561 lines
22 KiB
Rust
561 lines
22 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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#![allow(non_camel_case_types)]
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#![allow(unsigned_negation)]
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pub use self::const_val::*;
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use metadata::csearch;
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use middle::{astencode, def};
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use middle::pat_util::def_to_path;
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use middle::ty::{self, Ty};
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use middle::astconv_util::{ast_ty_to_prim_ty};
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use syntax::ast::{self, Expr};
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use syntax::codemap::Span;
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use syntax::parse::token::InternedString;
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use syntax::ptr::P;
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use syntax::{ast_map, ast_util, codemap};
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use std::cmp::Ordering;
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use std::collections::hash_map::Entry::Vacant;
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use std::{i8, i16, i32, i64};
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use std::rc::Rc;
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fn lookup_const<'a>(tcx: &'a ty::ctxt, e: &Expr) -> Option<&'a Expr> {
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let opt_def = tcx.def_map.borrow().get(&e.id).map(|d| d.full_def());
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match opt_def {
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Some(def::DefConst(def_id)) => {
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lookup_const_by_id(tcx, def_id)
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}
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Some(def::DefVariant(enum_def, variant_def, _)) => {
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lookup_variant_by_id(tcx, enum_def, variant_def)
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}
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_ => None
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}
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}
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fn lookup_variant_by_id<'a>(tcx: &'a ty::ctxt,
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enum_def: ast::DefId,
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variant_def: ast::DefId)
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-> Option<&'a Expr> {
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fn variant_expr<'a>(variants: &'a [P<ast::Variant>], id: ast::NodeId)
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-> Option<&'a Expr> {
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for variant in variants {
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if variant.node.id == id {
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return variant.node.disr_expr.as_ref().map(|e| &**e);
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}
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}
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None
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}
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if ast_util::is_local(enum_def) {
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match tcx.map.find(enum_def.node) {
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None => None,
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Some(ast_map::NodeItem(it)) => match it.node {
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ast::ItemEnum(ast::EnumDef { ref variants }, _) => {
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variant_expr(&variants[..], variant_def.node)
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}
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_ => None
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},
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Some(_) => None
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}
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} else {
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match tcx.extern_const_variants.borrow().get(&variant_def) {
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Some(&ast::DUMMY_NODE_ID) => return None,
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Some(&expr_id) => {
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return Some(tcx.map.expect_expr(expr_id));
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}
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None => {}
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}
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let expr_id = match csearch::maybe_get_item_ast(tcx, enum_def,
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box |a, b, c, d| astencode::decode_inlined_item(a, b, c, d)) {
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csearch::FoundAst::Found(&ast::IIItem(ref item)) => match item.node {
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ast::ItemEnum(ast::EnumDef { ref variants }, _) => {
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// NOTE this doesn't do the right thing, it compares inlined
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// NodeId's to the original variant_def's NodeId, but they
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// come from different crates, so they will likely never match.
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variant_expr(&variants[..], variant_def.node).map(|e| e.id)
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}
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_ => None
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},
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_ => None
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};
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tcx.extern_const_variants.borrow_mut().insert(variant_def,
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expr_id.unwrap_or(ast::DUMMY_NODE_ID));
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expr_id.map(|id| tcx.map.expect_expr(id))
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}
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}
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pub fn lookup_const_by_id<'a>(tcx: &'a ty::ctxt, def_id: ast::DefId)
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-> Option<&'a Expr> {
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if ast_util::is_local(def_id) {
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match tcx.map.find(def_id.node) {
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None => None,
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Some(ast_map::NodeItem(it)) => match it.node {
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ast::ItemConst(_, ref const_expr) => {
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Some(&**const_expr)
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}
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_ => None
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},
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Some(_) => None
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}
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} else {
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match tcx.extern_const_statics.borrow().get(&def_id) {
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Some(&ast::DUMMY_NODE_ID) => return None,
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Some(&expr_id) => {
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return Some(tcx.map.expect_expr(expr_id));
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}
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None => {}
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}
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let expr_id = match csearch::maybe_get_item_ast(tcx, def_id,
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box |a, b, c, d| astencode::decode_inlined_item(a, b, c, d)) {
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csearch::FoundAst::Found(&ast::IIItem(ref item)) => match item.node {
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ast::ItemConst(_, ref const_expr) => Some(const_expr.id),
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_ => None
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},
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_ => None
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};
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tcx.extern_const_statics.borrow_mut().insert(def_id,
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expr_id.unwrap_or(ast::DUMMY_NODE_ID));
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expr_id.map(|id| tcx.map.expect_expr(id))
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}
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}
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// FIXME (#33): this doesn't handle big integer/float literals correctly
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// (nor does the rest of our literal handling).
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#[derive(Clone, PartialEq)]
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pub enum const_val {
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const_float(f64),
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const_int(i64),
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const_uint(u64),
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const_str(InternedString),
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const_binary(Rc<Vec<u8> >),
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const_bool(bool)
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}
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pub fn const_expr_to_pat(tcx: &ty::ctxt, expr: &Expr, span: Span) -> P<ast::Pat> {
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let pat = match expr.node {
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ast::ExprTup(ref exprs) =>
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ast::PatTup(exprs.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect()),
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ast::ExprCall(ref callee, ref args) => {
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let def = tcx.def_map.borrow()[callee.id];
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if let Vacant(entry) = tcx.def_map.borrow_mut().entry(expr.id) {
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entry.insert(def);
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}
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let path = match def.full_def() {
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def::DefStruct(def_id) => def_to_path(tcx, def_id),
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def::DefVariant(_, variant_did, _) => def_to_path(tcx, variant_did),
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_ => unreachable!()
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};
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let pats = args.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect();
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ast::PatEnum(path, Some(pats))
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}
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ast::ExprStruct(ref path, ref fields, None) => {
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let field_pats = fields.iter().map(|field| codemap::Spanned {
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span: codemap::DUMMY_SP,
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node: ast::FieldPat {
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ident: field.ident.node,
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pat: const_expr_to_pat(tcx, &*field.expr, span),
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is_shorthand: false,
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},
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}).collect();
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ast::PatStruct(path.clone(), field_pats, false)
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}
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ast::ExprVec(ref exprs) => {
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let pats = exprs.iter().map(|expr| const_expr_to_pat(tcx, &**expr, span)).collect();
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ast::PatVec(pats, None, vec![])
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}
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ast::ExprPath(_, ref path) => {
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let opt_def = tcx.def_map.borrow().get(&expr.id).map(|d| d.full_def());
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match opt_def {
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Some(def::DefStruct(..)) =>
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ast::PatStruct(path.clone(), vec![], false),
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Some(def::DefVariant(..)) =>
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ast::PatEnum(path.clone(), None),
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_ => {
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match lookup_const(tcx, expr) {
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Some(actual) => return const_expr_to_pat(tcx, actual, span),
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_ => unreachable!()
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}
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}
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}
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}
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_ => ast::PatLit(P(expr.clone()))
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};
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P(ast::Pat { id: expr.id, node: pat, span: span })
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}
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pub fn eval_const_expr(tcx: &ty::ctxt, e: &Expr) -> const_val {
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match eval_const_expr_partial(tcx, e, None) {
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Ok(r) => r,
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Err(s) => tcx.sess.span_fatal(e.span, &s[..])
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}
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}
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pub fn eval_const_expr_partial<'tcx>(tcx: &ty::ctxt<'tcx>,
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e: &Expr,
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ty_hint: Option<Ty<'tcx>>)
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-> Result<const_val, String> {
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fn fromb(b: bool) -> Result<const_val, String> { Ok(const_int(b as i64)) }
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let ety = ty_hint.or_else(|| ty::expr_ty_opt(tcx, e));
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match e.node {
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ast::ExprUnary(ast::UnNeg, ref inner) => {
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match eval_const_expr_partial(tcx, &**inner, ety) {
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Ok(const_float(f)) => Ok(const_float(-f)),
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Ok(const_int(i)) => Ok(const_int(-i)),
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Ok(const_uint(i)) => Ok(const_uint(-i)),
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Ok(const_str(_)) => Err("negate on string".to_string()),
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Ok(const_bool(_)) => Err("negate on boolean".to_string()),
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ref err => ((*err).clone())
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}
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}
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ast::ExprUnary(ast::UnNot, ref inner) => {
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match eval_const_expr_partial(tcx, &**inner, ety) {
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Ok(const_int(i)) => Ok(const_int(!i)),
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Ok(const_uint(i)) => Ok(const_uint(!i)),
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Ok(const_bool(b)) => Ok(const_bool(!b)),
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_ => Err("not on float or string".to_string())
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}
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}
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ast::ExprBinary(op, ref a, ref b) => {
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let b_ty = match op.node {
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ast::BiShl | ast::BiShr => Some(tcx.types.uint),
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_ => ety
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};
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match (eval_const_expr_partial(tcx, &**a, ety),
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eval_const_expr_partial(tcx, &**b, b_ty)) {
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(Ok(const_float(a)), Ok(const_float(b))) => {
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match op.node {
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ast::BiAdd => Ok(const_float(a + b)),
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ast::BiSub => Ok(const_float(a - b)),
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ast::BiMul => Ok(const_float(a * b)),
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ast::BiDiv => Ok(const_float(a / b)),
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ast::BiRem => Ok(const_float(a % b)),
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ast::BiEq => fromb(a == b),
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ast::BiLt => fromb(a < b),
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ast::BiLe => fromb(a <= b),
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ast::BiNe => fromb(a != b),
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ast::BiGe => fromb(a >= b),
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ast::BiGt => fromb(a > b),
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_ => Err("can't do this op on floats".to_string())
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}
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}
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(Ok(const_int(a)), Ok(const_int(b))) => {
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let is_a_min_value = || {
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let int_ty = match ty::expr_ty_opt(tcx, e).map(|ty| &ty.sty) {
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Some(&ty::ty_int(int_ty)) => int_ty,
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_ => return false
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};
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let int_ty = if let ast::TyIs(_) = int_ty {
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tcx.sess.target.int_type
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} else {
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int_ty
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};
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match int_ty {
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ast::TyI8 => (a as i8) == i8::MIN,
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ast::TyI16 => (a as i16) == i16::MIN,
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ast::TyI32 => (a as i32) == i32::MIN,
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ast::TyI64 => (a as i64) == i64::MIN,
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ast::TyIs(_) => unreachable!()
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}
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};
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match op.node {
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ast::BiAdd => Ok(const_int(a + b)),
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ast::BiSub => Ok(const_int(a - b)),
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ast::BiMul => Ok(const_int(a * b)),
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ast::BiDiv => {
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if b == 0 {
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Err("attempted to divide by zero".to_string())
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} else if b == -1 && is_a_min_value() {
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Err("attempted to divide with overflow".to_string())
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} else {
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Ok(const_int(a / b))
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}
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}
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ast::BiRem => {
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if b == 0 {
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Err("attempted remainder with a divisor of zero".to_string())
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} else if b == -1 && is_a_min_value() {
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Err("attempted remainder with overflow".to_string())
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} else {
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Ok(const_int(a % b))
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}
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}
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ast::BiAnd | ast::BiBitAnd => Ok(const_int(a & b)),
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ast::BiOr | ast::BiBitOr => Ok(const_int(a | b)),
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ast::BiBitXor => Ok(const_int(a ^ b)),
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ast::BiShl => Ok(const_int(a << b as uint)),
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ast::BiShr => Ok(const_int(a >> b as uint)),
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ast::BiEq => fromb(a == b),
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ast::BiLt => fromb(a < b),
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ast::BiLe => fromb(a <= b),
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ast::BiNe => fromb(a != b),
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ast::BiGe => fromb(a >= b),
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ast::BiGt => fromb(a > b)
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}
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}
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(Ok(const_uint(a)), Ok(const_uint(b))) => {
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match op.node {
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ast::BiAdd => Ok(const_uint(a + b)),
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ast::BiSub => Ok(const_uint(a - b)),
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ast::BiMul => Ok(const_uint(a * b)),
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ast::BiDiv if b == 0 => {
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Err("attempted to divide by zero".to_string())
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}
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ast::BiDiv => Ok(const_uint(a / b)),
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ast::BiRem if b == 0 => {
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Err("attempted remainder with a divisor of \
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zero".to_string())
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}
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ast::BiRem => Ok(const_uint(a % b)),
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ast::BiAnd | ast::BiBitAnd => Ok(const_uint(a & b)),
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ast::BiOr | ast::BiBitOr => Ok(const_uint(a | b)),
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ast::BiBitXor => Ok(const_uint(a ^ b)),
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ast::BiShl => Ok(const_uint(a << b as uint)),
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ast::BiShr => Ok(const_uint(a >> b as uint)),
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ast::BiEq => fromb(a == b),
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ast::BiLt => fromb(a < b),
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ast::BiLe => fromb(a <= b),
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ast::BiNe => fromb(a != b),
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ast::BiGe => fromb(a >= b),
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ast::BiGt => fromb(a > b),
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}
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}
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// shifts can have any integral type as their rhs
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(Ok(const_int(a)), Ok(const_uint(b))) => {
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match op.node {
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ast::BiShl => Ok(const_int(a << b as uint)),
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ast::BiShr => Ok(const_int(a >> b as uint)),
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_ => Err("can't do this op on an int and uint".to_string())
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}
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}
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(Ok(const_uint(a)), Ok(const_int(b))) => {
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match op.node {
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ast::BiShl => Ok(const_uint(a << b as uint)),
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ast::BiShr => Ok(const_uint(a >> b as uint)),
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_ => Err("can't do this op on a uint and int".to_string())
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}
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}
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(Ok(const_bool(a)), Ok(const_bool(b))) => {
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Ok(const_bool(match op.node {
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ast::BiAnd => a && b,
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ast::BiOr => a || b,
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ast::BiBitXor => a ^ b,
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ast::BiBitAnd => a & b,
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ast::BiBitOr => a | b,
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ast::BiEq => a == b,
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ast::BiNe => a != b,
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_ => return Err("can't do this op on bools".to_string())
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}))
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}
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_ => Err("bad operands for binary".to_string())
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}
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}
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ast::ExprCast(ref base, ref target_ty) => {
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// This tends to get called w/o the type actually having been
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// populated in the ctxt, which was causing things to blow up
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// (#5900). Fall back to doing a limited lookup to get past it.
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let ety = ety.or_else(|| ast_ty_to_prim_ty(tcx, &**target_ty))
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.unwrap_or_else(|| {
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tcx.sess.span_fatal(target_ty.span,
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"target type not found for const cast")
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});
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// Prefer known type to noop, but always have a type hint.
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let base_hint = ty::expr_ty_opt(tcx, &**base).unwrap_or(ety);
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let val = try!(eval_const_expr_partial(tcx, &**base, Some(base_hint)));
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cast_const(val, ety)
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}
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ast::ExprPath(..) => {
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let opt_def = tcx.def_map.borrow().get(&e.id).map(|d| d.full_def());
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let (const_expr, const_ty) = match opt_def {
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Some(def::DefConst(def_id)) => {
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if ast_util::is_local(def_id) {
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match tcx.map.find(def_id.node) {
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Some(ast_map::NodeItem(it)) => match it.node {
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ast::ItemConst(ref ty, ref expr) => {
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(Some(&**expr), Some(&**ty))
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}
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_ => (None, None)
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},
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_ => (None, None)
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}
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} else {
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(lookup_const_by_id(tcx, def_id), None)
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}
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}
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Some(def::DefVariant(enum_def, variant_def, _)) => {
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(lookup_variant_by_id(tcx, enum_def, variant_def), None)
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}
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_ => (None, None)
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};
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let const_expr = match const_expr {
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Some(actual_e) => actual_e,
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None => return Err("non-constant path in constant expr".to_string())
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};
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let ety = ety.or_else(|| const_ty.and_then(|ty| ast_ty_to_prim_ty(tcx, ty)));
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eval_const_expr_partial(tcx, const_expr, ety)
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}
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ast::ExprLit(ref lit) => {
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Ok(lit_to_const(&**lit, ety))
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}
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ast::ExprParen(ref e) => eval_const_expr_partial(tcx, &**e, ety),
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ast::ExprBlock(ref block) => {
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match block.expr {
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Some(ref expr) => eval_const_expr_partial(tcx, &**expr, ety),
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None => Ok(const_int(0i64))
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}
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}
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ast::ExprTupField(ref base, index) => {
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// Get the base tuple if it is constant
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if let Some(&ast::ExprTup(ref fields)) = lookup_const(tcx, &**base).map(|s| &s.node) {
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// Check that the given index is within bounds and evaluate its value
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if fields.len() > index.node {
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return eval_const_expr_partial(tcx, &*fields[index.node], None)
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} else {
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return Err("tuple index out of bounds".to_string())
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}
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}
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Err("non-constant struct in constant expr".to_string())
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}
|
|
ast::ExprField(ref base, field_name) => {
|
|
// Get the base expression if it is a struct and it is constant
|
|
if let Some(&ast::ExprStruct(_, ref fields, _)) = lookup_const(tcx, &**base)
|
|
.map(|s| &s.node) {
|
|
// Check that the given field exists and evaluate it
|
|
if let Some(f) = fields.iter().find(|f|
|
|
f.ident.node.as_str() == field_name.node.as_str()) {
|
|
return eval_const_expr_partial(tcx, &*f.expr, None)
|
|
} else {
|
|
return Err("nonexistent struct field".to_string())
|
|
}
|
|
}
|
|
|
|
Err("non-constant struct in constant expr".to_string())
|
|
}
|
|
_ => Err("unsupported constant expr".to_string())
|
|
}
|
|
}
|
|
|
|
fn cast_const(val: const_val, ty: Ty) -> Result<const_val, String> {
|
|
macro_rules! define_casts {
|
|
($($ty_pat:pat => (
|
|
$intermediate_ty:ty,
|
|
$const_type:ident,
|
|
$target_ty:ty
|
|
)),*) => (match ty.sty {
|
|
$($ty_pat => {
|
|
match val {
|
|
const_bool(b) => Ok($const_type(b as $intermediate_ty as $target_ty)),
|
|
const_uint(u) => Ok($const_type(u as $intermediate_ty as $target_ty)),
|
|
const_int(i) => Ok($const_type(i as $intermediate_ty as $target_ty)),
|
|
const_float(f) => Ok($const_type(f as $intermediate_ty as $target_ty)),
|
|
_ => Err(concat!("can't cast this type to ",
|
|
stringify!($const_type)).to_string())
|
|
}
|
|
},)*
|
|
_ => Err("can't cast this type".to_string())
|
|
})
|
|
}
|
|
|
|
define_casts!{
|
|
ty::ty_int(ast::TyIs(_)) => (int, const_int, i64),
|
|
ty::ty_int(ast::TyI8) => (i8, const_int, i64),
|
|
ty::ty_int(ast::TyI16) => (i16, const_int, i64),
|
|
ty::ty_int(ast::TyI32) => (i32, const_int, i64),
|
|
ty::ty_int(ast::TyI64) => (i64, const_int, i64),
|
|
ty::ty_uint(ast::TyUs(_)) => (uint, const_uint, u64),
|
|
ty::ty_uint(ast::TyU8) => (u8, const_uint, u64),
|
|
ty::ty_uint(ast::TyU16) => (u16, const_uint, u64),
|
|
ty::ty_uint(ast::TyU32) => (u32, const_uint, u64),
|
|
ty::ty_uint(ast::TyU64) => (u64, const_uint, u64),
|
|
ty::ty_float(ast::TyF32) => (f32, const_float, f64),
|
|
ty::ty_float(ast::TyF64) => (f64, const_float, f64)
|
|
}
|
|
}
|
|
|
|
fn lit_to_const(lit: &ast::Lit, ty_hint: Option<Ty>) -> const_val {
|
|
match lit.node {
|
|
ast::LitStr(ref s, _) => const_str((*s).clone()),
|
|
ast::LitBinary(ref data) => {
|
|
const_binary(data.clone())
|
|
}
|
|
ast::LitByte(n) => const_uint(n as u64),
|
|
ast::LitChar(n) => const_uint(n as u64),
|
|
ast::LitInt(n, ast::SignedIntLit(_, ast::Plus)) => const_int(n as i64),
|
|
ast::LitInt(n, ast::UnsuffixedIntLit(ast::Plus)) => {
|
|
match ty_hint.map(|ty| &ty.sty) {
|
|
Some(&ty::ty_uint(_)) => const_uint(n),
|
|
_ => const_int(n as i64)
|
|
}
|
|
}
|
|
ast::LitInt(n, ast::SignedIntLit(_, ast::Minus)) |
|
|
ast::LitInt(n, ast::UnsuffixedIntLit(ast::Minus)) => const_int(-(n as i64)),
|
|
ast::LitInt(n, ast::UnsignedIntLit(_)) => const_uint(n),
|
|
ast::LitFloat(ref n, _) |
|
|
ast::LitFloatUnsuffixed(ref n) => {
|
|
const_float(n.parse::<f64>().unwrap() as f64)
|
|
}
|
|
ast::LitBool(b) => const_bool(b)
|
|
}
|
|
}
|
|
|
|
pub fn compare_const_vals(a: &const_val, b: &const_val) -> Option<Ordering> {
|
|
Some(match (a, b) {
|
|
(&const_int(a), &const_int(b)) => a.cmp(&b),
|
|
(&const_uint(a), &const_uint(b)) => a.cmp(&b),
|
|
(&const_float(a), &const_float(b)) => {
|
|
// This is pretty bad but it is the existing behavior.
|
|
if a == b {
|
|
Ordering::Equal
|
|
} else if a < b {
|
|
Ordering::Less
|
|
} else {
|
|
Ordering::Greater
|
|
}
|
|
}
|
|
(&const_str(ref a), &const_str(ref b)) => a.cmp(b),
|
|
(&const_bool(a), &const_bool(b)) => a.cmp(&b),
|
|
(&const_binary(ref a), &const_binary(ref b)) => a.cmp(b),
|
|
_ => return None
|
|
})
|
|
}
|
|
|
|
pub fn compare_lit_exprs<'tcx>(tcx: &ty::ctxt<'tcx>,
|
|
a: &Expr,
|
|
b: &Expr,
|
|
ty_hint: Option<Ty<'tcx>>)
|
|
-> Option<Ordering> {
|
|
let a = match eval_const_expr_partial(tcx, a, ty_hint) {
|
|
Ok(a) => a,
|
|
Err(s) => {
|
|
tcx.sess.span_err(a.span, &s[..]);
|
|
return None;
|
|
}
|
|
};
|
|
let b = match eval_const_expr_partial(tcx, b, ty_hint) {
|
|
Ok(b) => b,
|
|
Err(s) => {
|
|
tcx.sess.span_err(b.span, &s[..]);
|
|
return None;
|
|
}
|
|
};
|
|
compare_const_vals(&a, &b)
|
|
}
|