SD
SWC Developers•5mo ago
w00t

how can I mark a context?

I'm trying to mark a call expression for checking if I visited it later, but this doesn't print that it worked: 
impl VisitMut for CleanMarker {
    fn visit_mut_module_item(&mut self, node: &mut ast::ModuleItem) {
        if let ast::ModuleItem::Stmt(ast::Stmt::Expr(expr)) = node {
            match &*expr.expr {
                ast::Expr::Call(e) => {
                    e.ctxt.apply_mark(self.mark);
                    println!("mark call expression {:?}", e.ctxt);
                    println!("has mark {:?}", e.ctxt.has_mark(self.mark));
                }
                _ => {}
            }
        }
    }
}
impl VisitMut for CleanMarker {
    fn visit_mut_module_item(&mut self, node: &mut ast::ModuleItem) {
        if let ast::ModuleItem::Stmt(ast::Stmt::Expr(expr)) = node {
            match &*expr.expr {
                ast::Expr::Call(e) => {
                    e.ctxt.apply_mark(self.mark);
                    println!("mark call expression {:?}", e.ctxt);
                    println!("has mark {:?}", e.ctxt.has_mark(self.mark));
                }
                _ => {}
            }
        }
    }
}
how can I make this work?
3 Replies
kdy1
kdy1•5mo ago
You can add a FxHashSet<Span> to your transformer struct and perform contains check.
w00t
w00tOP•5mo ago
I cannot make it work 😭 . Sorry I'm a Rust newbie. It doesn't let me use the same mutable hashset in two visitors. Any hints on how I could restructure this? 
use std::collections::HashSet;
use swc_common::{Mark, Span, Spanned};
use swc_ecmascript::ast;
use swc_ecmascript::visit::VisitMut;

pub struct Treeshaker<'a> {
    pub marker: CleanMarker<'a>,
    pub cleaner: CleanSideEffects<'a>,
}

pub struct CleanSideEffects<'a> {
    pub did_drop: bool,
    pub set: &'a mut HashSet<Span>,
}

pub struct CleanMarker<'a> {
    pub set: &'a mut HashSet<Span>,
}

impl Treeshaker<'_> {
    pub fn new() -> Self {
        let mut set = HashSet::new();
        Self {
            marker: CleanMarker { set: &mut set },
            cleaner: CleanSideEffects {
                did_drop: false,
                set: &mut set,
            },
        }
    }
}

impl VisitMut for CleanMarker<'_> {
    fn visit_mut_module_item(&mut self, node: &mut ast::ModuleItem) {
        if let ast::ModuleItem::Stmt(ast::Stmt::Expr(expr)) = node {
            match &*expr.expr {
                ast::Expr::New(e) => {
                    self.set.insert(e.span());
                }
                ast::Expr::Call(e) => {
                    self.set.insert(e.span());
                }
                _ => {}
            }
        }
    }
}
use std::collections::HashSet;
use swc_common::{Mark, Span, Spanned};
use swc_ecmascript::ast;
use swc_ecmascript::visit::VisitMut;

pub struct Treeshaker<'a> {
    pub marker: CleanMarker<'a>,
    pub cleaner: CleanSideEffects<'a>,
}

pub struct CleanSideEffects<'a> {
    pub did_drop: bool,
    pub set: &'a mut HashSet<Span>,
}

pub struct CleanMarker<'a> {
    pub set: &'a mut HashSet<Span>,
}

impl Treeshaker<'_> {
    pub fn new() -> Self {
        let mut set = HashSet::new();
        Self {
            marker: CleanMarker { set: &mut set },
            cleaner: CleanSideEffects {
                did_drop: false,
                set: &mut set,
            },
        }
    }
}

impl VisitMut for CleanMarker<'_> {
    fn visit_mut_module_item(&mut self, node: &mut ast::ModuleItem) {
        if let ast::ModuleItem::Stmt(ast::Stmt::Expr(expr)) = node {
            match &*expr.expr {
                ast::Expr::New(e) => {
                    self.set.insert(e.span());
                }
                ast::Expr::Call(e) => {
                    self.set.insert(e.span());
                }
                _ => {}
            }
        }
    }
}
ctd 
impl VisitMut for CleanSideEffects<'_> {
    fn visit_mut_module(&mut self, node: &mut ast::Module) {
        node.body.retain(|item| match item {
            ast::ModuleItem::Stmt(ast::Stmt::Expr(expr)) => match &*expr.expr {
                ast::Expr::New(e) => {
                    if self.set.contains(&e.span()) {
                        return true;
                    }
                    self.did_drop = true;
                    false
                }
                ast::Expr::Call(e) => {
                    if self.set.contains(&e.span()) {
                        return true;
                    }
                    self.did_drop = true;
                    false
                }
                _ => true,
            },
            _ => true,
        });
    }
}
impl VisitMut for CleanSideEffects<'_> {
    fn visit_mut_module(&mut self, node: &mut ast::Module) {
        node.body.retain(|item| match item {
            ast::ModuleItem::Stmt(ast::Stmt::Expr(expr)) => match &*expr.expr {
                ast::Expr::New(e) => {
                    if self.set.contains(&e.span()) {
                        return true;
                    }
                    self.did_drop = true;
                    false
                }
                ast::Expr::Call(e) => {
                    if self.set.contains(&e.span()) {
                        return true;
                    }
                    self.did_drop = true;
                    false
                }
                _ => true,
            },
            _ => true,
        });
    }
}
Me and copilot figured it out 😎 I'll drop the url soon
w00t
w00tOP•5mo ago

Did you find this page helpful?