rust/src/rustc/middle/mem_categorization.rs

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/*!
* # 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.
*/
import syntax::ast;
import syntax::ast::{m_imm, m_const, m_mutbl};
import syntax::codemap::span;
import syntax::print::pprust;
import util::ppaux::{ty_to_str, region_to_str};
import util::common::indenter;
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())
}
// different kinds of pointers:
enum ptr_kind {uniq_ptr, gc_ptr, region_ptr(ty::region), unsafe_ptr}
// I am coining the term "components" to mean "pieces of a data
// structure accessible without a dereference":
enum comp_kind {
comp_tuple, // elt in a tuple
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
enum special_kind {
sk_method,
sk_static_item,
sk_self,
sk_heap_upvar
}
// 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.
type 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: ast::mutability, // mutability of expr as lvalue
ty: ty::t}; // type of the expr
// 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.
enum loan_path {
lp_local(ast::node_id),
lp_arg(ast::node_id),
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:
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).
fn opt_deref_kind(t: ty::t) -> option<deref_kind> {
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match ty::get(t).struct {
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ty::ty_uniq(*) |
ty::ty_evec(_, ty::vstore_uniq) |
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ty::ty_estr(ty::vstore_uniq) => {
some(deref_ptr(uniq_ptr))
}
ty::ty_rptr(r, _) |
ty::ty_evec(_, ty::vstore_slice(r)) |
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ty::ty_estr(ty::vstore_slice(r)) => {
some(deref_ptr(region_ptr(r)))
}
ty::ty_box(*) |
ty::ty_evec(_, ty::vstore_box) |
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ty::ty_estr(ty::vstore_box) => {
some(deref_ptr(gc_ptr))
}
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ty::ty_ptr(*) => {
some(deref_ptr(unsafe_ptr))
}
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ty::ty_enum(did, _) => {
some(deref_comp(comp_variant(did)))
}
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ty::ty_evec(mt, ty::vstore_fixed(_)) => {
some(deref_comp(comp_index(t, mt.mutbl)))
}
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ty::ty_estr(ty::vstore_fixed(_)) => {
some(deref_comp(comp_index(t, m_imm)))
}
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_ => none
}
}
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(
fmt!{"deref_cat() invoked on non-derefable type %s",
ty_to_str(tcx, t)});
}
}
}
fn cat_borrow_of_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_borrow_of_expr(expr);
}
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);
}
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);
}
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);
}
trait ast_node {
fn id() -> ast::node_id;
fn span() -> span;
}
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impl @ast::expr: ast_node {
fn id() -> ast::node_id { self.id }
fn span() -> span { self.span }
}
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impl @ast::pat: ast_node {
fn id() -> ast::node_id { self.id }
fn span() -> span { self.span }
}
trait get_type_for_node {
fn ty<N: ast_node>(node: N) -> ty::t;
}
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impl ty::ctxt: get_type_for_node {
fn ty<N: ast_node>(node: N) -> ty::t {
ty::node_id_to_type(self, node.id())
}
}
struct mem_categorization_ctxt {
tcx: ty::ctxt;
method_map: typeck::method_map;
}
impl &mem_categorization_ctxt {
fn cat_borrow_of_expr(expr: @ast::expr) -> cmt {
// Any expression can be borrowed (to account for auto-ref on method
// receivers), but @, ~, @vec, and ~vec are handled specially.
let expr_ty = ty::expr_ty(self.tcx, expr);
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match ty::get(expr_ty).struct {
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ty::ty_evec(*) | ty::ty_estr(*) => {
self.cat_index(expr, expr)
}
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ty::ty_uniq(*) | ty::ty_box(*) | ty::ty_rptr(*) => {
let cmt = self.cat_expr(expr);
self.cat_deref(expr, cmt, 0u, true).get()
}
/*
ty::ty_fn({proto, _}) {
self.cat_call(expr, expr, proto)
}
*/
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_ => {
self.cat_rvalue(expr, expr_ty)
}
}
}
fn cat_expr(expr: @ast::expr) -> cmt {
debug!{"cat_expr: id=%d expr=%s",
expr.id, pprust::expr_to_str(expr)};
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);
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match self.cat_deref(expr, base_cmt, 0u, true) {
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some(cmt) => return cmt,
none => {
tcx.sess.span_bug(
e_base.span,
fmt!{"Explicit deref of non-derefable type `%s`",
ty_to_str(tcx, tcx.ty(e_base))});
}
}
}
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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_autoderef(base);
self.cat_field(expr, base_cmt, f_name)
}
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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);
}
self.cat_index(expr, base)
}
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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)
}
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ast::expr_addr_of(*) | ast::expr_call(*) |
ast::expr_swap(*) | ast::expr_move(*) | ast::expr_assign(*) |
ast::expr_assign_op(*) | ast::expr_fn(*) | ast::expr_fn_block(*) |
ast::expr_assert(*) | ast::expr_ret(*) |
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ast::expr_loop_body(*) | ast::expr_do_body(*) | ast::expr_unary(*) |
ast::expr_copy(*) | ast::expr_cast(*) | ast::expr_fail(*) |
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(*) |
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ast::expr_unary_move(*) | ast::expr_repeat(*) => {
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return self.cat_rvalue(expr, expr_ty);
}
}
}
fn cat_def(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_class(*) |
ast::def_typaram_binder(*) | ast::def_region(_) |
ast::def_label(_) => {
@{id:id, span:span,
cat:cat_special(sk_static_item), lp:none,
mutbl:m_imm, ty:expr_ty}
}
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ast::def_arg(vid, mode) => {
// 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
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let {m,lp} = match ty::resolved_mode(self.tcx, mode) {
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ast::by_mutbl_ref => {
{m: m_mutbl, lp: none}
}
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ast::by_move | ast::by_copy => {
{m: m_imm, lp: some(@lp_arg(vid))}
}
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ast::by_ref => {
{m: m_imm, lp: none}
}
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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.
{m: m_imm, lp: none}
}
};
@{id:id, span:span,
cat:cat_arg(vid), lp:lp,
mutbl:m, ty:expr_ty}
}
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ast::def_self(_) => {
@{id:id, span:span,
cat:cat_special(sk_self), lp:none,
mutbl:m_imm, ty:expr_ty}
}
ast::def_upvar(upvid, inner, fn_node_id, _) => {
let ty = ty::node_id_to_type(self.tcx, fn_node_id);
let proto = ty::ty_fn_proto(ty);
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match proto {
ty::proto_vstore(ty::vstore_slice(_)) => {
let upcmt = self.cat_def(id, span, expr_ty, *inner);
@{id:id, span:span,
cat:cat_stack_upvar(upcmt), lp:upcmt.lp,
mutbl:upcmt.mutbl, ty:upcmt.ty}
}
ty::proto_bare |
ty::proto_vstore(ty::vstore_uniq) |
ty::proto_vstore(ty::vstore_box) => {
// FIXME #2152 allow mutation of moved upvars
@{id:id, span:span,
cat:cat_special(sk_heap_upvar), lp:none,
mutbl:m_imm, ty:expr_ty}
}
ty::proto_vstore(ty::vstore_fixed(_)) =>
fail ~"fixed vstore not allowed here"
}
}
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ast::def_local(vid, mutbl) => {
let m = if mutbl {m_mutbl} else {m_imm};
@{id:id, span:span,
cat:cat_local(vid), lp:some(@lp_local(vid)),
mutbl:m, ty:expr_ty}
}
ast::def_binding(vid, ast::bind_by_value) |
ast::def_binding(vid, ast::bind_by_ref(_)) => {
// by-value/by-ref bindings are local variables
@{id:id, span:span,
cat:cat_local(vid), lp:some(@lp_local(vid)),
mutbl:m_imm, ty:expr_ty}
}
ast::def_binding(pid, ast::bind_by_implicit_ref) => {
// implicit-by-ref bindings are "special" since they are
// implicit pointers.
// Technically, the mutability is not always imm, but we
// (choose to be) unsound for the moment since these
// implicit refs are going away and it reduces external
// dependencies.
@{id:id, span:span,
cat:cat_binding(pid), lp:none,
mutbl:m_imm, ty:expr_ty}
}
}
}
fn cat_variant<N: ast_node>(arg: N,
enum_did: ast::def_id,
cmt: cmt) -> cmt {
@{id: arg.id(), span: arg.span(),
cat: cat_comp(cmt, comp_variant(enum_did)),
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lp: cmt.lp.map(|l| @lp_comp(l, comp_variant(enum_did)) ),
mutbl: cmt.mutbl, // imm iff in an immutable context
ty: self.tcx.ty(arg)}
}
fn cat_rvalue(expr: @ast::expr, expr_ty: ty::t) -> cmt {
@{id:expr.id, span:expr.span,
cat:cat_rvalue, lp:none,
mutbl:m_imm, 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(base_m: ast::mutability,
comp_m: ast::mutability) -> ast::mutability {
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match comp_m {
m_imm => {base_m} // imm: as mutable as the container
m_mutbl | m_const => {comp_m}
}
}
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fn cat_field<N:ast_node>(node: N, base_cmt: cmt,
f_name: ast::ident) -> cmt {
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let f_mutbl = match field_mutbl(self.tcx, base_cmt.ty, f_name) {
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some(f_mutbl) => f_mutbl,
none => {
self.tcx.sess.span_bug(
node.span(),
fmt!{"Cannot find field `%s` in type `%s`",
*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);
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let lp = base_cmt.lp.map(|lp| @lp_comp(lp, f_comp) );
@{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<N:ast_node>(node: N, base_cmt: cmt, derefs: uint,
expl: bool) -> option<cmt> {
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do ty::deref(self.tcx, base_cmt.ty, expl).map |mt| {
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match deref_kind(self.tcx, base_cmt.ty) {
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deref_ptr(ptr) => {
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let lp = do base_cmt.lp.chain |l| {
// Given that the ptr itself is loanable, we can
// loan out deref'd uniq ptrs as the data they are
// the only way to reach the data they point at.
// Other ptr types admit aliases and are therefore
// not loanable.
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match ptr {
uniq_ptr => {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 => {
mt.mutbl
}
};
@{id:node.id(), span:node.span(),
cat:cat_deref(base_cmt, derefs, ptr), lp:lp,
mutbl:m, ty:mt.ty}
}
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deref_comp(comp) => {
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let lp = base_cmt.lp.map(|l| @lp_comp(l, comp) );
let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl);
@{id:node.id(), span:node.span(),
cat:cat_comp(base_cmt, comp), lp:lp,
mutbl:m, ty:mt.ty}
}
}
}
}
fn cat_index(expr: @ast::expr, base: @ast::expr) -> cmt {
let base_cmt = self.cat_autoderef(base);
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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(
expr.span,
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 {
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uniq_ptr => {base_cmt.lp.map(|lp| @lp_deref(lp, uniq_ptr))}
_ => {none}
};
// (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 => {
mt.mutbl
}
};
// (c) the deref is explicit in the resulting cmt
let deref_cmt = @{id:expr.id, span:expr.span,
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cat:cat_deref(base_cmt, 0u, ptr), lp:deref_lp,
mutbl:m, ty:mt.ty};
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comp(expr, deref_cmt, base_cmt.ty, m, mt.ty)
}
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deref_comp(_) => {
// fixed-length vectors have no deref
comp(expr, base_cmt, base_cmt.ty, mt.mutbl, mt.ty)
}
};
fn comp(expr: @ast::expr, of_cmt: cmt,
vect: ty::t, mutbl: ast::mutability, ty: ty::t) -> cmt {
let comp = comp_index(vect, mutbl);
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let index_lp = of_cmt.lp.map(|lp| @lp_comp(lp, comp) );
@{id:expr.id, span:expr.span,
cat:cat_comp(of_cmt, comp), lp:index_lp,
mutbl:mutbl, ty:ty}
}
}
fn cat_tuple_elt<N: ast_node>(elt: N, cmt: cmt) -> cmt {
@{id: elt.id(), span: elt.span(),
cat: cat_comp(cmt, comp_tuple),
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lp: cmt.lp.map(|l| @lp_comp(l, comp_tuple) ),
mutbl: cmt.mutbl, // imm iff in an immutable context
ty: self.tcx.ty(elt)}
}
fn cat_method_ref(expr: @ast::expr, expr_ty: ty::t) -> cmt {
@{id:expr.id, span:expr.span,
cat:cat_special(sk_method), lp:none,
mutbl:m_imm, ty:expr_ty}
}
fn cat_autoderef(base: @ast::expr) -> cmt {
// Creates a string of implicit derefences so long as base is
// dereferencable. n.b., it is important that these dereferences are
// associated with the field/index that caused the autoderef (expr).
// This is used later to adjust ref counts and so forth in trans.
// Given something like base.f where base has type @m1 @m2 T, we want
// to yield the equivalent categories to (**base).f.
let mut cmt = self.cat_expr(base);
let mut ctr = 0u;
loop {
ctr += 1u;
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match self.cat_deref(base, cmt, ctr, false) {
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none => return cmt,
some(cmt1) => cmt = cmt1
}
}
}
fn cat_pattern(cmt: cmt, pat: @ast::pat, op: fn(cmt, @ast::pat)) {
op(cmt, 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 alt, the id of `local(x)->@` is the `@y` pattern,
// and the id of `local(x)->@->@` is the id of the `y` pattern.
debug!{"cat_pattern: id=%d pat=%s cmt=%s",
pat.id, pprust::pat_to_str(pat),
self.cmt_to_repr(cmt)};
let _i = indenter();
let tcx = self.tcx;
match pat.node {
ast::pat_wild => {
// _
}
ast::pat_enum(_, none) => {
// variant(*)
}
ast::pat_enum(_, some(subpats)) => {
// variant(x, y, z)
let enum_did = match self.tcx.def_map.find(pat.id) {
some(ast::def_variant(enum_did, _)) => enum_did,
e => tcx.sess.span_bug(pat.span,
fmt!{"resolved to %?, not variant", e})
};
for subpats.each |subpat| {
let subcmt = self.cat_variant(subpat, enum_did, cmt);
self.cat_pattern(subcmt, subpat, op);
}
}
ast::pat_ident(_, _, some(subpat)) => {
self.cat_pattern(cmt, subpat, op);
}
ast::pat_ident(_, _, none) => {
// nullary variant or identifier: ignore
}
ast::pat_rec(field_pats, _) => {
// {f1: p1, ..., fN: pN}
for field_pats.each |fp| {
let cmt_field = self.cat_field(fp.pat, cmt, fp.ident);
self.cat_pattern(cmt_field, fp.pat, op);
}
}
ast::pat_struct(_, field_pats, _) => {
// {f1: p1, ..., fN: pN}
for field_pats.each |fp| {
let cmt_field = self.cat_field(fp.pat, cmt, fp.ident);
self.cat_pattern(cmt_field, fp.pat, op);
}
}
ast::pat_tup(subpats) => {
// (p1, ..., pN)
for subpats.each |subpat| {
let subcmt = self.cat_tuple_elt(subpat, cmt);
self.cat_pattern(subcmt, subpat, op);
}
}
ast::pat_box(subpat) | ast::pat_uniq(subpat) => {
// @p1, ~p1
match self.cat_deref(subpat, cmt, 0u, true) {
some(subcmt) => {
self.cat_pattern(subcmt, subpat, op);
}
none => {
tcx.sess.span_bug(pat.span, ~"Non derefable type");
}
}
}
ast::pat_lit(_) | ast::pat_range(_, _) => { /*always ok*/ }
}
}
fn cat_to_repr(cat: categorization) -> ~str {
match cat {
cat_special(sk_method) => ~"method",
cat_special(sk_static_item) => ~"static_item",
cat_special(sk_self) => ~"self",
cat_special(sk_heap_upvar) => ~"heap-upvar",
cat_stack_upvar(_) => ~"stack-upvar",
cat_rvalue => ~"rvalue",
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_deref(cmt, derefs, ptr) => {
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(mutbl: ast::mutability) -> ~str {
match mutbl {
m_mutbl => ~"mutable",
m_const => ~"const",
m_imm => ~"immutable"
}
}
fn ptr_sigil(ptr: ptr_kind) -> ~str {
match ptr {
uniq_ptr => ~"~",
gc_ptr => ~"@",
region_ptr(_) => ~"&",
unsafe_ptr => ~"*"
}
}
fn comp_to_repr(comp: comp_kind) -> ~str {
match comp {
comp_field(fld, _) => *fld,
comp_index(*) => ~"[]",
comp_tuple => ~"()",
comp_variant(_) => ~"<enum>"
}
}
fn lp_to_str(lp: @loan_path) -> ~str {
match *lp {
lp_local(node_id) => {
fmt!{"local(%d)", node_id}
}
lp_arg(node_id) => {
fmt!{"arg(%d)", node_id}
}
lp_deref(lp, ptr) => {
fmt!{"%s->(%s)", self.lp_to_str(lp),
self.ptr_sigil(ptr)}
}
lp_comp(lp, comp) => {
fmt!{"%s.%s", self.lp_to_str(lp),
self.comp_to_repr(comp)}
}
}
}
fn cmt_to_repr(cmt: cmt) -> ~str {
fmt!{"{%s id:%d m:%s lp:%s ty:%s}",
self.cat_to_repr(cmt.cat),
cmt.id,
self.mut_to_str(cmt.mutbl),
cmt.lp.map_default(~"none", |p| self.lp_to_str(p) ),
ty_to_str(self.tcx, cmt.ty)}
}
fn cmt_to_str(cmt: cmt) -> ~str {
let mut_str = self.mut_to_str(cmt.mutbl);
match cmt.cat {
cat_special(sk_method) => ~"method",
cat_special(sk_static_item) => ~"static item",
cat_special(sk_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_arg(_) => ~"argument",
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_variant(_)) => ~"enum content",
cat_comp(_, comp_index(t, _)) => {
match ty::get(t).struct {
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(r: ty::region) -> ~str {
region_to_str(self.tcx, r)
}
}
fn field_mutbl(tcx: ty::ctxt,
base_ty: ty::t,
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f_name: ast::ident) -> option<ast::mutability> {
// Need to refactor so that records/class fields can be treated uniformly.
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match ty::get(base_ty).struct {
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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);
}
}
}
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ty::ty_class(did, substs) => {
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for ty::lookup_class_fields(tcx, did).each |fld| {
if fld.ident == f_name {
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let m = match fld.mutability {
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ast::class_mutable => ast::m_mutbl,
ast::class_immutable => ast::m_imm
};
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return some(m);
}
}
}
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_ => { }
}
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return none;
}