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 function addChild(t:Object, child:Object):void
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.
Parameters
public function becomeRoot(newRoot:Object, oldRoot:Object):Object
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.
Parameters
| newRoot:Object |
|
| oldRoot:Object |
Returns
public function create(... args):Object
Private method used by generated code. Based on type and number of arguments will call one of:
createWithPayload
createFromToken
createFromType
Parameters
Returns
public function createFromToken(tokenType:int, fromToken:Token, text:String = null):Object
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[$tokenLabel] or IMAG[$tokenLabel, "IMAG"].
This should invoke createToken(Token).
Parameters
| tokenType:int |
|
| fromToken:Token |
|
| text:String (default = null )
|
Returns
public function createFromType(tokenType:int, text:String):Object
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).
Parameters
| tokenType:int |
|
| text:String |
Returns
public function createWithPayload(payload:Token):Object
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.
Parameters
Returns
public function deleteChild(t:Object, i:int):Object
Remove ith child and shift children down from right.
Parameters
Returns
public function dupNode(treeNode:Object):Object
Duplicate a single tree node.
Override if you want another kind of node to be built.
Parameters
Returns
public function dupTree(tree:Object):Object
Duplicate tree recursively, using dupNode() for each node
Parameters
Returns
public function errorNode(input:TokenStream, start:Token, stop:Token, e:RecognitionException):Object
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.
Parameters
Returns
public function getChild(t:Object, i:int):Object
Get a child 0..n-1 node
Parameters
Returns
public function getChildCount(t:Object):int
How many children? If 0, then this is a leaf node
Parameters
Returns
public function getChildIndex(t:Object):int
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.
Parameters
Returns
public function getParent(t:Object):Object
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.
Parameters
Returns
public function getText(t:Object):String
Parameters
Returns
public function getToken(t:Object):Token
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().
Parameters
Returns
public function getTokenStartIndex(t:Object):int
Get the token start index for this subtree; return -1 if no such index
Parameters
Returns
public function getTokenStopIndex(t:Object):int
Get the token stop index for this subtree; return -1 if no such index
Parameters
Returns
public function getType(t:Object):int
For tree parsing, I need to know the token type of a node
Parameters
Returns
public function getUniqueID(node:Object):int
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.
Parameters
Returns
public function isNil(tree:Object):Boolean
Is tree considered a nil node used to make lists of child nodes?
Parameters
Returns
public function nil():Object
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);"
Returns
public function replaceChildren(parent:Object, startChildIndex:int, stopChildIndex:int, t:Object):void
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.
Parameters
| parent:Object |
|
| startChildIndex:int |
|
| stopChildIndex:int |
|
| t:Object |
public function rulePostProcessing(root:Object):Object
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().
Parameters
Returns
public function setChild(t:Object, i:int, child:Object):void
Set ith child (0..n-1) to t; t must be non-null and non-nil node
Parameters
| t:Object |
|
| i:int |
|
| child:Object |
public function setChildIndex(t:Object, index:int):void
Parameters
public function setParent(t:Object, parent:Object):void
Parameters
public function setText(t:Object, text:String):void
Node constructors can set the text of a node
Parameters
public function setTokenBoundaries(t:Object, startToken:Token, stopToken:Token):void
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.
Parameters
public function setType(t:Object, type:int):void
Node constructors can set the type of a node
Parameters