From 9c824df381fe01b02372ee60f1b68435c7b9ef9c Mon Sep 17 00:00:00 2001
From: david-perez <d@vidp.dev>
Date: Mon, 22 Aug 2022 18:37:56 +0200
Subject: [PATCH] Make `ServerProtocolLoader` delegate to `ProtocolLoader`
 (#1524)

While the set of supported protocols and their implementation is
different among servers and clients, the logic to load a specific
protocol given a Smithy model is identical. This commit makes
`ServerProtocolLoader` inherit from `ProtocolLoader` so that said logic
can be reused among clients and servers.
---
 .../smithy/protocols/ServerProtocolLoader.kt  | 28 ++-----------------
 .../rust/codegen/smithy/protocols/Protocol.kt |  2 +-
 2 files changed, 4 insertions(+), 26 deletions(-)

diff --git a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/protocols/ServerProtocolLoader.kt b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/protocols/ServerProtocolLoader.kt
index 1f3cabcb9..ebbd163b6 100644
--- a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/protocols/ServerProtocolLoader.kt
+++ b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/protocols/ServerProtocolLoader.kt
@@ -9,35 +9,13 @@ import software.amazon.smithy.aws.traits.protocols.AwsJson1_0Trait
 import software.amazon.smithy.aws.traits.protocols.AwsJson1_1Trait
 import software.amazon.smithy.aws.traits.protocols.RestJson1Trait
 import software.amazon.smithy.aws.traits.protocols.RestXmlTrait
-import software.amazon.smithy.codegen.core.CodegenException
-import software.amazon.smithy.model.Model
-import software.amazon.smithy.model.knowledge.ServiceIndex
-import software.amazon.smithy.model.shapes.ServiceShape
-import software.amazon.smithy.model.shapes.ShapeId
-import software.amazon.smithy.model.traits.Trait
 import software.amazon.smithy.rust.codegen.smithy.ServerCodegenContext
-import software.amazon.smithy.rust.codegen.smithy.generators.protocol.ProtocolGenerator
 import software.amazon.smithy.rust.codegen.smithy.protocols.AwsJsonVersion
-import software.amazon.smithy.rust.codegen.smithy.protocols.ProtocolGeneratorFactory
+import software.amazon.smithy.rust.codegen.smithy.protocols.ProtocolLoader
 import software.amazon.smithy.rust.codegen.smithy.protocols.ProtocolMap
 
-/*
- * Protocol dispatcher, responsible for protocol selection.
- */
-class ServerProtocolLoader(private val supportedProtocols: ProtocolMap<ServerCodegenContext>) {
-    fun protocolFor(
-        model: Model,
-        serviceShape: ServiceShape,
-    ): Pair<ShapeId, ProtocolGeneratorFactory<ProtocolGenerator, ServerCodegenContext>> {
-        val protocols: MutableMap<ShapeId, Trait> = ServiceIndex.of(model).getProtocols(serviceShape)
-        val matchingProtocols =
-            protocols.keys.mapNotNull { protocolId -> supportedProtocols[protocolId]?.let { protocolId to it } }
-        if (matchingProtocols.isEmpty()) {
-            throw CodegenException("No matching protocol — service offers: ${protocols.keys}. We offer: ${supportedProtocols.keys}")
-        }
-        val pair = matchingProtocols.first()
-        return Pair(pair.first, pair.second)
-    }
+class ServerProtocolLoader(supportedProtocols: ProtocolMap<ServerCodegenContext>) :
+    ProtocolLoader<ServerCodegenContext>(supportedProtocols) {
 
     companion object {
         val DefaultProtocols = mapOf(
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/protocols/Protocol.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/protocols/Protocol.kt
index 10537993c..63a8569f3 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/protocols/Protocol.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/protocols/Protocol.kt
@@ -100,7 +100,7 @@ interface ProtocolGeneratorFactory<out T : ProtocolGenerator, C : CoreCodegenCon
     fun support(): ProtocolSupport
 }
 
-class ProtocolLoader<C : CoreCodegenContext>(private val supportedProtocols: ProtocolMap<C>) {
+open class ProtocolLoader<C : CoreCodegenContext>(private val supportedProtocols: ProtocolMap<C>) {
     fun protocolFor(
         model: Model,
         serviceShape: ServiceShape,
-- 
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