bpo-42128: Structural Pattern Matching (PEP 634) (GH-22917)
Co-authored-by: Guido van Rossum <guido@python.org>
Co-authored-by: Talin <viridia@gmail.com>
Co-authored-by: Pablo Galindo <pablogsal@gmail.com>
diff --git a/Include/Python-ast.h b/Include/Python-ast.h
index fc9f65c..bd127ca 100644
--- a/Include/Python-ast.h
+++ b/Include/Python-ast.h
@@ -44,6 +44,8 @@ typedef struct _alias *alias_ty;
typedef struct _withitem *withitem_ty;
+typedef struct _match_case *match_case_ty;
+
typedef struct _type_ignore *type_ignore_ty;
@@ -121,6 +123,14 @@ asdl_withitem_seq *_Py_asdl_withitem_seq_new(Py_ssize_t size, PyArena *arena);
typedef struct {
_ASDL_SEQ_HEAD
+ match_case_ty typed_elements[1];
+} asdl_match_case_seq;
+
+asdl_match_case_seq *_Py_asdl_match_case_seq_new(Py_ssize_t size, PyArena
+ *arena);
+
+typedef struct {
+ _ASDL_SEQ_HEAD
type_ignore_ty typed_elements[1];
} asdl_type_ignore_seq;
@@ -158,10 +168,10 @@ enum _stmt_kind {FunctionDef_kind=1, AsyncFunctionDef_kind=2, ClassDef_kind=3,
Return_kind=4, Delete_kind=5, Assign_kind=6,
AugAssign_kind=7, AnnAssign_kind=8, For_kind=9,
AsyncFor_kind=10, While_kind=11, If_kind=12, With_kind=13,
- AsyncWith_kind=14, Raise_kind=15, Try_kind=16,
- Assert_kind=17, Import_kind=18, ImportFrom_kind=19,
- Global_kind=20, Nonlocal_kind=21, Expr_kind=22, Pass_kind=23,
- Break_kind=24, Continue_kind=25};
+ AsyncWith_kind=14, Match_kind=15, Raise_kind=16, Try_kind=17,
+ Assert_kind=18, Import_kind=19, ImportFrom_kind=20,
+ Global_kind=21, Nonlocal_kind=22, Expr_kind=23, Pass_kind=24,
+ Break_kind=25, Continue_kind=26};
struct _stmt {
enum _stmt_kind kind;
union {
@@ -259,6 +269,11 @@ struct _stmt {
} AsyncWith;
struct {
+ expr_ty subject;
+ asdl_match_case_seq *cases;
+ } Match;
+
+ struct {
expr_ty exc;
expr_ty cause;
} Raise;
@@ -311,7 +326,8 @@ enum _expr_kind {BoolOp_kind=1, NamedExpr_kind=2, BinOp_kind=3, UnaryOp_kind=4,
YieldFrom_kind=15, Compare_kind=16, Call_kind=17,
FormattedValue_kind=18, JoinedStr_kind=19, Constant_kind=20,
Attribute_kind=21, Subscript_kind=22, Starred_kind=23,
- Name_kind=24, List_kind=25, Tuple_kind=26, Slice_kind=27};
+ Name_kind=24, List_kind=25, Tuple_kind=26, Slice_kind=27,
+ MatchAs_kind=28, MatchOr_kind=29};
struct _expr {
enum _expr_kind kind;
union {
@@ -454,6 +470,15 @@ struct _expr {
expr_ty step;
} Slice;
+ struct {
+ expr_ty pattern;
+ identifier name;
+ } MatchAs;
+
+ struct {
+ asdl_expr_seq *patterns;
+ } MatchOr;
+
} v;
int lineno;
int col_offset;
@@ -524,6 +549,12 @@ struct _withitem {
expr_ty optional_vars;
};
+struct _match_case {
+ expr_ty pattern;
+ expr_ty guard;
+ asdl_stmt_seq *body;
+};
+
enum _type_ignore_kind {TypeIgnore_kind=1};
struct _type_ignore {
enum _type_ignore_kind kind;
@@ -607,6 +638,10 @@ stmt_ty _Py_With(asdl_withitem_seq * items, asdl_stmt_seq * body, string
stmt_ty _Py_AsyncWith(asdl_withitem_seq * items, asdl_stmt_seq * body, string
type_comment, int lineno, int col_offset, int end_lineno,
int end_col_offset, PyArena *arena);
+#define Match(a0, a1, a2, a3, a4, a5, a6) _Py_Match(a0, a1, a2, a3, a4, a5, a6)
+stmt_ty _Py_Match(expr_ty subject, asdl_match_case_seq * cases, int lineno, int
+ col_offset, int end_lineno, int end_col_offset, PyArena
+ *arena);
#define Raise(a0, a1, a2, a3, a4, a5, a6) _Py_Raise(a0, a1, a2, a3, a4, a5, a6)
stmt_ty _Py_Raise(expr_ty exc, expr_ty cause, int lineno, int col_offset, int
end_lineno, int end_col_offset, PyArena *arena);
@@ -743,6 +778,13 @@ expr_ty _Py_Tuple(asdl_expr_seq * elts, expr_context_ty ctx, int lineno, int
expr_ty _Py_Slice(expr_ty lower, expr_ty upper, expr_ty step, int lineno, int
col_offset, int end_lineno, int end_col_offset, PyArena
*arena);
+#define MatchAs(a0, a1, a2, a3, a4, a5, a6) _Py_MatchAs(a0, a1, a2, a3, a4, a5, a6)
+expr_ty _Py_MatchAs(expr_ty pattern, identifier name, int lineno, int
+ col_offset, int end_lineno, int end_col_offset, PyArena
+ *arena);
+#define MatchOr(a0, a1, a2, a3, a4, a5) _Py_MatchOr(a0, a1, a2, a3, a4, a5)
+expr_ty _Py_MatchOr(asdl_expr_seq * patterns, int lineno, int col_offset, int
+ end_lineno, int end_col_offset, PyArena *arena);
#define comprehension(a0, a1, a2, a3, a4) _Py_comprehension(a0, a1, a2, a3, a4)
comprehension_ty _Py_comprehension(expr_ty target, expr_ty iter, asdl_expr_seq
* ifs, int is_async, PyArena *arena);
@@ -769,6 +811,9 @@ alias_ty _Py_alias(identifier name, identifier asname, PyArena *arena);
#define withitem(a0, a1, a2) _Py_withitem(a0, a1, a2)
withitem_ty _Py_withitem(expr_ty context_expr, expr_ty optional_vars, PyArena
*arena);
+#define match_case(a0, a1, a2, a3) _Py_match_case(a0, a1, a2, a3)
+match_case_ty _Py_match_case(expr_ty pattern, expr_ty guard, asdl_stmt_seq *
+ body, PyArena *arena);
#define TypeIgnore(a0, a1, a2) _Py_TypeIgnore(a0, a1, a2)
type_ignore_ty _Py_TypeIgnore(int lineno, string tag, PyArena *arena);
diff --git a/Include/internal/pycore_ast.h b/Include/internal/pycore_ast.h
index 058fbc0..2d0c5fb 100644
--- a/Include/internal/pycore_ast.h
+++ b/Include/internal/pycore_ast.h
@@ -91,6 +91,9 @@ struct ast_state {
PyObject *Lt_type;
PyObject *MatMult_singleton;
PyObject *MatMult_type;
+ PyObject *MatchAs_type;
+ PyObject *MatchOr_type;
+ PyObject *Match_type;
PyObject *Mod_singleton;
PyObject *Mod_type;
PyObject *Module_type;
@@ -137,6 +140,7 @@ struct ast_state {
PyObject *Yield_type;
PyObject *__dict__;
PyObject *__doc__;
+ PyObject *__match_args__;
PyObject *__module__;
PyObject *_attributes;
PyObject *_fields;
@@ -153,6 +157,7 @@ struct ast_state {
PyObject *bases;
PyObject *body;
PyObject *boolop_type;
+ PyObject *cases;
PyObject *cause;
PyObject *cmpop_type;
PyObject *col_offset;
@@ -175,6 +180,7 @@ struct ast_state {
PyObject *format_spec;
PyObject *func;
PyObject *generators;
+ PyObject *guard;
PyObject *handlers;
PyObject *id;
PyObject *ifs;
@@ -193,6 +199,7 @@ struct ast_state {
PyObject *level;
PyObject *lineno;
PyObject *lower;
+ PyObject *match_case_type;
PyObject *mod_type;
PyObject *module;
PyObject *msg;
@@ -204,6 +211,8 @@ struct ast_state {
PyObject *ops;
PyObject *optional_vars;
PyObject *orelse;
+ PyObject *pattern;
+ PyObject *patterns;
PyObject *posonlyargs;
PyObject *returns;
PyObject *right;
@@ -211,6 +220,7 @@ struct ast_state {
PyObject *slice;
PyObject *step;
PyObject *stmt_type;
+ PyObject *subject;
PyObject *tag;
PyObject *target;
PyObject *targets;
diff --git a/Include/internal/pycore_interp.h b/Include/internal/pycore_interp.h
index 58b1126..477cbf0 100644
--- a/Include/internal/pycore_interp.h
+++ b/Include/internal/pycore_interp.h
@@ -253,6 +253,10 @@ struct _is {
// importlib module
PyObject *importlib;
+ // Kept handy for pattern matching:
+ PyObject *map_abc; // _collections_abc.Mapping
+ PyObject *seq_abc; // _collections_abc.Sequence
+
/* Used in Modules/_threadmodule.c. */
long num_threads;
/* Support for runtime thread stack size tuning.
@@ -347,4 +351,3 @@ PyAPI_FUNC(void) _PyInterpreterState_IDDecref(struct _is *);
}
#endif
#endif /* !Py_INTERNAL_INTERP_H */
-
diff --git a/Include/object.h b/Include/object.h
index 0870e4c..1454583 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -359,6 +359,11 @@ given type object has a specified feature.
#define Py_TPFLAGS_HAVE_AM_SEND (1UL << 21)
#endif
+// This undocumented flag gives certain built-ins their unique pattern-matching
+// behavior, which allows a single positional subpattern to match against the
+// subject itself (rather than a mapped attribute on it):
+#define _Py_TPFLAGS_MATCH_SELF (1UL << 22)
+
/* These flags are used to determine if a type is a subclass. */
#define Py_TPFLAGS_LONG_SUBCLASS (1UL << 24)
#define Py_TPFLAGS_LIST_SUBCLASS (1UL << 25)
diff --git a/Include/opcode.h b/Include/opcode.h
index 998a5ce..ea484c5 100644
--- a/Include/opcode.h
+++ b/Include/opcode.h
@@ -30,6 +30,11 @@ extern "C" {
#define BINARY_TRUE_DIVIDE 27
#define INPLACE_FLOOR_DIVIDE 28
#define INPLACE_TRUE_DIVIDE 29
+#define GET_LEN 30
+#define MATCH_MAPPING 31
+#define MATCH_SEQUENCE 32
+#define MATCH_KEYS 33
+#define COPY_DICT_WITHOUT_KEYS 34
#define WITH_EXCEPT_START 49
#define GET_AITER 50
#define GET_ANEXT 51
@@ -117,6 +122,7 @@ extern "C" {
#define SET_ADD 146
#define MAP_ADD 147
#define LOAD_CLASSDEREF 148
+#define MATCH_CLASS 152
#define SETUP_ASYNC_WITH 154
#define FORMAT_VALUE 155
#define BUILD_CONST_KEY_MAP 156
diff --git a/Include/symtable.h b/Include/symtable.h
index abd19a7..6f0b7cb 100644
--- a/Include/symtable.h
+++ b/Include/symtable.h
@@ -33,6 +33,7 @@ struct symtable {
the symbol table */
int recursion_depth; /* current recursion depth */
int recursion_limit; /* recursion limit */
+ int in_pattern; /* whether we are currently in a pattern */
};
typedef struct _symtable_entry {