find variable Declaration reference Abstract syntax tree eclipse cdt C code

Question

I have a c code like this int x; x = 5;

I used eclipse cdt to generate the AST, and traverse on it, so this is the code of the traversed class

public class RuleChk extends AbstractRule {
    public RuleChk(IASTTranslationUnit ast) {
        super("RuleChk", false, ast);
        shouldVisitDeclarations = true;
        shouldVisitParameterDeclarations = true;
    }

    @Override
    public int visit(IASTSimpleDeclaration simpleDecl) {
        //if this node has init, e.g: x = 5, do business
        if(VisitorUtil.containNode(simpleDecl, CASTExpressionStatement){
           // Now I have the x = 5 node, 
           // I want to get the reference node of it's declaration
           // I mean (int x;) node
           IASTNode declNode = ?????
        }
        return super.visit(parameterDeclaration);
    }
}

what I want to visit the node that only has assignation(Initialization) and get the reference of declaration node for that varaiable.

HighCommander4 · Accepted Answer · 2017-11-16 18:19:49Z

2

I'm not sure how VisitorUtil works (it's not from the CDT code), but I assume it gives you a way to access the the found node. So:

Given the IASTExpressionStatement node that was found, use IASTExpression.getExpression() to get the contained expression.
See if it's an IASTBinaryExpression, and that is getOperator() is IASTBinaryExpression.op_assign.
Use IASTBinaryExpression.getOperand1() to get the assignment expression's left subexpression. Check that it's an IASTIdExpression, and get the variable it names via IASTIdExpression.getName().
Now that you have the name, use IASTName.resolveBinding() to get the variable's binding. This is the variable's representation in the semantic program model.
To find the variable's definition, use IASTTranslationUnit.getDefinitionsInAST(IBinding) if you only want it to look in the current file, or IASTTranslationUnit.getDefinitions(IBinding) if you want it to look in included header files as well (the latter requires the project to be indexed). The IASTTranslationUnit can be obtained from any IASTNode via IASTNode.getTranslationUnit().

answered Nov 16, 2017 at 18:19

HighCommander4

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2 Comments

Mostafa Hassan Over a year ago

I have done this before, but I need to get the declaration specifiers for the name, for the above example I want to return ( int )

HighCommander4 Over a year ago

@MostafaHassan Assuming the declaration is in the same file, getDefinitionInAST() will give you an IASTName. You can examine the surrounding AST to find the decl-specifiers. For example, the name's parent would be an IASTDeclarator, its parent an IASTSimpleDeclaration, and then you can use IASTSimpleDeclaration.getDeclSpecifier() to get the decl-specifier.

milo · Accepted Answer · 2023-12-12 00:57:55Z

0

like the answer above, but you can do it easiser using IASTTranslationUnit.getReferences(IBinding) which will give you all reference of IASTName to your IBinding, you can find the statement use parent method.

answered Dec 12, 2023 at 0:57

milo

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