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A framework for constructing recognizers, compilers, and translators from grammatical descriptions containing Java, C#, C++, or Python actions.
/*
[The "BSD license"]
Copyright (c) 2005-2009 Terence Parr
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package org.antlr.runtime.tree;
import org.antlr.runtime.Token;
import org.antlr.runtime.TokenStream;
import org.antlr.runtime.RecognitionException;
/** 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. :(
*/
public interface TreeAdaptor {
// C o n s t r u c t i o n
/** 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.
*/
public Object create(Token payload);
/** Duplicate a single tree node.
* Override if you want another kind of node to be built.
*/
public Object dupNode(Object treeNode);
/** Duplicate tree recursively, using dupNode() for each node */
public Object dupTree(Object tree);
/** 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);"
*/
public Object nil();
/** 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.
*/
public Object errorNode(TokenStream input, Token start, Token stop, RecognitionException e);
/** Is tree considered a nil node used to make lists of child nodes? */
public boolean isNil(Object tree);
/** 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.
*/
public void addChild(Object t, Object child);
/** 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.
*/
public Object becomeRoot(Object newRoot, Object oldRoot);
/** 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().
*/
public Object rulePostProcessing(Object root);
/** 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.
*/
public int getUniqueID(Object node);
// R e w r i t e R u l e s
/** 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.
*/
public Object becomeRoot(Token newRoot, Object oldRoot);
/** 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[$tokenLabel].
*
* This should invoke createToken(Token).
*/
public Object create(int tokenType, Token fromToken);
/** Same as create(tokenType,fromToken) except set the text too.
* This is invoked from an imaginary node ref on right side of a
* rewrite rule as IMAG[$tokenLabel, "IMAG"].
*
* This should invoke createToken(Token).
*/
public Object create(int tokenType, Token fromToken, 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).
*/
public Object create(int tokenType, String text);
// C o n t e n t
/** For tree parsing, I need to know the token type of a node */
public int getType(Object t);
/** Node constructors can set the type of a node */
public void setType(Object t, int type);
public String getText(Object t);
/** Node constructors can set the text of a node */
public void setText(Object t, String text);
/** 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().
*/
public Token getToken(Object t);
/** 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.
*/
public void setTokenBoundaries(Object t, Token startToken, Token stopToken);
/** Get the token start index for this subtree; return -1 if no such index */
public int getTokenStartIndex(Object t);
/** Get the token stop index for this subtree; return -1 if no such index */
public int getTokenStopIndex(Object t);
// N a v i g a t i o n / T r e e P a r s i n g
/** Get a child 0..n-1 node */
public Object getChild(Object t, int i);
/** Set ith child (0..n-1) to t; t must be non-null and non-nil node */
public void setChild(Object t, int i, Object child);
/** Remove ith child and shift children down from right. */
public Object deleteChild(Object t, int i);
/** How many children? If 0, then this is a leaf node */
public int getChildCount(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.
*/
public Object getParent(Object t);
public void setParent(Object t, Object parent);
/** 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.
*/
public int getChildIndex(Object t);
public void setChildIndex(Object t, int index);
/** 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.
*/
public void replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t);
}