Make ConfigSchemaGen as a subcommand of sourcekit-lsp-dev-utils

SourceKitLSPDevUtils/Sources/ConfigSchemaGen/JSONSchema.swift

@@ -0,0 +1,126 @@
+@propertyWrapper
+final class HeapBox<T> {
+  var wrappedValue: T
+  init(wrappedValue: T) {
+    self.wrappedValue = wrappedValue
+  }
+}
+
+/// JSON Schema representation for version draft-07
+/// https://json-schema.org/draft-07/draft-handrews-json-schema-01
+///
+/// NOTE: draft-07 is the latest version of JSON Schema that is supported by
+/// most of the tools. We may need to update this schema in the future.
+struct JSONSchema: Encodable {
+  enum CodingKeys: String, CodingKey {
+    case _schema = "$schema"
+    case id = "$id"
+    case comment = "$comment"
+    case title
+    case type
+    case description
+    case properties
+    case required
+    case `enum`
+    case items
+    case additionalProperties
+    case markdownDescription
+    case markdownEnumDescriptions
+  }
+  var _schema: String?
+  var id: String?
+  var comment: String?
+  var title: String?
+  var type: String?
+  var description: String?
+  var properties: [String: JSONSchema]?
+  var required: [String]?
+  var `enum`: [String]?
+  @HeapBox
+  var items: JSONSchema?
+  @HeapBox
+  var additionalProperties: JSONSchema?
+
+  /// VSCode extension: Markdown formatted description for rich hover
+  /// https://github.com/microsoft/vscode-wiki/blob/main/Setting-Descriptions.md
+  var markdownDescription: String?
+  /// VSCode extension: Markdown formatted descriptions for rich hover for enum values
+  /// https://github.com/microsoft/vscode-wiki/blob/main/Setting-Descriptions.md
+  var markdownEnumDescriptions: [String: String]?
+
+  func encode(to encoder: any Encoder) throws {
+    // Manually implement encoding to use `encodeIfPresent` for HeapBox-ed fields
+    var container = encoder.container(keyedBy: CodingKeys.self)
+    try container.encodeIfPresent(_schema, forKey: ._schema)
+    try container.encodeIfPresent(id, forKey: .id)
+    try container.encodeIfPresent(comment, forKey: .comment)
+    try container.encodeIfPresent(title, forKey: .title)
+    try container.encodeIfPresent(type, forKey: .type)
+    try container.encodeIfPresent(description, forKey: .description)
+    if let properties = properties, !properties.isEmpty {
+      try container.encode(properties, forKey: .properties)
+    }
+    if let required = required, !required.isEmpty {
+      try container.encode(required, forKey: .required)
+    }
+    try container.encodeIfPresent(`enum`, forKey: .enum)
+    try container.encodeIfPresent(items, forKey: .items)
+    try container.encodeIfPresent(additionalProperties, forKey: .additionalProperties)
+    try container.encodeIfPresent(markdownDescription, forKey: .markdownDescription)
+    if let markdownEnumDescriptions, !markdownEnumDescriptions.isEmpty {
+      try container.encode(markdownEnumDescriptions, forKey: .markdownEnumDescriptions)
+    }
+  }
+}
+
+struct JSONSchemaBuilder {
+  let context: OptionSchemaContext
+
+  func build(from typeSchema: OptionTypeSchama) throws -> JSONSchema {
+    var schema = try buildJSONSchema(from: typeSchema)
+    schema._schema = "http://json-schema.org/draft-07/schema#"
+    return schema
+  }
+
+  private func buildJSONSchema(from typeSchema: OptionTypeSchama) throws -> JSONSchema {
+    var schema = JSONSchema()
+    switch typeSchema.kind {
+    case .boolean: schema.type = "boolean"
+    case .integer: schema.type = "integer"
+    case .number: schema.type = "number"
+    case .string: schema.type = "string"
+    case .array(value: let value):
+      schema.type = "array"
+      schema.items = try buildJSONSchema(from: value)
+    case .dictionary(value: let value):
+      schema.type = "object"
+      schema.additionalProperties = try buildJSONSchema(from: value)
+    case .object(let object):
+      schema.type = "object"
+      var properties: [String: JSONSchema] = [:]
+      var required: [String] = []
+      for property in object.properties {
+        let propertyType = property.type
+        var propertySchema = try buildJSONSchema(from: propertyType)
+        propertySchema.description = property.description
+        // As we usually use Markdown syntax for doc comments, set `markdownDescription`
+        // too for better rendering in VSCode.
+        propertySchema.markdownDescription = property.description
+        properties[property.name] = propertySchema
+        if !propertyType.isOptional {
+          required.append(property.name)
+        }
+      }
+      schema.properties = properties
+      schema.required = required
+    case .enum(let enumInfo):
+      schema.type = "string"
+      schema.enum = enumInfo.cases.map(\.name)
+      // Set `markdownEnumDescriptions` for better rendering in VSCode rich hover
+      // Unlike `description`, `enumDescriptions` field is not a part of JSON Schema spec,
+      // so we only set `markdownEnumDescriptions` here.
+      schema.markdownEnumDescriptions = enumInfo.cases.reduce(into: [:]) { $0[$1.name] = $1.description }
+    }
+    return schema
+  }
+}