servo/components/macros/lib.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#![feature(macro_rules, plugin_registrar, quote, phase)]

#![deny(unused_imports, unused_variable)]

//! Exports macros for use in other Servo crates.

extern crate syntax;

#[phase(plugin, link)]
extern crate rustc;
#[cfg(test)]
extern crate sync;

use syntax::ast;
use syntax::attr::AttrMetaMethods;
use rustc::lint::{Context, LintPass, LintPassObject, LintArray};
use rustc::plugin::Registry;
use rustc::middle::ty::expr_ty;
use rustc::middle::{ty, def};
use rustc::middle::typeck::astconv::AstConv;
use rustc::util::ppaux::Repr;

declare_lint!(TRANSMUTE_TYPE_LINT, Allow,
              "Warn and report types being transmuted")
declare_lint!(UNROOTED_MUST_ROOT, Deny,
              "Warn and report usage of unrooted jsmanaged objects")

struct TransmutePass;
struct UnrootedPass;

impl LintPass for TransmutePass {
    fn get_lints(&self) -> LintArray {
        lint_array!(TRANSMUTE_TYPE_LINT)
    }

    fn check_expr(&mut self, cx: &Context, ex: &ast::Expr) {
        match ex.node {
            ast::ExprCall(ref expr, ref args) => {
                match expr.node {
                    ast::ExprPath(ref path) => {
                        if path.segments.last()
                                        .map_or(false, |ref segment| segment.identifier.name.as_str() == "transmute")
                           && args.len() == 1 {
                            let tcx = cx.tcx();
                            cx.span_lint(TRANSMUTE_TYPE_LINT, ex.span,
                                         format!("Transmute from {} to {} detected",
                                                 expr_ty(tcx, ex).repr(tcx),
                                                 expr_ty(tcx, &**args.get(0)).repr(tcx)
                                        ).as_slice());
                        }
                    }
                    _ => {}
                }
            }
            _ => {}
        }
    }
}

fn lint_unrooted_ty(cx: &Context, ty: &ast::Ty, warning: &str) {
    match ty.node {
        ast::TyBox(ref t) | ast::TyUniq(ref t) |
        ast::TyVec(ref t) | ast::TyFixedLengthVec(ref t, _) |
        ast::TyPtr(ast::MutTy { ty: ref t, ..}) | ast::TyRptr(_, ast::MutTy { ty: ref t, ..}) => lint_unrooted_ty(cx, &**t, warning),
        ast::TyPath(_, _, id) => {
                match cx.tcx.def_map.borrow().get_copy(&id) {
                    def::DefTy(def_id) => {
                        if ty::has_attr(cx.tcx, def_id, "must_root") {
                            cx.span_lint(UNROOTED_MUST_ROOT, ty.span, warning);
                        }
                    }
                    _ => (),
                }
            }
            _ => (),
    };
}

impl LintPass for UnrootedPass {
    fn get_lints(&self) -> LintArray {
        lint_array!(UNROOTED_MUST_ROOT)
    }

    fn check_struct_def(&mut self, cx: &Context, def: &ast::StructDef, _i: ast::Ident, _gen: &ast::Generics, id: ast::NodeId) {
        if cx.tcx.map.expect_item(id).attrs.iter().all(|a| !a.check_name("must_root")) {
            for ref field in def.fields.iter() {
                lint_unrooted_ty(cx, &*field.node.ty,
                                 "Type must be rooted, use #[must_root] on the struct definition to propagate");
            }
        }
    }

    fn check_variant(&mut self, cx: &Context, var: &ast::Variant, _gen: &ast::Generics) {
        let ref map = cx.tcx.map;
        if map.expect_item(map.get_parent(var.node.id)).attrs.iter().all(|a| !a.check_name("must_root")) {
            match var.node.kind {
                ast::TupleVariantKind(ref vec) => {
                    for ty in vec.iter() {
                        lint_unrooted_ty(cx, &*ty.ty,
                                         "Type must be rooted, use #[must_root] on the enum definition to propagate")
                    }
                }
                _ => () // Struct variants already caught by check_struct_def
            }
        }
    }

    fn check_fn(&mut self, cx: &Context, kind: &syntax::visit::FnKind, decl: &ast::FnDecl,
                block: &ast::Block, _span: syntax::codemap::Span, _id: ast::NodeId) {
        match *kind {
            syntax::visit::FkItemFn(i, _, _, _) |
            syntax::visit::FkMethod(i, _, _) if i.as_str() == "new" || i.as_str() == "new_inherited" => {
                return;
            }
            _ => ()
        }
        match block.rules {
            ast::DefaultBlock => {
                for arg in decl.inputs.iter() {
                    lint_unrooted_ty(cx, &*arg.ty,
                                     "Type must be rooted, use #[must_root] on the fn definition to propagate")
                }
            }
            _ => () // fn is `unsafe`
        }
    }

    // Partially copied from rustc::middle::lint::builtin
    // Catches `let` statements which store a #[must_root] value
    // Expressions which return out of blocks eventually end up in a `let`
    // statement or a function return (which will be caught when it is used elsewhere)
    fn check_stmt(&mut self, cx: &Context, s: &ast::Stmt) {
        // Catch the let binding
        let expr = match s.node {
            ast::StmtDecl(ref decl, _) => match decl.node {
                ast::DeclLocal(ref loc) => match loc.init {
                        Some(ref e) => &**e,
                        _ => return
                },
                _ => return
            },
            _ => return
        };

        let t = expr_ty(cx.tcx, &*expr);
        match ty::get(t).sty {
            ty::ty_struct(did, _) |
            ty::ty_enum(did, _) => {
                if ty::has_attr(cx.tcx, did, "must_root") {
                    cx.span_lint(UNROOTED_MUST_ROOT, expr.span,
                                 format!("Expression of type {} must be rooted", t.repr(cx.tcx)).as_slice());
                }
            }
            _ => {}
        }
    }
}

#[plugin_registrar]
pub fn plugin_registrar(reg: &mut Registry) {
    reg.register_lint_pass(box TransmutePass as LintPassObject);
    reg.register_lint_pass(box UnrootedPass as LintPassObject);
}

#[macro_export]
macro_rules! bitfield(
    ($bitfieldname:ident, $getter:ident, $setter:ident, $value:expr) => (
        impl $bitfieldname {
            #[inline]
            pub fn $getter(self) -> bool {
                let $bitfieldname(this) = self;
                (this & $value) != 0
            }

            #[inline]
            pub fn $setter(&mut self, value: bool) {
                let $bitfieldname(this) = *self;
                *self = $bitfieldname((this & !$value) | (if value { $value } else { 0 }))
            }
        }
    )
)


#[macro_export]
macro_rules! lazy_init(
    ($(static ref $N:ident : $T:ty = $e:expr;)*) => (
        $(
            #[allow(non_camel_case_types)]
            struct $N {__unit__: ()}
            static $N: $N = $N {__unit__: ()};
            impl Deref<$T> for $N {
                fn deref<'a>(&'a self) -> &'a $T {
                    unsafe {
                        static mut s: *const $T = 0 as *const $T;
                        static mut ONCE: ::sync::one::Once = ::sync::one::ONCE_INIT;
                        ONCE.doit(|| {
                            s = ::std::mem::transmute::<Box<$T>, *const $T>(box () ($e));
                        });
                        &*s
                    }
                }
            }

        )*
    )
)


#[cfg(test)]
mod tests {
    use std::collections::hashmap::HashMap;
    lazy_init! {
        static ref NUMBER: uint = times_two(3);
        static ref VEC: [Box<uint>, ..3] = [box 1, box 2, box 3];
        static ref OWNED_STRING: String = "hello".to_string();
        static ref HASHMAP: HashMap<uint, &'static str> = {
            let mut m = HashMap::new();
            m.insert(0u, "abc");
            m.insert(1, "def");
            m.insert(2, "ghi");
            m
        };
    }

    fn times_two(n: uint) -> uint {
        n * 2
    }

    #[test]
    fn test_basic() {
        assert_eq!(*OWNED_STRING, "hello".to_string());
        assert_eq!(*NUMBER, 6);
        assert!(HASHMAP.find(&1).is_some());
        assert!(HASHMAP.find(&3).is_none());
        assert_eq!(VEC.as_slice(), &[box 1, box 2, box 3]);
    }

    #[test]
    fn test_repeat() {
        assert_eq!(*NUMBER, 6);
        assert_eq!(*NUMBER, 6);
        assert_eq!(*NUMBER, 6);
    }
}