// 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 or the MIT license // , 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 syntax::ast; use syntax::ast::{m_imm, m_const, m_mutbl}; use syntax::codemap::span; use syntax::print::pprust; use util::ppaux::{ty_to_str, region_to_str}; use 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()) } impl categorization : cmp::Eq { pure fn eq(&self, other: &categorization) -> bool { match (*self) { cat_rvalue => { match (*other) { cat_rvalue => true, _ => false } } cat_special(e0a) => { match (*other) { cat_special(e0b) => e0a == e0b, _ => false } } cat_local(e0a) => { match (*other) { cat_local(e0b) => e0a == e0b, _ => false } } cat_binding(e0a) => { match (*other) { cat_binding(e0b) => e0a == e0b, _ => false } } cat_arg(e0a) => { match (*other) { cat_arg(e0b) => e0a == e0b, _ => false } } cat_stack_upvar(e0a) => { match (*other) { cat_stack_upvar(e0b) => e0a == e0b, _ => false } } cat_deref(e0a, e1a, e2a) => { match (*other) { cat_deref(e0b, e1b, e2b) => e0a == e0b && e1a == e1b && e2a == e2b, _ => false } } cat_comp(e0a, e1a) => { match (*other) { cat_comp(e0b, e1b) => e0a == e0b && e1a == e1b, _ => false } } cat_discr(e0a, e1a) => { match (*other) { cat_discr(e0b, e1b) => e0a == e0b && e1a == e1b, _ => false } } } } pure fn ne(&self, other: &categorization) -> bool { !(*self).eq(other) } } // different kinds of pointers: enum ptr_kind { uniq_ptr, gc_ptr, region_ptr(ty::Region), unsafe_ptr } impl ptr_kind : cmp::Eq { pure fn eq(&self, other: &ptr_kind) -> bool { match (*self) { uniq_ptr => { match (*other) { uniq_ptr => true, _ => false } } gc_ptr => { match (*other) { gc_ptr => true, _ => false } } region_ptr(e0a) => { match (*other) { region_ptr(e0b) => e0a == e0b, _ => false } } unsafe_ptr => { match (*other) { unsafe_ptr => true, _ => false } } } } pure fn ne(&self, other: &ptr_kind) -> bool { !(*self).eq(other) } } // 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_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 } impl comp_kind : cmp::Eq { pure fn eq(&self, other: &comp_kind) -> bool { match (*self) { comp_tuple => { match (*other) { comp_tuple => true, _ => false } } comp_anon_field => { match (*other) { comp_anon_field => true, _ => false } } comp_variant(e0a) => { match (*other) { comp_variant(e0b) => e0a == e0b, _ => false } } comp_field(e0a, e1a) => { match (*other) { comp_field(e0b, e1b) => e0a == e0b && e1a == e1b, _ => false } } comp_index(e0a, e1a) => { match (*other) { comp_index(e0b, e1b) => e0a == e0b && e1a == e1b, _ => false } } } } pure fn ne(&self, other: &comp_kind) -> bool { !(*self).eq(other) } } // different kinds of expressions we might evaluate enum special_kind { sk_method, sk_static_item, sk_self, sk_heap_upvar } impl special_kind : cmp::Eq { pure fn eq(&self, other: &special_kind) -> bool { ((*self) as uint) == ((*other) as uint) } pure fn ne(&self, other: &special_kind) -> bool { !(*self).eq(other) } } // 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 type cmt = @cmt_; impl cmt_ : cmp::Eq { pure fn eq(&self, other: &cmt_) -> bool { (*self).id == (*other).id && (*self).span == (*other).span && (*self).cat == (*other).cat && (*self).lp == (*other).lp && (*self).mutbl == (*other).mutbl && (*self).ty == (*other).ty } pure fn ne(&self, other: &cmt_) -> bool { !(*self).eq(other) } } // 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) } impl loan_path : cmp::Eq { pure fn eq(&self, other: &loan_path) -> bool { match (*self) { lp_local(e0a) => { match (*other) { lp_local(e0b) => e0a == e0b, _ => false } } lp_arg(e0a) => { match (*other) { lp_arg(e0b) => e0a == e0b, _ => false } } lp_deref(e0a, e1a) => { match (*other) { lp_deref(e0b, e1b) => e0a == e0b && e1a == e1b, _ => false } } lp_comp(e0a, e1a) => { match (*other) { lp_comp(e0b, e1b) => e0a == e0b && e1a == e1b, _ => false } } } } pure fn ne(&self, other: &loan_path) -> bool { !(*self).eq(other) } } // 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 { match ty::get(t).sty { ty::ty_uniq(*) | ty::ty_evec(_, ty::vstore_uniq) | ty::ty_estr(ty::vstore_uniq) => { Some(deref_ptr(uniq_ptr)) } ty::ty_fn(ref f) if (*f).meta.proto == ast::ProtoUniq => { Some(deref_ptr(uniq_ptr)) } ty::ty_rptr(r, _) | ty::ty_evec(_, ty::vstore_slice(r)) | ty::ty_estr(ty::vstore_slice(r)) => { Some(deref_ptr(region_ptr(r))) } ty::ty_fn(ref f) if (*f).meta.proto == ast::ProtoBorrowed => { Some(deref_ptr(region_ptr((*f).meta.region))) } ty::ty_box(*) | ty::ty_evec(_, ty::vstore_box) | ty::ty_estr(ty::vstore_box) => { Some(deref_ptr(gc_ptr)) } ty::ty_fn(ref f) if (*f).meta.proto == ast::ProtoBox => { Some(deref_ptr(gc_ptr)) } ty::ty_ptr(*) => { Some(deref_ptr(unsafe_ptr)) } ty::ty_enum(did, _) => { Some(deref_comp(comp_variant(did))) } 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 } } fn deref_kind(tcx: ty::ctxt, t: ty::t) -> deref_kind { match opt_deref_kind(t) { Some(k) => k, None => { tcx.sess.bug( fmt!("deref_cat() invoked on non-derefable type %s", ty_to_str(tcx, t))); } } } 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_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); } fn cat_expr_autoderefd( tcx: ty::ctxt, method_map: typeck::method_map, expr: @ast::expr, adj: @ty::AutoAdjustment) -> cmt { let mcx = &mem_categorization_ctxt { tcx: tcx, method_map: method_map }; return mcx.cat_expr_autoderefd(expr, adj); } 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( 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; } impl @ast::expr: ast_node { fn id() -> ast::node_id { self.id } fn span() -> span { self.span } } impl @ast::pat: ast_node { fn id() -> ast::node_id { self.id } fn span() -> span { self.span } } trait get_type_for_node { fn ty(node: N) -> ty::t; } impl ty::ctxt: get_type_for_node { fn ty(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_expr(expr: @ast::expr) -> cmt { match self.tcx.adjustments.find(expr.id) { None => { // No adjustments. self.cat_expr_unadjusted(expr) } Some(adjustment) => { match adjustment.autoref { Some(_) => { // Equivalent to &*expr or something similar. // This is an rvalue, effectively. let expr_ty = ty::expr_ty(self.tcx, expr); self.cat_rvalue(expr, expr_ty) } None => { // Equivalent to *expr or something similar. self.cat_expr_autoderefd(expr, adjustment) } } } } } fn cat_expr_autoderefd(expr: @ast::expr, adjustment: &ty::AutoAdjustment) -> cmt { let mut cmt = self.cat_expr_unadjusted(expr); for uint::range(1, adjustment.autoderefs+1) |deref| { cmt = self.cat_deref(expr, cmt, deref); } return cmt; } fn cat_expr_unadjusted(expr: @ast::expr) -> cmt { 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); match expr.node { ast::expr_unary(ast::deref, e_base) => { if self.method_map.contains_key(expr.id) { return self.cat_rvalue(expr, expr_ty); } let base_cmt = self.cat_expr(e_base); self.cat_deref(expr, base_cmt, 0) } ast::expr_field(base, f_name, _) => { if self.method_map.contains_key(expr.id) { 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) } ast::expr_index(base, _) => { if self.method_map.contains_key(expr.id) { return self.cat_rvalue(expr, expr_ty); } let base_cmt = self.cat_expr(base); self.cat_index(expr, base_cmt) } 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), 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_fail(*) | ast::expr_vstore(*) | ast::expr_vec(*) | ast::expr_tup(*) | ast::expr_if(*) | ast::expr_log(*) | ast::expr_binary(*) | ast::expr_while(*) | 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_unary_move(*) | ast::expr_repeat(*) => { return self.cat_rvalue(expr, expr_ty); } } } fn cat_def(id: ast::node_id, span: span, expr_ty: ty::t, def: ast::def) -> cmt { 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(_) => { @{id:id, span:span, cat:cat_special(sk_static_item), lp:None, mutbl:m_imm, ty:expr_ty} } 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 let {m,lp} = match ty::resolved_mode(self.tcx, mode) { ast::by_move | ast::by_copy => { {m: m_imm, lp: Some(@lp_arg(vid))} } ast::by_ref => { {m: m_imm, lp: 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. {m: m_imm, lp: None} } }; @{id:id, span:span, cat:cat_arg(vid), lp:lp, mutbl:m, ty:expr_ty} } ast::def_self(_) => { @{id:id, span:span, cat:cat_special(sk_self), lp:None, mutbl:m_imm, ty:expr_ty} } ast::def_upvar(_, inner, fn_node_id, _) => { let ty = ty::node_id_to_type(self.tcx, fn_node_id); let proto = ty::ty_fn_proto(ty); match proto { ast::ProtoBorrowed => { 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} } ast::ProtoUniq | ast::ProtoBox => { // 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} } ast::ProtoBare => { self.tcx.sess.span_bug( span, fmt!("Upvar in a bare closure?")); } } } 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, _) => { // 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} } } } fn cat_variant(arg: N, enum_did: ast::def_id, 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, // 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 { match comp_m { m_imm => {base_m} // imm: as mutable as the container m_mutbl | m_const => {comp_m} } } /// 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(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) ); @{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(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: ty::mk_tup(self.tcx, ~[]), mutbl: m_imm}; return self.cat_deref_common(node, base_cmt, deref_cnt, mt); } fn cat_deref(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(node: N, base_cmt: cmt, deref_cnt: uint, mt: ty::mt) -> cmt { match deref_kind(self.tcx, base_cmt.ty) { deref_ptr(ptr) => { let lp = do base_cmt.lp.chain_ref |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. 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. 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, 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); @{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_cmt: cmt) -> cmt { let mt = match ty::index(self.tcx, base_cmt.ty) { 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))); } }; return match deref_kind(self.tcx, base_cmt.ty) { deref_ptr(ptr) => { // (a) the contents are loanable if the base is loanable // and this is a *unique* vector let deref_lp = match ptr { uniq_ptr => {base_cmt.lp.map(|lp| @lp_deref(*lp, uniq_ptr))} _ => {None} }; // (b) for unique ptrs, we inherit mutability from the // owning reference. 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, cat:cat_deref(base_cmt, 0u, ptr), lp:deref_lp, mutbl:m, ty:mt.ty}; comp(expr, deref_cmt, base_cmt.ty, m, mt.ty) } deref_comp(_) => { // fixed-length vectors have no deref let m = self.inherited_mutability(base_cmt.mutbl, mt.mutbl); comp(expr, base_cmt, base_cmt.ty, m, 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); 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(elt: N, 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, // imm iff in an immutable context ty: self.tcx.ty(elt)} } fn cat_anon_struct_field(elt: N, 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, // 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_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. let _i = indenter(); let tcx = self.tcx; debug!("cat_pattern: id=%d pat=%s cmt=%s", pat.id, pprust::pat_to_str(pat, tcx.sess.intr()), self.cmt_to_repr(cmt)); match pat.node { ast::pat_wild => { // _ } ast::pat_enum(_, None) => { // variant(*) } ast::pat_enum(_, Some(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"); } } } 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, pat.id); 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, pat.id); 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) | ast::pat_region(subpat) => { // @p1, ~p1 let subcmt = self.cat_deref(subpat, cmt, 0); self.cat_pattern(subcmt, subpat, op); } 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, _) => self.tcx.sess.str_of(fld), comp_index(*) => ~"[]", comp_tuple => ~"()", comp_anon_field => ~"", comp_variant(_) => ~"" } } 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_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(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. fn field_mutbl(tcx: ty::ctxt, base_ty: ty::t, f_name: ast::ident, node_id: ast::node_id) -> Option { // Need to refactor so that records/class fields can be treated uniformly. match ty::get(base_ty).sty { ty::ty_rec(fields) => { for fields.each |f| { if f.ident == f_name { return Some(f.mt.mutbl); } } } ty::ty_struct(did, _) => { for ty::lookup_struct_fields(tcx, did).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); } } } 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); } } } _ => {} } } _ => { } } return None; }