImport tree) { JCImport that = (JCImport) parameter; result = tree.staticImport == that.staticImport && scan(tree.qualid, that.qualid); } @Override public void visitIndexed(JCArrayAccess tree) { JCArrayAccess that = (JCArrayAccess) parameter; result = scan(tree.indexed, that.indexed) && scan(tree.index, that.index); } @Override public void visitLabelled(JCLabeledStatement tree) { JCLabeledStatement that = (JCLabeledStatement) parameter; result = tree.label == that.label && scan(tree.body, that.body); } @Override public void visitLambda(JCLambda tree) { JCLambda that = (JCLambda) parameter; result = scan(tree.params, that.params) && scan(tree.body, that.body) && tree.paramKind == that.paramKind; } @Override public void visitLetExpr(LetExpr tree) { LetExpr that = (LetExpr) parameter; result = scan(tree.defs, that.defs) && scan(tree.expr, that.expr); } @Override public void visitLiteral(JCLiteral tree) { JCLiteral that = (JCLiteral) parameter; result = tree.typetag == that.typetag && Objects.equals(tree.value, that.value); } @Override public void visitMethodDef(JCMethodDecl tree) { JCMethodDecl that = (JCMethodDecl) parameter; result = scan(tree.mods, that.mods) && tree.name == that.name && scan(tree.restype, that.restype) && scan(tree.typarams, that.typarams) && scan(tree.recvparam, that.recvparam) && scan(tree.params, that.params) && scan(tree.thrown, that.thrown) && scan(tree.body, that.body) && scan(tree.defaultValue, that.defaultValue); } @Override public void visitModifiers(JCModifiers tree) { JCModifiers that = (JCModifiers) parameter; result = tree.flags == that.flags && scan(tree.annotations, that.annotations); } @Override public void visitModuleDef(JCModuleDecl tree) { JCModuleDecl that = (JCModuleDecl) parameter; result = scan(tree.mods, that.mods) && scan(tree.qualId, that.qualId) && scan(tree.directives, that.directives); } @Override public void visitNewArray(JCNewArray tree) { JCNewArray that = (JCNewArray) parameter; result = scan(tree.elemtype, that.elemtype) && scan(tree.dims, that.dims) && scan(tree.annotations, that.annotations) && scanDimAnnotations(tree.dimAnnotations, that.dimAnnotations) && scan(tree.elems, that.elems); } @Override public void visitNewClass(JCNewClass tree) { JCNewClass that = (JCNewClass) parameter; result = scan(tree.encl, that.encl) && scan(tree.typeargs, that.typeargs) && scan(tree.clazz, that.clazz) && scan(tree.args, that.args) && scan(tree.def, that.def) && tree.constructor == that.constructor; } @Override public void visitOpens(JCOpens tree) { JCOpens that = (JCOpens) parameter; result = scan(tree.qualid, that.qualid) && scan(tree.moduleNames, that.moduleNames); } @Override public void visitPackageDef(JCPackageDecl tree) { JCPackageDecl that = (JCPackageDecl) parameter; result = scan(tree.annotations, that.annotations) && scan(tree.pid, that.pid) && tree.packge == that.packge; } @Override public void visitProvides(JCProvides tree) { JCProvides that = (JCProvides) parameter; result = scan(tree.serviceName, that.serviceName) && scan(tree.implNames, that.implNames); } @Override public void visitReference(JCMemberReference tree) { JCMemberReference that = (JCMemberReference) parameter; result = tree.mode == that.mode && tree.kind == that.kind && tree.name == that.name && scan(tree.expr, that.expr) && scan(tree.typeargs, that.typeargs); } @Override public void visitRequires(JCRequires tree) { JCRequires that = (JCRequires) parameter; result = tree.isTransitive == that.isTransitive && tree.isStaticPhase == that.isStaticPhase && scan(tree.moduleName, that.moduleName); } @Override public void visitReturn(JCReturn tree) { JCReturn that = (JCReturn) parameter; result = scan(tree.expr, that.expr); } @Override public void visitSwitch(JCSwitch tree) { JCSwitch that = (JCSwitch) parameter; result = scan(tree.selector, that.selector) && scan(tree.cases, that.cases); } @Override public void visitSynchronized(JCSynchronized tree) { JCSynchronized that = (JCSynchronized) parameter; result = scan(tree.lock, that.lock) && scan(tree.body, that.body); } @Override public void visitThrow(JCThrow tree) { JCThrow that = (JCThrow) parameter; result = scan(tree.expr, that.expr); } @Override public void visitTopLevel(JCCompilationUnit tree) { JCCompilationUnit that = (JCCompilationUnit) parameter; result = scan(tree.defs, that.defs) && tree.modle == that.modle && tree.packge == that.packge; } @Override public void visitTry(JCTry tree) { JCTry that = (JCTry) parameter; result = scan(tree.body, that.body) && scan(tree.catchers, that.catchers) && scan(tree.finalizer, that.finalizer) && scan(tree.resources, that.resources); } @Override public void visitTypeApply(JCTypeApply tree) { JCTypeApply that = (JCTypeApply) parameter; result = scan(tree.clazz, that.clazz) && scan(tree.arguments, that.arguments); } @Override public void visitTypeArray(JCArrayTypeTree tree) { JCArrayTypeTree that = (JCArrayTypeTree) parameter; result = scan(tree.elemtype, that.elemtype); } @Override public void visitTypeBoundKind(TypeBoundKind tree) { TypeBoundKind that = (TypeBoundKind) parameter; result = tree.kind == that.kind; } @Override public void visitTypeCast(JCTypeCast tree) { JCTypeCast that = (JCTypeCast) parameter; result = scan(tree.clazz, that.clazz) && scan(tree.expr, that.expr); } @Override public void visitTypeIdent(JCPrimitiveTypeTree tree) { JCPrimitiveTypeTree that = (JCPrimitiveTypeTree) parameter; result = tree.typetag == that.typetag; } @Override public void visitTypeIntersection(JCTypeIntersection tree) { JCTypeIntersection that = (JCTypeIntersection) parameter; result = scan(tree.bounds, that.bounds); } @Override public void visitTypeParameter(JCTypeParameter tree) { JCTypeParameter that = (JCTypeParameter) parameter; result = tree.name == that.name && scan(tree.bounds, that.bounds) && scan(tree.annotations, that.annotations); } @Override public void visitTypeTest(JCInstanceOf tree) { JCInstanceOf that = (JCInstanceOf) parameter; result = scan(tree.expr, that.expr) && scan(tree.clazz, that.clazz); } @Override public void visitTypeUnion(JCTypeUnion tree) { JCTypeUnion that = (JCTypeUnion) parameter; result = scan(tree.alternatives, that.alternatives); } @Override public void visitUnary(JCUnary tree) { JCUnary that = (JCUnary) parameter; result = scan(tree.arg, that.arg) && tree.operator == that.operator; } @Override public void visitUses(JCUses tree) { JCUses that = (JCUses) parameter; result = scan(tree.qualid, that.qualid); } @Override public void visitVarDef(JCVariableDecl tree) { JCVariableDecl that = (JCVariableDecl) parameter; result = scan(tree.mods, that.mods) && tree.name == that.name && scan(tree.nameexpr, that.nameexpr) && scan(tree.vartype, that.vartype) && scan(tree.init, that.init); if (!result) { return; } equiv.put(tree.sym, that.sym); } @Override public void visitWhileLoop(JCWhileLoop tree) { JCWhileLoop that = (JCWhileLoop) parameter; result = scan(tree.cond, that.cond) && scan(tree.body, that.body); } @Override public void visitWildcard(JCWildcard tree) { JCWildcard that = (JCWildcard) parameter; result = scan(tree.kind, that.kind) && scan(tree.inner, that.inner); } }