interpreter: Introduce BooleanHolder for the bool primitive

8 files changed, 129 insertions, 68 deletions

diff --git a/mesonbuild/ast/interpreter.py b/mesonbuild/ast/interpreter.py
index 7e4bc62..4fd1378 100644
--- a/mesonbuild/ast/interpreter.py
+++ b/mesonbuild/ast/interpreter.py
@@ -366,7 +366,8 @@ class AstInterpreter(InterpreterBase):
                 if isinstance(src, str):
                     result = self.string_method_call(src, node.name, margs, mkwargs)
                 elif isinstance(src, bool):
-                    result = self.bool_method_call(src, node.name, margs, mkwargs)
+                    from ..interpreter import Interpreter, BooleanHolder
+                    result = BooleanHolder(src, T.cast(Interpreter, self)).method_call(node.name, margs, mkwargs)
                 elif isinstance(src, int):
                     from ..interpreter import Interpreter, IntegerHolder
                     result = IntegerHolder(src, T.cast(Interpreter, self)).method_call(node.name, margs, mkwargs)
diff --git a/mesonbuild/interpreter/__init__.py b/mesonbuild/interpreter/__init__.py
index 0a7717f..90d7faf 100644
--- a/mesonbuild/interpreter/__init__.py
+++ b/mesonbuild/interpreter/__init__.py
@@ -35,6 +35,7 @@ __all__ = [
     'ExternalProgramHolder',
     'extract_required_kwarg',
 
+    'BooleanHolder',
     'IntegerHolder',
 ]
 
@@ -47,5 +48,6 @@ from .interpreterobjects import (ExecutableHolder, BuildTargetHolder, CustomTarg
                                  extract_required_kwarg)
 
 from .primitives import (
+    BooleanHolder,
     IntegerHolder,
 )
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index d4d5564..41cb7b8 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -26,7 +26,7 @@ from ..programs import ExternalProgram, NonExistingExternalProgram
 from ..dependencies import Dependency
 from ..depfile import DepFile
 from ..interpreterbase import ContainerTypeInfo, InterpreterBase, KwargInfo, typed_kwargs, typed_pos_args
-from ..interpreterbase import noPosargs, noKwargs, permittedKwargs, noArgsFlattening, noSecondLevelHolderResolving, permissive_unholder_return
+from ..interpreterbase import noPosargs, noKwargs, permittedKwargs, noArgsFlattening, noSecondLevelHolderResolving, unholder_return
 from ..interpreterbase import InterpreterException, InvalidArguments, InvalidCode, SubdirDoneRequest
 from ..interpreterbase import Disabler, disablerIfNotFound
 from ..interpreterbase import FeatureNew, FeatureDeprecated, FeatureNewKwargs, FeatureDeprecatedKwargs
@@ -381,6 +381,7 @@ class Interpreter(InterpreterBase, HoldableObject):
         self.holder_map.update({
             # Primitives
             int: P_OBJ.IntegerHolder,
+            bool: P_OBJ.BooleanHolder,
 
             # Meson types
             mesonlib.File: OBJ.FileHolder,
diff --git a/mesonbuild/interpreter/primitives/__init__.py b/mesonbuild/interpreter/primitives/__init__.py
index 56af72a..5d16744 100644
--- a/mesonbuild/interpreter/primitives/__init__.py
+++ b/mesonbuild/interpreter/primitives/__init__.py
@@ -2,7 +2,9 @@
 # SPDX-license-identifier: Apache-2.0
 
 __all__ = [
+    'BooleanHolder',
     'IntegerHolder',
 ]
 
+from .boolean import BooleanHolder
 from .integer import IntegerHolder
diff --git a/mesonbuild/interpreter/primitives/boolean.py b/mesonbuild/interpreter/primitives/boolean.py
new file mode 100644
index 0000000..0a434af
--- /dev/null
+++ b/mesonbuild/interpreter/primitives/boolean.py
@@ -0,0 +1,53 @@
+# Copyright 2021 The Meson development team
+# SPDX-license-identifier: Apache-2.0
+
+from ...interpreterbase import (
+    ObjectHolder,
+    MesonOperator,
+    typed_pos_args,
+    noKwargs,
+    noPosargs,
+
+    TYPE_var,
+    TYPE_kwargs,
+
+    InvalidArguments
+)
+
+import typing as T
+
+if T.TYPE_CHECKING:
+    # Object holders need the actual interpreter
+    from ...interpreter import Interpreter
+
+class BooleanHolder(ObjectHolder[bool]):
+    def __init__(self, obj: bool, interpreter: 'Interpreter') -> None:
+        super().__init__(obj, interpreter)
+        self.methods.update({
+            'to_int': self.to_int_method,
+            'to_string': self.to_string_method,
+        })
+
+        self.trivial_operators.update({
+            MesonOperator.BOOL: (None, lambda x: self.held_object),
+            MesonOperator.NOT: (None, lambda x: not self.held_object),
+            MesonOperator.EQUALS: (bool, lambda x: self.held_object == x),
+            MesonOperator.NOT_EQUALS: (bool, lambda x: self.held_object != x),
+        })
+
+    def display_name(self) -> str:
+        return 'bool'
+
+    @noKwargs
+    @noPosargs
+    def to_int_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> int:
+        return 1 if self.held_object else 0
+
+    @noKwargs
+    @typed_pos_args('bool.to_string', optargs=[str, str])
+    def to_string_method(self, args: T.Tuple[T.Optional[str], T.Optional[str]], kwargs: TYPE_kwargs) -> str:
+        true_str = args[0] or 'true'
+        false_str = args[1] or 'false'
+        if any(x is not None for x in args) and not all(x is not None for x in args):
+            raise InvalidArguments('bool.to_string() must have either no arguments or exactly two string arguments that signify what values to return for true and false.')
+        return true_str if self.held_object else false_str
diff --git a/mesonbuild/interpreterbase/baseobjects.py b/mesonbuild/interpreterbase/baseobjects.py
index 4b538fb..80cf0b5 100644
--- a/mesonbuild/interpreterbase/baseobjects.py
+++ b/mesonbuild/interpreterbase/baseobjects.py
@@ -129,8 +129,8 @@ class MesonInterpreterObject(InterpreterObject):
 class MutableInterpreterObject:
     ''' Dummy class to mark the object type as mutable '''
 
-HoldableTypes = (HoldableObject, int)
-TYPE_HoldableTypes = T.Union[HoldableObject, int]
+HoldableTypes = (HoldableObject, int, bool)
+TYPE_HoldableTypes = T.Union[HoldableObject, int, bool]
 InterpreterObjectTypeVar = T.TypeVar('InterpreterObjectTypeVar', bound=TYPE_HoldableTypes)
 
 class ObjectHolder(InterpreterObject, T.Generic[InterpreterObjectTypeVar]):
diff --git a/mesonbuild/interpreterbase/decorators.py b/mesonbuild/interpreterbase/decorators.py
index 156b4c9..b9c4a1f 100644
--- a/mesonbuild/interpreterbase/decorators.py
+++ b/mesonbuild/interpreterbase/decorators.py
@@ -77,11 +77,11 @@ def noSecondLevelHolderResolving(f: TV_func) -> TV_func:
     setattr(f, 'no-second-level-holder-flattening', True)  # noqa: B010
     return f
 
-def permissive_unholder_return(f: TV_func) -> T.Callable[..., TYPE_var]:
+def unholder_return(f: TV_func) -> T.Callable[..., TYPE_var]:
     @wraps(f)
     def wrapped(*wrapped_args: T.Any, **wrapped_kwargs: T.Any) -> T.Any:
         res = f(*wrapped_args, **wrapped_kwargs)
-        return _unholder(res, permissive=True)
+        return _unholder(res)
     return T.cast(T.Callable[..., TYPE_var], wrapped)
 
 def disablerIfNotFound(f: TV_func) -> TV_func:
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index cfd72b5..3d419d4 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -51,6 +51,7 @@ from ._unholder import _unholder
 import os, copy, re, pathlib
 import typing as T
 import textwrap
+from functools import wraps
 
 if T.TYPE_CHECKING:
     from ..interpreter import Interpreter
@@ -69,11 +70,23 @@ FunctionType = T.Dict[
     T.Callable[[mparser.BaseNode, T.List[TYPE_var], T.Dict[str, TYPE_var]], TYPE_var]
 ]
 
+__FN = T.TypeVar('__FN', bound=T.Callable[['InterpreterBase', T.Any], T.Union[TYPE_var, InterpreterObject]])
+def _holderify_result(types: T.Union[None, T.Type, T.Tuple[T.Type, ...]] = None) -> T.Callable[[__FN], __FN]:
+    def inner(f: __FN) -> __FN:
+        @wraps(f)
+        def wrapper(self: 'InterpreterBase', node: mparser.BaseNode) -> T.Union[TYPE_var, InterpreterObject]:
+            res = f(self, node)
+            if types is not None and not isinstance(res, types):
+                raise mesonlib.MesonBugException(f'Expected {types} but got object `{res}` of type {type(res).__name__}')
+            return self._holderify(res)
+        return T.cast(__FN, wrapper)
+    return inner
+
 class MesonVersionString(str):
     pass
 
 class InterpreterBase:
-    elementary_types = (str, bool, list)
+    elementary_types = (str, list)
 
     def __init__(self, source_root: str, subdir: str, subproject: str):
         self.source_root = source_root
@@ -190,7 +203,7 @@ class InterpreterBase:
         elif isinstance(cur, mparser.StringNode):
             return cur.value
         elif isinstance(cur, mparser.BooleanNode):
-            return cur.value
+            return self._holderify(cur.value)
         elif isinstance(cur, mparser.IfClauseNode):
             return self.evaluate_if(cur)
         elif isinstance(cur, mparser.IdNode):
@@ -252,13 +265,15 @@ class InterpreterBase:
         assert not arguments
         return kwargs
 
-    def evaluate_notstatement(self, cur: mparser.NotNode) -> T.Union[bool, Disabler]:
+    @_holderify_result((bool, Disabler))
+    def evaluate_notstatement(self, cur: mparser.NotNode) -> T.Union[TYPE_var, InterpreterObject]:
         v = self.evaluate_statement(cur.value)
         if isinstance(v, Disabler):
             return v
-        if not isinstance(v, bool):
-            raise InterpreterException('Argument to "not" is not a boolean.')
-        return not v
+        # TYPING TODO: Remove this check once `evaluate_statement` only returns InterpreterObjects
+        if not isinstance(v, InterpreterObject):
+            raise mesonlib.MesonBugException(f'Argument to not ({v}) is not an InterpreterObject but {type(v).__name__}.')
+        return v.operator_call(MesonOperator.NOT, None)
 
     def evaluate_if(self, node: mparser.IfClauseNode) -> T.Optional[Disabler]:
         assert isinstance(node, mparser.IfClauseNode)
@@ -269,6 +284,9 @@ class InterpreterBase:
             result = self.evaluate_statement(i.condition)
             if isinstance(result, Disabler):
                 return result
+            if not isinstance(result, InterpreterObject):
+                raise mesonlib.MesonBugException(f'Argument to not ({result}) is not an InterpreterObject but {type(result).__name__}.')
+            result = result.operator_call(MesonOperator.BOOL, None)
             if not isinstance(result, bool):
                 raise InvalidCode(f'If clause {result!r} does not evaluate to true or false.')
             if result:
@@ -289,13 +307,14 @@ class InterpreterBase:
             return False
         return True
 
-    def evaluate_in(self, val1: T.Any, val2: T.Any) -> bool:
+    def _evaluate_in(self, val1: T.Any, val2: T.Any) -> bool:
         if not isinstance(val1, (str, int, float, mesonlib.HoldableObject)):
             raise InvalidArguments('lvalue of "in" operator must be a string, integer, float, or object')
         if not isinstance(val2, (list, dict)):
             raise InvalidArguments('rvalue of "in" operator must be an array or a dict')
         return val1 in val2
 
+    @_holderify_result((bool, Disabler))
     def evaluate_comparison(self, node: mparser.ComparisonNode) -> T.Union[TYPE_var, InterpreterObject]:
         val1 = self.evaluate_statement(node.left)
         if isinstance(val1, Disabler):
@@ -318,11 +337,11 @@ class InterpreterBase:
 
         # Check if the arguments should be reversed for simplicity (this essentially converts `in` to `contains`)
         if operator in (MesonOperator.IN, MesonOperator.NOT_IN) and isinstance(val2, InterpreterObject):
-            return self._holderify(val2.operator_call(operator, _unholder(val1)))
+            return val2.operator_call(operator, _unholder(val1))
 
         # Normal evaluation, with the same semantics
         elif operator not in (MesonOperator.IN, MesonOperator.NOT_IN) and isinstance(val1, InterpreterObject):
-            return self._holderify(val1.operator_call(operator, _unholder(val2)))
+            return val1.operator_call(operator, _unholder(val2))
 
         # OLD CODE, based on the builtin types -- remove once we have switched
         # over to all ObjectHolders.
@@ -331,9 +350,9 @@ class InterpreterBase:
         val1 = _unholder(val1)
         val2 = _unholder(val2)
         if node.ctype == 'in':
-            return self.evaluate_in(val1, val2)
+            return self._evaluate_in(val1, val2)
         elif node.ctype == 'notin':
-            return not self.evaluate_in(val1, val2)
+            return not self._evaluate_in(val1, val2)
         valid = self.validate_comparison_types(val1, val2)
         # Ordering comparisons of different types isn't allowed since PR #1810
         # (0.41.0).  Since PR #2884 we also warn about equality comparisons of
@@ -371,36 +390,41 @@ class InterpreterBase:
         else:
             raise InvalidCode('You broke my compare eval.')
 
-    def evaluate_andstatement(self, cur: mparser.AndNode) -> T.Union[bool, Disabler]:
+    @_holderify_result((bool, Disabler))
+    def evaluate_andstatement(self, cur: mparser.AndNode) -> T.Union[TYPE_var, InterpreterObject]:
         l = self.evaluate_statement(cur.left)
         if isinstance(l, Disabler):
             return l
-        if not isinstance(l, bool):
-            raise InterpreterException('First argument to "and" is not a boolean.')
-        if not l:
-            return False
+        if not isinstance(l, InterpreterObject):
+            raise mesonlib.MesonBugException(f'Firtst argument to and ({l}) is not an InterpreterObject but {type(l).__name__}.')
+        l_bool = l.operator_call(MesonOperator.BOOL, None)
+        if not l_bool:
+            return l_bool
         r = self.evaluate_statement(cur.right)
         if isinstance(r, Disabler):
             return r
-        if not isinstance(r, bool):
-            raise InterpreterException('Second argument to "and" is not a boolean.')
-        return r
+        if not isinstance(r, InterpreterObject):
+            raise mesonlib.MesonBugException(f'Second argument to and ({r}) is not an InterpreterObject but {type(r).__name__}.')
+        return r.operator_call(MesonOperator.BOOL, None)
 
-    def evaluate_orstatement(self, cur: mparser.OrNode) -> T.Union[bool, Disabler]:
+    @_holderify_result((bool, Disabler))
+    def evaluate_orstatement(self, cur: mparser.OrNode) -> T.Union[TYPE_var, InterpreterObject]:
         l = self.evaluate_statement(cur.left)
         if isinstance(l, Disabler):
             return l
-        if not isinstance(l, bool):
-            raise InterpreterException('First argument to "or" is not a boolean.')
-        if l:
-            return True
+        if not isinstance(l, InterpreterObject):
+            raise mesonlib.MesonBugException(f'Firtst argument to or ({l}) is not an InterpreterObject but {type(l).__name__}.')
+        l_bool = l.operator_call(MesonOperator.BOOL, None)
+        if l_bool:
+            return l_bool
         r = self.evaluate_statement(cur.right)
         if isinstance(r, Disabler):
             return r
-        if not isinstance(r, bool):
-            raise InterpreterException('Second argument to "or" is not a boolean.')
-        return r
+        if not isinstance(r, InterpreterObject):
+            raise mesonlib.MesonBugException(f'Second argument to ot ({r}) is not an InterpreterObject but {type(r).__name__}.')
+        return r.operator_call(MesonOperator.BOOL, None)
 
+    @_holderify_result()
     def evaluate_uminusstatement(self, cur: mparser.UMinusNode) -> T.Union[TYPE_var, InterpreterObject]:
         v = self.evaluate_statement(cur.value)
         if isinstance(v, Disabler):
@@ -408,7 +432,7 @@ class InterpreterBase:
         # TYPING TODO: Remove this check once `evaluate_statement` only returns InterpreterObjects
         if not isinstance(v, InterpreterObject):
             raise InterpreterException(f'Argument to negation ({v}) is not an InterpreterObject but {type(v).__name__}.')
-        return self._holderify(v.operator_call(MesonOperator.UMINUS, None))
+        return v.operator_call(MesonOperator.UMINUS, None)
 
     @FeatureNew('/ with string arguments', '0.49.0')
     def evaluate_path_join(self, l: str, r: str) -> str:
@@ -473,9 +497,10 @@ class InterpreterBase:
         result = self.evaluate_statement(node.condition)
         if isinstance(result, Disabler):
             return result
-        if not isinstance(result, bool):
-            raise InterpreterException('Ternary condition is not boolean.')
-        if result:
+        if not isinstance(result, InterpreterObject):
+            raise mesonlib.MesonBugException(f'Ternary condition ({result}) is not an InterpreterObject but {type(result).__name__}.')
+        result_bool = result.operator_call(MesonOperator.BOOL, None)
+        if result_bool:
             return self.evaluate_statement(node.trueblock)
         else:
             return self.evaluate_statement(node.falseblock)
@@ -554,7 +579,7 @@ class InterpreterBase:
             new_value = {**old_variable, **addition}
         elif isinstance(old_variable, InterpreterObject):
             # TODO: don't make _unholder permissive
-            new_value = self._holderify(old_variable.operator_call(MesonOperator.PLUS, _unholder(addition, permissive=True)))
+            new_value = self._holderify(old_variable.operator_call(MesonOperator.PLUS, _unholder(addition)))
         # Add other data types here.
         else:
             raise InvalidArguments('The += operator currently only works with arrays, dicts, strings or ints')
@@ -596,7 +621,8 @@ class InterpreterBase:
                 # We are already checking for the existence of __getitem__, so this should be save
                 raise InterpreterException('Index %d out of bounds of array of size %d.' % (index, len(iobject)))  # type: ignore
 
-    def function_call(self, node: mparser.FunctionNode) -> T.Optional[T.Union[TYPE_elementary, InterpreterObject]]:
+    @_holderify_result()
+    def function_call(self, node: mparser.FunctionNode) -> T.Optional[T.Union[TYPE_var, InterpreterObject]]:
         func_name = node.func_name
         (h_posargs, h_kwargs) = self.reduce_arguments(node.args)
         (posargs, kwargs) = self._unholder_args(h_posargs, h_kwargs)
@@ -609,8 +635,7 @@ class InterpreterBase:
                 func_args = flatten(posargs)
             if not getattr(func, 'no-second-level-holder-flattening', False):
                 func_args, kwargs = resolve_second_level_holders(func_args, kwargs)
-            res = func(node, func_args, kwargs)
-            return self._holderify(res)
+            return func(node, func_args, kwargs)
         else:
             self.unknown_function_called(func_name)
             return None
@@ -631,7 +656,7 @@ class InterpreterBase:
         if isinstance(obj, str):
             return self._holderify(self.string_method_call(obj, method_name, args, kwargs))
         if isinstance(obj, bool):
-            return self._holderify(self.bool_method_call(obj, method_name, args, kwargs))
+            raise mesonlib.MesonBugException('Booleans are now wrapped in object holders!')
         if isinstance(obj, int):
             raise mesonlib.MesonBugException('Integers are now wrapped in object holders!')
         if isinstance(obj, list):
@@ -653,7 +678,7 @@ class InterpreterBase:
         # TODO: remove `permissive` once all primitives are ObjectHolders
         if res is None:
             return None
-        if isinstance(res, (bool, str)):
+        if isinstance(res, str):
             return res
         elif isinstance(res, list):
             return [self._holderify(x, permissive=permissive) for x in res]
@@ -684,29 +709,6 @@ class InterpreterBase:
                        kwargs: T.Dict[str, T.Union[TYPE_var, InterpreterObject]]) -> T.Tuple[T.List[TYPE_var], TYPE_kwargs]:
         return [_unholder(x) for x in args], {k: _unholder(v) for k, v in kwargs.items()}
 
-    @noKwargs
-    def bool_method_call(self, obj: bool, method_name: str, posargs: T.List[TYPE_var], kwargs: TYPE_kwargs) -> T.Union[str, int]:
-        if method_name == 'to_string':
-            if not posargs:
-                if obj:
-                    return 'true'
-                else:
-                    return 'false'
-            elif len(posargs) == 2 and isinstance(posargs[0], str) and isinstance(posargs[1], str):
-                if obj:
-                    return posargs[0]
-                else:
-                    return posargs[1]
-            else:
-                raise InterpreterException('bool.to_string() must have either no arguments or exactly two string arguments that signify what values to return for true and false.')
-        elif method_name == 'to_int':
-            if obj:
-                return 1
-            else:
-                return 0
-        else:
-            raise InterpreterException('Unknown method "%s" for a boolean.' % method_name)
-
     @staticmethod
     def _get_one_string_posarg(posargs: T.List[TYPE_var], method_name: str) -> str:
         if len(posargs) > 1:
@@ -830,7 +832,7 @@ class InterpreterBase:
                     if element == item:
                         return True
                 return False
-            return check_contains([_unholder(x) for x in obj])
+            return self._holderify(check_contains([_unholder(x) for x in obj]))
         elif method_name == 'length':
             return self._holderify(len(obj))
         elif method_name == 'get':
@@ -876,7 +878,7 @@ class InterpreterBase:
             has_key = key in obj
 
             if method_name == 'has_key':
-                return has_key
+                return self._holderify(has_key)
 
             if has_key:
                 return obj[key]