[mypyc] Add librt.strings.isidentifier codepoint primitive

mypy/typeshed/stubs/librt/librt/strings.pyi

@@ -47,3 +47,4 @@ def isspace(c: i32, /) -> bool: ...
 def isdigit(c: i32, /) -> bool: ...
 def isalnum(c: i32, /) -> bool: ...
 def isalpha(c: i32, /) -> bool: ...
+def isidentifier(c: i32, /) -> bool: ...

mypyc/ir/deps.py

@@ -116,5 +116,4 @@ def get_header(self) -> str:
 STRING_WRITER_EXTRA_OPS: Final = SourceDep("stringwriter_extra_ops.c")
 BYTEARRAY_EXTRA_OPS: Final = SourceDep("bytearray_extra_ops.c")
 STR_EXTRA_OPS: Final = SourceDep("str_extra_ops.c")
-CODEPOINT_EXTRA_OPS: Final = SourceDep("codepoint_extra_ops.c")
 VECS_EXTRA_OPS: Final = SourceDep("vecs_extra_ops.c")

mypyc/lib-rt/strings/librt_strings.c

@@ -4,7 +4,6 @@
 #include <Python.h>
 #include <stdint.h>
 #include "CPy.h"
-#include "codepoint_extra_ops.h"
 #include "librt_strings.h"
 
 #define CPY_BOOL_ERROR 2
@@ -1154,15 +1153,11 @@ read_f64_be(PyObject *module, PyObject *const *args, size_t nargs) {
     return PyFloat_FromDouble(CPyBytes_ReadF64BEUnsafe(data + index));
 }
 
-// Codepoint classification helpers exposed to interpreted callers.
-// The C-side names are prefixed `cp_` to avoid colliding with libc's
-// <ctype.h> isspace / isdigit / etc. Compiled callers go through the
-// LibRTStrings_* static inlines in codepoint_extra_ops.h instead.
-//
-// All wrappers parse a single int argument as i32 (codepoint) and
-// dispatch to the corresponding LibRTStrings_* function. The parse
-// step accepts any int but rejects values outside the i32 range with
-// OverflowError, matching the input domain of the compiled fast path.
+// Python-level wrappers (`cp_*`) for interpreted callers. The C-side names
+// are prefixed `cp_` to avoid colliding with libc's <ctype.h> isspace etc.
+// The LibRTStrings_Is* helpers themselves are static inline in librt_strings.h
+// so they compile directly into mypyc-emitted code with no capsule
+// indirection.
 
 // Parse a Python int as i32 codepoint. Returns 0 on success and writes
 // the value to *out; returns -1 on error with a Python exception set.
@@ -1194,6 +1189,7 @@ DEFINE_CP_BOOL_WRAPPER(isspace, LibRTStrings_IsSpace)
 DEFINE_CP_BOOL_WRAPPER(isdigit, LibRTStrings_IsDigit)
 DEFINE_CP_BOOL_WRAPPER(isalnum, LibRTStrings_IsAlnum)
 DEFINE_CP_BOOL_WRAPPER(isalpha, LibRTStrings_IsAlpha)
+DEFINE_CP_BOOL_WRAPPER(isidentifier, LibRTStrings_IsIdentifier)
 
 static PyMethodDef librt_strings_module_methods[] = {
     {"write_i16_le", (PyCFunction) write_i16_le, METH_FASTCALL,
@@ -1268,6 +1264,9 @@ static PyMethodDef librt_strings_module_methods[] = {
     {"isalpha", cp_isalpha, METH_O,
      PyDoc_STR("Test whether a codepoint (i32) is a Unicode letter.")
     },
+    {"isidentifier", cp_isidentifier, METH_O,
+     PyDoc_STR("Test whether a codepoint (i32) is a valid identifier start (XID_Start).")
+    },
     {NULL, NULL, 0, NULL}
 };
 

mypyc/lib-rt/strings/librt_strings.h

@@ -3,6 +3,8 @@
 
 #include <Python.h>
 #include <stdbool.h>
+#include <stdint.h>
+#include "CPy.h"
 #include "librt_strings_common.h"
 
 // ABI version -- only an exact match is compatible. This will only be changed in
@@ -28,4 +30,47 @@ typedef struct {
     char data[WRITER_EMBEDDED_BUF_LEN];  // Default buffer
 } StringWriterObject;
 
+// Codepoint classification helpers. Inputs are signed i32 for compatibility
+// with mypyc's int32_rprimitive; negative values are non-codepoints and
+// return false. Defined `static inline` so they compile statically into
+// both the librt.strings module and any mypyc-compiled extension that
+// includes this header, avoiding the capsule indirection that would dwarf
+// the work of a single Py_UNICODE_IS* macro call.
+
+static inline bool LibRTStrings_IsSpace(int32_t c) {
+    return c >= 0 && Py_UNICODE_ISSPACE((Py_UCS4)c);
+}
+
+static inline bool LibRTStrings_IsDigit(int32_t c) {
+    return c >= 0 && Py_UNICODE_ISDIGIT((Py_UCS4)c);
+}
+
+static inline bool LibRTStrings_IsAlnum(int32_t c) {
+    return c >= 0 && Py_UNICODE_ISALNUM((Py_UCS4)c);
+}
+
+static inline bool LibRTStrings_IsAlpha(int32_t c) {
+    return c >= 0 && Py_UNICODE_ISALPHA((Py_UCS4)c);
+}
+
+// True if c could start a valid identifier (XID_Start, per PEP 3131).
+// ASCII fast path covers `[A-Za-z_]`; non-ASCII delegates to CPython's
+// PyUnicode_IsIdentifier on a 1-character string. Aborts via
+// CPyError_OutOfMemory on allocation failure to keep this ERR_NEVER.
+static inline bool LibRTStrings_IsIdentifier(int32_t c) {
+    if (c < 0) return false;
+    if (c < 128) {
+        return (c >= 'a' && c <= 'z')
+            || (c >= 'A' && c <= 'Z')
+            || c == '_';
+    }
+    PyObject *s = PyUnicode_FromOrdinal((int)c);
+    if (s == NULL) {
+        CPyError_OutOfMemory();
+    }
+    int r = PyUnicode_IsIdentifier(s);
+    Py_DECREF(s);
+    return r == 1;
+}
+
 #endif  // LIBRT_STRINGS_H

mypyc/primitives/librt_strings_ops.py

@@ -1,9 +1,4 @@
-from mypyc.ir.deps import (
-    BYTES_WRITER_EXTRA_OPS,
-    CODEPOINT_EXTRA_OPS,
-    LIBRT_STRINGS,
-    STRING_WRITER_EXTRA_OPS,
-)
+from mypyc.ir.deps import BYTES_WRITER_EXTRA_OPS, LIBRT_STRINGS, STRING_WRITER_EXTRA_OPS
 from mypyc.ir.ops import ERR_MAGIC, ERR_MAGIC_OVERLAPPING, ERR_NEVER
 from mypyc.ir.rtypes import (
     bool_rprimitive,
@@ -402,7 +397,7 @@
     return_type=bool_rprimitive,
     c_function_name="LibRTStrings_IsSpace",
     error_kind=ERR_NEVER,
-    dependencies=[LIBRT_STRINGS, CODEPOINT_EXTRA_OPS],
+    dependencies=[LIBRT_STRINGS],
 )
 
 function_op(
@@ -411,7 +406,7 @@
     return_type=bool_rprimitive,
     c_function_name="LibRTStrings_IsDigit",
     error_kind=ERR_NEVER,
-    dependencies=[LIBRT_STRINGS, CODEPOINT_EXTRA_OPS],
+    dependencies=[LIBRT_STRINGS],
 )
 
 function_op(
@@ -420,7 +415,7 @@
     return_type=bool_rprimitive,
     c_function_name="LibRTStrings_IsAlnum",
     error_kind=ERR_NEVER,
-    dependencies=[LIBRT_STRINGS, CODEPOINT_EXTRA_OPS],
+    dependencies=[LIBRT_STRINGS],
 )
 
 function_op(
@@ -429,5 +424,17 @@
     return_type=bool_rprimitive,
     c_function_name="LibRTStrings_IsAlpha",
     error_kind=ERR_NEVER,
-    dependencies=[LIBRT_STRINGS, CODEPOINT_EXTRA_OPS],
+    dependencies=[LIBRT_STRINGS],
+)
+
+# isidentifier checks XID_Start semantics for a single codepoint, matching
+# str.isidentifier() on a 1-character string. The non-ASCII path allocates
+# and aborts via CPyError_OutOfMemory on failure, so this stays ERR_NEVER.
+function_op(
+    name="librt.strings.isidentifier",
+    arg_types=[int32_rprimitive],
+    return_type=bool_rprimitive,
+    c_function_name="LibRTStrings_IsIdentifier",
+    error_kind=ERR_NEVER,
+    dependencies=[LIBRT_STRINGS],
 )

mypyc/test-data/irbuild-librt-strings.test

@@ -387,3 +387,17 @@ def is_a(c):
 L0:
     r0 = LibRTStrings_IsAlpha(c)
     return r0
+
+[case testLibrtStringsIsIdentifierIR]
+from librt.strings import isidentifier
+from mypy_extensions import i32
+
+def is_id(c: i32) -> bool:
+    return isidentifier(c)
+[out]
+def is_id(c):
+    c :: i32
+    r0 :: bool
+L0:
+    r0 = LibRTStrings_IsIdentifier(c)
+    return r0

mypyc/test-data/run-librt-strings.test

@@ -1443,7 +1443,7 @@ def test_new_without_init_is_usable() -> None:
 [case testLibrtStringsCodepointClassifiers_librt]
 from typing import Any
 from mypy_extensions import i32
-from librt.strings import isspace, isdigit, isalnum, isalpha
+from librt.strings import isspace, isdigit, isalnum, isalpha, isidentifier
 
 from testutil import assertRaises
 
@@ -1455,6 +1455,7 @@ def test_codepoint_classifiers() -> None:
         assert not isdigit(bad)
         assert not isalnum(bad)
         assert not isalpha(bad)
+        assert not isidentifier(bad)
     # Verify each codepoint primitive agrees with the matching str method
     # across all Unicode codepoints, including the ord(chr(i)) round-trip.
     # Any forces generic dispatch on the str side.
@@ -1466,6 +1467,7 @@ def test_codepoint_classifiers() -> None:
         assert isdigit(o) == isdigit(i) == a.isdigit()
         assert isalnum(o) == isalnum(i) == a.isalnum()
         assert isalpha(o) == isalpha(i) == a.isalpha()
+        assert isidentifier(o) == isidentifier(i) == a.isidentifier()
 
 
 def test_codepoint_classifiers_via_any() -> None:
@@ -1476,6 +1478,7 @@ def test_codepoint_classifiers_via_any() -> None:
         (isdigit, "5", "a"),
         (isalnum, "A", " "),
         (isalpha, "A", " "),
+        (isidentifier, "A", "0"),
     ):
         f: Any = fn
         assert f(ord(true_input)) is True