org.eclipse.jdt.internal.compiler.ast.CombinedBinaryExpression Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of ecj Show documentation
Show all versions of ecj Show documentation
This is Eclipse JDT Core Batch Compiler used by Scout SDK
The newest version!
/*******************************************************************************
* Copyright (c) 2006, 2012 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Stephan Herrmann - Contribution for
* bug 345305 - [compiler][null] Compiler misidentifies a case of "variable can only be null"
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.ast;
import org.eclipse.jdt.internal.compiler.ASTVisitor;
import org.eclipse.jdt.internal.compiler.codegen.CodeStream;
import org.eclipse.jdt.internal.compiler.flow.FlowContext;
import org.eclipse.jdt.internal.compiler.flow.FlowInfo;
import org.eclipse.jdt.internal.compiler.impl.Constant;
import org.eclipse.jdt.internal.compiler.lookup.BlockScope;
import org.eclipse.jdt.internal.compiler.lookup.TypeBinding;
import org.eclipse.jdt.internal.compiler.lookup.TypeIds;
/**
* CombinedBinaryExpression is an implementation of BinaryExpression that
* specifically attempts to mitigate the issues raised by expressions which
* have a very deep leftmost branch. It does so by maintaining a table of
* direct references to its subexpressions, and implementing non-recursive
* variants of the most significant recursive algorithms of its ancestors.
* The subexpressions table only holds intermediate binary expressions. Its
* role is to provide the reversed navigation through the left relationship
* of BinaryExpression to Expression. To cope with potentially very deep
* left branches, an instance of CombinedBinaryExpression is created once in
* a while, using variable thresholds held by {@link #arityMax}.
* As a specific case, the topmost node of all binary expressions that are
* deeper than one is a CombinedBinaryExpression, but it has no references
* table.
* Notes:
*
* - CombinedBinaryExpression is not meant to behave in other ways than
* BinaryExpression in any observable respect;
* - visitors that implement their own traversal upon binary expressions
* should consider taking advantage of combined binary expressions, or
* else face a risk of StackOverflowError upon deep instances;
* - callers that need to change the operator should rebuild the expression
* from scratch, or else amend the references table as needed to cope with
* the resulting, separated expressions.
*
*/
public class CombinedBinaryExpression extends BinaryExpression {
/**
* The number of consecutive binary expressions of this' left branch that
* bear the same operator as this.
* Notes:
* - the presence of a CombinedBinaryExpression instance resets
* arity, even when its operator is compatible;
* - this property is maintained by the parser.
*
*/
public int arity;
/**
* The threshold that will trigger the creation of the next full-fledged
* CombinedBinaryExpression. This field is only maintained for the
* topmost binary expression (it is 0 otherwise). It enables a variable
* policy, which scales better with very large expressions.
*/
public int arityMax;
/**
* Upper limit for {@link #arityMax}.
*/
public static final int ARITY_MAX_MAX = 160;
/**
* Default lower limit for {@link #arityMax}.
*/
public static final int ARITY_MAX_MIN = 20;
/**
* Default value for the first term of the series of {@link #arityMax}
* values. Changing this allows for experimentation. Not meant to be
* changed during a parse operation.
*/
public static int defaultArityMaxStartingValue = ARITY_MAX_MIN;
/**
* A table of references to the binary expressions of this' left branch.
* Instances of CombinedBinaryExpression are not repeated here. Instead,
* the left subexpression of referencesTable[0] may be a combined binary
* expression, if appropriate. Null when this only cares about tracking
* the expression's arity.
*/
public BinaryExpression referencesTable[];
/**
* Make a new CombinedBinaryExpression. If arity is strictly greater than one,
* a references table is built and initialized with the reverse relationship of
* the one defined by {@link BinaryExpression#left}. arity and left must be
* compatible with each other (that is, there must be at least arity - 1
* consecutive compatible binary expressions into the leftmost branch of left,
* the topmost of which being left's immediate left expression).
* @param left the left branch expression
* @param right the right branch expression
* @param operator the operator for this binary expression - only PLUS for now
* @param arity the number of binary expressions of a compatible operator that
* already exist into the leftmost branch of left (including left); must
* be strictly greater than 0
*/
public CombinedBinaryExpression(Expression left, Expression right, int operator, int arity) {
super(left, right, operator);
initArity(left, arity);
}
public CombinedBinaryExpression(CombinedBinaryExpression expression) {
super(expression);
initArity(expression.left, expression.arity);
}
public FlowInfo analyseCode(BlockScope currentScope, FlowContext flowContext,
FlowInfo flowInfo) {
// keep implementation in sync with BinaryExpression#analyseCode
if (this.referencesTable == null) {
return super.analyseCode(currentScope, flowContext, flowInfo);
}
try {
BinaryExpression cursor;
if ((cursor = this.referencesTable[0]).resolvedType.id !=
TypeIds.T_JavaLangString) {
cursor.left.checkNPE(currentScope, flowContext, flowInfo);
}
flowInfo = cursor.left.analyseCode(currentScope, flowContext, flowInfo).
unconditionalInits();
for (int i = 0, end = this.arity; i < end; i ++) {
if ((cursor = this.referencesTable[i]).resolvedType.id !=
TypeIds.T_JavaLangString) {
cursor.right.checkNPE(currentScope, flowContext, flowInfo);
}
flowInfo = cursor.right.
analyseCode(currentScope, flowContext, flowInfo).
unconditionalInits();
}
if (this.resolvedType.id != TypeIds.T_JavaLangString) {
this.right.checkNPE(currentScope, flowContext, flowInfo);
}
return this.right.analyseCode(currentScope, flowContext, flowInfo).
unconditionalInits();
} finally {
// account for exception possibly thrown by arithmetics
flowContext.recordAbruptExit();
}
}
public void generateOptimizedStringConcatenation(BlockScope blockScope,
CodeStream codeStream, int typeID) {
// keep implementation in sync with BinaryExpression and Expression
// #generateOptimizedStringConcatenation
if (this.referencesTable == null) {
super.generateOptimizedStringConcatenation(blockScope, codeStream,
typeID);
} else {
if ((((this.bits & ASTNode.OperatorMASK) >> ASTNode.OperatorSHIFT) ==
OperatorIds.PLUS)
&& ((this.bits & ASTNode.ReturnTypeIDMASK) == TypeIds.T_JavaLangString)) {
if (this.constant != Constant.NotAConstant) {
codeStream.generateConstant(this.constant, this.implicitConversion);
codeStream.invokeStringConcatenationAppendForType(
this.implicitConversion & TypeIds.COMPILE_TYPE_MASK);
} else {
BinaryExpression cursor = this.referencesTable[0];
int restart = 0;
// int cursorTypeID;
int pc = codeStream.position;
for (restart = this.arity - 1; restart >= 0; restart--) {
if ((cursor = this.referencesTable[restart]).constant !=
Constant.NotAConstant) {
codeStream.generateConstant(cursor.constant,
cursor.implicitConversion);
codeStream.invokeStringConcatenationAppendForType(
cursor.implicitConversion & TypeIds.COMPILE_TYPE_MASK);
break;
}
// never happens for now - may reconsider if we decide to
// cover more than string concatenation
// if (!((((cursor = this.referencesTable[restart]).bits &
// ASTNode.OperatorMASK) >> ASTNode.OperatorSHIFT) ==
// OperatorIds.PLUS) &
// ((cursorTypeID = cursor.bits & ASTNode.ReturnTypeIDMASK) ==
// TypeIds.T_JavaLangString)) {
// if (cursorTypeID == T_JavaLangString &&
// cursor.constant != Constant.NotAConstant &&
// cursor.constant.stringValue().length() == 0) {
// break; // optimize str + ""
// }
// cursor.generateCode(blockScope, codeStream, true);
// codeStream.invokeStringConcatenationAppendForType(
// cursorTypeID);
// break;
// }
}
restart++;
if (restart == 0) { // reached the leftmost expression
cursor.left.generateOptimizedStringConcatenation(
blockScope,
codeStream,
cursor.left.implicitConversion & TypeIds.COMPILE_TYPE_MASK);
}
int pcAux;
for (int i = restart; i < this.arity; i++) {
codeStream.recordPositionsFrom(pc,
(cursor = this.referencesTable[i]).left.sourceStart);
pcAux = codeStream.position;
cursor.right.generateOptimizedStringConcatenation(blockScope,
codeStream, cursor.right.implicitConversion &
TypeIds.COMPILE_TYPE_MASK);
codeStream.recordPositionsFrom(pcAux, cursor.right.sourceStart);
}
codeStream.recordPositionsFrom(pc, this.left.sourceStart);
pc = codeStream.position;
this.right.generateOptimizedStringConcatenation(
blockScope,
codeStream,
this.right.implicitConversion & TypeIds.COMPILE_TYPE_MASK);
codeStream.recordPositionsFrom(pc, this.right.sourceStart);
}
} else {
super.generateOptimizedStringConcatenation(blockScope, codeStream,
typeID);
}
}
}
public void generateOptimizedStringConcatenationCreation(BlockScope blockScope,
CodeStream codeStream, int typeID) {
// keep implementation in sync with BinaryExpression
// #generateOptimizedStringConcatenationCreation
if (this.referencesTable == null) {
super.generateOptimizedStringConcatenationCreation(blockScope,
codeStream, typeID);
} else {
if ((((this.bits & ASTNode.OperatorMASK) >> ASTNode.OperatorSHIFT) ==
OperatorIds.PLUS) &&
((this.bits & ASTNode.ReturnTypeIDMASK) ==
TypeIds.T_JavaLangString) &&
this.constant == Constant.NotAConstant) {
int pc = codeStream.position;
BinaryExpression cursor = this.referencesTable[this.arity - 1];
// silence warnings
int restart = 0;
for (restart = this.arity - 1; restart >= 0; restart--) {
if (((((cursor = this.referencesTable[restart]).bits &
ASTNode.OperatorMASK) >> ASTNode.OperatorSHIFT) ==
OperatorIds.PLUS) &&
((cursor.bits & ASTNode.ReturnTypeIDMASK) ==
TypeIds.T_JavaLangString)) {
if (cursor.constant != Constant.NotAConstant) {
codeStream.newStringContatenation(); // new: java.lang.StringBuffer
codeStream.dup();
codeStream.ldc(cursor.constant.stringValue());
codeStream.invokeStringConcatenationStringConstructor();
// invokespecial: java.lang.StringBuffer.(Ljava.lang.String;)V
break;
}
} else {
cursor.generateOptimizedStringConcatenationCreation(blockScope,
codeStream, cursor.implicitConversion &
TypeIds.COMPILE_TYPE_MASK);
break;
}
}
restart++;
if (restart == 0) { // reached the leftmost expression
cursor.left.generateOptimizedStringConcatenationCreation(
blockScope,
codeStream,
cursor.left.implicitConversion & TypeIds.COMPILE_TYPE_MASK);
}
int pcAux;
for (int i = restart; i < this.arity; i++) {
codeStream.recordPositionsFrom(pc,
(cursor = this.referencesTable[i]).left.sourceStart);
pcAux = codeStream.position;
cursor.right.generateOptimizedStringConcatenation(blockScope,
codeStream, cursor.right.implicitConversion &
TypeIds.COMPILE_TYPE_MASK);
codeStream.recordPositionsFrom(pcAux, cursor.right.sourceStart);
}
codeStream.recordPositionsFrom(pc, this.left.sourceStart);
pc = codeStream.position;
this.right.generateOptimizedStringConcatenation(
blockScope,
codeStream,
this.right.implicitConversion & TypeIds.COMPILE_TYPE_MASK);
codeStream.recordPositionsFrom(pc, this.right.sourceStart);
} else {
super.generateOptimizedStringConcatenationCreation(blockScope,
codeStream, typeID);
}
}
}
private void initArity(Expression expression, int value) {
this.arity = value;
if (value > 1) {
this.referencesTable = new BinaryExpression[value];
this.referencesTable[value - 1] = (BinaryExpression) expression;
for (int i = value - 1; i > 0; i--) {
this.referencesTable[i - 1] =
(BinaryExpression) this.referencesTable[i].left;
}
} else {
this.arityMax = defaultArityMaxStartingValue;
}
}
public StringBuffer printExpressionNoParenthesis(int indent,
StringBuffer output) {
// keep implementation in sync with
// BinaryExpression#printExpressionNoParenthesis and
// OperatorExpression#printExpression
if (this.referencesTable == null) {
return super.printExpressionNoParenthesis(indent, output);
}
String operatorString = operatorToString();
for (int i = this.arity - 1; i >= 0; i--) {
output.append('(');
}
output = this.referencesTable[0].left.
printExpression(indent, output);
for (int i = 0, end = this.arity;
i < end; i++) {
output.append(' ').append(operatorString).append(' ');
output = this.referencesTable[i].right.
printExpression(0, output);
output.append(')');
}
output.append(' ').append(operatorString).append(' ');
return this.right.printExpression(0, output);
}
public TypeBinding resolveType(BlockScope scope) {
// keep implementation in sync with BinaryExpression#resolveType
if (this.referencesTable == null) {
return super.resolveType(scope);
}
BinaryExpression cursor;
if ((cursor = this.referencesTable[0]).left instanceof CastExpression) {
cursor.left.bits |= ASTNode.DisableUnnecessaryCastCheck;
// will check later on
}
cursor.left.resolveType(scope);
for (int i = 0, end = this.arity; i < end; i ++) {
this.referencesTable[i].nonRecursiveResolveTypeUpwards(scope);
}
nonRecursiveResolveTypeUpwards(scope);
return this.resolvedType;
}
public void traverse(ASTVisitor visitor, BlockScope scope) {
if (this.referencesTable == null) {
super.traverse(visitor, scope);
} else {
if (visitor.visit(this, scope)) {
int restart;
for (restart = this.arity - 1;
restart >= 0;
restart--) {
if (!visitor.visit(
this.referencesTable[restart], scope)) {
visitor.endVisit(
this.referencesTable[restart], scope);
break;
}
}
restart++;
// restart now points to the deepest BE for which
// visit returned true, if any
if (restart == 0) {
this.referencesTable[0].left.traverse(visitor, scope);
}
for (int i = restart, end = this.arity;
i < end; i++) {
this.referencesTable[i].right.traverse(visitor, scope);
visitor.endVisit(this.referencesTable[i], scope);
}
this.right.traverse(visitor, scope);
}
visitor.endVisit(this, scope);
}
}
/**
* Change {@link #arityMax} if and as needed. The current policy is to double
* arityMax each time this method is called, until it reaches
* {@link #ARITY_MAX_MAX}. Other policies may consider incrementing it less
* agressively. Call only after an appropriate value has been assigned to
* {@link #left}.
*/
// more sophisticate increment policies would leverage the leftmost expression
// to hold an indication of the number of uses of a given arityMax in a row
public void tuneArityMax() {
if (this.arityMax < ARITY_MAX_MAX) {
this.arityMax *= 2;
}
}
}