Abstract syntax tree classes for working with Java programs

Abstract syntax tree classes for working with Java programs¶用于Java程序的抽象语法树类。

CodeQL has a large selection of classes for representing the abstract syntax tree of Java programs.

CodeQL有大量的类用于表示Java程序的抽象语法树。

The abstract syntax tree (AST) represents the syntactic structure of a program. Nodes on the AST represent elements such as statements and expressions.

抽象语法树（AST）表示程序的语法结构。AST中的节点代表了诸如语句和表达式等元素。

Statement classes

This table lists all subclasses of Stmt.

本表列出了Stmt的所有子类。

Statement syntax	CodeQL class	Superclasses	Remarks
`;`	EmptyStmt
Expr `;`	ExprStmt
`{` Stmt `... }`	BlockStmt
`if (` Expr `)` Stmt `else` Stmt	IfStmt	ConditionalStmt
`if (` Expr `)` Stmt
`while (` Expr `)` Stmt	WhileStmt	ConditionalStmt, LoopStmt
`do` Stmt `while (` Expr `)`	DoStmt	ConditionalStmt, LoopStmt
`for (` Expr `;` Expr `;` Expr `)` Stmt	ForStmt	ConditionalStmt, LoopStmt
`for (` VarAccess `:` Expr `)` Stmt	EnhancedForStmt	LoopStmt
`switch (` Expr `) {` SwitchCase `... }`	SwitchStmt
`try {` Stmt `... } finally {` Stmt `... }`	TryStmt
`return` Expr `;`	ReturnStmt
`return ;`
`throw` Expr `;`	ThrowStmt
`break ;`	BreakStmt	JumpStmt
`break label ;`
`continue ;`	ContinueStmt	JumpStmt
`continue label ;`
`label :` Stmt	LabeledStmt
`synchronized (` Expr `)` Stmt	SynchronizedStmt
`assert` Expr `:` Expr `;`	AssertStmt
`assert` Expr `;`
TypeAccess `name ;`	LocalVariableDeclStmt
`class name {` Member `... } ;`	LocalClassDeclStmt
`this (` Expr `, ... ) ;`	ThisConstructorInvocationStmt
`super (` Expr `, ... ) ;`	SuperConstructorInvocationStmt
`catch (` TypeAccess `name ) {` Stmt `... }`	CatchClause		can only occur as child of a TryStmt
`case` Literal `:` Stmt `...`	ConstCase		can only occur as child of a SwitchStmt
`default :` Stmt `...`	DefaultCase		can only occur as child of a SwitchStmt

Expression classes

There are many expression classes, so we present them by category. All classes in this section are subclasses of Expr.

表达式类有很多，所以我们按类别来介绍。本节中的所有类都是Expr.Literals的子类。

Literals

All classes in this subsection are subclasses of Literal.

本小节中的所有类都是Literal的子类。

Expression syntax example	CodeQL class
`true`	BooleanLiteral
`23`	IntegerLiteral
`23l`	LongLiteral
`4.2f`	FloatingPointLiteral
`4.2`	DoubleLiteral
`'a'`	CharacterLiteral
`"Hello"`	StringLiteral
`null`	NullLiteral

Unary expressions

All classes in this subsection are subclasses of UnaryExpr.

本小节中的所有类都是UnaryExpr的子类。

Expression syntax	CodeQL class	Superclasses	Remarks
Expr`++`	PostIncExpr	UnaryAssignExpr
Expr`--`	PostDecExpr	UnaryAssignExpr
`++`Expr	PreIncExpr	UnaryAssignExpr
`--`Expr	PreDecExpr	UnaryAssignExpr
`~`Expr	BitNotExpr	BitwiseExpr	see below for other subclasses of BitwiseExpr
`-`Expr	MinusExpr
`+`Expr	PlusExpr
`!`Expr	LogNotExpr	LogicExpr	see below for other subclasses of LogicExpr

Binary expressions

All classes in this subsection are subclasses of BinaryExpr.

本小节中的所有类都是BinaryExpr的子类。

Expression syntax	CodeQL class	Superclasses
Expr `*` Expr	MulExpr
Expr `/` Expr	DivExpr
Expr `%` Expr	RemExpr
Expr `+` Expr	AddExpr
Expr `-` Expr	SubExpr
Expr `<<` Expr	LShiftExpr
Expr `>>` Expr	RShiftExpr
Expr `>>>` Expr	URShiftExpr
Expr `&&` Expr	AndLogicalExpr	LogicExpr
Expr `		` Expr
Expr `<` Expr	LTExpr	ComparisonExpr
Expr `>` Expr	GTExpr	ComparisonExpr
Expr `<=` Expr	LEExpr	ComparisonExpr
Expr `>=` Expr	GEExpr	ComparisonExpr
Expr `==` Expr	EQExpr	EqualityTest
Expr `!=` Expr	NEExpr	EqualityTest
Expr `&` Expr	AndBitwiseExpr	BitwiseExpr
Expr `	` Expr	OrBitwiseExpr
Expr `^` Expr	XorBitwiseExpr	BitwiseExpr

Assignment expressions

All classes in this table are subclasses of Assignment.

本表中的所有类都是Assignment的子类。

| Expression syntax | CodeQL class | Superclasses | | — | — | — | | Expr = Expr | AssignExpr | | | Expr += Expr | AssignAddExpr | AssignOp | | Expr -= Expr | AssignSubExpr | AssignOp | | Expr *= Expr | AssignMulExpr | AssignOp | | Expr /= Expr | AssignDivExpr | AssignOp | | Expr %= Expr | AssignRemExpr | AssignOp | | Expr &= Expr | AssignAndExpr | AssignOp | | Expr ` | =[Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html) | [AssignOrExpr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignOrExpr.html) | | [Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html)^=[Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html) | [AssignXorExpr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignXorExpr.html) | [AssignOp](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignOp.html) | | [Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html)«=[Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html) | [AssignLShiftExpr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignLShiftExpr.html) | [AssignOp](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignOp.html) | | [Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html)»=[Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html) | [AssignRShiftExpr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignRShiftExpr.html) | [AssignOp](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$AssignOp.html) | | [Expr](https://codeql.github.com/codeql-standard-libraries/java/semmle/code/java/Expr.qll/type.Expr$Expr.html)»>=` Expr | AssignURShiftExpr | AssignOp |

Accesses

Expression syntax examples	CodeQL class
`this`	ThisAccess
`Outer.this`
`super`	SuperAccess
`Outer.super`
`x`	VarAccess
`e.f`
`a[i]`	ArrayAccess
`f(...)`	MethodAccess
`e.m(...)`
`String`	TypeAccess
`java.lang.String`
`? extends Number`	WildcardTypeAccess
`? super Double`

A VarAccess that refers to a field is a FieldAccess.

一个指向字段的VarAccess是一个FieldAccess。

Miscellaneous

Expression syntax examples	CodeQL class	Remarks
`(int) f`	CastExpr
`(23 + 42)`	ParExpr
`o instanceof String`	InstanceOfExpr
Expr `?` Expr `:` Expr	ConditionalExpr
`String. class`	TypeLiteral
`new A()`	ClassInstanceExpr
`new String[3][2]`	ArrayCreationExpr
`new int[] { 23, 42 }`
`{ 23, 42 }`	ArrayInit	can only appear as an initializer or as a child of an ArrayCreationExpr只能作为初始化器或ArrayCreationExpr的子代出现。
`@Annot(key=val)`	Annotation

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