feat: add is_opted_in method to Account type (#126)

examples/sizes.txt

@@ -1,7 +1,7 @@
 Name                                       O0 size O1 size O2 size 
 abi_routing/Reference                      1179    1019    1019    
 amm/ConstantProductAMM                     1213    1114    1114    
-application/Reference                      168     161     161     
+application/Reference                      175     168     168     
 arc4_numeric_comparisons/UIntNOrdering     1220    908     908     
 arc4_types/Arc4Arrays                      588     376     376     
 arc4_types/Arc4BoolEval                    569     20      20      
@@ -15,7 +15,7 @@ arc4_types/Arc4StringTypes                 328     8       8
 arc4_types/Arc4StructsFromAnotherModule    67      12      12      
 arc4_types/Arc4StructsType                 296     237     237     
 arc4_types/Arc4TuplesType                  799     146     146     
-asset/Reference                            259     252     252     
+asset/Reference                            268     261     261     
 auction/Auction                            564     523     523     
 augmented_assignment/Augmented             157     156     156     
 avm_types_in_abi/Test                      226     173     173     

src/puya/awst_build/eb/reference_types/account.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import typing
+from typing import Sequence
 
 from immutabledict import immutabledict
 
@@ -10,10 +11,16 @@
     AddressConstant,
     BytesComparisonExpression,
     EqualityComparison,
+    Expression,
     IntrinsicCall,
     Literal,
+    TupleItemExpression,
+)
+from puya.awst_build.eb.base import (
+    BuilderComparisonOp,
+    ExpressionBuilder,
+    IntermediateExpressionBuilder,
 )
-from puya.awst_build.eb.base import BuilderComparisonOp, ExpressionBuilder
 from puya.awst_build.eb.bytes_backed import BytesBackedClassExpressionBuilder
 from puya.awst_build.eb.reference_types.base import ReferenceValueExpressionBuilder
 from puya.awst_build.eb.var_factory import var_expression
@@ -57,6 +64,48 @@ def call(
                 raise CodeError("Invalid/unhandled arguments", location)
 
 
+class AccountOptedInExpressionBuilder(IntermediateExpressionBuilder):
+    def __init__(self, expr: Expression, source_location: SourceLocation):
+        super().__init__(source_location)
+        self.expr = expr
+
+    def call(
+        self,
+        args: Sequence[ExpressionBuilder | Literal],
+        arg_kinds: list[mypy.nodes.ArgKind],
+        arg_names: list[str | None],
+        location: SourceLocation,
+        original_expr: mypy.nodes.CallExpr,
+    ) -> ExpressionBuilder:
+        match args:
+            case [ExpressionBuilder(value_type=wtypes.asset_wtype) as asset]:
+                return var_expression(
+                    TupleItemExpression(
+                        base=IntrinsicCall(
+                            op_code="asset_holding_get",
+                            immediates=["AssetBalance"],
+                            stack_args=[self.expr, asset.rvalue()],
+                            wtype=wtypes.WTuple.from_types(
+                                (wtypes.uint64_wtype, wtypes.bool_wtype)
+                            ),
+                            source_location=location,
+                        ),
+                        index=1,
+                        source_location=location,
+                    )
+                )
+            case [ExpressionBuilder(value_type=wtypes.application_wtype) as app]:
+                return var_expression(
+                    IntrinsicCall(
+                        op_code="app_opted_in",
+                        stack_args=[self.expr, app.rvalue()],
+                        source_location=location,
+                        wtype=wtypes.bool_wtype,
+                    )
+                )
+        raise CodeError("Unexpected argument", location)
+
+
 class AccountExpressionBuilder(ReferenceValueExpressionBuilder):
     wtype = wtypes.account_wtype
     native_wtype = wtypes.bytes_wtype
@@ -80,6 +129,11 @@ class AccountExpressionBuilder(ReferenceValueExpressionBuilder):
     field_op_code = "acct_params_get"
     field_bool_comment = "account funded"
 
+    def member_access(self, name: str, location: SourceLocation) -> ExpressionBuilder | Literal:
+        if name == "is_opted_in":
+            return AccountOptedInExpressionBuilder(self.expr, location)
+        return super().member_access(name, location)
+
     def bool_eval(self, location: SourceLocation, *, negate: bool = False) -> ExpressionBuilder:
         cmp_with_zero_expr = BytesComparisonExpression(
             source_location=location,

src/puyapy-stubs/_reference.pyi

@@ -117,6 +117,13 @@ class Account(BytesBacked):
         Account must be an available resource
         ```
         """
+    def is_opted_in(self, aseet_or_app: Asset | Application) -> bool:
+        """Returns true if this account is opted in to the specified Asset or Application.
+
+        ```{note}
+        Account and Asset/Application must be an available resource
+        ```
+        """
 
 class Asset:
     """An Asset on the Algorand network."""

test_cases/application/contract.py

@@ -3,6 +3,7 @@
     Bytes,
     Contract,
     LocalState,
+    Txn,
     UInt64,
     op,
     subroutine,
@@ -35,6 +36,7 @@ def clear_state_program(self) -> bool:
 
     @subroutine
     def validate_asset(self, app: Application) -> None:
+        assert not Txn.sender.is_opted_in(app), "app opted in"
         assert app.creator == op.Global.creator_address, "expected creator"
         assert app.global_num_uint == 1, "expected global_num_uint"
         assert app.global_num_byte_slice == 2, "expected global_num_byte_slice"