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Groovy: A powerful, dynamic language for the JVM
/*
* Copyright 2003-2009 the original author or authors.
*
* 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.codehaus.groovy.classgen;
import org.codehaus.groovy.GroovyBugError;
import org.codehaus.groovy.ast.*;
import org.codehaus.groovy.ast.Variable;
import org.codehaus.groovy.ast.expr.*;
import org.codehaus.groovy.ast.stmt.BlockStatement;
import org.codehaus.groovy.ast.stmt.CatchStatement;
import org.codehaus.groovy.ast.stmt.ForStatement;
import org.codehaus.groovy.ast.stmt.Statement;
import org.codehaus.groovy.control.SourceUnit;
import org.codehaus.groovy.syntax.Types;
import org.objectweb.asm.Opcodes;
import java.util.LinkedList;
/**
* goes through an AST and initializes the scopes
*
* @author Jochen Theodorou
*/
public class VariableScopeVisitor extends ClassCodeVisitorSupport {
private static final Expression CALL = new ConstantExpression("call");
private VariableScope currentScope = null;
private VariableScope headScope = new VariableScope();
private ClassNode currentClass = null;
private SourceUnit source;
private boolean inClosure = false;
private boolean inPropertyExpression = false;
private boolean isSpecialConstructorCall = false;
private boolean inConstructor = false;
private LinkedList stateStack = new LinkedList();
private class StateStackElement {
VariableScope scope;
ClassNode clazz;
boolean closure;
boolean inConstructor;
StateStackElement() {
scope = VariableScopeVisitor.this.currentScope;
clazz = VariableScopeVisitor.this.currentClass;
closure = VariableScopeVisitor.this.inClosure;
inConstructor = VariableScopeVisitor.this.inConstructor;
}
}
public VariableScopeVisitor(SourceUnit source) {
this.source = source;
currentScope = headScope;
}
// ------------------------------
// helper methods
//------------------------------
private void pushState(boolean isStatic) {
stateStack.add(new StateStackElement());
currentScope = new VariableScope(currentScope);
currentScope.setInStaticContext(isStatic);
}
private void pushState() {
pushState(currentScope.isInStaticContext());
}
private void popState() {
// a scope in a closure is never really static
// the checking needs this to be as the surrounding
// method to correctly check the access to variables.
// But a closure and all nested scopes are a result
// of calling a non static method, so the context
// is not static.
if (inClosure) currentScope.setInStaticContext(false);
StateStackElement element = (StateStackElement) stateStack.removeLast();
currentScope = element.scope;
currentClass = element.clazz;
inClosure = element.closure;
inConstructor = element.inConstructor;
}
private void declare(Parameter[] parameters, ASTNode node) {
for (Parameter parameter : parameters) {
if (parameter.hasInitialExpression()) {
parameter.getInitialExpression().visit(this);
}
declare(parameter, node);
}
}
private void declare(VariableExpression vex) {
vex.setInStaticContext(currentScope.isInStaticContext());
declare(vex, vex);
vex.setAccessedVariable(vex);
}
private void declare(Variable var, ASTNode expr) {
String scopeType = "scope";
String variableType = "variable";
if (expr.getClass() == FieldNode.class) {
scopeType = "class";
variableType = "field";
} else if (expr.getClass() == PropertyNode.class) {
scopeType = "class";
variableType = "property";
}
StringBuffer msg = new StringBuffer();
msg.append("The current ").append(scopeType);
msg.append(" already contains a ").append(variableType);
msg.append(" of the name ").append(var.getName());
if (currentScope.getDeclaredVariable(var.getName()) != null) {
addError(msg.toString(), expr);
return;
}
for (VariableScope scope = currentScope.getParent(); scope != null; scope = scope.getParent()) {
// if we are in a class and no variable is declared until
// now, then we can break the loop, because we are allowed
// to declare a variable of the same name as a class member
if (scope.getClassScope() != null) break;
if (scope.getDeclaredVariable(var.getName()) != null) {
// variable already declared
addError(msg.toString(), expr);
break;
}
}
// declare the variable even if there was an error to allow more checks
currentScope.putDeclaredVariable(var);
}
protected SourceUnit getSourceUnit() {
return source;
}
private Variable findClassMember(ClassNode cn, String name) {
if (cn == null) return null;
if (cn.isScript()) {
return new DynamicVariable(name, false);
}
for (FieldNode fn : cn.getFields()) {
if (fn.getName().equals(name)) return fn;
}
for (MethodNode mn : cn.getMethods()) {
String pName = getPropertyName(mn);
if (pName != null && pName.equals(name))
return new PropertyNode(pName, mn.getModifiers(), getPropertyType(mn), cn, null, null, null);
}
for (PropertyNode pn : cn.getProperties()) {
if (pn.getName().equals(name)) return pn;
}
Variable ret = findClassMember(cn.getSuperClass(), name);
if (ret != null) return ret;
return findClassMember(cn.getOuterClass(), name);
}
private ClassNode getPropertyType(MethodNode m) {
if (m.getReturnType() != ClassHelper.VOID_TYPE) {
return m.getReturnType();
}
return m.getParameters()[0].getType();
}
private String getPropertyName(MethodNode m) {
String name = m.getName();
if (!(name.startsWith("set") || name.startsWith("get"))) return null;
String pname = name.substring(3);
if (pname.length() == 0) return null;
pname = java.beans.Introspector.decapitalize(pname);
if (name.startsWith("get") && (m.getReturnType() == ClassHelper.VOID_TYPE || m.getParameters().length != 0)) {
return null;
}
if (name.startsWith("set") && m.getParameters().length != 1) {
return null;
}
return pname;
}
// -------------------------------
// different Variable based checks
// -------------------------------
private Variable checkVariableNameForDeclaration(String name, Expression expression) {
if ("super".equals(name) || "this".equals(name)) return null;
VariableScope scope = currentScope;
Variable var = new DynamicVariable(name, currentScope.isInStaticContext());
// try to find a declaration of a variable
while (true) {
Variable var1;
var1 = scope.getDeclaredVariable(var.getName());
if (var1 != null) {
var = var1;
break;
}
var1 = scope.getReferencedLocalVariable(var.getName());
if (var1 != null) {
var = var1;
break;
}
var1 = scope.getReferencedClassVariable(var.getName());
if (var1 != null) {
var = var1;
break;
}
ClassNode classScope = scope.getClassScope();
if (classScope != null) {
Variable member = findClassMember(classScope, var.getName());
if (member != null) {
boolean staticScope = currentScope.isInStaticContext() || isSpecialConstructorCall;
boolean staticMember = member.isInStaticContext();
// We don't allow a static context (e.g. a static method) to access
// a non-static variable (e.g. a non-static field).
if (! (staticScope && ! staticMember))
var = member;
}
break;
}
scope = scope.getParent();
}
VariableScope end = scope;
scope = currentScope;
while (scope != end) {
if (end.isClassScope() ||
(end.isReferencedClassVariable(name) && end.getDeclaredVariable(name) == null)) {
scope.putReferencedClassVariable(var);
} else {
var.setClosureSharedVariable(var.isClosureSharedVariable() || inClosure);
scope.putReferencedLocalVariable(var);
}
scope = scope.getParent();
}
return var;
}
/**
* a property on "this", like this.x is transformed to a
* direct field access, so we need to check the
* static context here
*
* @param pe the property expression to check
*/
private void checkPropertyOnExplicitThis(PropertyExpression pe) {
if (!currentScope.isInStaticContext()) return;
Expression object = pe.getObjectExpression();
if (!(object instanceof VariableExpression)) return;
VariableExpression ve = (VariableExpression) object;
if (!ve.getName().equals("this")) return;
String name = pe.getPropertyAsString();
if (name.equals("class")) return;
if (name == null) return;
Variable member = findClassMember(currentClass, name);
if (member == null) return;
checkVariableContextAccess(member, pe);
}
private void checkVariableContextAccess(Variable v, Expression expr) {
if (inPropertyExpression || v.isInStaticContext() || !currentScope.isInStaticContext()) return;
String msg = v.getName() +
" is declared in a dynamic context, but you tried to" +
" access it from a static context.";
addError(msg, expr);
// declare a static variable to be able to continue the check
DynamicVariable v2 = new DynamicVariable(v.getName(), currentScope.isInStaticContext());
currentScope.putDeclaredVariable(v2);
}
// ------------------------------
// code visit
// ------------------------------
public void visitBlockStatement(BlockStatement block) {
pushState();
block.setVariableScope(currentScope);
super.visitBlockStatement(block);
popState();
}
public void visitForLoop(ForStatement forLoop) {
pushState();
forLoop.setVariableScope(currentScope);
Parameter p = forLoop.getVariable();
p.setInStaticContext(currentScope.isInStaticContext());
if (p != ForStatement.FOR_LOOP_DUMMY) declare(p, forLoop);
super.visitForLoop(forLoop);
popState();
}
public void visitDeclarationExpression(DeclarationExpression expression) {
// visit right side first to avoid the usage of a
// variable before its declaration
expression.getRightExpression().visit(this);
// no need to visit left side, just get the variable name
if (expression.isMultipleAssignmentDeclaration()) {
ArgumentListExpression list = (ArgumentListExpression) expression.getLeftExpression();
for (Expression e : list.getExpressions()) {
VariableExpression exp = (VariableExpression) e;
declare(exp);
}
} else {
declare(expression.getVariableExpression());
}
}
public void visitVariableExpression(VariableExpression expression) {
String name = expression.getName();
Variable v = checkVariableNameForDeclaration(name, expression);
if (v == null) return;
expression.setAccessedVariable(v);
checkVariableContextAccess(v, expression);
}
public void visitPropertyExpression(PropertyExpression expression) {
boolean ipe = inPropertyExpression;
inPropertyExpression = true;
expression.getObjectExpression().visit(this);
inPropertyExpression = false;
expression.getProperty().visit(this);
checkPropertyOnExplicitThis(expression);
inPropertyExpression = ipe;
}
public void visitClosureExpression(ClosureExpression expression) {
pushState();
inClosure = true;
expression.setVariableScope(currentScope);
if (expression.isParameterSpecified()) {
Parameter[] parameters = expression.getParameters();
for (Parameter parameter : parameters) {
parameter.setInStaticContext(currentScope.isInStaticContext());
if (parameter.hasInitialExpression()) {
parameter.getInitialExpression().visit(this);
}
declare(parameter, expression);
}
} else if (expression.getParameters() != null) {
Parameter var = new Parameter(ClassHelper.OBJECT_TYPE, "it");
var.setInStaticContext(currentScope.isInStaticContext());
currentScope.putDeclaredVariable(var);
}
super.visitClosureExpression(expression);
popState();
}
public void visitCatchStatement(CatchStatement statement) {
pushState();
Parameter p = statement.getVariable();
p.setInStaticContext(currentScope.isInStaticContext());
declare(p, statement);
super.visitCatchStatement(statement);
popState();
}
public void visitFieldExpression(FieldExpression expression) {
String name = expression.getFieldName();
//TODO: change that to get the correct scope
Variable v = checkVariableNameForDeclaration(name, expression);
checkVariableContextAccess(v, expression);
}
// ------------------------------
// class visit
// ------------------------------
public void visitClass(ClassNode node) {
pushState();
currentClass = node;
currentScope.setClassScope(node);
super.visitClass(node);
popState();
}
protected void visitConstructorOrMethod(MethodNode node, boolean isConstructor) {
pushState(node.isStatic());
inConstructor = isConstructor;
node.setVariableScope(currentScope);
// GROOVY-2156
Parameter[] parameters = node.getParameters();
for (Parameter parameter : parameters) {
visitAnnotations(parameter);
}
declare(node.getParameters(), node);
super.visitConstructorOrMethod(node, isConstructor);
popState();
}
public void visitMethodCallExpression(MethodCallExpression call) {
if (call.isImplicitThis() && call.getMethod() instanceof ConstantExpression) {
ConstantExpression methodNameConstant = (ConstantExpression) call.getMethod();
Object value = methodNameConstant.getText();
if (!(value instanceof String)) {
throw new GroovyBugError("tried to make a method call with a non-String constant method name.");
}
String methodName = (String) value;
Variable v = checkVariableNameForDeclaration(methodName, call);
if (v != null && !(v instanceof DynamicVariable)) {
checkVariableContextAccess(v, call);
}
if (v instanceof VariableExpression || v instanceof Parameter) {
VariableExpression object = new VariableExpression(v);
object.setSourcePosition(methodNameConstant);
call.setObjectExpression(object);
call.setMethod(CALL);
}
}
super.visitMethodCallExpression(call);
}
public void visitConstructorCallExpression(ConstructorCallExpression call) {
isSpecialConstructorCall = call.isSpecialCall();
super.visitConstructorCallExpression(call);
isSpecialConstructorCall = false;
if (!call.isUsingAnnonymousInnerClass()) return;
pushState();
InnerClassNode innerClass = (InnerClassNode) call.getType();
innerClass.setVariableScope(currentScope);
for (MethodNode method : innerClass.getMethods()) {
Parameter[] parameters = method.getParameters();
if (parameters.length == 0) parameters = null; // null means no implicit "it"
ClosureExpression cl = new ClosureExpression(parameters, method.getCode());
visitClosureExpression(cl);
}
boolean ic = inClosure;
inClosure = true;
for (FieldNode field : innerClass.getFields()) {
final Expression expression = field.getInitialExpression();
if (expression != null) {
expression.visit(this);
}
}
for (Statement statement : innerClass.getObjectInitializerStatements()) {
statement.visit(this);
}
inClosure = ic;
popState();
}
public void visitBinaryExpression(BinaryExpression expression) {
super.visitBinaryExpression(expression);
if (inConstructor) return;
switch (expression.getOperation().getType()){
case Types.EQUAL: // = assignment
case Types.BITWISE_AND_EQUAL:
case Types.BITWISE_OR_EQUAL:
case Types.BITWISE_XOR_EQUAL:
case Types.PLUS_EQUAL:
case Types.MINUS_EQUAL:
case Types.MULTIPLY_EQUAL:
case Types.DIVIDE_EQUAL:
case Types.INTDIV_EQUAL:
case Types.MOD_EQUAL:
case Types.POWER_EQUAL:
case Types.LEFT_SHIFT_EQUAL:
case Types.RIGHT_SHIFT_EQUAL:
case Types.RIGHT_SHIFT_UNSIGNED_EQUAL:
checkFinalFieldAccess(expression.getLeftExpression());
break;
default: break;
}
}
private void checkFinalFieldAccess(Expression expression) {
if (!(expression instanceof VariableExpression)) return;
VariableExpression ve = (VariableExpression) expression;
Variable v = ve.getAccessedVariable();
boolean error = false;
if (v instanceof PropertyNode) {
PropertyNode pn = (PropertyNode) v;
error = (pn.getModifiers()&Opcodes.ACC_FINAL)!=0;
} else if (v instanceof FieldNode) {
FieldNode fn = (FieldNode) v;
error = (fn.getModifiers()&Opcodes.ACC_FINAL)!=0;
}
if (error) addError("cannnot access final field or property " +
"outside of constructor.", expression);
}
public void visitProperty(PropertyNode node) {
pushState(node.isStatic());
super.visitProperty(node);
popState();
}
public void visitField(FieldNode node) {
pushState(node.isStatic());
super.visitField(node);
popState();
}
}