| DOM/AST Questions [message #146285] |
Tue, 31 May 2005 00:30  |
Eclipse User |
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Hello,
I have a some questions regarding the new DOM/AST in the CDT 3.0.
I have code that visits specific AST nodes that modifies the AST as it
visits (which is unsafe). The code (from an ASTVisitor's visit method)
for instance:
-----------------------------
/*
* This code finds WhileStatements, changes them to IfStatements,
* and then inserts it into the AST where the WhileStatement was.
*/
public int visit(IASTStatement statement) {
if(statement instanceof IASTWhileStatement){
IASTWhileStatement ws = (IASTWhileStatement)statement;
IASTExpression cond = ws.getCondition();
IASTStatement body = ws.getBody();
CASTIfStatement ifstmt = new CASTIfStatement();
ifstmt.setCondition(cond);
ifstmt.setThenClause(body);
IASTStatement parent = (IASTStatement)statement.getParent();
if(parent instanceof IASTCompoundStatement){
IASTCompoundStatement parentCS = (IASTCompoundStatement)parent;
IASTStatement[] children = parentCS.getStatements();
for(int i=0; i<children.length; ++i){
if(children[i] == ws){
children[i] = ifstmt;
break;
}
}
ifstmt.setParent(statement.getParent());
//statement.setParent(null);
}
}
return PROCESS_CONTINUE;
}
-----------------------------
[statement.setParent(null);] can be done, however, it prevents the
visitation of any nodes not yet visited since it cuts off the link back up
to the parent.
Questions:
1 - Probably a dumb one..but besides manually copying the AST into a new
type of tree structure, is there a better way to do this without directly
changing the working AST?
2 - Is the creation of AST nodes without declaring internal classes
available? ASTNodeFactory perhaps?
3 - The code successfully changes the nodes to IfStatements, however, when
I use the getRawSignature() method, it still shows the code as being while
statements...how does the raw signature relate to the AST if it does at
all?
4 - Say all AST manipulations work as intended..is there a
pretty-printer/unparser/formatter in the implementation (since the
getRawSignature() method doesn't seem to reflect AST changes)?
Any help or comments is appreciated.
Thanks!
-=-Mike
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| Re: DOM/AST Questions [message #146344 is a reply to message #146285] |
Tue, 31 May 2005 11:38  |
| Eclipse User |
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Hi,
> Questions:
> 1 - Probably a dumb one..but besides manually copying the AST into a new
> type of tree structure, is there a better way to do this without directly
> changing the working AST?
I would visit first to identify the nodes you want to edit, and then edit
them serially afterwards.
A visit is not an expensive operation (~50 milliseconds on ~4MB source code
parsed).
> 2 - Is the creation of AST nodes without declaring internal classes
> available? ASTNodeFactory perhaps?
Currently not available.
> 3 - The code successfully changes the nodes to IfStatements, however, when
> I use the getRawSignature() method, it still shows the code as being while
> statements...how does the raw signature relate to the AST if it does at
> all?
Raw Signature maps back to what is actually in the file using the location
information
(offsets, files, macros, etc.)
> 4 - Say all AST manipulations work as intended..is there a
> pretty-printer/unparser/formatter in the implementation (since the
> getRawSignature() method doesn't seem to reflect AST changes)?
Refer to org.eclipse.cdt.core.dom.ast.ASTSignatureUtil.
There is also ASTTypeUtil.
Unfortunately, up to this point we have not made a pervasive "toString()"
style representation that is available for absolutely every IASTNode.
Regarding writing code using our AST : we have designed this AST for use
with an ASTRewriter.
Currently, that component is not available. Its one thing to generate code
off of an AST; it is entirely
another to tweak code slightly programmatically, without losing formatting
and comment structure.
Caveat emptor.
JohnC
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| Re: DOM/AST Questions [message #849324 is a reply to message #146344] |
Wed, 18 April 2012 23:43 |
| Eclipse User |
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Hi John,
Can you please elaborate by giving an example on how to use ASTRewrite?
It will be helpful if you can show this by using ASTRewrite.insertBefore(parentNode,insertionNode,newNode, editGroup) method to insert a node to a source code.
I could not find any successful usage of insertBefore method anywhere. Programmers are complaining about getting IllegalArgumentException when they used this.
Thanks in advance.
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