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Split record_var_binding into methods for expected and actual

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This allows unify to maintain the same subtype relationship between
expected and actual throughout unify, which we are going to need
for mutable? and for function types.
This commit is contained in:
Brian Anderson 2011-10-17 15:06:19 -07:00
parent 1a64153b24
commit f7a825c614
1 changed files with 26 additions and 4 deletions
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30
src/comp/middle/ty.rs
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@ -1840,13 +1840,35 @@ mod unify {
}
}
}
fn record_var_binding(cx: @ctxt, key: int, typ: t) -> result {
fn record_var_binding_for_expected(
cx: @ctxt, key: int, typ: t) -> result {
record_var_binding(
cx, key, typ,
fn (cx: @ctxt, old_type: t, new_type: t) -> result {
unify_step(cx, old_type, new_type)
})
}
fn record_var_binding_for_actual(
cx: @ctxt, key: int, typ: t) -> result {
record_var_binding(
cx, key, typ,
fn (cx: @ctxt, old_type: t, new_type: t) -> result {
unify_step(cx, new_type, old_type)
})
}
fn record_var_binding(
cx: @ctxt, key: int, typ: t,
unify_types: fn(@ctxt, t, t) -> result) -> result {
ufind::grow(cx.vb.sets, (key as uint) + 1u);
let root = ufind::find(cx.vb.sets, key as uint);
let result_type = typ;
alt smallintmap::find::<t>(cx.vb.types, root) {
some(old_type) {
alt unify_step(cx, old_type, typ) {
alt unify_types(cx, old_type, typ) {
ures_ok(unified_type) { result_type = unified_type; }
rs { ret rs; }
}
@ -2099,7 +2121,7 @@ mod unify {
}
_ {
// Just bind the type variable to the expected type.
alt record_var_binding(cx, actual_id, expected) {
alt record_var_binding_for_actual(cx, actual_id, expected) {
ures_ok(_) {/* fall through */ }
rs { ret rs; }
}
@ -2113,7 +2135,7 @@ mod unify {
ty::ty_var(expected_id) {
// Add a binding. (`actual` can't actually be a var here.)
alt record_var_binding(cx, expected_id, actual) {
alt record_var_binding_for_expected(cx, expected_id, actual) {
ures_ok(_) {/* fall through */ }
rs { ret rs; }
}