interpreter: Add IntegerHolder

12 files changed, 186 insertions, 65 deletions

diff --git a/mesonbuild/ast/interpreter.py b/mesonbuild/ast/interpreter.py
index 8c2be37..7e4bc62 100644
--- a/mesonbuild/ast/interpreter.py
+++ b/mesonbuild/ast/interpreter.py
@@ -368,7 +368,8 @@ class AstInterpreter(InterpreterBase):
                 elif isinstance(src, bool):
                     result = self.bool_method_call(src, node.name, margs, mkwargs)
                 elif isinstance(src, int):
-                    result = self.int_method_call(src, node.name, margs, mkwargs)
+                    from ..interpreter import Interpreter, IntegerHolder
+                    result = IntegerHolder(src, T.cast(Interpreter, self)).method_call(node.name, margs, mkwargs)
                 elif isinstance(src, list):
                     result = self.array_method_call(src, node.name, margs, mkwargs)
                 elif isinstance(src, dict):
diff --git a/mesonbuild/interpreter/__init__.py b/mesonbuild/interpreter/__init__.py
index 62b09bf..0a7717f 100644
--- a/mesonbuild/interpreter/__init__.py
+++ b/mesonbuild/interpreter/__init__.py
@@ -16,6 +16,28 @@
 
 """Meson interpreter."""
 
+__all__ = [
+    'Interpreter',
+    'permitted_dependency_kwargs',
+
+    'CompilerHolder',
+
+    'ExecutableHolder',
+    'BuildTargetHolder',
+    'CustomTargetHolder',
+    'CustomTargetIndexHolder',
+    'MachineHolder',
+    'Test',
+    'ConfigurationDataObject',
+    'SubprojectHolder',
+    'DependencyHolder',
+    'GeneratedListHolder',
+    'ExternalProgramHolder',
+    'extract_required_kwarg',
+
+    'IntegerHolder',
+]
+
 from .interpreter import Interpreter, permitted_dependency_kwargs
 from .compiler import CompilerHolder
 from .interpreterobjects import (ExecutableHolder, BuildTargetHolder, CustomTargetHolder,
@@ -23,3 +45,7 @@ from .interpreterobjects import (ExecutableHolder, BuildTargetHolder, CustomTarg
                                  ConfigurationDataObject, SubprojectHolder, DependencyHolder,
                                  GeneratedListHolder, ExternalProgramHolder,
                                  extract_required_kwarg)
+
+from .primitives import (
+    IntegerHolder,
+)
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index 1a34885..db4f9e9 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -58,6 +58,7 @@ from .type_checking import (
     NoneType,
     in_set_validator,
 )
+from . import primitives as P_OBJ
 
 from pathlib import Path
 import os
@@ -376,6 +377,10 @@ class Interpreter(InterpreterBase, HoldableObject):
             holderify all returned values from methods and functions.
         '''
         self.holder_map.update({
+            # Primitives
+            int: P_OBJ.IntegerHolder,
+
+            # Meson types
             mesonlib.File: OBJ.FileHolder,
             build.SharedLibrary: OBJ.SharedLibraryHolder,
             build.StaticLibrary: OBJ.StaticLibraryHolder,
diff --git a/mesonbuild/interpreter/primitives/__init__.py b/mesonbuild/interpreter/primitives/__init__.py
new file mode 100644
index 0000000..56af72a
--- /dev/null
+++ b/mesonbuild/interpreter/primitives/__init__.py
@@ -0,0 +1,8 @@
+# Copyright 2021 The Meson development team
+# SPDX-license-identifier: Apache-2.0
+
+__all__ = [
+    'IntegerHolder',
+]
+
+from .integer import IntegerHolder
diff --git a/mesonbuild/interpreter/primitives/integer.py b/mesonbuild/interpreter/primitives/integer.py
new file mode 100644
index 0000000..296a3ca
--- /dev/null
+++ b/mesonbuild/interpreter/primitives/integer.py
@@ -0,0 +1,84 @@
+# Copyright 2021 The Meson development team
+# SPDX-license-identifier: Apache-2.0
+
+from ...interpreterbase import (
+    ObjectHolder,
+    MesonOperator,
+    typed_operator,
+    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 IntegerHolder(ObjectHolder[int]):
+    def __init__(self, obj: int, interpreter: 'Interpreter') -> None:
+        super().__init__(obj, interpreter)
+        self.methods.update({
+            'is_even': self.is_even_method,
+            'is_odd': self.is_odd_method,
+            'to_string': self.to_string_method,
+        })
+
+
+        self.trivial_operators.update({
+            # Arithmetic
+            MesonOperator.UMINUS: (None, lambda x: -self.held_object),
+            MesonOperator.PLUS: (int, lambda x: self.held_object + x),
+            MesonOperator.MINUS: (int, lambda x: self.held_object - x),
+            MesonOperator.TIMES: (int, lambda x: self.held_object * x),
+
+            # Comparison
+            MesonOperator.EQUALS: (int, lambda x: self.held_object == x),
+            MesonOperator.NOT_EQUALS: (int, lambda x: self.held_object != x),
+            MesonOperator.GREATER: (int, lambda x: self.held_object > x),
+            MesonOperator.LESS: (int, lambda x: self.held_object < x),
+            MesonOperator.GREATER_EQUALS: (int, lambda x: self.held_object >= x),
+            MesonOperator.LESS_EQUALS: (int, lambda x: self.held_object <= x),
+        })
+
+        # Use actual methods for functions that require additional checks
+        self.operators.update({
+            MesonOperator.DIV: self.op_div,
+            MesonOperator.MOD: self.op_mod,
+        })
+
+    def display_name(self) -> str:
+        return 'int'
+
+    @noKwargs
+    @noPosargs
+    def is_even_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> bool:
+        return self.held_object % 2 == 0
+
+    @noKwargs
+    @noPosargs
+    def is_odd_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> bool:
+        return self.held_object % 2 != 0
+
+    @noKwargs
+    @noPosargs
+    def to_string_method(self, args: T.List[TYPE_var], kwargs: TYPE_kwargs) -> str:
+        return str(self.held_object)
+
+    @typed_operator(MesonOperator.DIV, int)
+    def op_div(self, other: int) -> int:
+        if other == 0:
+            raise InvalidArguments('Tried to divide by 0')
+        return self.held_object // other
+
+    @typed_operator(MesonOperator.MOD, int)
+    def op_mod(self, other: int) -> int:
+        if other == 0:
+            raise InvalidArguments('Tried to divide by 0')
+        return self.held_object % other
+
diff --git a/mesonbuild/interpreterbase/__init__.py b/mesonbuild/interpreterbase/__init__.py
index c3605b2..e630bbf 100644
--- a/mesonbuild/interpreterbase/__init__.py
+++ b/mesonbuild/interpreterbase/__init__.py
@@ -69,6 +69,9 @@ __all__ = [
     'TYPE_kwargs',
     'TYPE_nkwargs',
     'TYPE_key_resolver',
+    'TYPE_HoldableTypes',
+
+    'HoldableTypes',
 ]
 
 from .baseobjects import (
@@ -88,6 +91,9 @@ from .baseobjects import (
     TYPE_kwargs,
     TYPE_nkwargs,
     TYPE_key_resolver,
+    TYPE_HoldableTypes,
+
+    HoldableTypes,
 )
 
 from .decorators import (
@@ -102,6 +108,8 @@ from .decorators import (
     typed_pos_args,
     ContainerTypeInfo,
     KwargInfo,
+    typed_operator,
+    unary_operator,
     typed_kwargs,
     FeatureCheckBase,
     FeatureNew,
@@ -122,3 +130,4 @@ from .exceptions import (
 from .disabler import Disabler, is_disabled
 from .helpers import check_stringlist, default_resolve_key, flatten, resolve_second_level_holders
 from .interpreterbase import MesonVersionString, InterpreterBase
+from .operator import MesonOperator
diff --git a/mesonbuild/interpreterbase/_unholder.py b/mesonbuild/interpreterbase/_unholder.py
index 10c7cfc..55f3423 100644
--- a/mesonbuild/interpreterbase/_unholder.py
+++ b/mesonbuild/interpreterbase/_unholder.py
@@ -12,21 +12,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .baseobjects import InterpreterObject, MesonInterpreterObject, ObjectHolder, TYPE_var
+from .baseobjects import InterpreterObject, MesonInterpreterObject, ObjectHolder, TYPE_var, HoldableTypes
 from .exceptions import InvalidArguments
 from ..mesonlib import HoldableObject, MesonBugException
 
 import typing as T
 
 def _unholder(obj: T.Union[TYPE_var, InterpreterObject], *, permissive: bool = False) -> TYPE_var:
-    if isinstance(obj, (int, bool, str)):
+    if isinstance(obj, (bool, str)):
         return obj
     elif isinstance(obj, list):
         return [_unholder(x, permissive=permissive) for x in obj]
     elif isinstance(obj, dict):
         return {k: _unholder(v, permissive=permissive) for k, v in obj.items()}
     elif isinstance(obj, ObjectHolder):
-        assert isinstance(obj.held_object, HoldableObject)
+        assert isinstance(obj.held_object, HoldableTypes)
         return obj.held_object
     elif isinstance(obj, MesonInterpreterObject):
         return obj
diff --git a/mesonbuild/interpreterbase/baseobjects.py b/mesonbuild/interpreterbase/baseobjects.py
index b28654a..4b538fb 100644
--- a/mesonbuild/interpreterbase/baseobjects.py
+++ b/mesonbuild/interpreterbase/baseobjects.py
@@ -111,6 +111,9 @@ class InterpreterObject:
         ))
 
     def op_equals(self, other: TYPE_var) -> bool:
+        # We use `type(...) == type(...)` here to enforce an *exact* match for comparison. We
+        # don't want comparisons to be possible where `isinstance(derived_obj, type(base_obj))`
+        # would pass because this comparison must never be true: `derived_obj == base_obj`
         if type(self) != type(other):
             self._throw_comp_exception(other, '==')
         return self == other
@@ -148,6 +151,7 @@ class ObjectHolder(InterpreterObject, T.Generic[InterpreterObjectTypeVar]):
 
     # Override default comparison operators for the held object
     def op_equals(self, other: TYPE_var) -> bool:
+        # See the comment from InterpreterObject why we are using `type()` here.
         if type(self.held_object) != type(other):
             self._throw_comp_exception(other, '==')
         return self.held_object == other
diff --git a/mesonbuild/interpreterbase/decorators.py b/mesonbuild/interpreterbase/decorators.py
index 717853f..156b4c9 100644
--- a/mesonbuild/interpreterbase/decorators.py
+++ b/mesonbuild/interpreterbase/decorators.py
@@ -139,7 +139,7 @@ def typed_operator(operator: MesonOperator,
     return inner
 
 def unary_operator(operator: MesonOperator) -> T.Callable[['_TV_FN_Operator'], '_TV_FN_Operator']:
-    """Decorator that does type checking for operator calls.
+    """Decorator that does type checking for unary operator calls.
 
     This decorator is for unary operators that do not take any other objects.
     It should be impossible for a user to accidentally break this. Triggering
diff --git a/mesonbuild/interpreterbase/interpreterbase.py b/mesonbuild/interpreterbase/interpreterbase.py
index b6e7d0d..d990e61 100644
--- a/mesonbuild/interpreterbase/interpreterbase.py
+++ b/mesonbuild/interpreterbase/interpreterbase.py
@@ -15,7 +15,7 @@
 # This class contains the basic functionality needed to run any interpreter
 # or an interpreter-based tool.
 
-from .. import mparser, mesonlib, mlog
+from .. import mparser, mesonlib
 from .. import environment
 
 from .baseobjects import (
@@ -29,6 +29,8 @@ from .baseobjects import (
     TYPE_elementary,
     TYPE_var,
     TYPE_kwargs,
+
+    HoldableTypes,
 )
 
 from .exceptions import (
@@ -54,7 +56,10 @@ if T.TYPE_CHECKING:
     from ..interpreter import Interpreter
 
 HolderMapType = T.Dict[
-    T.Type[mesonlib.HoldableObject],
+    T.Union[
+        T.Type[mesonlib.HoldableObject],
+        T.Type[int],
+    ],
     # For some reason, this has to be a callable and can't just be ObjectHolder[InterpreterObjectTypeVar]
     T.Callable[[InterpreterObjectTypeVar, 'Interpreter'], ObjectHolder[InterpreterObjectTypeVar]]
 ]
@@ -68,7 +73,7 @@ class MesonVersionString(str):
     pass
 
 class InterpreterBase:
-    elementary_types = (int, str, bool, list)
+    elementary_types = (str, bool, list)
 
     def __init__(self, source_root: str, subdir: str, subproject: str):
         self.source_root = source_root
@@ -197,7 +202,7 @@ class InterpreterBase:
         elif isinstance(cur, mparser.DictNode):
             return self.evaluate_dictstatement(cur)
         elif isinstance(cur, mparser.NumberNode):
-            return cur.value
+            return self._holderify(cur.value)
         elif isinstance(cur, mparser.AndNode):
             return self.evaluate_andstatement(cur)
         elif isinstance(cur, mparser.OrNode):
@@ -396,13 +401,14 @@ class InterpreterBase:
             raise InterpreterException('Second argument to "or" is not a boolean.')
         return r
 
-    def evaluate_uminusstatement(self, cur: mparser.UMinusNode) -> T.Union[int, Disabler]:
+    def evaluate_uminusstatement(self, cur: mparser.UMinusNode) -> T.Union[TYPE_var, InterpreterObject]:
         v = self.evaluate_statement(cur.value)
         if isinstance(v, Disabler):
             return v
-        if not isinstance(v, int):
-            raise InterpreterException('Argument to negation is not an integer.')
-        return -v
+        # 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))
 
     @FeatureNew('/ with string arguments', '0.49.0')
     def evaluate_path_join(self, l: str, r: str) -> str:
@@ -412,16 +418,7 @@ class InterpreterBase:
             raise InvalidCode('The division operator can only append a string.')
         return self.join_path_strings((l, r))
 
-    def evaluate_division(self, l: T.Any, r: T.Any) -> T.Union[int, str]:
-        if isinstance(l, str) or isinstance(r, str):
-            return self.evaluate_path_join(l, r)
-        if isinstance(l, int) and isinstance(r, int):
-            if r == 0:
-                raise InvalidCode('Division by zero.')
-            return l // r
-        raise InvalidCode('Division works only with strings or integers.')
-
-    def evaluate_arithmeticstatement(self, cur: mparser.ArithmeticNode) -> T.Union[int, str, dict, list, Disabler]:
+    def evaluate_arithmeticstatement(self, cur: mparser.ArithmeticNode) -> T.Union[TYPE_var, InterpreterObject]:
         l = self.evaluate_statement(cur.left)
         if isinstance(l, Disabler):
             return l
@@ -455,17 +452,19 @@ class InterpreterBase:
         elif cur.operation == 'sub':
             if not isinstance(l, int) or not isinstance(r, int):
                 raise InvalidCode('Subtraction works only with integers.')
-            return l - r
+            raise mesonlib.MesonBugException('The integer was not held by an ObjectHolder!')
         elif cur.operation == 'mul':
             if not isinstance(l, int) or not isinstance(r, int):
                 raise InvalidCode('Multiplication works only with integers.')
-            return l * r
+            raise mesonlib.MesonBugException('The integer was not held by an ObjectHolder!')
         elif cur.operation == 'div':
-            return self.evaluate_division(l, r)
+            if isinstance(l, str) and isinstance(r, str):
+                return self.evaluate_path_join(l, r)
+            raise InvalidCode('Division works only with strings or integers.')
         elif cur.operation == 'mod':
             if not isinstance(l, int) or not isinstance(r, int):
                 raise InvalidCode('Modulo works only with integers.')
-            return l % r
+            raise mesonlib.MesonBugException('The integer was not held by an ObjectHolder!')
         else:
             raise InvalidCode('You broke me.')
 
@@ -488,7 +487,7 @@ class InterpreterBase:
         def replace(match: T.Match[str]) -> str:
             var = str(match.group(1))
             try:
-                val = self.variables[var]
+                val = _unholder(self.variables[var])
                 if not isinstance(val, (str, int, float, bool)):
                     raise InvalidCode(f'Identifier "{var}" does not name a formattable variable ' +
                         '(has to be an integer, a string, a floating point number or a boolean).')
@@ -508,7 +507,7 @@ class InterpreterBase:
                 raise InvalidArguments('Foreach on array does not unpack')
             varname = node.varnames[0]
             for item in items:
-                self.set_variable(varname, item)
+                self.set_variable(varname, self._holderify(item, permissive=True))
                 try:
                     self.evaluate_codeblock(node.block)
                 except ContinueRequest:
@@ -538,15 +537,12 @@ class InterpreterBase:
         # Remember that all variables are immutable. We must always create a
         # full new variable and then assign it.
         old_variable = self.get_variable(varname)
-        new_value = None  # type: T.Union[str, int, float, bool, dict, list]
+        # TYPING TODO: This should only be InterpreterObject in the future
+        new_value: T.Union[None, TYPE_var, InterpreterObject] = None
         if isinstance(old_variable, str):
             if not isinstance(addition, str):
                 raise InvalidArguments('The += operator requires a string on the right hand side if the variable on the left is a string')
             new_value = old_variable + addition
-        elif isinstance(old_variable, int):
-            if not isinstance(addition, int):
-                raise InvalidArguments('The += operator requires an int on the right hand side if the variable on the left is an int')
-            new_value = old_variable + addition
         elif isinstance(old_variable, list):
             if isinstance(addition, list):
                 new_value = old_variable + addition
@@ -556,6 +552,9 @@ class InterpreterBase:
             if not isinstance(addition, dict):
                 raise InvalidArguments('The += operator requires a dict on the right hand side if the variable on the left is a dict')
             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)))
         # Add other data types here.
         else:
             raise InvalidArguments('The += operator currently only works with arrays, dicts, strings or ints')
@@ -569,7 +568,7 @@ class InterpreterBase:
         if not hasattr(iobject, '__getitem__'):
             raise InterpreterException(
                 'Tried to index an object that doesn\'t support indexing.')
-        index = self.evaluate_statement(node.index)
+        index = _unholder(self.evaluate_statement(node.index))
 
         if isinstance(iobject, dict):
             if not isinstance(index, str):
@@ -630,11 +629,11 @@ class InterpreterBase:
         if is_disabled(args, kwargs):
             return Disabler()
         if isinstance(obj, str):
-            return self.string_method_call(obj, method_name, args, kwargs)
+            return self._holderify(self.string_method_call(obj, method_name, args, kwargs))
         if isinstance(obj, bool):
-            return self.bool_method_call(obj, method_name, args, kwargs)
+            return self._holderify(self.bool_method_call(obj, method_name, args, kwargs))
         if isinstance(obj, int):
-            return self.int_method_call(obj, method_name, args, kwargs)
+            raise mesonlib.MesonBugException('Integers are now wrapped in object holders!')
         if isinstance(obj, list):
             return self.array_method_call(obj, method_name, args, kwargs)
         if isinstance(obj, dict):
@@ -656,16 +655,17 @@ class InterpreterBase:
         obj.current_node = node
         return self._holderify(obj.method_call(method_name, args, kwargs))
 
-    def _holderify(self, res: T.Union[TYPE_var, InterpreterObject, None]) -> T.Union[TYPE_elementary, InterpreterObject]:
+    def _holderify(self, res: T.Union[TYPE_var, InterpreterObject, None], *, permissive: bool = False) -> T.Union[TYPE_elementary, InterpreterObject]:
+        # TODO: remove `permissive` once all primitives are ObjectHolders
         if res is None:
             return None
-        if isinstance(res, (int, bool, str)):
+        if isinstance(res, (bool, str)):
             return res
         elif isinstance(res, list):
-            return [self._holderify(x) for x in res]
+            return [self._holderify(x, permissive=permissive) for x in res]
         elif isinstance(res, dict):
-            return {k: self._holderify(v) for k, v in res.items()}
-        elif isinstance(res, mesonlib.HoldableObject):
+            return {k: self._holderify(v, permissive=permissive) for k, v in res.items()}
+        elif isinstance(res, HoldableTypes):
             # Always check for an exact match first.
             cls = self.holder_map.get(type(res), None)
             if cls is not None:
@@ -678,6 +678,8 @@ class InterpreterBase:
                     return cls(res, T.cast('Interpreter', self))
             raise mesonlib.MesonBugException(f'Object {res} of type {type(res).__name__} is neither in self.holder_map nor self.bound_holder_map.')
         elif isinstance(res, ObjectHolder):
+            if permissive:
+                return res
             raise mesonlib.MesonBugException(f'Returned object {res} of type {type(res).__name__} is an object holder.')
         elif isinstance(res, MesonInterpreterObject):
             return res
@@ -711,26 +713,6 @@ class InterpreterBase:
         else:
             raise InterpreterException('Unknown method "%s" for a boolean.' % method_name)
 
-    @noKwargs
-    def int_method_call(self, obj: int, method_name: str, posargs: T.List[TYPE_var], kwargs: TYPE_kwargs) -> T.Union[str, bool]:
-        if method_name == 'is_even':
-            if not posargs:
-                return obj % 2 == 0
-            else:
-                raise InterpreterException('int.is_even() must have no arguments.')
-        elif method_name == 'is_odd':
-            if not posargs:
-                return obj % 2 != 0
-            else:
-                raise InterpreterException('int.is_odd() must have no arguments.')
-        elif method_name == 'to_string':
-            if not posargs:
-                return str(obj)
-            else:
-                raise InterpreterException('int.to_string() must have no arguments.')
-        else:
-            raise InterpreterException('Unknown method "%s" for an integer.' % method_name)
-
     @staticmethod
     def _get_one_string_posarg(posargs: T.List[TYPE_var], method_name: str) -> str:
         if len(posargs) > 1:
@@ -856,7 +838,7 @@ class InterpreterBase:
                 return False
             return check_contains([_unholder(x) for x in obj])
         elif method_name == 'length':
-            return len(obj)
+            return self._holderify(len(obj))
         elif method_name == 'get':
             index = posargs[0]
             fallback = None
diff --git a/run_mypy.py b/run_mypy.py
index fc69063..f6add90 100755
--- a/run_mypy.py
+++ b/run_mypy.py
@@ -15,6 +15,7 @@ modules = [
     'mesonbuild/cmake',
     'mesonbuild/compilers',
     'mesonbuild/dependencies',
+    'mesonbuild/interpreter/primitives',
     'mesonbuild/interpreterbase',
     'mesonbuild/linkers',
     'mesonbuild/scripts',
diff --git a/test cases/failing/50 executable comparison/test.json b/test cases/failing/50 executable comparison/test.json
index 585b382..7f6bd3b 100644
--- a/test cases/failing/50 executable comparison/test.json
+++ b/test cases/failing/50 executable comparison/test.json
@@ -1,7 +1,8 @@
 {
   "stdout": [
     {
-      "line": "test cases/failing/50 executable comparison/meson.build:6:0: ERROR: exe1 can only be compared for equality."
+      "match": "re",
+      "line": "test cases/failing/50 executable comparison/meson.build:6:0: ERROR: Object <ExecutableHolder prog1@exe: prog1(.exe)?> of type Executable does not support the `<` operator."
     }
   ]
 }