How do I go to StringLiterals with Eclipse AST?
I need to create an Eclipse plugin that will display a tooltip when I hover over a string literal. But only if this string literal is the first parameter of the special method.
Here is the Test.java file I am using to test my plugin:
package test;
public class Test {
public static void main(String[] args) {
String hello = "Hello";
String world = Translator.get("Test.worldLabel");
System.out.println(hello + " " + world);
}
}
I have created a class that implements IJavaEditorTextHover and I need to compile the currently edited Java file to calculate if the cursor hovers over a line to be translated or not.
- Hovering "Hello" will do nothing.
- Hovering "Test.worldLabel" will display my tooltip because this literal is included inside the call to the Translator.get () method.
I first used this (170 is inside "Test.worldLabel"):
ITypeRoot typeRoot = (ITypeRoot)
JavaUI.getEditorInputJavaElement(editorPart.getEditorInput());
JavaElement foundElement = (JavaElement) typeRoot.getElementAt(170);
But foundElement contains the whole main () method: it's not thin enough.
Then the correct way is, I think:
private static ASTNode parse(ICompilationUnit unit, int position) {
ASTParser parser = ASTParser.newParser(AST.JLS3);
parser.setKind(ASTParser.K_COMPILATION_UNIT);
parser.setSource(unit);
parser.setResolveBindings(true);
parser.setIgnoreMethodBodies(false);
// TODO Future optimisation: parser.setFocalPosition(position);
return parser.createAST((IProgressMonitor) null); // parse
}
And in my implementation IJavaEditorTextHover.getHoverInfo (...):
ICompilationUnit compilationUnit = (ICompilationUnit)
JavaUI.getEditorInputJavaElement(editor.getEditorInput())
int position = 170/*hoverRegion.getOffset()*/;
ASTNode ast = parse(compilationUnit, position);
And so, here's my question:
How, from this ast node, do I get an ASTNode emitting a StringLiteral at position 170 in the source code (Test.worldLabel string)?
Bonus question: did I pick the right solution? Based on results.
Edit: Well, here is the solution I found:
private StringLiteral findStringLiteralAtPosition(final ASTNode parent, final int position) {
final List<StringLiteral> stringLiterals = new ArrayList<StringLiteral>();
parent.accept(new ASTVisitor() {
@Override
public boolean visit(StringLiteral stringLiteral) {
int start = stringLiteral.getStartPosition();
int end = start + stringLiteral.getLength();
if (start <= position && position <= end) {
stringLiterals.add(stringLiteral);
}
return super.visit(stringLiteral);
}
});
return (stringLiterals.size() > 0 ? stringLiterals.get(0) : null);
}
Is it a good seam? Or is it an easier way or more efficient?
source to share
One solution will not use offset logic at all. You can generalize the solution with parent node validation.
Here's some sample code:
public boolean visit(StringLiteral stringLiteral) {
// Check if parent is a method inovacation.
if (stringLiteral.getParent().getNodeType() == ASTNode.METHOD_INVOCATION) {
// get the parent method inovacation.
MethodInvocation miNode = (MethodInvocation) stringLiteral.getParent();
//To do: null and empty check on argument list.
// Check if is the special method and this is the 1st argument
if (miNode.getName().toString().equals("SpecialMethod")
&& miNode.arguments().get(0).toString().equals(stringLiteral.toString())) {
System.out.println("Found it : " + stringLiteral.toString());
}
}
return true;
}
source to share