rust/src/librustc/middle/mem_categorization.rs

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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
* # Categorization
*
* The job of the categorization module is to analyze an expression to
* determine what kind of memory is used in evaluating it (for example,
* where dereferences occur and what kind of pointer is dereferenced;
* whether the memory is mutable; etc)
*
* Categorization effectively transforms all of our expressions into
* expressions of the following forms (the actual enum has many more
* possibilities, naturally, but they are all variants of these base
* forms):
*
* E = rvalue // some computed rvalue
* | x // address of a local variable, arg, or upvar
* | *E // deref of a ptr
* | E.comp // access to an interior component
*
* Imagine a routine ToAddr(Expr) that evaluates an expression and returns an
* address where the result is to be found. If Expr is an lvalue, then this
* is the address of the lvalue. If Expr is an rvalue, this is the address of
* some temporary spot in memory where the result is stored.
*
* Now, cat_expr() classies the expression Expr and the address A=ToAddr(Expr)
* as follows:
*
* - cat: what kind of expression was this? This is a subset of the
* full expression forms which only includes those that we care about
* for the purpose of the analysis.
* - mutbl: mutability of the address A
* - ty: the type of data found at the address A
*
* The resulting categorization tree differs somewhat from the expressions
* themselves. For example, auto-derefs are explicit. Also, an index a[b] is
* decomposed into two operations: a derefence to reach the array data and
* then an index to jump forward to the relevant item.
*/
use core::prelude::*;
use middle::ty;
use middle::typeck;
use util::ppaux::{ty_to_str, region_to_str};
use util::common::indenter;
use core::cmp;
use core::to_bytes;
use core::uint;
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use syntax::ast::{m_imm, m_const, m_mutbl};
use syntax::ast;
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use syntax::codemap::span;
use syntax::print::pprust;
#[deriving_eq]
pub enum categorization {
cat_rvalue, // result of eval'ing some misc expr
cat_special(special_kind), //
cat_local(ast::node_id), // local variable
cat_binding(ast::node_id), // pattern binding
cat_arg(ast::node_id), // formal argument
cat_stack_upvar(cmt), // upvar in stack closure
cat_deref(cmt, uint, ptr_kind), // deref of a ptr
cat_comp(cmt, comp_kind), // adjust to locate an internal component
cat_discr(cmt, ast::node_id), // match discriminant (see preserve())
cat_self(ast::node_id), // explicit `self`
}
// different kinds of pointers:
#[deriving_eq]
pub enum ptr_kind {
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uniq_ptr,
gc_ptr(ast::mutability),
region_ptr(ast::mutability, ty::Region),
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unsafe_ptr
}
// I am coining the term "components" to mean "pieces of a data
// structure accessible without a dereference":
#[deriving_eq]
pub enum comp_kind {
comp_tuple, // elt in a tuple
comp_anon_field, // anonymous field (in e.g.
// struct Foo(int, int);
comp_variant(ast::def_id), // internals to a variant of given enum
comp_field(ast::ident, // name of field
ast::mutability), // declared mutability of field
comp_index(ty::t, // type of vec/str/etc being deref'd
ast::mutability) // mutability of vec content
}
// different kinds of expressions we might evaluate
#[deriving_eq]
pub enum special_kind {
sk_method,
sk_static_item,
sk_implicit_self, // old by-reference `self`
sk_heap_upvar
}
#[deriving_eq]
pub enum MutabilityCategory {
McImmutable, // Immutable.
McReadOnly, // Read-only (`const`)
McDeclared, // Directly declared as mutable.
McInherited // Inherited from the fact that owner is mutable.
}
// a complete categorization of a value indicating where it originated
// and how it is located, as well as the mutability of the memory in
// which the value is stored.
//
// note: cmt stands for "categorized mutable type".
#[deriving_eq]
pub struct cmt_ {
id: ast::node_id, // id of expr/pat producing this value
span: span, // span of same expr/pat
cat: categorization, // categorization of expr
lp: Option<@loan_path>, // loan path for expr, if any
mutbl: MutabilityCategory, // mutability of expr as lvalue
ty: ty::t // type of the expr
}
pub type cmt = @cmt_;
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// a loan path is like a category, but it exists only when the data is
// interior to the stack frame. loan paths are used as the key to a
// map indicating what is borrowed at any point in time.
#[deriving_eq]
pub enum loan_path {
lp_local(ast::node_id),
lp_arg(ast::node_id),
lp_self,
lp_deref(@loan_path, ptr_kind),
lp_comp(@loan_path, comp_kind)
}
// We pun on *T to mean both actual deref of a ptr as well
// as accessing of components:
pub enum deref_kind {deref_ptr(ptr_kind), deref_comp(comp_kind)}
// Categorizes a derefable type. Note that we include vectors and strings as
// derefable (we model an index as the combination of a deref and then a
// pointer adjustment).
pub fn opt_deref_kind(t: ty::t) -> Option<deref_kind> {
match ty::get(t).sty {
ty::ty_uniq(*) |
ty::ty_evec(_, ty::vstore_uniq) |
ty::ty_estr(ty::vstore_uniq) |
ty::ty_closure(ty::ClosureTy {sigil: ast::OwnedSigil, _}) => {
Some(deref_ptr(uniq_ptr))
}
ty::ty_rptr(r, mt) |
ty::ty_evec(mt, ty::vstore_slice(r)) => {
Some(deref_ptr(region_ptr(mt.mutbl, r)))
}
ty::ty_estr(ty::vstore_slice(r)) |
ty::ty_closure(ty::ClosureTy {sigil: ast::BorrowedSigil,
region: r, _}) => {
Some(deref_ptr(region_ptr(ast::m_imm, r)))
}
ty::ty_box(mt) |
ty::ty_evec(mt, ty::vstore_box) => {
Some(deref_ptr(gc_ptr(mt.mutbl)))
}
ty::ty_estr(ty::vstore_box) |
ty::ty_closure(ty::ClosureTy {sigil: ast::ManagedSigil, _}) => {
Some(deref_ptr(gc_ptr(ast::m_imm)))
}
ty::ty_ptr(*) => {
Some(deref_ptr(unsafe_ptr))
}
ty::ty_enum(did, _) => {
Some(deref_comp(comp_variant(did)))
}
ty::ty_struct(_, _) => {
Some(deref_comp(comp_anon_field))
}
ty::ty_evec(mt, ty::vstore_fixed(_)) => {
Some(deref_comp(comp_index(t, mt.mutbl)))
}
ty::ty_estr(ty::vstore_fixed(_)) => {
Some(deref_comp(comp_index(t, m_imm)))
}
_ => None
}
}
pub fn deref_kind(tcx: ty::ctxt, t: ty::t) -> deref_kind {
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match opt_deref_kind(t) {
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Some(k) => k,
None => {
tcx.sess.bug(
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fmt!("deref_cat() invoked on non-derefable type %s",
ty_to_str(tcx, t)));
}
}
}
pub fn cat_expr(tcx: ty::ctxt,
method_map: typeck::method_map,
expr: @ast::expr)
-> cmt {
let mcx = &mem_categorization_ctxt {
tcx: tcx, method_map: method_map
};
return mcx.cat_expr(expr);
}
pub fn cat_expr_unadjusted(tcx: ty::ctxt,
method_map: typeck::method_map,
expr: @ast::expr)
-> cmt {
let mcx = &mem_categorization_ctxt {
tcx: tcx, method_map: method_map
};
return mcx.cat_expr_unadjusted(expr);
}
pub fn cat_expr_autoderefd(
tcx: ty::ctxt,
method_map: typeck::method_map,
expr: @ast::expr,
autoderefs: uint) -> cmt
{
let mcx = &mem_categorization_ctxt {
tcx: tcx, method_map: method_map
};
return mcx.cat_expr_autoderefd(expr, autoderefs);
}
pub fn cat_def(
tcx: ty::ctxt,
method_map: typeck::method_map,
expr_id: ast::node_id,
expr_span: span,
expr_ty: ty::t,
def: ast::def) -> cmt {
let mcx = &mem_categorization_ctxt {
tcx: tcx, method_map: method_map
};
return mcx.cat_def(expr_id, expr_span, expr_ty, def);
}
pub fn cat_variant<N:ast_node>(
tcx: ty::ctxt,
method_map: typeck::method_map,
arg: N,
enum_did: ast::def_id,
cmt: cmt) -> cmt {
let mcx = &mem_categorization_ctxt {
tcx: tcx, method_map: method_map
};
return mcx.cat_variant(arg, enum_did, cmt);
}
pub trait ast_node {
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fn id(&self) -> ast::node_id;
fn span(&self) -> span;
}
impl ast_node for @ast::expr {
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fn id(&self) -> ast::node_id { self.id }
fn span(&self) -> span { self.span }
}
impl ast_node for @ast::pat {
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fn id(&self) -> ast::node_id { self.id }
fn span(&self) -> span { self.span }
}
pub trait get_type_for_node {
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fn ty<N:ast_node>(&self, node: N) -> ty::t;
}
impl get_type_for_node for ty::ctxt {
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fn ty<N:ast_node>(&self, node: N) -> ty::t {
ty::node_id_to_type(*self, node.id())
}
}
pub struct mem_categorization_ctxt {
tcx: ty::ctxt,
method_map: typeck::method_map,
}
impl ToStr for MutabilityCategory {
pure fn to_str(&self) -> ~str {
fmt!("%?", *self)
}
}
pub impl MutabilityCategory {
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static fn from_mutbl(&self, m: ast::mutability) -> MutabilityCategory {
match m {
m_imm => McImmutable,
m_const => McReadOnly,
m_mutbl => McDeclared
}
}
fn inherit(&self) -> MutabilityCategory {
match *self {
McImmutable => McImmutable,
McReadOnly => McReadOnly,
McDeclared => McInherited,
McInherited => McInherited
}
}
fn is_mutable(&self) -> bool {
match *self {
McImmutable | McReadOnly => false,
McDeclared | McInherited => true
}
}
fn is_immutable(&self) -> bool {
match *self {
McImmutable => true,
McReadOnly | McDeclared | McInherited => false
}
}
fn to_user_str(&self) -> ~str {
match *self {
McDeclared | McInherited => ~"mutable",
McImmutable => ~"immutable",
McReadOnly => ~"const"
}
}
}
pub impl mem_categorization_ctxt {
fn cat_expr(&self, expr: @ast::expr) -> cmt {
match self.tcx.adjustments.find(&expr.id) {
None => {
// No adjustments.
self.cat_expr_unadjusted(expr)
}
Some(@ty::AutoAddEnv(*)) => {
// Convert a bare fn to a closure by adding NULL env.
// Result is an rvalue.
let expr_ty = ty::expr_ty_adjusted(self.tcx, expr);
self.cat_rvalue(expr, expr_ty)
}
Some(
@ty::AutoDerefRef(
ty::AutoDerefRef {
autoref: Some(_), _})) => {
// Equivalent to &*expr or something similar.
// Result is an rvalue.
let expr_ty = ty::expr_ty_adjusted(self.tcx, expr);
self.cat_rvalue(expr, expr_ty)
}
Some(
@ty::AutoDerefRef(
ty::AutoDerefRef {
autoref: None, autoderefs: autoderefs})) => {
// Equivalent to *expr or something similar.
self.cat_expr_autoderefd(expr, autoderefs)
}
}
}
fn cat_expr_autoderefd(&self,
expr: @ast::expr,
autoderefs: uint) -> cmt {
let mut cmt = self.cat_expr_unadjusted(expr);
for uint::range(1, autoderefs+1) |deref| {
cmt = self.cat_deref(expr, cmt, deref);
}
return cmt;
}
fn cat_expr_unadjusted(&self, expr: @ast::expr) -> cmt {
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debug!("cat_expr: id=%d expr=%s",
expr.id, pprust::expr_to_str(expr, self.tcx.sess.intr()));
let tcx = self.tcx;
let expr_ty = tcx.ty(expr);
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match expr.node {
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ast::expr_unary(ast::deref, e_base) => {
if self.method_map.contains_key(&expr.id) {
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return self.cat_rvalue(expr, expr_ty);
}
let base_cmt = self.cat_expr(e_base);
self.cat_deref(expr, base_cmt, 0)
}
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ast::expr_field(base, f_name, _) => {
if self.method_map.contains_key(&expr.id) {
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return self.cat_method_ref(expr, expr_ty);
}
let base_cmt = self.cat_expr(base);
self.cat_field(expr, base_cmt, f_name, expr.id)
}
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ast::expr_index(base, _) => {
if self.method_map.contains_key(&expr.id) {
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return self.cat_rvalue(expr, expr_ty);
}
let base_cmt = self.cat_expr(base);
self.cat_index(expr, base_cmt)
}
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ast::expr_path(_) => {
let def = self.tcx.def_map.get(&expr.id);
self.cat_def(expr.id, expr.span, expr_ty, def)
}
ast::expr_paren(e) => self.cat_expr_unadjusted(e),
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ast::expr_addr_of(*) | ast::expr_call(*) |
ast::expr_swap(*) | ast::expr_assign(*) |
ast::expr_assign_op(*) | ast::expr_fn(*) | ast::expr_fn_block(*) |
ast::expr_assert(*) | ast::expr_ret(*) |
ast::expr_loop_body(*) | ast::expr_do_body(*) |
ast::expr_unary(*) | ast::expr_method_call(*) |
ast::expr_copy(*) | ast::expr_cast(*) |
ast::expr_vstore(*) | ast::expr_vec(*) | ast::expr_tup(*) |
ast::expr_if(*) | ast::expr_log(*) |
ast::expr_binary(*) | ast::expr_while(*) |
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ast::expr_block(*) | ast::expr_loop(*) | ast::expr_match(*) |
ast::expr_lit(*) | ast::expr_break(*) | ast::expr_mac(*) |
ast::expr_again(*) | ast::expr_rec(*) | ast::expr_struct(*) |
ast::expr_repeat(*) => {
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return self.cat_rvalue(expr, expr_ty);
}
}
}
fn cat_def(&self,
id: ast::node_id,
span: span,
expr_ty: ty::t,
def: ast::def) -> cmt {
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match def {
ast::def_fn(*) | ast::def_static_method(*) | ast::def_mod(_) |
ast::def_foreign_mod(_) | ast::def_const(_) |
ast::def_use(_) | ast::def_variant(*) |
ast::def_ty(_) | ast::def_prim_ty(_) |
ast::def_ty_param(*) | ast::def_struct(*) |
ast::def_typaram_binder(*) | ast::def_region(_) |
ast::def_label(_) | ast::def_self_ty(*) => {
@cmt_ {
id:id,
span:span,
cat:cat_special(sk_static_item),
lp:None,
mutbl: McImmutable,
ty:expr_ty
}
}
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ast::def_arg(vid, mode, mutbl) => {
// Idea: make this could be rewritten to model by-ref
// stuff as `&const` and `&mut`?
// m: mutability of the argument
// lp: loan path, must be none for aliasable things
let m = if mutbl {McDeclared} else {McImmutable};
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let lp = match ty::resolved_mode(self.tcx, mode) {
ast::by_copy => Some(@lp_arg(vid)),
ast::by_ref => None,
ast::by_val => {
// by-value is this hybrid mode where we have a
// pointer but we do not own it. This is not
// considered loanable because, for example, a by-ref
// and and by-val argument might both actually contain
// the same unique ptr.
None
}
};
@cmt_ {
id:id,
span:span,
cat:cat_arg(vid),
lp:lp,
mutbl: m,
ty:expr_ty
}
}
ast::def_self(self_id, is_implicit) => {
let cat, loan_path;
if is_implicit {
cat = cat_special(sk_implicit_self);
loan_path = None;
} else {
cat = cat_self(self_id);
loan_path = Some(@lp_self);
};
@cmt_ {
id:id,
span:span,
cat:cat,
lp:loan_path,
mutbl: McImmutable,
ty:expr_ty
}
}
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ast::def_upvar(_, inner, fn_node_id, _) => {
let ty = ty::node_id_to_type(self.tcx, fn_node_id);
let sigil = ty::ty_closure_sigil(ty);
match sigil {
ast::BorrowedSigil => {
let upcmt = self.cat_def(id, span, expr_ty, *inner);
@cmt_ {
id:id,
span:span,
cat:cat_stack_upvar(upcmt),
lp:upcmt.lp,
mutbl:upcmt.mutbl,
ty:upcmt.ty
}
}
ast::OwnedSigil | ast::ManagedSigil => {
// FIXME #2152 allow mutation of moved upvars
@cmt_ {
id:id,
span:span,
cat:cat_special(sk_heap_upvar),
lp:None,
mutbl:McImmutable,
ty:expr_ty
}
}
}
}
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ast::def_local(vid, mutbl) => {
let m = if mutbl {McDeclared} else {McImmutable};
@cmt_ {
id:id,
span:span,
cat:cat_local(vid),
lp:Some(@lp_local(vid)),
mutbl:m,
ty:expr_ty
}
}
ast::def_binding(vid, _) => {
// by-value/by-ref bindings are local variables
@cmt_ {
id:id,
span:span,
cat:cat_local(vid),
lp:Some(@lp_local(vid)),
mutbl:McImmutable,
ty:expr_ty
}
}
}
}
fn cat_variant<N:ast_node>(&self,
arg: N,
enum_did: ast::def_id,
cmt: cmt) -> cmt {
@cmt_ {
id: arg.id(),
span: arg.span(),
cat: cat_comp(cmt, comp_variant(enum_did)),
lp: cmt.lp.map(|l| @lp_comp(*l, comp_variant(enum_did)) ),
mutbl: cmt.mutbl.inherit(),
ty: self.tcx.ty(arg)
}
}
fn cat_rvalue<N:ast_node>(&self, elt: N, expr_ty: ty::t) -> cmt {
@cmt_ {
id:elt.id(),
span:elt.span(),
cat:cat_rvalue,
lp:None,
mutbl:McImmutable,
ty:expr_ty
}
}
/// inherited mutability: used in cases where the mutability of a
/// component is inherited from the base it is a part of. For
/// example, a record field is mutable if it is declared mutable
/// or if the container is mutable.
fn inherited_mutability(&self,
base_m: MutabilityCategory,
comp_m: ast::mutability) -> MutabilityCategory
{
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match comp_m {
m_imm => base_m.inherit(),
m_const => McReadOnly,
m_mutbl => McDeclared
}
}
/// The `field_id` parameter is the ID of the enclosing expression or
/// pattern. It is used to determine which variant of an enum is in use.
fn cat_field<N:ast_node>(&self,
node: N,
base_cmt: cmt,
f_name: ast::ident,
field_id: ast::node_id) -> cmt {
let f_mutbl = match field_mutbl(self.tcx, base_cmt.ty,
f_name, field_id) {
Some(f_mutbl) => f_mutbl,
None => {
self.tcx.sess.span_bug(
node.span(),
fmt!("Cannot find field `%s` in type `%s`",
*self.tcx.sess.str_of(f_name),
ty_to_str(self.tcx, base_cmt.ty)));
}
};
let m = self.inherited_mutability(base_cmt.mutbl, f_mutbl);
let f_comp = comp_field(f_name, f_mutbl);
let lp = base_cmt.lp.map(|lp| @lp_comp(*lp, f_comp) );
@cmt_ {
id: node.id(),
span: node.span(),
cat: cat_comp(base_cmt, f_comp),
lp:lp,
mutbl: m,
ty: self.tcx.ty(node)
}
}
fn cat_deref_fn<N:ast_node>(&self,
node: N,
base_cmt: cmt,
deref_cnt: uint) -> cmt
{
// Bit of a hack: the "dereference" of a function pointer like
// `@fn()` is a mere logical concept. We interpret it as
// dereferencing the environment pointer; of course, we don't
// know what type lies at the other end, so we just call it
// `()` (the empty tuple).
let mt = ty::mt {ty: ty::mk_tup(self.tcx, ~[]),
mutbl: m_imm};
return self.cat_deref_common(node, base_cmt, deref_cnt, mt);
}
fn cat_deref<N:ast_node>(&self,
node: N,
base_cmt: cmt,
deref_cnt: uint) -> cmt
{
let mt = match ty::deref(self.tcx, base_cmt.ty, true) {
Some(mt) => mt,
None => {
self.tcx.sess.span_bug(
node.span(),
fmt!("Explicit deref of non-derefable type: %s",
ty_to_str(self.tcx, base_cmt.ty)));
}
};
return self.cat_deref_common(node, base_cmt, deref_cnt, mt);
}
fn cat_deref_common<N:ast_node>(&self,
node: N,
base_cmt: cmt,
deref_cnt: uint,
mt: ty::mt) -> cmt
{
match deref_kind(self.tcx, base_cmt.ty) {
deref_ptr(ptr) => {
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let lp = do base_cmt.lp.chain_ref |l| {
// Given that the ptr itself is loanable, we can
// loan out deref'd uniq ptrs or mut ptrs as the data
// they are the only way to mutably reach the data they
// point at. Other ptr types admit mutable aliases and
// are therefore not loanable.
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match ptr {
uniq_ptr => Some(@lp_deref(*l, ptr)),
region_ptr(ast::m_mutbl, _) => {
Some(@lp_deref(*l, ptr))
}
gc_ptr(*) | region_ptr(_, _) | unsafe_ptr => None
}
};
// for unique ptrs, we inherit mutability from the
// owning reference.
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let m = match ptr {
uniq_ptr => {
self.inherited_mutability(base_cmt.mutbl, mt.mutbl)
}
gc_ptr(*) | region_ptr(_, _) | unsafe_ptr => {
MutabilityCategory::from_mutbl(mt.mutbl)
}
};
@cmt_ {
id:node.id(),
span:node.span(),
cat:cat_deref(base_cmt, deref_cnt, ptr),
lp:lp,
mutbl:m,
ty:mt.ty
}
}
deref_comp(comp) => {
let lp = base_cmt.lp.map(|l| @lp_comp(*l, comp) );
let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl);
@cmt_ {
id:node.id(),
span:node.span(),
cat:cat_comp(base_cmt, comp),
lp:lp,
mutbl:m,
ty:mt.ty
}
}
}
}
fn cat_index<N:ast_node>(&self,
elt: N,
base_cmt: cmt) -> cmt {
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let mt = match ty::index(self.tcx, base_cmt.ty) {
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Some(mt) => mt,
None => {
self.tcx.sess.span_bug(
elt.span(),
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fmt!("Explicit index of non-index type `%s`",
ty_to_str(self.tcx, base_cmt.ty)));
}
};
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return match deref_kind(self.tcx, base_cmt.ty) {
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deref_ptr(ptr) => {
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// (a) the contents are loanable if the base is loanable
// and this is a *unique* vector
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let deref_lp = match ptr {
uniq_ptr => {base_cmt.lp.map(|lp| @lp_deref(*lp, uniq_ptr))}
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_ => {None}
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};
// (b) for unique ptrs, we inherit mutability from the
// owning reference.
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let m = match ptr {
uniq_ptr => {
self.inherited_mutability(base_cmt.mutbl, mt.mutbl)
}
gc_ptr(_) | region_ptr(_, _) | unsafe_ptr => {
MutabilityCategory::from_mutbl(mt.mutbl)
}
};
// (c) the deref is explicit in the resulting cmt
let deref_cmt = @cmt_ {
id:elt.id(),
span:elt.span(),
cat:cat_deref(base_cmt, 0u, ptr),
lp:deref_lp,
mutbl:m,
ty:mt.ty
};
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comp(elt, deref_cmt, base_cmt.ty, m, mt)
}
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deref_comp(_) => {
// fixed-length vectors have no deref
let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl);
comp(elt, base_cmt, base_cmt.ty, m, mt)
}
};
fn comp<N:ast_node>(elt: N, of_cmt: cmt,
vect: ty::t, mutbl: MutabilityCategory,
mt: ty::mt) -> cmt
{
let comp = comp_index(vect, mt.mutbl);
let index_lp = of_cmt.lp.map(|lp| @lp_comp(*lp, comp) );
@cmt_ {
id:elt.id(),
span:elt.span(),
cat:cat_comp(of_cmt, comp),
lp:index_lp,
mutbl:mutbl,
ty:mt.ty
}
}
}
fn cat_tuple_elt<N:ast_node>(&self,
elt: N,
cmt: cmt) -> cmt {
@cmt_ {
id: elt.id(),
span: elt.span(),
cat: cat_comp(cmt, comp_tuple),
lp: cmt.lp.map(|l| @lp_comp(*l, comp_tuple) ),
mutbl: cmt.mutbl.inherit(),
ty: self.tcx.ty(elt)
}
}
fn cat_anon_struct_field<N:ast_node>(&self,
elt: N,
cmt: cmt) -> cmt {
@cmt_ {
id: elt.id(),
span: elt.span(),
cat: cat_comp(cmt, comp_anon_field),
lp: cmt.lp.map(|l| @lp_comp(*l, comp_anon_field)),
mutbl: cmt.mutbl.inherit(),
ty: self.tcx.ty(elt)
}
}
fn cat_method_ref(&self,
expr: @ast::expr,
expr_ty: ty::t) -> cmt {
@cmt_ {
id:expr.id,
span:expr.span,
cat:cat_special(sk_method),
lp:None,
mutbl:McImmutable,
ty:expr_ty
}
}
fn cat_pattern(&self,
cmt: cmt,
pat: @ast::pat,
op: fn(cmt, @ast::pat))
{
// Here, `cmt` is the categorization for the value being
// matched and pat is the pattern it is being matched against.
//
// In general, the way that this works is that we walk down
// the pattern, constructing a cmt that represents the path
// that will be taken to reach the value being matched.
//
// When we encounter named bindings, we take the cmt that has
// been built up and pass it off to guarantee_valid() so that
// we can be sure that the binding will remain valid for the
// duration of the arm.
//
// The correspondence between the id in the cmt and which
// pattern is being referred to is somewhat...subtle. In
// general, the id of the cmt is the id of the node that
// produces the value. For patterns, that's actually the
// *subpattern*, generally speaking.
//
// To see what I mean about ids etc, consider:
//
// let x = @@3;
// match x {
// @@y { ... }
// }
//
// Here the cmt for `y` would be something like
//
// local(x)->@->@
//
// where the id of `local(x)` is the id of the `x` that appears
// in the match, the id of `local(x)->@` is the `@y` pattern,
// and the id of `local(x)->@->@` is the id of the `y` pattern.
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let tcx = self.tcx;
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debug!("cat_pattern: id=%d pat=%s cmt=%s",
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pat.id, pprust::pat_to_str(pat, tcx.sess.intr()),
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self.cmt_to_repr(cmt));
let _i = indenter();
op(cmt, pat);
match pat.node {
ast::pat_wild => {
// _
}
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ast::pat_enum(_, None) => {
// variant(*)
}
ast::pat_enum(_, Some(ref subpats)) => {
match self.tcx.def_map.find(&pat.id) {
Some(ast::def_variant(enum_did, _)) => {
// variant(x, y, z)
for subpats.each |subpat| {
let subcmt = self.cat_variant(*subpat, enum_did, cmt);
self.cat_pattern(subcmt, *subpat, op);
}
}
Some(ast::def_struct(*)) => {
for subpats.each |subpat| {
let cmt_field = self.cat_anon_struct_field(*subpat,
cmt);
self.cat_pattern(cmt_field, *subpat, op);
}
}
_ => {
self.tcx.sess.span_bug(
pat.span,
~"enum pattern didn't resolve to enum or struct");
}
}
}
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ast::pat_ident(_, _, Some(subpat)) => {
self.cat_pattern(cmt, subpat, op);
}
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ast::pat_ident(_, _, None) => {
// nullary variant or identifier: ignore
}
ast::pat_rec(ref field_pats, _) |
ast::pat_struct(_, ref field_pats, _) => {
// {f1: p1, ..., fN: pN}
for field_pats.each |fp| {
let cmt_field = self.cat_field(fp.pat, cmt, fp.ident, pat.id);
self.cat_pattern(cmt_field, fp.pat, op);
}
}
ast::pat_tup(ref subpats) => {
// (p1, ..., pN)
for subpats.each |subpat| {
let subcmt = self.cat_tuple_elt(*subpat, cmt);
self.cat_pattern(subcmt, *subpat, op);
}
}
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ast::pat_box(subpat) | ast::pat_uniq(subpat) |
ast::pat_region(subpat) => {
// @p1, ~p1
let subcmt = self.cat_deref(subpat, cmt, 0);
self.cat_pattern(subcmt, subpat, op);
}
ast::pat_vec(ref pats, opt_tail_pat) => {
for pats.each |pat| {
let elt_cmt = self.cat_index(*pat, cmt);
self.cat_pattern(elt_cmt, *pat, op);
}
for opt_tail_pat.each |tail_pat| {
let tail_ty = self.tcx.ty(*tail_pat);
let tail_cmt = self.cat_rvalue(*tail_pat, tail_ty);
self.cat_pattern(tail_cmt, *tail_pat, op);
}
}
ast::pat_lit(_) | ast::pat_range(_, _) => {
/*always ok*/
}
}
}
fn cat_to_repr(&self, cat: categorization) -> ~str {
match cat {
cat_special(sk_method) => ~"method",
cat_special(sk_static_item) => ~"static_item",
cat_special(sk_implicit_self) => ~"implicit-self",
cat_special(sk_heap_upvar) => ~"heap-upvar",
cat_stack_upvar(_) => ~"stack-upvar",
cat_rvalue => ~"rvalue",
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cat_local(node_id) => fmt!("local(%d)", node_id),
cat_binding(node_id) => fmt!("binding(%d)", node_id),
cat_arg(node_id) => fmt!("arg(%d)", node_id),
cat_self(node_id) => fmt!("self(%d)", node_id),
cat_deref(cmt, derefs, ptr) => {
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fmt!("%s->(%s, %u)", self.cat_to_repr(cmt.cat),
self.ptr_sigil(ptr), derefs)
}
cat_comp(cmt, comp) => {
fmt!("%s.%s", self.cat_to_repr(cmt.cat), *self.comp_to_repr(comp))
}
cat_discr(cmt, _) => self.cat_to_repr(cmt.cat)
}
}
fn mut_to_str(&self, mutbl: ast::mutability) -> ~str {
match mutbl {
m_mutbl => ~"mutable",
m_const => ~"const",
m_imm => ~"immutable"
}
}
fn ptr_sigil(&self, ptr: ptr_kind) -> ~str {
match ptr {
uniq_ptr => ~"~",
gc_ptr(_) => ~"@",
region_ptr(_, _) => ~"&",
unsafe_ptr => ~"*"
}
}
fn comp_to_repr(&self, comp: comp_kind) -> @~str {
match comp {
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comp_field(fld, _) => self.tcx.sess.str_of(fld),
comp_index(*) => @~"[]",
comp_tuple => @~"()",
comp_anon_field => @~"<anonymous field>",
comp_variant(_) => @~"<enum>"
}
}
fn lp_to_str(&self, lp: @loan_path) -> ~str {
match *lp {
lp_local(node_id) => {
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fmt!("local(%d)", node_id)
}
lp_arg(node_id) => {
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fmt!("arg(%d)", node_id)
}
lp_self => ~"self",
lp_deref(lp, ptr) => {
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fmt!("%s->(%s)", self.lp_to_str(lp),
self.ptr_sigil(ptr))
}
lp_comp(lp, comp) => {
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fmt!("%s.%s", self.lp_to_str(lp),
*self.comp_to_repr(comp))
}
}
}
fn cmt_to_repr(&self, cmt: cmt) -> ~str {
fmt!("{%s id:%d m:%? lp:%s ty:%s}",
self.cat_to_repr(cmt.cat),
cmt.id,
cmt.mutbl,
cmt.lp.map_default(~"none", |p| self.lp_to_str(*p) ),
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ty_to_str(self.tcx, cmt.ty))
}
fn cmt_to_str(&self, cmt: cmt) -> ~str {
let mut_str = cmt.mutbl.to_user_str();
match cmt.cat {
cat_special(sk_method) => ~"method",
cat_special(sk_static_item) => ~"static item",
cat_special(sk_implicit_self) => ~"self reference",
cat_special(sk_heap_upvar) => {
~"captured outer variable in a heap closure"
}
cat_rvalue => ~"non-lvalue",
cat_local(_) => mut_str + ~" local variable",
cat_binding(_) => ~"pattern binding",
cat_self(_) => ~"self value",
cat_arg(_) => ~"argument",
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cat_deref(_, _, pk) => fmt!("dereference of %s %s pointer",
mut_str, self.ptr_sigil(pk)),
cat_stack_upvar(_) => {
~"captured outer " + mut_str + ~" variable in a stack closure"
}
cat_comp(_, comp_field(*)) => mut_str + ~" field",
cat_comp(_, comp_tuple) => ~"tuple content",
cat_comp(_, comp_anon_field) => ~"anonymous field",
cat_comp(_, comp_variant(_)) => ~"enum content",
cat_comp(_, comp_index(t, _)) => {
match ty::get(t).sty {
ty::ty_evec(*) => mut_str + ~" vec content",
ty::ty_estr(*) => mut_str + ~" str content",
_ => mut_str + ~" indexed content"
}
}
cat_discr(cmt, _) => {
self.cmt_to_str(cmt)
}
}
}
fn region_to_str(&self, r: ty::Region) -> ~str {
region_to_str(self.tcx, r)
}
}
/// The node_id here is the node of the expression that references the field.
/// This function looks it up in the def map in case the type happens to be
/// an enum to determine which variant is in use.
pub fn field_mutbl(tcx: ty::ctxt,
base_ty: ty::t,
f_name: ast::ident,
node_id: ast::node_id)
-> Option<ast::mutability> {
// Need to refactor so that records/class fields can be treated uniformly.
match /*bad*/copy ty::get(base_ty).sty {
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ty::ty_rec(fields) => {
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for fields.each |f| {
if f.ident == f_name {
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return Some(f.mt.mutbl);
}
}
}
ty::ty_struct(did, _) => {
for ty::lookup_struct_fields(tcx, did).each |fld| {
if fld.ident == f_name {
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let m = match fld.mutability {
ast::struct_mutable => ast::m_mutbl,
ast::struct_immutable => ast::m_imm
};
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return Some(m);
}
}
}
ty::ty_enum(*) => {
match tcx.def_map.get(&node_id) {
ast::def_variant(_, variant_id) => {
for ty::lookup_struct_fields(tcx, variant_id).each |fld| {
if fld.ident == f_name {
let m = match fld.mutability {
ast::struct_mutable => ast::m_mutbl,
ast::struct_immutable => ast::m_imm
};
return Some(m);
}
}
}
_ => {}
}
}
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_ => { }
}
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return None;
}
pub impl categorization {
fn derefs_through_mutable_box(&const self) -> bool {
match *self {
cat_deref(_, _, gc_ptr(ast::m_mutbl)) => {
true
}
cat_deref(subcmt, _, _) |
cat_comp(subcmt, _) |
cat_discr(subcmt, _) |
cat_stack_upvar(subcmt) => {
subcmt.cat.derefs_through_mutable_box()
}
cat_rvalue |
cat_special(*) |
cat_local(*) |
cat_binding(*) |
cat_arg(*) |
cat_self(*) => {
false
}
}
}
fn is_mutable_box(&const self) -> bool {
match *self {
cat_deref(_, _, gc_ptr(ast::m_mutbl)) => true,
_ => false
}
}
}