[mypyc] Add str.isspace primitive (#20842)

Benchmarked this locally, for 500m `isspace()` calls mypyc was at 7.5
secs vs Python's 10 secs.

Author: VaggelisD

mypyc/lib-rt/CPy.h

@@ -780,7 +780,7 @@ Py_ssize_t CPyStr_Count(PyObject *unicode, PyObject *substring, CPyTagged start)
 Py_ssize_t CPyStr_CountFull(PyObject *unicode, PyObject *substring, CPyTagged start, CPyTagged end);
 CPyTagged CPyStr_Ord(PyObject *obj);
 PyObject *CPyStr_Multiply(PyObject *str, CPyTagged count);
-
+bool CPyStr_IsSpace(PyObject *str);
 
 // Bytes operations
 

mypyc/lib-rt/str_ops.c

@@ -630,3 +630,27 @@ PyObject *CPyStr_Multiply(PyObject *str, CPyTagged count) {
     }
     return PySequence_Repeat(str, temp_count);
 }
+
+
+bool CPyStr_IsSpace(PyObject *str) {
+    Py_ssize_t len = PyUnicode_GET_LENGTH(str);
+    if (len == 0) return false;
+
+    if (PyUnicode_IS_ASCII(str)) {
+        const Py_UCS1 *data = PyUnicode_1BYTE_DATA(str);
+        for (Py_ssize_t i = 0; i < len; i++) {
+            if (!_Py_ascii_whitespace[data[i]])
+                return false;
+        }
+        return true;
+    }
+
+    int kind = PyUnicode_KIND(str);
+    const void *data = PyUnicode_DATA(str);
+    for (Py_ssize_t i = 0; i < len; i++) {
+        Py_UCS4 ch = PyUnicode_READ(kind, data, i);
+        if (!Py_UNICODE_ISSPACE(ch))
+            return false;
+    }
+    return true;
+}

mypyc/primitives/str_ops.py

@@ -397,6 +397,14 @@
     error_kind=ERR_NEG_INT,
 )
 
+method_op(
+    name="isspace",
+    arg_types=[str_rprimitive],
+    return_type=bool_rprimitive,
+    c_function_name="CPyStr_IsSpace",
+    error_kind=ERR_NEVER,
+)
+
 # obj.decode()
 method_op(
     name="decode",

mypyc/test-data/fixtures/ir.py

@@ -131,6 +131,7 @@ def removeprefix(self, prefix: str, /) -> str: ...
     def removesuffix(self, suffix: str, /) -> str: ...
     def islower(self) -> bool: ...
     def count(self, substr: str, start: Optional[int] = None, end: Optional[int] = None) -> int: pass
+    def isspace(self) -> bool: ...
 
 class float:
     def __init__(self, x: object) -> None: pass

mypyc/test-data/irbuild-str.test

@@ -972,3 +972,14 @@ def i_times_s(s, n):
 L0:
     r0 = CPyStr_Multiply(s, n)
     return r0
+
+[case testStrIsSpace]
+def is_space(x: str) -> bool:
+    return x.isspace()
+[out]
+def is_space(x):
+    x :: str
+    r0 :: bool
+L0:
+    r0 = CPyStr_IsSpace(x)
+    return r0

mypyc/test-data/run-strings.test

@@ -1257,3 +1257,15 @@ FMT: Final = "{} {}"
 
 def test_format() -> None:
     assert FMT.format(400 + 20, "roll" + "up") == "420 rollup"
+
+[case testIsSpace]
+from typing import Any
+
+def test_isspace() -> None:
+    # Verify correctness across all Unicode codepoints.
+    # Exercises UCS-1 (0x00-0xFF), UCS-2 (0x100-0xFFFF), and UCS-4 (0x10000-x10FFFF inclusive) string kinds.
+    # Any forces generic dispatch so we compare our primitive against stdlib's
+    for i in range(0x110000):
+        c = chr(i)
+        a: Any = c
+        assert c.isspace() == a.isspace()