org.antlr.runtime.tree

Interface TreeAdaptor

All Known Implementing Classes:

BaseTreeAdaptor, CommonTreeAdaptor, DebugTreeAdaptor, TreeWizard.TreePatternTreeAdaptor

public interface TreeAdaptor

How to create and navigate trees. Rather than have a separate factory and adaptor, I've merged them. Makes sense to encapsulate. This takes the place of the tree construction code generated in the generated code in 2.x and the ASTFactory. I do not need to know the type of a tree at all so they are all generic Objects. This may increase the amount of typecasting needed. :(

Method Summary

Methods

Modifier and Type	Method and Description
void	addChild(Object t, Object child) Add a child to the tree t.
Object	becomeRoot(Object newRoot, Object oldRoot) If oldRoot is a nil root, just copy or move the children to newRoot.
Object	becomeRoot(Token newRoot, Object oldRoot) Create a node for newRoot make it the root of oldRoot.
Object	create(int tokenType, String text) Create a new node derived from a token, with a new token type.
Object	create(int tokenType, Token fromToken) Create a new node derived from a token, with a new token type.
Object	create(int tokenType, Token fromToken, String text) Same as create(tokenType,fromToken) except set the text too.
Object	create(Token payload) Create a tree node from Token object; for CommonTree type trees, then the token just becomes the payload.
Object	deleteChild(Object t, int i) Remove ith child and shift children down from right.
Object	dupNode(Object treeNode) Duplicate a single tree node.
Object	dupTree(Object tree) Duplicate tree recursively, using dupNode() for each node
Object	errorNode(TokenStream input, Token start, Token stop, RecognitionException e) Return a tree node representing an error.
Object	getChild(Object t, int i) Get a child 0..n-1 node
int	getChildCount(Object t) How many children? If 0, then this is a leaf node
int	getChildIndex(Object t) What index is this node in the child list? Range: 0..n-1 If your node type doesn't handle this, it's ok but the tree rewrites in tree parsers need this functionality.
Object	getParent(Object t) Who is the parent node of this node; if null, implies node is root.
String	getText(Object t)
Token	getToken(Object t) Return the token object from which this node was created.
int	getTokenStartIndex(Object t) Get the token start index for this subtree; return -1 if no such index
int	getTokenStopIndex(Object t) Get the token stop index for this subtree; return -1 if no such index
int	getType(Object t) For tree parsing, I need to know the token type of a node
int	getUniqueID(Object node) For identifying trees.
boolean	isNil(Object tree) Is tree considered a nil node used to make lists of child nodes?
Object	nil() Return a nil node (an empty but non-null node) that can hold a list of element as the children.
void	replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t) Replace from start to stop child index of parent with t, which might be a list.
Object	rulePostProcessing(Object root) Given the root of the subtree created for this rule, post process it to do any simplifications or whatever you want.
void	setChild(Object t, int i, Object child) Set ith child (0..n-1) to t; t must be non-null and non-nil node
void	setChildIndex(Object t, int index)
void	setParent(Object t, Object parent)
void	setText(Object t, String text) Node constructors can set the text of a node
void	setTokenBoundaries(Object t, Token startToken, Token stopToken) Where are the bounds in the input token stream for this node and all children? Each rule that creates AST nodes will call this method right before returning.
void	setType(Object t, int type) Node constructors can set the type of a node

Method Detail

create

Object create(Token payload)

Create a tree node from Token object; for CommonTree type trees, then the token just becomes the payload. This is the most common create call. Override if you want another kind of node to be built.

dupNode

Object dupNode(Object treeNode)

Duplicate a single tree node. Override if you want another kind of node to be built.

dupTree

Object dupTree(Object tree)

Duplicate tree recursively, using dupNode() for each node

nil

Object nil()

Return a nil node (an empty but non-null node) that can hold a list of element as the children. If you want a flat tree (a list) use "t=adaptor.nil(); t.addChild(x); t.addChild(y);"

errorNode

Object errorNode(TokenStream input,
               Token start,
               Token stop,
               RecognitionException e)

Return a tree node representing an error. This node records the tokens consumed during error recovery. The start token indicates the input symbol at which the error was detected. The stop token indicates the last symbol consumed during recovery. You must specify the input stream so that the erroneous text can be packaged up in the error node. The exception could be useful to some applications; default implementation stores ptr to it in the CommonErrorNode. This only makes sense during token parsing, not tree parsing. Tree parsing should happen only when parsing and tree construction succeed.

isNil

boolean isNil(Object tree)

Is tree considered a nil node used to make lists of child nodes?

addChild

void addChild(Object t,
            Object child)

Add a child to the tree t. If child is a flat tree (a list), make all in list children of t. Warning: if t has no children, but child does and child isNil then you can decide it is ok to move children to t via t.children = child.children; i.e., without copying the array. Just make sure that this is consistent with have the user will build ASTs. Do nothing if t or child is null.

becomeRoot

Object becomeRoot(Object newRoot,
                Object oldRoot)

If oldRoot is a nil root, just copy or move the children to newRoot. If not a nil root, make oldRoot a child of newRoot. old=^(nil a b c), new=r yields ^(r a b c) old=^(a b c), new=r yields ^(r ^(a b c)) If newRoot is a nil-rooted single child tree, use the single child as the new root node. old=^(nil a b c), new=^(nil r) yields ^(r a b c) old=^(a b c), new=^(nil r) yields ^(r ^(a b c)) If oldRoot was null, it's ok, just return newRoot (even if isNil). old=null, new=r yields r old=null, new=^(nil r) yields ^(nil r) Return newRoot. Throw an exception if newRoot is not a simple node or nil root with a single child node--it must be a root node. If newRoot is ^(nil x) return x as newRoot. Be advised that it's ok for newRoot to point at oldRoot's children; i.e., you don't have to copy the list. We are constructing these nodes so we should have this control for efficiency.

rulePostProcessing

Object rulePostProcessing(Object root)

Given the root of the subtree created for this rule, post process it to do any simplifications or whatever you want. A required behavior is to convert ^(nil singleSubtree) to singleSubtree as the setting of start/stop indexes relies on a single non-nil root for non-flat trees. Flat trees such as for lists like "idlist : ID+ ;" are left alone unless there is only one ID. For a list, the start/stop indexes are set in the nil node. This method is executed after all rule tree construction and right before setTokenBoundaries().

getUniqueID

int getUniqueID(Object node)

For identifying trees. How to identify nodes so we can say "add node to a prior node"? Even becomeRoot is an issue. Use System.identityHashCode(node) usually.

becomeRoot

Object becomeRoot(Token newRoot,
                Object oldRoot)

Create a node for newRoot make it the root of oldRoot. If oldRoot is a nil root, just copy or move the children to newRoot. If not a nil root, make oldRoot a child of newRoot. Return node created for newRoot. Be advised: when debugging ASTs, the DebugTreeAdaptor manually calls create(Token child) and then plain becomeRoot(node, node) because it needs to trap calls to create, but it can't since it delegates to not inherits from the TreeAdaptor.

create

Object create(int tokenType,
            Token fromToken)

Create a new node derived from a token, with a new token type. This is invoked from an imaginary node ref on right side of a rewrite rule as IMAG[$tokenLabel]. This should invoke createToken(Token).

create

Object create(int tokenType,
            Token fromToken,
            String text)

Same as create(tokenType,fromToken) except set the text too. This is invoked from an imaginary node ref on right side of a rewrite rule as IMAG[$tokenLabel, "IMAG"]. This should invoke createToken(Token).

create

Object create(int tokenType,
            String text)

Create a new node derived from a token, with a new token type. This is invoked from an imaginary node ref on right side of a rewrite rule as IMAG["IMAG"]. This should invoke createToken(int,String).

getType

int getType(Object t)

For tree parsing, I need to know the token type of a node

setType

void setType(Object t,
           int type)

Node constructors can set the type of a node

getText

String getText(Object t)

setText

void setText(Object t,
           String text)

Node constructors can set the text of a node

getToken

Token getToken(Object t)

Return the token object from which this node was created. Currently used only for printing an error message. The error display routine in BaseRecognizer needs to display where the input the error occurred. If your tree of limitation does not store information that can lead you to the token, you can create a token filled with the appropriate information and pass that back. See BaseRecognizer.getErrorMessage().

setTokenBoundaries

void setTokenBoundaries(Object t,
                      Token startToken,
                      Token stopToken)

Where are the bounds in the input token stream for this node and all children? Each rule that creates AST nodes will call this method right before returning. Flat trees (i.e., lists) will still usually have a nil root node just to hold the children list. That node would contain the start/stop indexes then.

getTokenStartIndex

int getTokenStartIndex(Object t)

Get the token start index for this subtree; return -1 if no such index

getTokenStopIndex

int getTokenStopIndex(Object t)

Get the token stop index for this subtree; return -1 if no such index

getChild

Object getChild(Object t,
              int i)

Get a child 0..n-1 node

setChild

void setChild(Object t,
            int i,
            Object child)

Set ith child (0..n-1) to t; t must be non-null and non-nil node

deleteChild

Object deleteChild(Object t,
                 int i)

Remove ith child and shift children down from right.

getChildCount

int getChildCount(Object t)

How many children? If 0, then this is a leaf node

getParent

Object getParent(Object t)

Who is the parent node of this node; if null, implies node is root. If your node type doesn't handle this, it's ok but the tree rewrites in tree parsers need this functionality.

setParent

void setParent(Object t,
             Object parent)

getChildIndex

int getChildIndex(Object t)

What index is this node in the child list? Range: 0..n-1 If your node type doesn't handle this, it's ok but the tree rewrites in tree parsers need this functionality.

setChildIndex

void setChildIndex(Object t,
                 int index)

replaceChildren

void replaceChildren(Object parent,
                   int startChildIndex,
                   int stopChildIndex,
                   Object t)

Replace from start to stop child index of parent with t, which might be a list. Number of children may be different after this call. If parent is null, don't do anything; must be at root of overall tree. Can't replace whatever points to the parent externally. Do nothing.