Antlr3.Runtime/Antlr.Runtime.Tree/ITreeAdaptor.cs

/*
 * [The "BSD licence"]
 * Copyright (c) 2005-2008 Terence Parr
 * All rights reserved.
 *
 * Conversion to C#:
 * Copyright (c) 2008 Sam Harwell, Pixel Mine, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

namespace Antlr.Runtime.Tree {

    /** <summary>
     *  How to create and navigate trees.  Rather than have a separate factory
     *  and adaptor, I've merged them.  Makes sense to encapsulate.
     *  </summary>
     *
     *  <remarks>
     *  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. :(
     *  </remarks>
     */
    public interface ITreeAdaptor {
        #region Construction

        /** <summary>
         *  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.
         *  </summary>
         *
         *  <remarks>
         *  Override if you want another kind of node to be built.
         *  </remarks>
         */
        object Create(IToken payload);

        /** <summary>Duplicate a single tree node.</summary>
         *  <remarks>Override if you want another kind of node to be built.</remarks>
         */
        object DupNode(object treeNode);

        /** <summary>Duplicate tree recursively, using dupNode() for each node</summary> */
        object DupTree(object tree);

        /** <summary>
         *  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);"
         *  </summary>
         */
        object Nil();

        /** <summary>
         *  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.
         *  </summary>
         *
         *  </remarks>
         *  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.
         *  </remarks>
         */
        object ErrorNode(ITokenStream input, IToken start, IToken stop, RecognitionException e);

        /** <summary>Is tree considered a nil node used to make lists of child nodes?</summary> */
        bool IsNil(object tree);

        /** <summary>
         *  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.
         *  </summary>
         */
        void AddChild(object t, object child);

        /** <summary>
         *  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.
         *  </summary>
         *
         *  <remarks>
         *    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.
         *  </remarks>
         */
        object BecomeRoot(object newRoot, object oldRoot);

        /** <summary>
         *  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.
         *  </summary>
         *
         *  <remarks>
         *  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().
         *  </remarks>
         */
        object RulePostProcessing(object root);

        /** <summary>For identifying trees.</summary>
         *
         *  <remarks>
         *  How to identify nodes so we can say "add node to a prior node"?
         *  Even becomeRoot is an issue.  Use System.identityHashCode(node)
         *  usually.
         *  </remarks>
         */
        int GetUniqueID(object node);


        // R e w r i t e  R u l e s

        /** <summary>
         *  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.
         *  </summary>
         *
         *  <returns>
         *  Return node created for newRoot.
         *  </returns>
         *
         *  <remarks>
         *  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.
         *  </remarks>
         */
        object BecomeRoot(IToken newRoot, object oldRoot);

        /** <summary>
         *  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].
         *  </summary>
         *
         *  <remarks>
         *  This should invoke createToken(Token).
         *  </remarks>
         */
        object Create(int tokenType, IToken fromToken);

        /** <summary>
         *  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"].
         *  </summary>
         *
         *  <remarks>
         *  This should invoke createToken(Token).
         *  </remarks>
         */
        object Create(int tokenType, IToken fromToken, string text);

        /** <summary>
         *  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"].
         *  </summary>
         *
         *  <remarks>
         *  This should invoke createToken(int,String).
         *  </remarks>
         */
        object Create(int tokenType, string text);

        #endregion


        #region Content

        /** <summary>For tree parsing, I need to know the token type of a node</summary> */
        int GetType(object t);

        /** <summary>Node constructors can set the type of a node</summary> */
        void SetType(object t, int type);

        string GetText(object t);

        /** <summary>Node constructors can set the text of a node</summary> */
        void SetText(object t, string text);

        /** <summary>
         *  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().
         *  </summary>
         */
        IToken GetToken(object t);

        /** <summary>
         *  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.
         *  </summary>
         */
        void SetTokenBoundaries(object t, IToken startToken, IToken stopToken);

        /** <summary>Get the token start index for this subtree; return -1 if no such index</summary> */
        int GetTokenStartIndex(object t);

        /** <summary>Get the token stop index for this subtree; return -1 if no such index</summary> */
        int GetTokenStopIndex(object t);

        #endregion


        #region Navigation / Tree Parsing

        /** <summary>Get a child 0..n-1 node</summary> */
        object GetChild(object t, int i);

        /** <summary>Set ith child (0..n-1) to t; t must be non-null and non-nil node</summary> */
        void SetChild(object t, int i, object child);

        /** <summary>Remove ith child and shift children down from right.</summary> */
        object DeleteChild(object t, int i);

        /** <summary>How many children?  If 0, then this is a leaf node</summary> */
        int GetChildCount(object t);

        /** <summary>
         *  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.
         *  </summary>
         */
        object GetParent(object t);
        void SetParent(object t, object parent);

        /** <summary>
         *  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.
         *  </summary>
         */
        int GetChildIndex(object t);
        void SetChildIndex(object t, int index);

        /** <summary>
         *  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.
         *  </summary>
         *
         *  <remarks>
         *  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.
         *  </remarks>
         */
        void ReplaceChildren(object parent, int startChildIndex, int stopChildIndex, object t);

        #endregion
    }
}