intermediate changes

ref:614ed510ddd3cdf86a8c5dbf19afd113397e0172

1 files changed, 221 insertions, 0 deletions

diff --git a/contrib/python/pytest/py3/_pytest/mark/expression.py b/contrib/python/pytest/py3/_pytest/mark/expression.py
new file mode 100644
index 00000000000..dc3991b10c4
--- /dev/null
+++ b/contrib/python/pytest/py3/_pytest/mark/expression.py
@@ -0,0 +1,221 @@
+r"""Evaluate match expressions, as used by `-k` and `-m`.
+
+The grammar is:
+
+expression: expr? EOF
+expr:       and_expr ('or' and_expr)*
+and_expr:   not_expr ('and' not_expr)*
+not_expr:   'not' not_expr | '(' expr ')' | ident
+ident:      (\w|:|\+|-|\.|\[|\])+
+
+The semantics are:
+
+- Empty expression evaluates to False.
+- ident evaluates to True of False according to a provided matcher function.
+- or/and/not evaluate according to the usual boolean semantics.
+"""
+import ast
+import enum
+import re
+import types
+from typing import Callable
+from typing import Iterator
+from typing import Mapping
+from typing import Optional
+from typing import Sequence
+from typing import TYPE_CHECKING
+
+import attr
+
+if TYPE_CHECKING:
+    from typing import NoReturn
+
+
+__all__ = [
+    "Expression",
+    "ParseError",
+]
+
+
+class TokenType(enum.Enum):
+    LPAREN = "left parenthesis"
+    RPAREN = "right parenthesis"
+    OR = "or"
+    AND = "and"
+    NOT = "not"
+    IDENT = "identifier"
+    EOF = "end of input"
+
+
[email protected](frozen=True, slots=True)
+class Token:
+    type = attr.ib(type=TokenType)
+    value = attr.ib(type=str)
+    pos = attr.ib(type=int)
+
+
+class ParseError(Exception):
+    """The expression contains invalid syntax.
+
+    :param column: The column in the line where the error occurred (1-based).
+    :param message: A description of the error.
+    """
+
+    def __init__(self, column: int, message: str) -> None:
+        self.column = column
+        self.message = message
+
+    def __str__(self) -> str:
+        return f"at column {self.column}: {self.message}"
+
+
+class Scanner:
+    __slots__ = ("tokens", "current")
+
+    def __init__(self, input: str) -> None:
+        self.tokens = self.lex(input)
+        self.current = next(self.tokens)
+
+    def lex(self, input: str) -> Iterator[Token]:
+        pos = 0
+        while pos < len(input):
+            if input[pos] in (" ", "\t"):
+                pos += 1
+            elif input[pos] == "(":
+                yield Token(TokenType.LPAREN, "(", pos)
+                pos += 1
+            elif input[pos] == ")":
+                yield Token(TokenType.RPAREN, ")", pos)
+                pos += 1
+            else:
+                match = re.match(r"(:?\w|:|\+|-|\.|\[|\])+", input[pos:])
+                if match:
+                    value = match.group(0)
+                    if value == "or":
+                        yield Token(TokenType.OR, value, pos)
+                    elif value == "and":
+                        yield Token(TokenType.AND, value, pos)
+                    elif value == "not":
+                        yield Token(TokenType.NOT, value, pos)
+                    else:
+                        yield Token(TokenType.IDENT, value, pos)
+                    pos += len(value)
+                else:
+                    raise ParseError(
+                        pos + 1, 'unexpected character "{}"'.format(input[pos]),
+                    )
+        yield Token(TokenType.EOF, "", pos)
+
+    def accept(self, type: TokenType, *, reject: bool = False) -> Optional[Token]:
+        if self.current.type is type:
+            token = self.current
+            if token.type is not TokenType.EOF:
+                self.current = next(self.tokens)
+            return token
+        if reject:
+            self.reject((type,))
+        return None
+
+    def reject(self, expected: Sequence[TokenType]) -> "NoReturn":
+        raise ParseError(
+            self.current.pos + 1,
+            "expected {}; got {}".format(
+                " OR ".join(type.value for type in expected), self.current.type.value,
+            ),
+        )
+
+
+# True, False and None are legal match expression identifiers,
+# but illegal as Python identifiers. To fix this, this prefix
+# is added to identifiers in the conversion to Python AST.
+IDENT_PREFIX = "$"
+
+
+def expression(s: Scanner) -> ast.Expression:
+    if s.accept(TokenType.EOF):
+        ret: ast.expr = ast.NameConstant(False)
+    else:
+        ret = expr(s)
+        s.accept(TokenType.EOF, reject=True)
+    return ast.fix_missing_locations(ast.Expression(ret))
+
+
+def expr(s: Scanner) -> ast.expr:
+    ret = and_expr(s)
+    while s.accept(TokenType.OR):
+        rhs = and_expr(s)
+        ret = ast.BoolOp(ast.Or(), [ret, rhs])
+    return ret
+
+
+def and_expr(s: Scanner) -> ast.expr:
+    ret = not_expr(s)
+    while s.accept(TokenType.AND):
+        rhs = not_expr(s)
+        ret = ast.BoolOp(ast.And(), [ret, rhs])
+    return ret
+
+
+def not_expr(s: Scanner) -> ast.expr:
+    if s.accept(TokenType.NOT):
+        return ast.UnaryOp(ast.Not(), not_expr(s))
+    if s.accept(TokenType.LPAREN):
+        ret = expr(s)
+        s.accept(TokenType.RPAREN, reject=True)
+        return ret
+    ident = s.accept(TokenType.IDENT)
+    if ident:
+        return ast.Name(IDENT_PREFIX + ident.value, ast.Load())
+    s.reject((TokenType.NOT, TokenType.LPAREN, TokenType.IDENT))
+
+
+class MatcherAdapter(Mapping[str, bool]):
+    """Adapts a matcher function to a locals mapping as required by eval()."""
+
+    def __init__(self, matcher: Callable[[str], bool]) -> None:
+        self.matcher = matcher
+
+    def __getitem__(self, key: str) -> bool:
+        return self.matcher(key[len(IDENT_PREFIX) :])
+
+    def __iter__(self) -> Iterator[str]:
+        raise NotImplementedError()
+
+    def __len__(self) -> int:
+        raise NotImplementedError()
+
+
+class Expression:
+    """A compiled match expression as used by -k and -m.
+
+    The expression can be evaulated against different matchers.
+    """
+
+    __slots__ = ("code",)
+
+    def __init__(self, code: types.CodeType) -> None:
+        self.code = code
+
+    @classmethod
+    def compile(self, input: str) -> "Expression":
+        """Compile a match expression.
+
+        :param input: The input expression - one line.
+        """
+        astexpr = expression(Scanner(input))
+        code: types.CodeType = compile(
+            astexpr, filename="<pytest match expression>", mode="eval",
+        )
+        return Expression(code)
+
+    def evaluate(self, matcher: Callable[[str], bool]) -> bool:
+        """Evaluate the match expression.
+
+        :param matcher:
+            Given an identifier, should return whether it matches or not.
+            Should be prepared to handle arbitrary strings as input.
+
+        :returns: Whether the expression matches or not.
+        """
+        ret: bool = eval(self.code, {"__builtins__": {}}, MatcherAdapter(matcher))
+        return ret