javafe.ast
Class ASTNode

java.lang.Object
  javafe.ast.ASTNode

All Implemented Interfaces:

java.lang.Cloneable

Direct Known Subclasses:

AnOverview, CatchClause, CompilationUnit, Condition, DecreasesInfo, DefPred, GenericVarDecl, GuardedCmd, IdentifierNode, ImportDecl, InitBlock, LexicalPragma, ModifierPragma, Name, ObjectDesignator, RoutineDecl, Spec, Stmt, Type, TypeDecl, TypeDeclElemPragma, TypeModifierPragma, VarInit

public abstract class ASTNode

extends java.lang.Object

implements java.lang.Cloneable

ASTNode is the root of the abstract syntax tree node hierarchy. Every class representing a node in the AST is a (direct or indirect) subclass of this class.

In designing our AST classes, the following, broad approach was taken:

• Design package javafe.ast to stand alone.
• Have a large, deep hierarchy, using the type system to encode many invariants. (Used a program to generate boilerplate code, making it the large hierarchy more manageable.)
• Represent children with public fields.
• Put most code outside AST classes.
• Support both switch-based and visitor-based traversal.
• Liberal use of locations. AST classes contain location fields that indicate the corresponding part of the source program.
• Use generic decorations.
• Rewrite tree to handle disambiguation. Expression names and method names are ambiguous: the be of the form package.type.members or type.members or local-variable.members or even members. The parser does not attempt to disambiguate among these, but rather generates either ExprName or MethodName. A later pass replaces these nodes with either VariableAccess or concrete subclasses of FieldAccess or MethodInvocation.
• Fill in fields and decorations to handle resolution. The nodes that need to be resolved are: TypeName, VariableAccess, (three subclasses of) FieldAccess, (three subclasses of) MethodInvocation, ConstructorInvocation, and NewInstanceExpr. All nodes except TypeName have a field named decl of the approriate type that is initialized to null and is filled in by name resolution. For TypeName we use a decoration rather than a field to avoid a dependency on the javafe.tc package.

Measurements (circa SRC ESC/Java):

Node abstract classes: 13
Node concrete classes: 59
Sequence classes: 12
Total classes: 84

Input to code generator: 842 lines of code (513 excluding comments)
Code generator: 993 (675)
Total lines of code: 1835 (1188)
Output of code generator: 4298

The complete list of subclasses is shown below. The names of subclasses of this class correspond (in general) to the syntactic units that they represent. Any exceptions to this rule are documented. All non-leaf classes are abstract. In parenthesis, the names and types of fields holding the locally-defined children classes are listed; a postfix * on a type indicates a sequence. Square brackets indicate optional elements; the only these fields can be null.

 ASTNode
    CompilationUnit ([Name pkgName], [LexicalPragma* lexicalPragmas], ImportDecl* imports, TypeDecl* elems)
    ImportDecl ()
       SingleTypeImport (TypeName typeName)
       OnDemandImport (Name pkgName)
    TypeDecl (int modifiers, [ModifierPragma* pmodifiers], Identifier id, [TypeModifierPragma* tmodifiers], TypeName* superInterfaces, TypeDeclElem* elems)
       ClassDecl ([TypeName superClass])
       InterfaceDecl ()
    TypeDeclElem () NOTE: This is an interface
       TypeDecl
       FieldDecl
       RoutineDecl (int modifiers, [ModifierPragma* pmodifiers], FormalParaDecl* args, TypeName* raises, [BlockStmt body])
          ConstructorDecl ([TypeModifierPragma* tmodifiers])
          MethodDecl (Identifier id, Type returnType)
       InitBlock (int modifiers, [ModifierPragma* pmodifiers], BlockStmt block)
       TypeDeclElemPragma ()
    GenericVarDecl (int modifiers, [ModifierPragma* pmodifiers], Identifier id, Type type)
       LocalVarDecl ([VarInit init])
       FieldDecl ([VarInit init])
       FormalParaDecl ()
    Stmt ()
       GenericBlockStmt (Stmt* stmts)
          BlockStmt ()
          SwitchStmt (Expr expr)
       AssertStmt (Expr expr, String l)
       VarDeclStmt (LocalVarDecl decl)
       ClassDeclStmt (ClassDecl anonDecl)
       WhileStmt (Expr expr, Stmt stmt)
       DoStmt (Expr expr, Stmt stmt)
       SynchronizeStmt (Expr expr, BlockStmt stmt)
       EvalStmt (Expr expr)
       ReturnStmt ([Expr expr])
       ThrowStmt (Expr expr)
       BranchStmt ([Identifier label])
          BreakStmt ()
          ContinueStmt ()
       LabelStmt (Identifier label, Stmt stmt)
       IfStmt (Expr expr, Stmt thn, Stmt els)
       ForStmt (Stmt* forInit, Expr test, Expr* forUpdate, Stmt body)
       SkipStmt ()
       SwitchLabel ([Expr expr])
       TryFinallyStmt (Stmt tryClause, Stmt finallyClause)
       TryCatchStmt (Stmt tryClause, CatchClause* catchClauses)
       StmtPragma ()
       ConstructorInvocation (boolean superCall, [Expr enclosingInstance], Expr* args)
    CatchClause (FormalParaDecl arg, Stmt body)
    VarInit ()
       ArrayInit (VarInit* elems)
       Expr ()
          ThisExpr (Type classPrefix)
          LiteralExpr (int tag, [Object value])
          ArrayRefExpr (Expr array, Expr index)
          NewInstanceExpr ([Expr enclosingInstance], TypeName type, Expr* args, [ClassDecl decl])
          NewArrayExpr (Type type, Expr* dims, [ArrayInit init])
          CondExpr (Expr test, Expr thn, Expr els)
          InstanceOfExpr (Expr expr, Type type)
          CastExpr (Expr expr, Type type)
          BinaryExpr (int op, Expr left, Expr right)
          UnaryExpr (int op, Expr expr)
          ParenExpr (Expr expr)
          AmbiguousVariableAccess (Name name)
          VariableAccess (Identifier id)
          FieldAccess (ObjectDesignator od, Identifier id)
          AmbiguousMethodInvocation (Name name, Expr* args)
          MethodInvocation (ObjectDesignator od, Identifier id, Expr* args)
          ClassLiteral (Type type)
    ObjectDesignator ()  // "expr.", "type." or "super."
       ExprObjectDesignator (Expr expr)
       TypeObjectDesignator (Type type)
       SuperObjectDesignator ()
    Type ()
       ErrorType() // was previously represented as a PrimitiveType
       PrimitiveType (int tag)
         JavafePrimitiveType  ()  // this is a new type introduced to allow for other (e.g., esc) primitive types
       TypeName (Name name)
       ArrayType (Type elemType)
    Name ()
       SimpleName (Identifier id)
       CompoundName (Identifier* ids)
    ModifierPragma ()
    LexicalPragma ()
    TypeModifierPragma ()
 

Field Summary

int	bogusField
private java.lang.Object[]	decorations The decorations that have been attached to this node.
static int	dotCounter
int	dotId

Constructor Summary

protected

ASTNode()

Method Summary

abstract void	accept(Visitor v) Accept a visit from v.
abstract java.lang.Object	accept(VisitorArgResult v, java.lang.Object o)
void	check()
abstract java.lang.Object	childAt(int i) Return the first-but-ith child of a node.
abstract int	childCount() Return the number of children a node has.
java.lang.Object	clone() Clone node, where the clone has the same decorations as original.
java.lang.Object	clone(boolean b)
java.lang.Object[]	getDecorations()
int	getEndLoc()
abstract int	getStartLoc()
abstract int	getTag() Return the tag of a node.
boolean	isInternal() returns true iff this in an internally declared node.
void	setDecorations(java.lang.Object[] d)
abstract java.lang.String	toString() Return a string representation of this.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

decorations

private java.lang.Object[] decorations

The decorations that have been attached to this node. This is a package-level field accessed by the ASTDecoration class. There are different ways to implement decorations; this way is not space-efficient, but it's pretty fast.

bogusField

public int bogusField

dotCounter

public static int dotCounter

dotId

public int dotId

Constructor Detail

ASTNode

protected ASTNode()

Method Detail

getStartLoc

public abstract int getStartLoc()

getEndLoc

public int getEndLoc()

isInternal

public boolean isInternal()

returns true iff this in an internally declared node. Note that internally declared types have no associated location.

clone

public java.lang.Object clone(boolean b)

clone

public java.lang.Object clone()

Clone node, where the clone has the same decorations as original.

getDecorations

public java.lang.Object[] getDecorations()

setDecorations

public void setDecorations(java.lang.Object[] d)

childCount

public abstract int childCount()

Return the number of children a node has.

childAt

public abstract java.lang.Object childAt(int i)

Return the first-but-ith child of a node.

getTag

public abstract int getTag()

Return the tag of a node.

toString

public abstract java.lang.String toString()

Return a string representation of this. Meant for debugging use only, not for presentation.

accept

public abstract void accept(Visitor v)

Accept a visit from v. This method simply calls the method of v corresponding to the allocated type of this, passing this as the argument. See the design patterns book.

accept

public abstract java.lang.Object accept(VisitorArgResult v,
                                        java.lang.Object o)

check

public void check()