Cleanup to type5 solver

- Replaces weird CheckResult class with proper data classes.
- When a constraint results in new constraints, those are
  treated first
- Minor readability change to function return type
- Code cleanup
- TODO cleanup
- Typo fixes

TODO.md

@@ -24,7 +24,4 @@
 - Read https://bytecodealliance.org/articles/multi-value-all-the-wasm
 
 - Implement type class 'inheritance'
-- Remove FunctionInstance, replace with a substitutions dict
-  - See phft2 in fromast.py:expression_function_call
-- Move unify into the typeconstraints (or other way around) - it's done on two levels now (partly in solver)
 - Rework type classes - already started on a separate dir for those, but quite a few things are still in other places.

phasm/type5/constrainedexpr.py

@@ -10,7 +10,7 @@ from .typeexpr import TypeExpr, TypeVariable, instantiate
 
 class TypeConstraint:
     """
-    Base class for type contraints
+    Base class for type constraints
     """
     __slots__ = ()
 

phasm/type5/constraints.py

@@ -75,6 +75,33 @@ class Context:
         assert tvar not in self.ptst_update
         self.ptst_update[tvar] = (arg, orig_var)
 
+class Success:
+    """
+    The contsraint checks out.
+
+    Nothing new was learned and nothing new needs to be checked.
+    """
+
+    def to_str(self, type_namer: Callable[[TypeExpr], str]) -> str:
+        return '(ok)'
+
+class SkipForNow:
+    """
+    Not enough information to resolve this constraint
+    """
+
+    def to_str(self, type_namer: Callable[[TypeExpr], str]) -> str:
+        return '(skip for now)'
+
+class ConstraintList(list['ConstraintBase']):
+    """
+    A new list of constraints.
+
+    Sometimes, checking one constraint means you get a list of new contraints.
+    """
+    def to_str(self, type_namer: Callable[[TypeExpr], str]) -> str:
+        return f'(got {len(self)} new constraints)'
+
 @dataclasses.dataclass
 class Failure:
     """
@@ -82,52 +109,38 @@ class Failure:
     """
     msg: str
 
+    def to_str(self, type_namer: Callable[[TypeExpr], str]) -> str:
+        return f'ERR: {self.msg}'
+
 @dataclasses.dataclass
 class ReplaceVariable:
+    """
+    A variable should be replaced.
+
+    Either by another variable or by a (concrete) type.
+    """
     var: TypeVariable
     typ: TypeExpr
 
-@dataclasses.dataclass
-class CheckResult:
-    # TODO: Refactor this, don't think we use most of the variants
-    _: dataclasses.KW_ONLY
-    done: bool = True
-    replace: ReplaceVariable | None = None
-    new_constraints: list[ConstraintBase] = dataclasses.field(default_factory=list)
-    failures: list[Failure] = dataclasses.field(default_factory=list)
-
     def to_str(self, type_namer: Callable[[TypeExpr], str]) -> str:
-        if not self.done and not self.replace and not self.new_constraints and not self.failures:
-            return '(skip for now)'
+        return f'{{{self.var.name} := {type_namer(self.typ)}}}'
 
-        if self.done and not self.replace and not self.new_constraints and not self.failures:
-            return '(ok)'
-
-        if self.done and self.replace and not self.new_constraints and not self.failures:
-            return f'{{{self.replace.var.name} := {type_namer(self.replace.typ)}}}'
-
-        if self.done and not self.replace and self.new_constraints and not self.failures:
-            return f'(got {len(self.new_constraints)} new constraints)'
-
-        if self.done and not self.replace and not self.new_constraints and self.failures:
-            return 'ERR: ' + '; '.join(x.msg for x in self.failures)
-
-        return f'{self.done} {self.replace} {self.new_constraints} {self.failures}'
-
-def skip_for_now() -> CheckResult:
-    return CheckResult(done=False)
-
-def replace(var: TypeVariable, typ: TypeExpr) -> CheckResult:
-    return CheckResult(replace=ReplaceVariable(var, typ))
-
-def new_constraints(lst: Iterable[ConstraintBase]) -> CheckResult:
-    return CheckResult(new_constraints=list(lst))
+CheckResult: TypeAlias = Success | SkipForNow | ConstraintList | Failure | ReplaceVariable
 
 def ok() -> CheckResult:
-    return CheckResult(done=True)
+    return Success()
+
+def skip_for_now() -> CheckResult:
+    return SkipForNow()
+
+def new_constraints(lst: Iterable[ConstraintBase]) -> CheckResult:
+    return ConstraintList(lst)
 
 def fail(msg: str) -> CheckResult:
-    return CheckResult(failures=[Failure(msg)])
+    return Failure(msg)
+
+def replace(var: TypeVariable, typ: TypeExpr) -> CheckResult:
+    return ReplaceVariable(var, typ)
 
 class ConstraintBase:
     __slots__ = ("ctx", "sourceref", )
@@ -399,7 +412,7 @@ class CanBeSubscriptedConstraint(ConstraintBase):
 
     def check(self) -> CheckResult:
         if not is_concrete(self.container_type5):
-            return CheckResult(done=False)
+            return skip_for_now()
 
         tp_args = self.ctx.build.type5_is_tuple(self.container_type5)
         if tp_args is not None:
@@ -462,7 +475,7 @@ class CanAccessStructMemberConstraint(ConstraintBase):
 
     def check(self) -> CheckResult:
         if not is_concrete(self.struct_type5):
-            return CheckResult(done=False)
+            return skip_for_now()
 
         st_args = self.ctx.build.type5_is_struct(self.struct_type5)
         if st_args is None:
@@ -514,11 +527,11 @@ class FromTupleConstraint(ConstraintBase):
 
     def check(self) -> CheckResult:
         if not is_concrete(self.ret_type5):
-            return CheckResult(done=False)
+            return skip_for_now()
 
         da_arg = self.ctx.build.type5_is_dynamic_array(self.ret_type5)
         if da_arg is not None:
-            return CheckResult(new_constraints=[
+            return new_constraints([
                 UnifyTypesConstraint(self.ctx, self.sourceref, da_arg, x)
                 for x in self.member_type5_list
             ])
@@ -529,7 +542,7 @@ class FromTupleConstraint(ConstraintBase):
             if sa_len != len(self.member_type5_list):
                 return fail('Tuple element count mismatch')
 
-            return CheckResult(new_constraints=[
+            return new_constraints([
                 UnifyTypesConstraint(self.ctx, self.sourceref, sa_typ, x)
                 for x in self.member_type5_list
             ])
@@ -539,7 +552,7 @@ class FromTupleConstraint(ConstraintBase):
             if len(tp_args) != len(self.member_type5_list):
                 return fail('Tuple element count mismatch')
 
-            return CheckResult(new_constraints=[
+            return new_constraints([
                 UnifyTypesConstraint(self.ctx, self.sourceref, act_typ, exp_typ)
                 for act_typ, exp_typ in zip(tp_args, self.member_type5_list, strict=True)
             ])

phasm/type5/fromast.py

@@ -241,7 +241,7 @@ def statement_return(ctx: Context, fun: ourlang.Function, inp: ourlang.Statement
         type5 = fun.type5.expr if isinstance(fun.type5, ConstrainedExpr) else fun.type5
 
     yield from expression(ctx, inp.value, phft)
-    yield UnifyTypesConstraint(ctx, inp.sourceref, type5, phft, prefix=f'{fun.name} returns')
+    yield UnifyTypesConstraint(ctx, inp.sourceref, type5, phft, prefix=f'{fun.name}(...)')
 
 def statement_if(ctx: Context, fun: ourlang.Function, inp: ourlang.StatementIf) -> ConstraintGenerator:
     test_phft = ctx.make_placeholder(inp.test)

phasm/type5/solver.py

@@ -1,7 +1,7 @@
 from typing import Any
 
 from ..ourlang import Module
-from .constraints import ConstraintBase, Context
+from .constraints import ConstraintBase, ConstraintList, Context, Failure, ReplaceVariable, SkipForNow, Success
 from .fromast import phasm_type5_generate_constraints
 from .typeexpr import TypeExpr, TypeVariable, is_concrete, replace_variable
 
@@ -30,58 +30,68 @@ def phasm_type5(inp: Module[Any], verbose: bool = False) -> None:
             print("Validating")
 
         new_constraint_list: list[ConstraintBase] = []
-        for constraint in sorted(constraint_list, key=lambda x: x.complexity()):
+
+        # Iterate using a while and pop since on ReplaceVariable
+        # we want to iterate over the list as well, and since on
+        # ConstraintList we want to treat those first.
+        remaining_constraint_list = sorted(constraint_list, key=lambda x: x.complexity())
+        while remaining_constraint_list:
+            constraint = remaining_constraint_list.pop(0)
             result = constraint.check()
 
             if verbose:
                 print(f"{constraint.sourceref!s}  {constraint!s}")
                 print(f"{constraint.sourceref!s}  => {result.to_str(inp.build.type5_name)}")
 
-            if not result:
-                # None or empty list
-                # Means it checks out and we don't need do anything
-                continue
+            match result:
+                case Success():
+                    # This constraint was valid
+                    continue
+                case SkipForNow():
+                    # We have to check later
+                    new_constraint_list.append(constraint)
+                    continue
+                case ConstraintList(items):
+                    # This constraint was valid, but we have new once
+                    # Do this as the first next items, so when users are reading the
+                    # solver output they don't need to context switch.
+                    remaining_constraint_list = items + remaining_constraint_list
 
-            if result.replace is not None:
-                action_var = result.replace.var
-                assert action_var not in placeholder_types  # When does this happen?
+                    if verbose:
+                        for new_const in items:
+                            print(f"{constraint.sourceref!s}  => + {new_const!s}")
 
-                action_typ: TypeExpr = result.replace.typ
-                assert not isinstance(action_typ, TypeVariable) or action_typ not in placeholder_types  # When does this happen?
+                    continue
+                case Failure(msg):
+                    error_list.append((str(constraint.sourceref), str(constraint), msg, ))
+                    continue
+                case ReplaceVariable(action_var, action_typ):
+                    assert action_var not in placeholder_types  # When does this happen?
+                    assert not isinstance(action_typ, TypeVariable) or action_typ not in placeholder_types  # When does this happen?
+                    assert action_var != action_typ  # When does this happen?
 
-                assert action_var != action_typ  # When does this happen?
+                    # Ensure all existing found types are updated
+                    # if they have this variable somewhere inside them.
+                    placeholder_types = {
+                        k: replace_variable(v, action_var, action_typ)
+                        for k, v in placeholder_types.items()
+                    }
 
-                # Ensure all existing found types are updated
-                placeholder_types = {
-                    k: replace_variable(v, action_var, action_typ)
-                    for k, v in placeholder_types.items()
-                }
-                placeholder_types[action_var] = action_typ
+                    # Add the new variable to the registry
+                    placeholder_types[action_var] = action_typ
 
-                for oth_const in new_constraint_list + constraint_list:
-                    if oth_const is constraint and result.done:
-                        continue
+                    # Also update all constraints that may refer to this variable
+                    # that they now have more detailed information.
+                    for oth_const in new_constraint_list + remaining_constraint_list:
+                        old_str = str(oth_const)
+                        oth_const.replace_variable(action_var, action_typ)
+                        new_str = str(oth_const)
 
-                    old_str = str(oth_const)
-                    oth_const.replace_variable(action_var, action_typ)
-                    new_str = str(oth_const)
+                        if verbose and old_str != new_str:
+                            print(f"{oth_const.sourceref!s}  => - {old_str!s}")
+                            print(f"{oth_const.sourceref!s}  => + {new_str!s}")
 
-                    if verbose and old_str != new_str:
-                        print(f"{oth_const.sourceref!s}  => - {old_str!s}")
-                        print(f"{oth_const.sourceref!s}  => + {new_str!s}")
-
-            for failure in result.failures:
-                error_list.append((str(constraint.sourceref), str(constraint), failure.msg, ))
-
-            new_constraint_list.extend(result.new_constraints)
-            if verbose:
-                for new_const in result.new_constraints:
-                    print(f"{oth_const.sourceref!s}  => + {new_const!s}")
-
-            if result.done:
-                continue
-
-            new_constraint_list.append(constraint)
+                    continue
 
         if error_list:
             raise Type5SolverException(error_list)