Teach typechecker about record types.
This commit is contained in:
Graydon Hoare
parent
6c5a05b819
commit
a94046f5d2
1 changed files with 109 additions and 1 deletions
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@ -26,6 +26,7 @@ type fn_ctxt = rec(@ty ret_ty,
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@crate_ctxt ccx);
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type arg = rec(ast.mode mode, @ty ty);
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type field = rec(ast.ident label, @ty ty);
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// NB: If you change this, you'll probably want to change the corresponding
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// AST structure in front/ast.rs as well.
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@ -41,6 +42,7 @@ tag sty {
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ty_box(@ty);
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ty_vec(@ty);
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ty_tup(vec[@ty]);
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ty_rec(vec[field]);
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ty_fn(vec[arg], @ty); // TODO: effect
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ty_var(int); // ephemeral type var
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ty_local(ast.def_id); // type of a local var
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@ -52,6 +54,9 @@ tag type_err {
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terr_mismatch;
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terr_tuple_size(uint, uint);
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terr_tuple_mutability;
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terr_record_size(uint, uint);
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terr_record_mutability;
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terr_record_fields(ast.ident,ast.ident);
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terr_arg_count;
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}
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@ -78,6 +83,10 @@ fn ast_ty_to_str(&@ast.ty ty) -> str {
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ret s + ast_ty_to_str(input.ty);
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}
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fn ast_field_to_str(&tup(ast.ident, @ast.ty) f) -> str {
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ret ast_ty_to_str(f._1) + " " + f._0;
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}
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auto s;
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alt (ty.node) {
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case (ast.ty_nil) { s = "()"; }
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@ -97,6 +106,14 @@ fn ast_ty_to_str(&@ast.ty ty) -> str {
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s += ")";
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}
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case (ast.ty_rec(?elems)) {
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auto f = ast_field_to_str;
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s = "rec(";
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s += _str.connect(_vec.map[tup(ast.ident, @ast.ty),str]
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(f, elems), ",");
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s += ")";
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}
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case (ast.ty_fn(?inputs, ?output)) {
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auto f = ast_fn_input_to_str;
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s = "fn(";
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@ -154,6 +171,10 @@ fn ty_to_str(&@ty typ) -> str {
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ret s + ty_to_str(input.ty);
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}
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fn field_to_str(&field f) -> str {
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ret ty_to_str(f.ty) + " " + f.label;
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}
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auto s = "";
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if (typ.mut == ast.mut) {
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s += "mutable ";
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@ -176,6 +197,12 @@ fn ty_to_str(&@ty typ) -> str {
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s = "tup(" + _str.connect(strs, ",") + ")";
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}
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case (ty_rec(?elems)) {
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auto f = field_to_str;
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auto strs = _vec.map[field,str](f, elems);
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s = "rec(" + _str.connect(strs, ",") + ")";
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}
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case (ty_fn(?inputs, ?output)) {
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auto f = fn_input_to_str;
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s = "fn(" + _str.connect(_vec.map[arg,str](f, inputs),
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@ -222,6 +249,14 @@ fn ast_ty_to_ty(ty_getter getter, &@ast.ty ast_ty) -> @ty {
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}
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sty = ty_tup(flds);
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}
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case (ast.ty_rec(?fields)) {
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let vec[field] flds = vec();
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for (tup(ast.ident, @ast.ty) f in fields) {
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append[field](flds, rec(label=f._0,
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ty=ast_ty_to_ty(getter, f._1)));
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}
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sty = ty_rec(flds);
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}
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case (ast.ty_fn(?inputs, ?output)) {
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auto f = bind ast_arg_to_arg(getter, _);
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@ -281,6 +316,19 @@ fn type_err_to_str(&type_err err) -> str {
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case (terr_tuple_mutability) {
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ret "tuple elements differ in mutability";
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}
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case (terr_record_size(?e_sz, ?a_sz)) {
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ret "expected a record with " + _uint.to_str(e_sz, 10u) +
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" fields but found one with " + _uint.to_str(a_sz, 10u) +
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" fields";
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}
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case (terr_record_mutability) {
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ret "record elements differ in mutability";
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}
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case (terr_record_fields(?e_fld, ?a_fld)) {
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ret "expected a record with field '" + e_fld +
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"' but found one with field '" + a_fld +
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"'";
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}
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case (terr_arg_count) {
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ret "incorrect number of function parameters";
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}
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@ -445,8 +493,9 @@ fn type_is_nil(@ty t) -> bool {
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fn type_is_structural(@ty t) -> bool {
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alt (t.struct) {
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// FIXME: cover rec and tag when we support them.
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// FIXME: cover tag when we support it.
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case (ty_tup(_)) { ret true; }
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case (ty_rec(_)) { ret true; }
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}
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ret false;
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}
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@ -726,6 +775,65 @@ fn unify(&fn_ctxt fcx, @ty expected, @ty actual) -> unify_result {
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}
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}
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case (ty_rec(?expected_fields)) {
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alt (actual.struct) {
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case (ty_rec(?actual_fields)) {
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auto expected_len = _vec.len[field](expected_fields);
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auto actual_len = _vec.len[field](actual_fields);
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if (expected_len != actual_len) {
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auto err = terr_record_size(expected_len,
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actual_len);
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ret ures_err(err, expected, actual);
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}
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// TODO: implement an iterator that can iterate over
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// two arrays simultaneously.
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let vec[field] result_fields = vec();
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auto i = 0u;
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while (i < expected_len) {
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auto expected_field = expected_fields.(i);
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auto actual_field = actual_fields.(i);
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if (expected_field.ty.mut != actual_field.ty.mut) {
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auto err = terr_record_mutability;
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ret ures_err(err, expected, actual);
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}
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if (!_str.eq(expected_field.label,
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actual_field.label)) {
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auto err =
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terr_record_fields(expected_field.label,
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actual_field.label);
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ret ures_err(err, expected, actual);
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}
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auto result = unify_step(fcx,
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bindings,
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expected_field.ty,
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actual_field.ty);
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alt (result) {
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case (ures_ok(?rty)) {
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append[field](result_fields,
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rec(ty=rty with expected_field));
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}
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case (_) {
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ret result;
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}
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}
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i += 1u;
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}
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ret ures_ok(plain_ty(ty_rec(result_fields)));
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}
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// TODO: ty_var
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case (_) {
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ret ures_err(terr_mismatch, expected, actual);
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}
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}
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}
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case (ty_fn(?expected_inputs, ?expected_output)) {
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alt (actual.struct) {
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case (ty_fn(?actual_inputs, ?actual_output)) {
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