Class TreeNode

java.lang.Object
  TreeNode

Direct Known Subclasses:

LeafNode, TreeNode1, TreeNode2, TreeNode3, TreeNode4, TreeNodeList

public abstract class TreeNode

extends java.lang.Object

TreeNode is the abstract parent class for a parse tree node. It contains an integer ID data field that is common to all types of node. The ID defines what type of tree node this is, e.g., an IF node, a PLUS, etc. The ID values are those defined for symbols in sym.java.

Extensions of TreeNode add additional data fields to hold information necessary for a particular node type. The TreeNode extensions are the following:

• TreeNode1 -- a node with one subtree reference, used to define unary expressions, or other unary constructs, such as a single declaration

• TreeNode2 -- a node with two subtree references, used to define binary expressions, or other binary constructs, such an assignment statement

• TreeNode3 -- a node with three subtree references, used to define trinary expressions, or other trinary constructs, such as an if-then-else statement

• TreeNode4 -- a node with four subtree references, used to define quartinary constructs

• TreeNodeList -- a node with an indefinite number of subtree references, used to define node lists of any form, or equivalently, n-ary constructs

• LeafNode -- a leaf node with value information, but no subtree references

See the documentation for each of these extending classes for further detail.

Field Summary

int	id The ID of this node.

Constructor Summary

TreeNode()
Construct a tree node with id = 0.

TreeNode(int id)
Construct a tree node with the given id.

Method Summary

static java.lang.String	symPrint(int id) Print a readable string value for a numeric-valued tree ID.
java.lang.String	toString() Output the String representation of a pre-order tree traversal.
abstract java.lang.String	toString(int level) This is the recursive work-doer for toString.

Methods inherited from class java.lang.Object

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

Field Detail

id

public int id

The ID of this node. Yea, it's public. Take that, you pain-in-the-xxx software engineers.

Constructor Detail

TreeNode

public TreeNode()

Construct a tree node with id = 0. This is used, e.g., for nodes in a list, that don't need individual id's.

TreeNode

public TreeNode(int id)

Construct a tree node with the given id.

Method Detail

toString

public java.lang.String toString()

Output the String representation of a pre-order tree traversal. The value of each node is written on a separate line, with subtree nodes indented two spaces per each level of depth, starting at depth 0 for the root.

For example, the following tree

looks like this from TreeNode.toString

 +
   a
   *
     b
     c
                                                                  

The implementation of toString() uses an int-valued overload to perform recursive traversal, passing an incrementing level value to successive recursive invocations. See the definitions of toString(int) in each TreeNode extension for further details.

toString

public abstract java.lang.String toString(int level)

This is the recursive work-doer for toString. See its definition in extending classes for details.

symPrint

public static java.lang.String symPrint(int id)

Print a readable string value for a numeric-valued tree ID. This method uses the mapping defined in the symNames class.