antlr
Class ASTFactory

java.lang.Object
  |
  +--antlr.ASTFactory
Direct Known Subclasses:
XMLASTFactory

public class ASTFactory
extends Object

AST Support code shared by TreeParser and Parser. We use delegation to share code (and have only one bit of code to maintain) rather than subclassing or superclassing (forces AST support code to be loaded even when you don't want to do AST stuff). Typically, setASTNodeType is used to specify the homogeneous type of node to create, but you can override create to make heterogeneous nodes etc...


Field Summary
protected  String theASTNodeType
          Name of AST class to create during tree construction.
protected  Class theASTNodeTypeClass
           
protected  Hashtable tokenTypeToASTClassMap
          How to specify the classname to create for a particular token type.
 
Constructor Summary
ASTFactory()
           
ASTFactory(Hashtable tokenTypeToClassMap)
          Create factory with a specific mapping from token type to Java AST node type.
 
Method Summary
 void addASTChild(ASTPair currentAST, AST child)
          Add a child to the current AST
 AST create()
          Create a new empty AST node; if the user did not specify an AST node type, then create a default one: CommonAST.
 AST create(AST tr)
          Create a new empty AST node; if the user did not specify an AST node type, then create a default one: CommonAST.
protected  AST create(Class c)
           
 AST create(int type)
           
 AST create(int type, String txt)
           
 AST create(int type, String txt, String className)
          Create an AST node with the token type and text passed in, but with a specific Java object type.
protected  AST create(String className)
           
 AST create(Token tok)
           
 AST create(Token tok, String className)
          ANTLR generates reference to this when you reference a token that has a specified heterogeneous AST node type.
protected  AST createUsingCtor(Token token, String className)
           
 AST dup(AST t)
          Copy a single node with same Java AST objec type.
 AST dupList(AST t)
          Duplicate tree including siblings of root.
 AST dupTree(AST t)
          Duplicate a tree, assuming this is a root node of a tree-- duplicate that node and what's below; ignore siblings of root node.
 void error(String e)
          To change where error messages go, can subclass/override this method and then setASTFactory in Parser and TreeParser.
 Class getASTNodeType(int tokenType)
          For a given token type, what is the AST node object type to create for it?
 Hashtable getTokenTypeToASTClassMap()
           
 AST make(AST[] nodes)
          Make a tree from a list of nodes.
 AST make(ASTArray nodes)
          Make a tree from a list of nodes, where the nodes are contained in an ASTArray object
 void makeASTRoot(ASTPair currentAST, AST root)
          Make an AST the root of current AST
 void setASTNodeClass(String t)
           
 void setASTNodeType(String t)
          Deprecated. since 2.7.1
 void setTokenTypeASTNodeType(int tokenType, String className)
          Specify an "override" for the Java AST object created for a specific token.
 void setTokenTypeToASTClassMap(Hashtable tokenTypeToClassMap)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

theASTNodeType

protected String theASTNodeType
Name of AST class to create during tree construction. Null implies that the create method should create a default AST type such as CommonAST. This is for homogeneous nodes.


theASTNodeTypeClass

protected Class theASTNodeTypeClass

tokenTypeToASTClassMap

protected Hashtable tokenTypeToASTClassMap
How to specify the classname to create for a particular token type. Note that ANTLR allows you to say, for example, tokens { PLUS; ... } and it tracks everything statically. #[PLUS] will make you a PLUSNode w/o use of this table. For tokens that ANTLR cannot track statically like #[i], you can use this table to map PLUS (Integer) -> PLUSNode (Class) etc... ANTLR sets the class map from the tokens {...} section via the ASTFactory(Hashtable) ctor in antlr.Parser.

Constructor Detail

ASTFactory

public ASTFactory()

ASTFactory

public ASTFactory(Hashtable tokenTypeToClassMap)
Create factory with a specific mapping from token type to Java AST node type. Your subclasses of ASTFactory can override and reuse the map stuff.

Method Detail

setTokenTypeASTNodeType

public void setTokenTypeASTNodeType(int tokenType,
                                    String className)
                             throws IllegalArgumentException
Specify an "override" for the Java AST object created for a specific token. It is provided as a convenience so you can specify node types dynamically. ANTLR sets the token type mapping automatically from the tokens{...} section, but you can change that mapping with this method. ANTLR does it's best to statically determine the node type for generating parsers, but it cannot deal with dynamic values like #[LT(1)]. In this case, it relies on the mapping. Beware differences in the tokens{...} section and what you set via this method. Make sure they are the same. Set className to null to remove the mapping.

IllegalArgumentException
Since:
2.7.2

getASTNodeType

public Class getASTNodeType(int tokenType)
For a given token type, what is the AST node object type to create for it?

Since:
2.7.2

addASTChild

public void addASTChild(ASTPair currentAST,
                        AST child)
Add a child to the current AST


create

public AST create()
Create a new empty AST node; if the user did not specify an AST node type, then create a default one: CommonAST.


create

public AST create(int type)

create

public AST create(int type,
                  String txt)

create

public AST create(int type,
                  String txt,
                  String className)
Create an AST node with the token type and text passed in, but with a specific Java object type. Typically called when you say @[PLUS,"+",PLUSNode] in an antlr action.

Since:
2.7.2

create

public AST create(AST tr)
Create a new empty AST node; if the user did not specify an AST node type, then create a default one: CommonAST.


create

public AST create(Token tok)

create

public AST create(Token tok,
                  String className)
ANTLR generates reference to this when you reference a token that has a specified heterogeneous AST node type. This is also a special case node creation routine for backward compatibility. Before, ANTLR generated "new T(tokenObject)" and so I must call the appropriate constructor not T().

Since:
2.7.2

create

protected AST create(String className)
Since:
2.7.2

createUsingCtor

protected AST createUsingCtor(Token token,
                              String className)
Since:
2.7.2

create

protected AST create(Class c)
Since:
2.7.2

dup

public AST dup(AST t)
Copy a single node with same Java AST objec type. Ignore the tokenType->Class mapping since you know the type of the node, t.getClass(), and doing a dup. clone() is not used because we want all AST creation to go thru the factory so creation can be tracked. Returns null if t is null.


dupList

public AST dupList(AST t)
Duplicate tree including siblings of root.


dupTree

public AST dupTree(AST t)
Duplicate a tree, assuming this is a root node of a tree-- duplicate that node and what's below; ignore siblings of root node.


make

public AST make(AST[] nodes)
Make a tree from a list of nodes. The first element in the array is the root. If the root is null, then the tree is a simple list not a tree. Handles null children nodes correctly. For example, build(a, b, null, c) yields tree (a b c). build(null,a,b) yields tree (nil a b).


make

public AST make(ASTArray nodes)
Make a tree from a list of nodes, where the nodes are contained in an ASTArray object


makeASTRoot

public void makeASTRoot(ASTPair currentAST,
                        AST root)
Make an AST the root of current AST


setASTNodeClass

public void setASTNodeClass(String t)

setASTNodeType

public void setASTNodeType(String t)
Deprecated. since 2.7.1

Specify the type of node to create during tree building.


getTokenTypeToASTClassMap

public Hashtable getTokenTypeToASTClassMap()

setTokenTypeToASTClassMap

public void setTokenTypeToASTClassMap(Hashtable tokenTypeToClassMap)

error

public void error(String e)
To change where error messages go, can subclass/override this method and then setASTFactory in Parser and TreeParser. This method removes a prior dependency on class antlr.Tool.



Copyright 1999-2003 Oliver Zeigermann. All Rights Reserved.