Add xml.inlayHint.enabled setting and documentation

README.md

@@ -49,6 +49,8 @@ This VS Code extension provides support for creating and editing XML documents,
   * [Minify XML](https://github.com/redhat-developer/vscode-xml/blob/main/docs/Commands.md#minify-xml-document)
   * [Generate XML from Grammar](https://github.com/redhat-developer/vscode-xml/blob/main/docs/GenerateXMLFromGrammar.md#generate-xml-from-grammar)
   * [Generate Schema from XML](https://github.com/redhat-developer/vscode-xml/blob/main/docs/BindingWithGrammar.md#binding-with-new-grammar)
+  * *[Code Lens](https://github.com/redhat-developer/vscode-xml/blob/main/docs/CodeLens.md) when `xml.codeLens.enabled` is enabled*
+  * *[Inlay Hints](https://github.com/redhat-developer/vscode-xml/blob/main/docs/InlayHint.md) when `xml.inlayHint.enabled` is enabled*
 
 See the [changelog](CHANGELOG.md) for the latest release.
 
@@ -100,6 +102,7 @@ The following settings are supported:
 * `xml.autoCloseTags.enabled` : Enable/disable autoclosing of XML tags. Default is `true`.
   **IMPORTANT**: The following settings must be turned of for this to work: `editor.autoClosingTags`, `editor.autoClosingBrackets`.
 * [`xml.codeLens.enabled`](https://github.com/redhat-developer/vscode-xml/blob/main/docs/CodeLens.md): Enable/disable XML CodeLens. Default is `false`.
+* [`xml.inlayHint.enabled`](https://github.com/redhat-developer/vscode-xml/blob/main/docs/InlayHint.md): Enable/disable XML Inlay Hints (default values, attribute types, element types). Default is `false`.
 * [`xml.preferences.showSchemaDocumentationType`](https://github.com/redhat-developer/vscode-xml/blob/main/docs/Preferences.md#documentation-type): Specifies the source of the XML schema documentation displayed on hover and completion. Default is `all`.
 * [`xml.validation.enabled`](https://github.com/redhat-developer/vscode-xml/blob/main/docs/Validation.md): Enable/disable all validation. Default is `true`.
  * [`xml.validation.namespaces.enabled`](https://github.com/redhat-developer/vscode-xml/blob/main/docs/Validation.md#xmlvalidationsnamespacesenabled): Enable/disable namespaces validation. Default is `always`. Ignored if [`xml.validation.enabled`](https://github.com/redhat-developer/vscode-xml/blob/main/docs/Validation.md) is set to `false`.

docs/InlayHint.md

@@ -0,0 +1,123 @@
+
+## Inlay Hint
+
+Inlay hints display grammar-derived information directly in the editor to help you understand the structure of your XML documents without having to look at the schema.
+
+To enable inlay hints, set `xml.inlayHint.enabled` to `true` (default is `false`).
+
+There are three kinds of inlay hints, each controlled by its own setting:
+
+| Setting | Default | Description |
+|---------|---------|-------------|
+| `xml.inlayHint.enabled` | `false` | Enable/disable XML inlay hints |
+| `xml.inlayHint.showDefaultValue` | `true` | Show default attribute values from the grammar |
+| `xml.inlayHint.showAttributeType` | `true` | Show attribute types (e.g., `: xs:integer`) |
+| `xml.inlayHint.showElementType` | `true` | Show element types (e.g., `: xs:boolean`) |
+
+Types equal to `xs:string` are automatically filtered out as they are too common to be informative.
+
+### Default attribute values
+
+When an XML file is bound to a grammar (XSD, DTD) that defines `default` or `fixed` attribute values, inlay hints show these values next to the element's start tag for attributes that are not explicitly set.
+
+For example, given the following XSD (`form.xsd`):
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
+    <xs:element name="form">
+        <xs:complexType>
+            <xs:sequence>
+                <xs:element name="input" type="inputType" maxOccurs="unbounded" />
+            </xs:sequence>
+            <xs:attribute name="lang" type="xs:string" default="en" />
+            <xs:attribute name="method" type="xs:string" default="GET" />
+            <xs:attribute name="maxRetries" type="xs:int" />
+            <xs:attribute name="debug" type="xs:boolean" default="false" />
+        </xs:complexType>
+    </xs:element>
+    <xs:complexType name="inputType">
+        <xs:attribute name="name" type="xs:string" />
+        <xs:attribute name="type" type="xs:string" default="text" />
+        <xs:attribute name="maxLength" type="xs:integer" />
+        <xs:attribute name="required" type="xs:boolean" default="false" />
+    </xs:complexType>
+</xs:schema>
+```
+
+And the following XML (`form.xml`):
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<form
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="form.xsd"
+    maxRetries="3">
+    <input name="username" />
+    <input name="email" maxLength="255" required="true" />
+</form>
+```
+
+Inlay hints for default attribute values will appear:
+
+- On `<form>`: `lang="en"`, `method="GET"`, `debug="false"`
+- On `<input name="username" />`: `type="text"`, `required="false"`
+- On `<input name="email" ...>`: `type="text"` (but not `required` since it is explicitly set)
+
+![XSD default attribute value inlay hints](./images/InlayHint/InlayHintDefaultValueXSD.png)
+
+Default attribute values defined in DTD `ATTLIST` declarations are also shown.
+
+Given the following DTD (`note.dtd`):
+
+```dtd
+<!ELEMENT note (#PCDATA)>
+<!ATTLIST note
+    status CDATA "draft"
+    priority CDATA "normal">
+```
+
+And the following XML (`note.xml`):
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE note SYSTEM "note.dtd">
+<note>Remember to review the inlay hint PR.</note>
+```
+
+Inlay hints `status="draft"` and `priority="normal"` will appear after the `note` tag name.
+
+![DTD default attribute value inlay hints](./images/InlayHint/InlayHintDefaultValueDTD.png)
+
+### Attribute types
+
+When enabled, attribute type hints show the XSD type of each attribute after the attribute name (before the `=` sign).
+
+Using the same `form.xsd` and `form.xml` above, the following attribute type hints are shown:
+
+- `maxRetries` → `: xs:int`
+- `maxLength` → `: xs:integer`
+- `required` → `: xs:boolean`
+- `lang`, `method`, `name`, `type` → no type hint (`xs:string` is filtered out)
+
+![Attribute type inlay hints](./images/InlayHint/InlayHintAttributeType.png)
+
+### Element types
+
+When enabled, element type hints show the XSD type of each element after the element tag name.
+
+Using the same `form.xsd` and `form.xml` above, the following element type hints are shown:
+
+- `<input>` → `: inputType`
+- `<form>` → no type hint (anonymous complex type, no named type)
+
+![Element type inlay hints](./images/InlayHint/InlayHintElementType.png)
+
+Elements with anonymous (inline) complex types do not show a type hint, since they have no named type.
+
+### Settings
+
+- `xml.inlayHint.enabled`: Enable/disable XML inlay hints. Default is `false`.
+- `xml.inlayHint.showDefaultValue`: Show default attribute values from grammar. Default is `true`.
+- `xml.inlayHint.showAttributeType`: Show attribute types. Default is `true`.
+- `xml.inlayHint.showElementType`: Show element types. Default is `true`.

docs/Preferences.md

@@ -136,6 +136,10 @@ See the [Formatting page](Formatting.md#formatting).
 
 Use `xml.codeLens.enabled` in order to enable or disable code lens. Please see [the Code Lens page](CodeLens.md#code-lens) for more information.
 
+## Inlay Hint
+
+Use `xml.inlayHint.enabled` to enable inlay hints (default is `false`). Once enabled, use `xml.inlayHint.showDefaultValue`, `xml.inlayHint.showAttributeType`, and `xml.inlayHint.showElementType` to control individual inlay hint features. Please see [the Inlay Hint page](InlayHint.md#inlay-hint) for more information.
+
 ## Tag Auto Closing
 
 The closing tags for elements should automatically be added when typing `>` to complete an opening tag.

package.json

@@ -709,6 +709,26 @@
           "default": false,
           "markdownDescription": "Enable/disable XML CodeLens. Default is `false`. See [here](command:xml.open.docs?%5B%7B%22page%22%3A%22CodeLens%22%2C%22section%22%3A%22Code%20Lens%22%7D%5D) for information about CodeLens features"
         },
+        "xml.inlayHint.enabled": {
+          "type": "boolean",
+          "default": false,
+          "markdownDescription": "Enable/disable XML inlay hints. Default is `false`. See [here](command:xml.open.docs?%5B%7B%22page%22%3A%22InlayHint%22%2C%22section%22%3A%22Inlay%20Hint%22%7D%5D) for more information."
+        },
+        "xml.inlayHint.showDefaultValue": {
+          "type": "boolean",
+          "default": true,
+          "markdownDescription": "Show default attribute values defined by the grammar (XSD, DTD) as inlay hints. Default is `true`. See [here](command:xml.open.docs?%5B%7B%22page%22%3A%22InlayHint%22%2C%22section%22%3A%22Inlay%20Hint%22%7D%5D) for more information."
+        },
+        "xml.inlayHint.showAttributeType": {
+          "type": "boolean",
+          "default": true,
+          "markdownDescription": "Show the type of XML attributes (e.g., `: xs:integer`) as inlay hints after the attribute name. Types equal to `xs:string` are filtered out. Default is `true`. See [here](command:xml.open.docs?%5B%7B%22page%22%3A%22InlayHint%22%2C%22section%22%3A%22Inlay%20Hint%22%7D%5D) for more information."
+        },
+        "xml.inlayHint.showElementType": {
+          "type": "boolean",
+          "default": true,
+          "markdownDescription": "Show the type of XML elements (e.g., `: xs:integer`) as inlay hints before the closing `>` of the start tag. Types equal to `xs:string` are filtered out. Default is `true`. See [here](command:xml.open.docs?%5B%7B%22page%22%3A%22InlayHint%22%2C%22section%22%3A%22Inlay%20Hint%22%7D%5D) for more information."
+        },
         "xml.semanticTokens.enabled": {
           "type": "boolean",
           "default": true,