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bpo-34822: Simplify AST for subscription. (GH-9605)
* Remove the slice type. * Make Slice a kind of the expr type instead of the slice type. * Replace ExtSlice(slices) with Tuple(slices, Load()). * Replace Index(value) with a value itself. All non-terminal nodes in AST for expressions are now of the expr type.
This commit is contained in:
Serhiy Storchaka
GitHub
parent
e5e56328af
commit
13d52c2686
15 changed files with 300 additions and 709 deletions
88
Python/ast.c
88
Python/ast.c
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@ -39,31 +39,6 @@ validate_comprehension(asdl_seq *gens)
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return 1;
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}
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static int
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validate_slice(slice_ty slice)
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{
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switch (slice->kind) {
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case Slice_kind:
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return (!slice->v.Slice.lower || validate_expr(slice->v.Slice.lower, Load)) &&
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(!slice->v.Slice.upper || validate_expr(slice->v.Slice.upper, Load)) &&
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(!slice->v.Slice.step || validate_expr(slice->v.Slice.step, Load));
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case ExtSlice_kind: {
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Py_ssize_t i;
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if (!validate_nonempty_seq(slice->v.ExtSlice.dims, "dims", "ExtSlice"))
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return 0;
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for (i = 0; i < asdl_seq_LEN(slice->v.ExtSlice.dims); i++)
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if (!validate_slice(asdl_seq_GET(slice->v.ExtSlice.dims, i)))
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return 0;
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return 1;
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}
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case Index_kind:
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return validate_expr(slice->v.Index.value, Load);
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default:
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PyErr_SetString(PyExc_SystemError, "unknown slice node");
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return 0;
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}
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}
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static int
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validate_keywords(asdl_seq *keywords)
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{
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@ -309,10 +284,14 @@ validate_expr(expr_ty exp, expr_context_ty ctx)
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case Attribute_kind:
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return validate_expr(exp->v.Attribute.value, Load);
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case Subscript_kind:
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return validate_slice(exp->v.Subscript.slice) &&
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return validate_expr(exp->v.Subscript.slice, Load) &&
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validate_expr(exp->v.Subscript.value, Load);
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case Starred_kind:
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return validate_expr(exp->v.Starred.value, ctx);
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case Slice_kind:
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return (!exp->v.Slice.lower || validate_expr(exp->v.Slice.lower, Load)) &&
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(!exp->v.Slice.upper || validate_expr(exp->v.Slice.upper, Load)) &&
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(!exp->v.Slice.step || validate_expr(exp->v.Slice.step, Load));
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case List_kind:
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return validate_exprs(exp->v.List.elts, ctx, 0);
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case Tuple_kind:
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@ -2471,7 +2450,7 @@ ast_for_atom(struct compiling *c, const node *n)
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}
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}
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static slice_ty
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static expr_ty
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ast_for_slice(struct compiling *c, const node *n)
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{
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node *ch;
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@ -2485,13 +2464,7 @@ ast_for_slice(struct compiling *c, const node *n)
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*/
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ch = CHILD(n, 0);
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if (NCH(n) == 1 && TYPE(ch) == test) {
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/* 'step' variable hold no significance in terms of being used over
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other vars */
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step = ast_for_expr(c, ch);
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if (!step)
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return NULL;
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return Index(step, c->c_arena);
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return ast_for_expr(c, ch);
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}
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if (TYPE(ch) == test) {
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@ -2533,7 +2506,8 @@ ast_for_slice(struct compiling *c, const node *n)
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}
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}
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return Slice(lower, upper, step, c->c_arena);
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return Slice(lower, upper, step, LINENO(n), n->n_col_offset,
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n->n_end_lineno, n->n_end_col_offset, c->c_arena);
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}
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static expr_ty
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@ -2621,7 +2595,7 @@ ast_for_trailer(struct compiling *c, const node *n, expr_ty left_expr, const nod
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REQ(CHILD(n, 2), RSQB);
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n = CHILD(n, 1);
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if (NCH(n) == 1) {
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slice_ty slc = ast_for_slice(c, CHILD(n, 0));
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expr_ty slc = ast_for_slice(c, CHILD(n, 0));
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if (!slc)
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return NULL;
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return Subscript(left_expr, slc, Load, LINENO(start), start->n_col_offset,
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@ -2629,47 +2603,27 @@ ast_for_trailer(struct compiling *c, const node *n, expr_ty left_expr, const nod
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c->c_arena);
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}
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else {
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/* The grammar is ambiguous here. The ambiguity is resolved
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by treating the sequence as a tuple literal if there are
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no slice features.
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*/
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Py_ssize_t j;
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slice_ty slc;
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expr_ty e;
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int simple = 1;
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asdl_seq *slices, *elts;
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slices = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
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if (!slices)
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int j;
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expr_ty slc, e;
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asdl_seq *elts;
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elts = _Py_asdl_seq_new((NCH(n) + 1) / 2, c->c_arena);
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if (!elts)
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return NULL;
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for (j = 0; j < NCH(n); j += 2) {
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slc = ast_for_slice(c, CHILD(n, j));
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if (!slc)
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return NULL;
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if (slc->kind != Index_kind)
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simple = 0;
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asdl_seq_SET(slices, j / 2, slc);
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}
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if (!simple) {
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return Subscript(left_expr, ExtSlice(slices, c->c_arena),
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Load, LINENO(start), start->n_col_offset,
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n_copy->n_end_lineno, n_copy->n_end_col_offset, c->c_arena);
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}
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/* extract Index values and put them in a Tuple */
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elts = _Py_asdl_seq_new(asdl_seq_LEN(slices), c->c_arena);
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if (!elts)
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return NULL;
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for (j = 0; j < asdl_seq_LEN(slices); ++j) {
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slc = (slice_ty)asdl_seq_GET(slices, j);
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assert(slc->kind == Index_kind && slc->v.Index.value);
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asdl_seq_SET(elts, j, slc->v.Index.value);
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asdl_seq_SET(elts, j / 2, slc);
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}
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e = Tuple(elts, Load, LINENO(n), n->n_col_offset,
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n->n_end_lineno, n->n_end_col_offset, c->c_arena);
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n->n_end_lineno, n->n_end_col_offset,
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c->c_arena);
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if (!e)
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return NULL;
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return Subscript(left_expr, Index(e, c->c_arena),
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return Subscript(left_expr, e,
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Load, LINENO(start), start->n_col_offset,
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n_copy->n_end_lineno, n_copy->n_end_col_offset, c->c_arena);
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n_copy->n_end_lineno, n_copy->n_end_col_offset,
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c->c_arena);
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}
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}
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}
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