edu.illinois.cs.cogcomp.lbjava.IR

Class ASTNode

java.lang.Object

edu.illinois.cs.cogcomp.lbjava.IR.ASTNode

Direct Known Subclasses:

Argument, AST, CatchClause, ClassifierExpression, ConstraintExpression, Declaration, Expression, InferenceDeclaration.HeadFinder, InferenceDeclaration.NormalizerDeclaration, List, Operator, Statement, SwitchBlock, SwitchGroup, SwitchLabel, Type

public abstract class ASTNode
extends Object

Abstract node class that every AST node extends.

Every AST node must

• have a unique ID number and store the line and byte offset where it was found in the source file.
• include a special symbol at the beginning of the Javadoc comment of each of its AST node child member variables indicating whether that member variable is allowed to be set to null. The symbol (ø) is used to indicate that the variable is allowed to be null, and the symbol (¬ø) indicates that the variable will never be null.
• return an ASTNodeIterator through the abstract iterator() method that traverses its children in the order in which the code would be executed. If the node is composed of declarative constructs rather than executable code, the iterator will traverse those constructs in the order in which they appear in the source.
• override the clone() method such that it returns a deep copy of itself, except that the line and byte offset of the copy are both set to -1.
• override the runPass(Pass) method so that it simply calls the Pass's run(.) method whose argument type is the type of the node.
• return a String representation of itself through the toString() and write(StringBuffer) methods. Only the write(StringBuffer) method need be overridden by each node, as toString() will simply invoke write(StringBuffer) to produce its result. (This is much more efficient than having toString() call its childrens' toString() methods recursively through the AST and concatenating them all together.) The String produced will not be very readable (e.g., it won't contain any new lines), but it will be compilable by the LBJava compiler.

Most ASTNodes will also contain more than one constructor. There will be one constructor that includes all references to its children as well as line and byte offset information, etc. This constructor is commonly used by the node's clone() method. In addition, there may be at least one constructor designed to be more useful for the JavaCUP parser, taking TokenValues as input.

Author:

Nick Rizzolo

Field Summary

Fields

Modifier and Type	Field and Description
int	byteOffset The byte offset from the beginning of the source file at which the source code represented by this node is found.
int	line The line on which the source code represented by this node is found.
int	nodeID Stores the ID of this node as provided by nextID.
SymbolTable	symbolTable The table of variable types representing this node's scope.

Constructor Summary

Constructors

Constructor and Description
ASTNode() Default constructor.
ASTNode(int line, int byteOffset) Initializing constructor.

Method Summary

Modifier and Type	Method and Description
Object	clone() Creates a new object with the same primitive data, and recursively creates new member data objects as well.
abstract ASTNodeIterator	iterator() Returns an iterator used to successively access the children of this node.
abstract void	runPass(Pass pass) Ensures that the correct run() method is called for this type of node.
String	toString() Calls the write(StringBuffer) method to produce a string representation of this node.
abstract void	write(StringBuffer buffer) Writes a string representation of this ASTNode to the specified buffer.

Methods inherited from class java.lang.Object

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

Field Detail

nodeID

public int nodeID

Stores the ID of this node as provided by nextID.

line

public int line

The line on which the source code represented by this node is found.

byteOffset

public int byteOffset

The byte offset from the beginning of the source file at which the source code represented by this node is found.

symbolTable

public SymbolTable symbolTable

The table of variable types representing this node's scope.

Constructor Detail

ASTNode

public ASTNode()

Default constructor.

ASTNode

public ASTNode(int line,
               int byteOffset)

Initializing constructor. This constructor is called via the super operator from every other node.

Parameters:

line - The line on which the source code represented by this node is found.

byteOffset - The byte offset from the beginning of the source file at which the source code represented by this node is found.

Method Detail

iterator

public abstract ASTNodeIterator iterator()

Returns an iterator used to successively access the children of this node.

Returns:

An iterator used to successively access the children of this node.

clone

public Object clone()

Creates a new object with the same primitive data, and recursively creates new member data objects as well.

Overrides:

clone in class Object

Returns:

The clone node.

runPass

public abstract void runPass(Pass pass)

Ensures that the correct run() method is called for this type of node.

Parameters:

pass - The pass whose run() method should be called.

toString

public String toString()

Calls the write(StringBuffer) method to produce a string representation of this node.

Overrides:

toString in class Object

Returns:

A textual representation of this node.

write

public abstract void write(StringBuffer buffer)

Writes a string representation of this ASTNode to the specified buffer. The representation written is parsable by the LBJava compiler, but not very readable.

Parameters:

buffer - The buffer to write to.