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bpo-43892: Make match patterns explicit in the AST (GH-25585)

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Co-authored-by: Brandt Bucher <brandtbucher@gmail.com>
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Nick Coghlan 2021-04-29 15:58:44 +10:00 • committed by GitHub
parent e52ab42ced
commit 1e7b858575
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20 changed files with 3460 additions and 1377 deletions
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124
Python/ast_opt.c
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@ -411,7 +411,7 @@ static int astfold_arg(arg_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_withitem(withitem_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_excepthandler(excepthandler_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_match_case(match_case_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_pattern(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
static int astfold_pattern(pattern_ty node_, PyArena *ctx_, _PyASTOptimizeState *state);
#define CALL(FUNC, TYPE, ARG) \
if (!FUNC((ARG), ctx_, state)) \
@ -602,10 +602,6 @@ astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
case Constant_kind:
// Already a constant, nothing further to do
break;
case MatchAs_kind:
case MatchOr_kind:
// These can't occur outside of patterns.
Py_UNREACHABLE();
// No default case, so the compiler will emit a warning if new expression
// kinds are added without being handled here
}
@ -797,112 +793,48 @@ astfold_withitem(withitem_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
}
static int
astfold_pattern_negative(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
astfold_pattern(pattern_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
assert(node_->kind == UnaryOp_kind);
assert(node_->v.UnaryOp.op == USub);
assert(node_->v.UnaryOp.operand->kind == Constant_kind);
PyObject *value = node_->v.UnaryOp.operand->v.Constant.value;
assert(PyComplex_CheckExact(value) ||
PyFloat_CheckExact(value) ||
PyLong_CheckExact(value));
PyObject *negated = PyNumber_Negative(value);
if (negated == NULL) {
// Currently, this is really only used to form complex/negative numeric
// constants in MatchValue and MatchMapping nodes
// We still recurse into all subexpressions and subpatterns anyway
if (++state->recursion_depth > state->recursion_limit) {
PyErr_SetString(PyExc_RecursionError,
"maximum recursion depth exceeded during compilation");
return 0;
}
assert(PyComplex_CheckExact(negated) ||
PyFloat_CheckExact(negated) ||
PyLong_CheckExact(negated));
return make_const(node_, negated, ctx_);
}
static int
astfold_pattern_complex(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
expr_ty left = node_->v.BinOp.left;
expr_ty right = node_->v.BinOp.right;
if (left->kind == UnaryOp_kind) {
CALL(astfold_pattern_negative, expr_ty, left);
}
assert(left->kind = Constant_kind);
assert(right->kind = Constant_kind);
// LHS must be real, RHS must be imaginary:
if (!(PyFloat_CheckExact(left->v.Constant.value) ||
PyLong_CheckExact(left->v.Constant.value)) ||
!PyComplex_CheckExact(right->v.Constant.value))
{
// Not actually valid, but it's the compiler's job to complain:
return 1;
}
PyObject *new;
if (node_->v.BinOp.op == Add) {
new = PyNumber_Add(left->v.Constant.value, right->v.Constant.value);
}
else {
assert(node_->v.BinOp.op == Sub);
new = PyNumber_Subtract(left->v.Constant.value, right->v.Constant.value);
}
if (new == NULL) {
return 0;
}
assert(PyComplex_CheckExact(new));
return make_const(node_, new, ctx_);
}
static int
astfold_pattern_keyword(keyword_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
CALL(astfold_pattern, expr_ty, node_->value);
return 1;
}
static int
astfold_pattern(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
// Don't blindly optimize the pattern as an expr; it plays by its own rules!
// Currently, this is only used to form complex/negative numeric constants.
switch (node_->kind) {
case Attribute_kind:
case MatchValue_kind:
CALL(astfold_expr, expr_ty, node_->v.MatchValue.value);
break;
case BinOp_kind:
CALL(astfold_pattern_complex, expr_ty, node_);
case MatchSingleton_kind:
break;
case Call_kind:
CALL_SEQ(astfold_pattern, expr, node_->v.Call.args);
CALL_SEQ(astfold_pattern_keyword, keyword, node_->v.Call.keywords);
case MatchSequence_kind:
CALL_SEQ(astfold_pattern, pattern, node_->v.MatchSequence.patterns);
break;
case Constant_kind:
case MatchMapping_kind:
CALL_SEQ(astfold_expr, expr, node_->v.MatchMapping.keys);
CALL_SEQ(astfold_pattern, pattern, node_->v.MatchMapping.patterns);
break;
case Dict_kind:
CALL_SEQ(astfold_pattern, expr, node_->v.Dict.keys);
CALL_SEQ(astfold_pattern, expr, node_->v.Dict.values);
case MatchClass_kind:
CALL(astfold_expr, expr_ty, node_->v.MatchClass.cls);
CALL_SEQ(astfold_pattern, pattern, node_->v.MatchClass.patterns);
CALL_SEQ(astfold_pattern, pattern, node_->v.MatchClass.kwd_patterns);
break;
// Not actually valid, but it's the compiler's job to complain:
case JoinedStr_kind:
break;
case List_kind:
CALL_SEQ(astfold_pattern, expr, node_->v.List.elts);
case MatchStar_kind:
break;
case MatchAs_kind:
CALL(astfold_pattern, expr_ty, node_->v.MatchAs.pattern);
if (node_->v.MatchAs.pattern) {
CALL(astfold_pattern, expr_ty, node_->v.MatchAs.pattern);
}
break;
case MatchOr_kind:
CALL_SEQ(astfold_pattern, expr, node_->v.MatchOr.patterns);
CALL_SEQ(astfold_pattern, pattern, node_->v.MatchOr.patterns);
break;
case Name_kind:
break;
case Starred_kind:
CALL(astfold_pattern, expr_ty, node_->v.Starred.value);
break;
case Tuple_kind:
CALL_SEQ(astfold_pattern, expr, node_->v.Tuple.elts);
break;
case UnaryOp_kind:
CALL(astfold_pattern_negative, expr_ty, node_);
break;
default:
Py_UNREACHABLE();
// No default case, so the compiler will emit a warning if new pattern
// kinds are added without being handled here
}
state->recursion_depth--;
return 1;
}