Add IDL version 0.5.0

- Remove onVersion since LoaderVisitor is version independent
- Simplify ModelLoader and use InputStream. This commit simplifies
  ModelLoader to be a single class with static methods rather than a
  series of internal-only ModelLoader interfaces. Further, it converts
  model loading to using InputStreams rather than Strings so that files
  can be parsed and streamed directly from their source rather than first
  loaded into a string and then into a Model. We should follow up on this
  by making the SmithyModelLexer streaming too.
- Update specification for 0.5.0 IDL

aws/smithy-aws-traits/README.md

@@ -30,7 +30,7 @@ See the Smithy specification for details on how these traits are used.
 Example usage:
 
 ```smithy
-$version: "0.4.0"
+$version: "0.5.0"
 namespace ns.foo
 
 @aws.api#service(sdkId: "Some Value")

docs/source/spec/core.rst

@@ -87,22 +87,8 @@ Version compatibility
 
 A single version statement can appear in a model file. Different versions MAY
 be encountered when merging multiple model files together. Multiple versions
-are supported if and only if all of the version statements are compatible
-according to the following constraints:
-
-1. Each version MUST specify the same major version number. For example,
-   ``0.2.0`` and ``1.0.0`` are **not** compatible because they use different
-   major version numbers.
-2. When dealing with a major version of "0" (for example, ``0.2.0``), versions
-   that use the same minor version are considered compatible regardless of the
-   patch version. For example, if models are loaded that use a version of
-   ``0.2.0``, ``0.1.1``, and ``0.1.2``, then all of the models are considered
-   to be compatible. However, ``0.2.0`` and ``0.1.99`` are **not** compatible.
-3. When dealing with a major version of "1" or higher, all versions that use
-   the same major version number are considered compatible. For example, if
-   models are loaded that use a version of ``1.0.0``, ``1.0.1``, and
-   ``1.1.0``, then all of the models are considered to be compatible.
-   However, ``1.0.0`` and ``2.0.0`` are **not** compatible.
+are supported if and only if all of the version statements are supported by
+the tool loading the models.
 
 
 .. _metadata:
@@ -114,6 +100,8 @@ Model metadata
 to a model using a :ref:`metadata statement <metadata-statement>`. Metadata
 statements start with ``metadata``, followed by the key to set, followed by
 ``=``, followed by the JSON-like :ref:`node value <node-values>` to assign.
+Metadata statements MUST appear before any namespace statements or shapes
+are defined.
 
 .. tabs::
 
@@ -155,20 +143,18 @@ models without naming conflicts.
 
 A :ref:`namespace statement <namespace-statement>` is used to change the
 *current namespace*. A namespace MUST be defined before a shape can be
-defined. Any number of namespaces can appear in a model.
+defined. Only a single namespace can appear in an IDL model file, but any
+number of namespaces can appear in a JSON AST model file.
 
 The following example defines a string shape named ``MyString`` in the
-``smithy.example`` namespace and a string shape named ``MyString`` in the
-``another.example`` namespace:
+``smithy.example`` namespace:
 
 .. tabs::
 
     .. code-tab:: smithy
 
         namespace smithy.example
-        string MyString
 
-        namespace another.example
         string MyString
 
     .. code-tab:: json
@@ -178,9 +164,6 @@ The following example defines a string shape named ``MyString`` in the
             "shapes": {
                 "smithy.example#MyString": {
                     "type": "string"
-                },
-                "another.example#MyString": {
-                    "type": "string"
                 }
             }
         }
@@ -2378,30 +2361,21 @@ Consider the following metadata definition:
 
 .. code-block:: smithy
 
-    namespace smithy.example
-
     metadata foo = {
-        MyString: MyString,
+        String: String,
     }
 
-    string MyString
-
-The object key remains the same literal string value while the value is
-treated as a shape ID and resolves to the string literal
-``"smithy.example#MyString"``. This IDL model is equivalent to the
-following JSON AST model:
+The object key remains the same literal string value of ``String`` while the
+value is treated as a shape ID and resolves to the string literal
+``"smithy.api#String"``. This IDL model is equivalent to the following
+JSON AST model:
 
 .. code-block:: json
 
     {
         "smithy": "0.5.0",
-        "shapes": {
-            "smithy.example#MyString": {
-                "type": "string"
-            }
-        },
         "metadata": {
-            "MyString": "smithy.example#MyString"
+            "String": "smithy.api#String"
         }
     }
 

docs/source/spec/language-specification.rst

@@ -94,6 +94,7 @@ Version statement
 
 The version control statement is used to set the :ref:`version <smithy-version>`
 of a Smithy model file. The value of a version statement MUST be a string.
+Only a single version statement can appear in a model file.
 
 Example:
 
@@ -133,7 +134,27 @@ Example:
     metadata example.null = null
 
 Top-level metadata key-value pair conflicts are resolved by
-:ref:`merging metadata <merging-metadata>`
+:ref:`merging metadata <merging-metadata>`. Metadata statements MUST appear
+before any namespace statements or shapes are defined.
+
+
+.. _namespace-statement:
+
+Namespace statement
+-------------------
+
+The namespace statement is used to set the *current namespace*. Shapes
+can only be defined if a current namespace is defined. Only a single
+namespace can appear in an IDL model file.
+
+.. productionlist:: smithy
+    namespace_statement     :"namespace" `namespace`
+
+Example:
+
+::
+
+    namespace com.foo.baz
 
 
 .. _use-statement:
@@ -142,8 +163,9 @@ Use statement
 -------------
 
 A use statement is used to import shapes and traits into the current namespace
-so that they can be referred to using relative shape. A use statement MUST come
-before any shapes are defined in an IDL model file.
+so that they can be referred to using relative shape. A use statement MUST
+come after a :ref:`namespace statement <namespace-statement>` and before any
+shapes are defined in an IDL model file.
 
 .. productionlist:: smithy
     use_statement         :"use" `absolute_shape_id`
@@ -189,25 +211,6 @@ See :ref:`relative-shape-id` for an in-depth description of how relative
 shape IDs are resolved in the IDL.
 
 
-.. _namespace-statement:
-
-Namespace statement
--------------------
-
-The namespace statement is used to set the *current namespace*. Shapes
-can only be defined if a current namespace is defined. Any number of namespace
-statements can appear in a model.
-
-.. productionlist:: smithy
-    namespace_statement     :"namespace" `namespace`
-
-Example:
-
-::
-
-    namespace com.foo.baz
-
-
 Shape statements
 ----------------
 

smithy-model/src/main/java/software/amazon/smithy/model/loader/AstModelLoader.java

@@ -88,7 +88,6 @@ enum AstModelLoader {
     void load(ObjectNode model, StringNode version, LoaderVisitor visitor) {
         model.expectNoAdditionalProperties(TOP_LEVEL_PROPERTIES);
         visitor.onOpenFile(model.getSourceLocation().getFilename());
-        visitor.onVersion(version.getSourceLocation(), version.expectStringNode().getValue());
         loadMetadata(model, visitor);
         loadShapes(model, visitor);
     }

smithy-model/src/main/java/software/amazon/smithy/model/loader/DeprecatedAstModelLoader.java

@@ -94,8 +94,6 @@ void load(ObjectNode model, StringNode version, LoaderVisitor visitor) {
                        + "(" + version.getSourceLocation() + ")");
 
         visitor.onOpenFile(model.getSourceLocation().getFilename());
-        visitor.onVersion(version.getSourceLocation(), version.expectStringNode().getValue());
-
         try {
             model.getMember(METADATA).ifPresent(value -> {
                 ObjectNode metadata = value.expectObjectNode("`metadata` must be an object");