1/*
2 [The "BSD license"]
3 Copyright (c) 2005-2009 Terence Parr
4 All rights reserved.
5
6 Redistribution and use in source and binary forms, with or without
7 modification, are permitted provided that the following conditions
8 are met:
9 1. Redistributions of source code must retain the above copyright
10     notice, this list of conditions and the following disclaimer.
11 2. Redistributions in binary form must reproduce the above copyright
12     notice, this list of conditions and the following disclaimer in the
13     documentation and/or other materials provided with the distribution.
14 3. The name of the author may not be used to endorse or promote products
15     derived from this software without specific prior written permission.
16
17 THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28package org.antlr.runtime.tree;
29
30import org.antlr.runtime.Token;
31import org.antlr.runtime.TokenStream;
32import org.antlr.runtime.RecognitionException;
33
34import java.util.HashMap;
35import java.util.Map;
36
37/** A TreeAdaptor that works with any Tree implementation. */
38public abstract class BaseTreeAdaptor implements TreeAdaptor {
39	/** System.identityHashCode() is not always unique; we have to
40	 *  track ourselves.  That's ok, it's only for debugging, though it's
41	 *  expensive: we have to create a hashtable with all tree nodes in it.
42	 */
43	protected Map treeToUniqueIDMap;
44	protected int uniqueNodeID = 1;
45
46	public Object nil() {
47		return create(null);
48	}
49
50	/** create tree node that holds the start and stop tokens associated
51	 *  with an error.
52	 *
53	 *  If you specify your own kind of tree nodes, you will likely have to
54	 *  override this method. CommonTree returns Token.INVALID_TOKEN_TYPE
55	 *  if no token payload but you might have to set token type for diff
56	 *  node type.
57     *
58     *  You don't have to subclass CommonErrorNode; you will likely need to
59     *  subclass your own tree node class to avoid class cast exception.
60	 */
61	public Object errorNode(TokenStream input, Token start, Token stop,
62							RecognitionException e)
63	{
64		CommonErrorNode t = new CommonErrorNode(input, start, stop, e);
65		//System.out.println("returning error node '"+t+"' @index="+input.index());
66		return t;
67	}
68
69	public boolean isNil(Object tree) {
70		return ((Tree)tree).isNil();
71	}
72
73	public Object dupTree(Object tree) {
74		return dupTree(tree, null);
75	}
76
77	/** This is generic in the sense that it will work with any kind of
78	 *  tree (not just Tree interface).  It invokes the adaptor routines
79	 *  not the tree node routines to do the construction.
80	 */
81	public Object dupTree(Object t, Object parent) {
82		if ( t==null ) {
83			return null;
84		}
85		Object newTree = dupNode(t);
86		// ensure new subtree root has parent/child index set
87		setChildIndex(newTree, getChildIndex(t)); // same index in new tree
88		setParent(newTree, parent);
89		int n = getChildCount(t);
90		for (int i = 0; i < n; i++) {
91			Object child = getChild(t, i);
92			Object newSubTree = dupTree(child, t);
93			addChild(newTree, newSubTree);
94		}
95		return newTree;
96	}
97
98	/** Add a child to the tree t.  If child is a flat tree (a list), make all
99	 *  in list children of t.  Warning: if t has no children, but child does
100	 *  and child isNil then you can decide it is ok to move children to t via
101	 *  t.children = child.children; i.e., without copying the array.  Just
102	 *  make sure that this is consistent with have the user will build
103	 *  ASTs.
104	 */
105	public void addChild(Object t, Object child) {
106		if ( t!=null && child!=null ) {
107			((Tree)t).addChild((Tree)child);
108		}
109	}
110
111	/** If oldRoot is a nil root, just copy or move the children to newRoot.
112	 *  If not a nil root, make oldRoot a child of newRoot.
113	 *
114	 *    old=^(nil a b c), new=r yields ^(r a b c)
115	 *    old=^(a b c), new=r yields ^(r ^(a b c))
116	 *
117	 *  If newRoot is a nil-rooted single child tree, use the single
118	 *  child as the new root node.
119	 *
120	 *    old=^(nil a b c), new=^(nil r) yields ^(r a b c)
121	 *    old=^(a b c), new=^(nil r) yields ^(r ^(a b c))
122	 *
123	 *  If oldRoot was null, it's ok, just return newRoot (even if isNil).
124	 *
125	 *    old=null, new=r yields r
126	 *    old=null, new=^(nil r) yields ^(nil r)
127	 *
128	 *  Return newRoot.  Throw an exception if newRoot is not a
129	 *  simple node or nil root with a single child node--it must be a root
130	 *  node.  If newRoot is ^(nil x) return x as newRoot.
131	 *
132	 *  Be advised that it's ok for newRoot to point at oldRoot's
133	 *  children; i.e., you don't have to copy the list.  We are
134	 *  constructing these nodes so we should have this control for
135	 *  efficiency.
136	 */
137	public Object becomeRoot(Object newRoot, Object oldRoot) {
138        //System.out.println("becomeroot new "+newRoot.toString()+" old "+oldRoot);
139        Tree newRootTree = (Tree)newRoot;
140		Tree oldRootTree = (Tree)oldRoot;
141		if ( oldRoot==null ) {
142			return newRoot;
143		}
144		// handle ^(nil real-node)
145		if ( newRootTree.isNil() ) {
146            int nc = newRootTree.getChildCount();
147            if ( nc==1 ) newRootTree = (Tree)newRootTree.getChild(0);
148            else if ( nc >1 ) {
149				// TODO: make tree run time exceptions hierarchy
150				throw new RuntimeException("more than one node as root (TODO: make exception hierarchy)");
151			}
152        }
153		// add oldRoot to newRoot; addChild takes care of case where oldRoot
154		// is a flat list (i.e., nil-rooted tree).  All children of oldRoot
155		// are added to newRoot.
156		newRootTree.addChild(oldRootTree);
157		return newRootTree;
158	}
159
160	/** Transform ^(nil x) to x and nil to null */
161	public Object rulePostProcessing(Object root) {
162		//System.out.println("rulePostProcessing: "+((Tree)root).toStringTree());
163		Tree r = (Tree)root;
164		if ( r!=null && r.isNil() ) {
165			if ( r.getChildCount()==0 ) {
166				r = null;
167			}
168			else if ( r.getChildCount()==1 ) {
169				r = (Tree)r.getChild(0);
170				// whoever invokes rule will set parent and child index
171				r.setParent(null);
172				r.setChildIndex(-1);
173			}
174		}
175		return r;
176	}
177
178	public Object becomeRoot(Token newRoot, Object oldRoot) {
179		return becomeRoot(create(newRoot), oldRoot);
180	}
181
182	public Object create(int tokenType, Token fromToken) {
183		fromToken = createToken(fromToken);
184		//((ClassicToken)fromToken).setType(tokenType);
185		fromToken.setType(tokenType);
186		Tree t = (Tree)create(fromToken);
187		return t;
188	}
189
190	public Object create(int tokenType, Token fromToken, String text) {
191        if (fromToken == null) return create(tokenType, text);
192		fromToken = createToken(fromToken);
193		fromToken.setType(tokenType);
194		fromToken.setText(text);
195		Tree t = (Tree)create(fromToken);
196		return t;
197	}
198
199	public Object create(int tokenType, String text) {
200		Token fromToken = createToken(tokenType, text);
201		Tree t = (Tree)create(fromToken);
202		return t;
203	}
204
205	public int getType(Object t) {
206		return ((Tree)t).getType();
207	}
208
209	public void setType(Object t, int type) {
210		throw new NoSuchMethodError("don't know enough about Tree node");
211	}
212
213	public String getText(Object t) {
214		return ((Tree)t).getText();
215	}
216
217	public void setText(Object t, String text) {
218		throw new NoSuchMethodError("don't know enough about Tree node");
219	}
220
221	public Object getChild(Object t, int i) {
222		return ((Tree)t).getChild(i);
223	}
224
225	public void setChild(Object t, int i, Object child) {
226		((Tree)t).setChild(i, (Tree)child);
227	}
228
229	public Object deleteChild(Object t, int i) {
230		return ((Tree)t).deleteChild(i);
231	}
232
233	public int getChildCount(Object t) {
234		return ((Tree)t).getChildCount();
235	}
236
237	public int getUniqueID(Object node) {
238		if ( treeToUniqueIDMap==null ) {
239			 treeToUniqueIDMap = new HashMap();
240		}
241		Integer prevID = (Integer)treeToUniqueIDMap.get(node);
242		if ( prevID!=null ) {
243			return prevID.intValue();
244		}
245		int ID = uniqueNodeID;
246		treeToUniqueIDMap.put(node, new Integer(ID));
247		uniqueNodeID++;
248		return ID;
249		// GC makes these nonunique:
250		// return System.identityHashCode(node);
251	}
252
253	/** Tell me how to create a token for use with imaginary token nodes.
254	 *  For example, there is probably no input symbol associated with imaginary
255	 *  token DECL, but you need to create it as a payload or whatever for
256	 *  the DECL node as in ^(DECL type ID).
257	 *
258	 *  If you care what the token payload objects' type is, you should
259	 *  override this method and any other createToken variant.
260	 */
261	public abstract Token createToken(int tokenType, String text);
262
263	/** Tell me how to create a token for use with imaginary token nodes.
264	 *  For example, there is probably no input symbol associated with imaginary
265	 *  token DECL, but you need to create it as a payload or whatever for
266	 *  the DECL node as in ^(DECL type ID).
267	 *
268	 *  This is a variant of createToken where the new token is derived from
269	 *  an actual real input token.  Typically this is for converting '{'
270	 *  tokens to BLOCK etc...  You'll see
271	 *
272	 *    r : lc='{' ID+ '}' -> ^(BLOCK[$lc] ID+) ;
273	 *
274	 *  If you care what the token payload objects' type is, you should
275	 *  override this method and any other createToken variant.
276	 */
277	public abstract Token createToken(Token fromToken);
278}
279
280