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package org.antlr.runtime.tree;

import org.antlr.runtime.IntStream;
import org.antlr.runtime.Token;
import org.antlr.runtime.TokenStream;

A stream of tree nodes, accessing nodes from a tree of some kind
/** A stream of tree nodes, accessing nodes from a tree of some kind */
public interface TreeNodeStream extends IntStream {
Get a tree node at an absolute index i; 0..n-1. If you don't want to buffer up nodes, then this method makes no sense for you.
/** Get a tree node at an absolute index {@code i}; 0..n-1. * If you don't want to buffer up nodes, then this method makes no * sense for you. */
public Object get(int i);
Get tree node at current input pointer + k ahead where k==1 is next node. k<0 indicates nodes in the past. So LT(-1) is previous node, but implementations are not required to provide results for k < -1. LT(0) is undefined. For k<=n, return null. Return null for LT(0) and any index that results in an absolute address that is negative.

This is analogous to TokenStream.LT, but this returns a tree node instead of a Token. Makes code generation identical for both parser and tree grammars.

/** * Get tree node at current input pointer + {@code k} ahead where * {@code k==1} is next node. {@code k<0} indicates nodes in the past. So * {@code LT(-1)} is previous node, but implementations are not required to * provide results for {@code k < -1}. {@code LT(0)} is undefined. For * {@code k<=n}, return {@code null}. Return {@code null} for {@code LT(0)} * and any index that results in an absolute address that is negative. * <p> * This is analogous to {@link TokenStream#LT}, but this returns a tree node * instead of a {@link Token}. Makes code generation identical for both * parser and tree grammars.</p> */
public Object LT(int k);
Where is this stream pulling nodes from? This is not the name, but the object that provides node objects.
/** Where is this stream pulling nodes from? This is not the name, but * the object that provides node objects. */
public Object getTreeSource();
If the tree associated with this stream was created from a TokenStream, you can specify it here. Used to do rule $text attribute in tree parser. Optional unless you use tree parser rule $text attribute or output=template and rewrite=true options.
/** * If the tree associated with this stream was created from a * {@link TokenStream}, you can specify it here. Used to do rule * {@code $text} attribute in tree parser. Optional unless you use tree * parser rule {@code $text} attribute or {@code output=template} and * {@code rewrite=true} options. */
public TokenStream getTokenStream();
What adaptor can tell me how to interpret/navigate nodes and trees. E.g., get text of a node.
/** What adaptor can tell me how to interpret/navigate nodes and * trees. E.g., get text of a node. */
public TreeAdaptor getTreeAdaptor();
As we flatten the tree, we use Token.UP, Token.DOWN nodes to represent the tree structure. When debugging we need unique nodes so we have to instantiate new ones. When doing normal tree parsing, it's slow and a waste of memory to create unique navigation nodes. Default should be false.
/** * As we flatten the tree, we use {@link Token#UP}, {@link Token#DOWN} nodes * to represent the tree structure. When debugging we need unique nodes so * we have to instantiate new ones. When doing normal tree parsing, it's * slow and a waste of memory to create unique navigation nodes. Default * should be {@code false}. */
public void setUniqueNavigationNodes(boolean uniqueNavigationNodes);
Reset the tree node stream in such a way that it acts like a freshly constructed stream.
/** Reset the tree node stream in such a way that it acts like * a freshly constructed stream. */
public void reset();
Return the text of all nodes from start to stop, inclusive. If the stream does not buffer all the nodes then it can still walk recursively from start until stop. You can always return null or "" too, but users should not access $ruleLabel.text in an action of course in that case.
/** * Return the text of all nodes from {@code start} to {@code stop}, * inclusive. If the stream does not buffer all the nodes then it can still * walk recursively from start until stop. You can always return * {@code null} or {@code ""} too, but users should not access * {@code $ruleLabel.text} in an action of course in that case. */
public String toString(Object start, Object stop); // REWRITING TREES (used by tree parser)
Replace children of parent from index startChildIndex to stopChildIndex with t, which might be a list. Number of children may be different after this call. The stream is notified because it is walking the tree and might need to know you are monkeying with the underlying tree. Also, it might be able to modify the node stream to avoid restreaming for future phases.

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.

/** * Replace children of {@code parent} from index {@code startChildIndex} to * {@code stopChildIndex} with {@code t}, which might be a list. Number of * children may be different after this call. The stream is notified because * it is walking the tree and might need to know you are monkeying with the * underlying tree. Also, it might be able to modify the node stream to * avoid restreaming for future phases. * <p> * If {@code parent} is {@code null}, don't do anything; must be at root of * overall tree. Can't replace whatever points to the parent externally. Do * nothing.</p> */
public void replaceChildren(Object parent, int startChildIndex, int stopChildIndex, Object t); }