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digitalmars.D.internals - dmd TransitiveVistor read expressions

reply Andrey <andrey kabylin.ru> writes:
Hello, I'm trying to figure it out how dmd compiler is working 
and using his parser and tools for my little utility, I learned 
how to parse a file and working with parsed data via visitor, I 
wrote this:
 class CollectVisitor : TransitiveVisitor {
     override void visit(ASTBase.Import imp) {
         writeln();
         writeln("visit import");
     }
 
     override void visit(ASTBase.StructDeclaration d) {
         writeln();
         writeln("visit struct");
     }
 
     override void visit(ASTBase.UserAttributeDeclaration d) {
         writeln();
         writeln("visit attribute");
         writeln("attributes:");
 
         foreach (a; *d.atts) {
             // How can I here read data from a?
         }
 
         writeln("declarations:");
         foreach (s; *d.decl) {
             writeln("  ", s.ident.toString());
         }
     }
 }
I'm trying to parse this file:
  Tag
  Tag1
 struct A {
     void greet() {
         writeln("Hello world!");
     }
 }
 
  Tag
 struct B {
     void greet() {
         writeln("Hello world!");
     }
 }
I can parse it, and read some data from structs (so far only name), but how can I retrieve some info from UDAs? e.g. name? atts is array of expressions, but I don't understand how retrieve something from expression (I need name of attribute and its parameters).
Oct 08
next sibling parent Andrey <andrey kabylin.ru> writes:
I understood, I need to read the op field from expression and 
cast to needed expression type
Oct 08
prev sibling parent Jacob Carlborg <doob me.com> writes:
On 2017-10-08 10:12, Andrey wrote:

 I can parse it, and read some data from structs (so far only name), but 
 how can I retrieve some info from UDAs? e.g. name? atts is array of 
 expressions, but I don't understand how retrieve something from 
 expression (I need name of attribute and its parameters).
You can have a look here [1]. This looks for the selector("foo") UDA on a method declaration, extracts the string "foo" and stores it for later processing. [1] https://github.com/dlang/dmd/blob/master/src/ddmd/objc.d#L199 -- /Jacob Carlborg
Oct 09