Enable shapes-only codegen

This adds an alternative generation mode that only generates "data
shapes".

Author: JordonPhillips

README.md

@@ -28,7 +28,7 @@ This repository does *not* contain any generated clients, such as for S3 or othe
 AWS services. Rather, these are the tools that facilitate the generation of those
 clients and non-AWS Smithy clients.
 
-### How do I use this?
+### How do I use this to create a client?
 
 The first step is to create a Smithy package. If this is your first time working
 with Smithy, follow [this quickstart guide](https://smithy.io/2.0/quickstart.html)
@@ -82,9 +82,9 @@ this file, see the
     "sources": ["model"],
     "maven": {
         "dependencies": [
-            "software.amazon.smithy:smithy-model:[1.34.0,2.0)",
-            "software.amazon.smithy:smithy-aws-traits:[1.34.0,2.0)",
-            "software.amazon.smithy.python:smithy-python-codegen:0.1.0"
+            "software.amazon.smithy:smithy-model:[1.54.0,2.0)",
+            "software.amazon.smithy:smithy-aws-traits:[1.54.0,2.0)",
+            "software.amazon.smithy.python.codegen:core:0.0.1"
         ]
     },
     "projections": {
@@ -175,6 +175,154 @@ Only for now. Once the generator has been published, the Smithy CLI will be able
 to run it without a separate Java installation. Similarly, once the python
 helper libraries have been published you won't need to install them locally.
 
+### How do I generate types for shapes without a client?
+
+If all you want are concrete Python classes for the shapes in your Smithy model,
+all you need to do is replace `python-client-codegen` with
+`python-type-codegen` when following the steps above. Your `smithy-build.json`
+would now look like:
+
+```json
+{
+    "version": "1.0",
+    "sources": ["model"],
+    "maven": {
+        "dependencies": [
+            "software.amazon.smithy:smithy-model:[1.54.0,2.0)",
+            "software.amazon.smithy.python.codegen.plugins:types:0.0.1"
+        ]
+    },
+    "projections": {
+        "shapes": {
+            "plugins": {
+                "python-type-codegen": {
+                    "service": "com.example#EchoService",
+                    "module": "echo",
+                    "moduleVersion": "0.0.1"
+                }
+            }
+        }
+    }
+}
+```
+
+The module with the generated shape classes can be found in
+`build/smithy/client/python-type-codegen` after you run `smithy-build`.
+
+Unlike when generating a client, a service shape is not required for shape
+generation. If a service is not provided then every shape found in the model
+will be generated. Any naming conflicts may be resolved by using the
+[`renameShapes` transform](https://smithy.io/2.0/guides/smithy-build-json.html#renameshapes)
+(or renaming the shapes in the model of course).
+
+The set of shapes generated can also be constrained by using the
+[`includeShapesBySelector` transform](https://smithy.io/2.0/guides/smithy-build-json.html#includeshapesbyselector).
+For example, to generate only shapes within the `com.example` namespace:
+
+```json
+{
+    "version": "1.0",
+    "sources": ["model"],
+    "maven": {
+        "dependencies": [
+            "software.amazon.smithy:smithy-model:[1.54.0,2.0)",
+            "software.amazon.smithy.python.codegen.plugins:types:0.0.1"
+        ]
+    },
+    "projections": {
+        "shapes": {
+            "transforms": [
+                {
+                    "name": "includeShapesBySelector",
+                    "args": {
+                        "selector": "[id|namespace = 'com.example']"
+                    }
+                }
+            ],
+            "plugins": {
+                "python-type-codegen": {
+                    "module": "echo",
+                    "moduleVersion": "0.0.1"
+                }
+            }
+        }
+    }
+}
+```
+
+Input and output shapes (shapes with the `@input` or `@output` traits and
+operation inputs / outputs created as part of an operation definition) are not
+generated by default. To generate these shapes anyway, remove the traits with
+the
+[`excludeTraits` transform](https://smithy.io/2.0/guides/smithy-build-json.html#excludetraits):
+
+```json
+{
+    "version": "1.0",
+    "sources": ["model"],
+    "maven": {
+        "dependencies": [
+            "software.amazon.smithy:smithy-model:[1.54.0,2.0)",
+            "software.amazon.smithy.python.codegen.plugins:types:0.0.1"
+        ]
+    },
+    "projections": {
+        "shapes": {
+            "transforms": [
+                {
+                    "name": "excludeTraits",
+                    "args": {
+                        "traits": ["input", "output"]
+                    }
+                }
+            ],
+            "plugins": {
+                "python-type-codegen": {
+                    "module": "echo",
+                    "moduleVersion": "0.0.1"
+                }
+            }
+        }
+    }
+}
+```
+
+You can also generate both a client package and a shape package in one build,
+but they won't depend on each other. To do this, just add both plugins in the
+projection, or create a projection for each plugin. Below is an example showing
+both plugins in one projection:
+
+```json
+{
+    "version": "1.0",
+    "sources": ["model"],
+    "maven": {
+        "dependencies": [
+            "software.amazon.smithy:smithy-model:[1.54.0,2.0)",
+            "software.amazon.smithy:smithy-aws-traits:[1.54.0,2.0)",
+            "software.amazon.smithy.python.codegen:core:0.0.1",
+            "software.amazon.smithy.python.codegen.plugins:types:0.0.1"
+        ]
+    },
+    "projections": {
+        "client": {
+            "plugins": {
+                "python-client-codegen": {
+                    "service": "com.example#EchoService",
+                    "module": "echo",
+                    "moduleVersion": "0.0.1"
+                },
+                "python-type-codegen": {
+                    "service": "com.example#EchoService",
+                    "module": "echo",
+                    "moduleVersion": "0.0.1"
+                }
+            }
+        }
+    }
+}
+```
+
 ### Core Modules and Interfaces
 
 * `smithy-core` provides transport-agnostic core modules and interfaces

codegen/build.gradle.kts

@@ -15,5 +15,5 @@
 
 allprojects {
     group = "software.amazon.smithy.python"
-    version = "0.1.0"
+    version = "0.0.1"
 }

codegen/buildSrc/src/main/kotlin/smithy-python.codegen-plugin-conventions.gradle.kts

@@ -0,0 +1,35 @@
+import org.gradle.api.Project
+
+plugins {
+    id("smithy-python.module-conventions")
+    id("smithy-python.integ-test-conventions")
+}
+
+// Workaround per: https://github.com/gradle/gradle/issues/15383
+val Project.libs get() = the<org.gradle.accessors.dm.LibrariesForLibs>()
+
+group = "software.amazon.smithy.python.codegen.plugins"
+
+dependencies {
+    implementation(libs.smithy.codegen)
+    implementation(project(":core"))
+
+    // Avoid circular dependency in codegen core
+    if (project.name != "core") {
+        api(project(":core"))
+    }
+}
+
+val generatedSrcDir = layout.buildDirectory.dir("generated-src").get()
+
+// Add generated sources to integration test sources
+sourceSets {
+    named("it") {
+        java {
+            srcDir(generatedSrcDir)
+        }
+    }
+}
+
+// Ensure integ tests are executed as part of test suite
+tasks["test"].finalizedBy("integ")