Implement client error correction

codegen/build.gradle.kts

@@ -15,5 +15,5 @@
 
 allprojects {
     group = "software.amazon.smithy.python"
-    version = "0.3.0"
+    version = "0.3.1"
 }

codegen/core/src/main/java/software/amazon/smithy/python/codegen/HttpProtocolTestGenerator.java

@@ -763,12 +763,15 @@ public Void nullNode(NullNode node) {
 
         @Override
         public Void numberNode(NumberNode node) {
-            // TODO: Add support for timestamp, int-enum, and others
             if (inputShape.isTimestampShape()) {
                 var parsed = CodegenUtils.parseTimestampNode(model, inputShape, node);
                 writer.writeInline(CodegenUtils.getDatetimeConstructor(writer, parsed));
             } else if (inputShape.isFloatShape() || inputShape.isDoubleShape()) {
                 writer.writeInline("float($L)", node.getValue());
+            } else if (inputShape.isIntEnumShape()) {
+                var enumSymbol =
+                        context.symbolProvider().toSymbol(inputShape).expectProperty(SymbolProperties.ENUM_SYMBOL);
+                writer.writeInline("$T($L)", enumSymbol, node.getValue());
             } else {
                 writer.writeInline("$L", node.getValue());
             }
@@ -800,6 +803,10 @@ public Void stringNode(StringNode node) {
                 };
 
                 writer.writeInline("float($S)", value);
+            } else if (inputShape.isEnumShape()) {
+                var enumSymbol =
+                        context.symbolProvider().toSymbol(inputShape).expectProperty(SymbolProperties.ENUM_SYMBOL);
+                writer.writeInline("$T($S)", enumSymbol, node.getValue());
             } else {
                 writer.writeInline("$S", node.getValue());
             }

codegen/core/src/main/java/software/amazon/smithy/python/codegen/PythonSymbolProvider.java

@@ -329,15 +329,9 @@ public Symbol intEnumShape(IntEnumShape shape) {
     }
 
     private Symbol genericEnum(Shape shape) {
-        var enumSymbol = createGeneratedSymbolBuilder(shape, getDefaultShapeName(shape), SHAPES_FILE).build();
-
-        // We add this enum symbol as a property on a generic string/int symbol
-        // rather than returning the enum symbol directly because we only
-        // generate the enum constants for convenience. We actually want
-        // to pass around plain types rather than what is effectively
-        // a namespace class.
-        return createSymbolBuilder(shape, shape.isEnumShape() ? "str" : "int")
-                .putProperty(SymbolProperties.ENUM_SYMBOL, escaper.escapeSymbol(shape, enumSymbol))
+        Symbol symbol = createGeneratedSymbolBuilder(shape, getDefaultShapeName(shape), SHAPES_FILE).build();
+        return symbol.toBuilder()
+                .putProperty(SymbolProperties.ENUM_SYMBOL, escaper.escapeSymbol(shape, symbol))
                 .build();
     }
 

codegen/core/src/main/java/software/amazon/smithy/python/codegen/generators/EnumGenerator.java

@@ -13,7 +13,23 @@
 import software.amazon.smithy.utils.SmithyInternalApi;
 
 /**
- * Renders enums.
+ * Renders enums as a {@code StrEnum} subclass.
+ *
+ * <p>Beyond the named members, the generated class has:
+ * <ul>
+ *   <li>{@code is_unknown} — public. {@code True} when the value didn't come
+ *       from a known member: either the service returned a value newer than
+ *       this SDK or client error correction filled in a placeholder.</li>
+ *   <li>{@code _missing_} — invoked when deserializing a value the SDK
+ *       doesn't recognize.</li>
+ *   <li>{@code _unknown} — invoked from {@link MemberErrorCorrectionGenerator}
+ *       to fill a missing required member.</li>
+ *   <li>{@code __eq__} / {@code __hash__} — overridden so an unknown value
+ *       is not equal to any known member, even if its underlying string
+ *       happens to match one.</li>
+ * </ul>
+ *
+ * @see <a href="https://smithy.io/2.0/spec/simple-types.html#enum">Smithy spec: enum</a>
  */
 @SmithyInternalApi
 public final class EnumGenerator implements Runnable {
@@ -30,6 +46,7 @@ public void run() {
         var enumSymbol = context.symbolProvider().toSymbol(shape).expectProperty(SymbolProperties.ENUM_SYMBOL);
         context.writerDelegator().useShapeWriter(shape, writer -> {
             writer.addStdlibImport("enum", "StrEnum");
+            writer.addStdlibImport("typing", "Self");
             writer.openBlock("class $L(StrEnum):", "", enumSymbol.getName(), () -> {
                 shape.getTrait(DocumentationTrait.class).ifPresent(trait -> {
                     writer.writeDocs(trait.getValue(), context);
@@ -43,6 +60,43 @@ public void run() {
                         writer.writeDocs(trait.getValue(), context);
                     });
                 }
+
+                writer.write("""
+
+                        @classmethod
+                        def _unknown(cls, value: str) -> "Self":
+                            pseudo = str.__new__(cls, value)
+                            pseudo._name_ = f"<smithy-unknown:{value}>"
+                            pseudo._value_ = value
+                            return pseudo
+
+                        @classmethod
+                        def _missing_(cls, value: object) -> "Self | None":
+                            if isinstance(value, str):
+                                return cls._unknown(value)
+                            return None
+
+                        @property
+                        def is_unknown(self) -> bool:
+                            \"""True if this value was not known at SDK generation time.\"""
+                            return self._name_ not in type(self).__members__
+
+                        def __eq__(self, other: object) -> bool:
+                            if self.is_unknown:
+                                return (
+                                    isinstance(other, type(self))
+                                    and other.is_unknown
+                                    and self._value_ == other._value_
+                                )
+                            if isinstance(other, type(self)) and other.is_unknown:
+                                return False
+                            return super().__eq__(other)
+
+                        def __hash__(self) -> int:
+                            if self.is_unknown:
+                                return hash(("<smithy-unknown>", type(self).__name__, self._value_))
+                            return super().__hash__()
+                        """);
             });
         });
     }

codegen/core/src/main/java/software/amazon/smithy/python/codegen/generators/IntEnumGenerator.java

@@ -13,6 +13,25 @@
 import software.amazon.smithy.python.codegen.SymbolProperties;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
+/**
+ * Renders intEnums as an {@code IntEnum} subclass.
+ *
+ * <p>Beyond the named members, the generated class has:
+ * <ul>
+ *   <li>{@code is_unknown} — public. {@code True} when the value didn't come
+ *       from a known member: either the service returned a value newer than
+ *       this SDK or client error correction filled in a placeholder.</li>
+ *   <li>{@code _missing_} — invoked when deserializing a value the SDK
+ *       doesn't recognize.</li>
+ *   <li>{@code _unknown} — invoked from {@link MemberErrorCorrectionGenerator}
+ *       to fill a missing required member.</li>
+ *   <li>{@code __eq__} / {@code __hash__} — overridden so an unknown value
+ *       is not equal to any known member, even if its underlying integer
+ *       happens to match one.</li>
+ * </ul>
+ *
+ * @see <a href="https://smithy.io/2.0/spec/simple-types.html#intenum">Smithy spec: intEnum</a>
+ */
 @SmithyInternalApi
 public final class IntEnumGenerator implements Runnable {
 
@@ -27,6 +46,7 @@ public void run() {
         var enumSymbol = directive.symbol().expectProperty(SymbolProperties.ENUM_SYMBOL);
         directive.context().writerDelegator().useShapeWriter(directive.shape(), writer -> {
             writer.addStdlibImport("enum", "IntEnum");
+            writer.addStdlibImport("typing", "Self");
             writer.openBlock("class $L(IntEnum):", "", enumSymbol.getName(), () -> {
                 directive.shape().getTrait(DocumentationTrait.class).ifPresent(trait -> {
                     writer.writeDocs(trait.getValue(), directive.context());
@@ -35,11 +55,48 @@ public void run() {
                 for (MemberShape member : directive.shape().members()) {
                     var name = directive.symbolProvider().toMemberName(member);
                     var value = member.expectTrait(EnumValueTrait.class).expectIntValue();
-                    writer.write("$L = $L\n", name, value);
+                    writer.write("$L = $L", name, value);
                     member.getTrait(DocumentationTrait.class).ifPresent(trait -> {
                         writer.writeDocs(trait.getValue(), directive.context());
                     });
                 }
+
+                writer.write("""
+
+                        @classmethod
+                        def _unknown(cls, value: int) -> "Self":
+                            pseudo = int.__new__(cls, value)
+                            pseudo._name_ = f"<smithy-unknown:{value}>"
+                            pseudo._value_ = value
+                            return pseudo
+
+                        @classmethod
+                        def _missing_(cls, value: object) -> "Self | None":
+                            if isinstance(value, int):
+                                return cls._unknown(value)
+                            return None
+
+                        @property
+                        def is_unknown(self) -> bool:
+                            \"""True if this value was not known at SDK generation time.\"""
+                            return self._name_ not in type(self).__members__
+
+                        def __eq__(self, other: object) -> bool:
+                            if self.is_unknown:
+                                return (
+                                    isinstance(other, type(self))
+                                    and other.is_unknown
+                                    and self._value_ == other._value_
+                                )
+                            if isinstance(other, type(self)) and other.is_unknown:
+                                return False
+                            return super().__eq__(other)
+
+                        def __hash__(self) -> int:
+                            if self.is_unknown:
+                                return hash(("<smithy-unknown>", type(self).__name__, self._value_))
+                            return super().__hash__()
+                        """);
             });
         });
     }

codegen/core/src/main/java/software/amazon/smithy/python/codegen/generators/MemberDeserializerGenerator.java

@@ -135,7 +135,11 @@ public Void integerShape(IntegerShape shape) {
 
     @Override
     public Void intEnumShape(IntEnumShape shape) {
-        writeDeserializer("integer");
+        pushMemberState();
+        var enumSymbol = context.symbolProvider().toSymbol(shape).expectProperty(SymbolProperties.ENUM_SYMBOL);
+        writer.write("$T(${deserializer:L}.read_integer(${C|}))",
+                enumSymbol,
+                writer.consumer(w -> writeSchema()));
         return null;
     }
 
@@ -183,7 +187,11 @@ public Void stringShape(StringShape shape) {
 
     @Override
     public Void enumShape(EnumShape shape) {
-        writeDeserializer("string");
+        pushMemberState();
+        var enumSymbol = context.symbolProvider().toSymbol(shape).expectProperty(SymbolProperties.ENUM_SYMBOL);
+        writer.write("$T(${deserializer:L}.read_string(${C|}))",
+                enumSymbol,
+                writer.consumer(w -> writeSchema()));
         return null;
     }