Add API to get the language in which a symbol is defined and the symbol provider for a source file

Sources/IndexStoreDB/IndexStoreDB.swift

@@ -35,6 +35,11 @@ public struct PathMapping {
   }
 }
 
+public enum SymbolProviderKind {
+  case clang
+  case swift
+}
+
 /// IndexStoreDB index.
 public final class IndexStoreDB {
 
@@ -148,13 +153,18 @@ public final class IndexStoreDB {
     return indexstoredb_index_remove_unit_out_file_paths(impl, cPaths, cPaths.count, waitForProcessing)
   }
 
+  /// Invoke `body` with every occurrance of `usr` in one of the specified roles.
+  ///
+  /// Stop iteration if `body` returns `false`.
+  /// - Returns: `false` if iteration was terminated by `body` returning `true` or `true` if iteration finished.
   @discardableResult
   public func forEachSymbolOccurrence(byUSR usr: String, roles: SymbolRole, _ body: @escaping (SymbolOccurrence) -> Bool) -> Bool {
     return indexstoredb_index_symbol_occurrences_by_usr(impl, usr, roles.rawValue) { occur in
       return body(SymbolOccurrence(occur))
     }
   }
 
+  /// Returns all occurrences of `usr` in one of the specified roles.
   public func occurrences(ofUSR usr: String, roles: SymbolRole) -> [SymbolOccurrence] {
     var result: [SymbolOccurrence] = []
     forEachSymbolOccurrence(byUSR: usr, roles: roles) { occur in
@@ -275,6 +285,41 @@ public final class IndexStoreDB {
     return result
   }
 
+  public func symbolProvider(for sourceFilePath: String) -> SymbolProviderKind? {
+    var result: SymbolProviderKind? = nil
+    indexstoredb_index_units_containing_file(impl, sourceFilePath) { unit in
+      let providerKind: SymbolProviderKind? = switch indexstoredb_unit_info_symbol_provider_kind(unit) {
+      case INDEXSTOREDB_SYMBOL_PROVIDER_KIND_SWIFT:
+        .swift
+      case INDEXSTOREDB_SYMBOL_PROVIDER_KIND_CLANG:
+        .clang
+      case INDEXSTOREDB_SYMBOL_PROVIDER_KIND_UNKNOWN:
+        nil
+      default:
+        preconditionFailure("Unknown enum case in indexstoredb_symbol_provider_kind_t")
+      }
+
+      let mainFilePath = String(cString: indexstoredb_unit_info_main_file_path(unit))
+      if providerKind == .swift && mainFilePath != sourceFilePath {
+        // We have a unit that is "included" from Swift. This happens for header
+        // files that Swift files depend on. But Swift doesn't have includes and
+        // we shouldn't infer the header file's language to Swift based on this unit.
+        // Ignore it.
+        return true
+      }
+
+      if result == nil {
+        result = providerKind
+      } else if result != providerKind {
+        // Found two conflicting provider kinds. Return nil as we don't know the provider in this case.
+        result = nil
+        return false
+      }
+      return true
+    }
+    return result
+  }
+
   @discardableResult
   public func foreachFileIncludedByFile(path: String, body: @escaping (String) -> Bool) -> Bool {
     return indexstoredb_index_files_included_by_file(impl, path) { targetPath, line in

Sources/IndexStoreDB/Symbol.swift

@@ -45,18 +45,33 @@ public enum IndexSymbolKind: Hashable {
   case commentTag
 }
 
+public enum Language: Hashable {
+  case c
+  case cxx
+  case objc
+  case swift
+}
+
 public struct Symbol: Equatable {
 
   public var usr: String
   public var name: String
   public var kind: IndexSymbolKind
   public var properties: SymbolProperty
+  public var language: Language
 
-  public init(usr: String, name: String, kind: IndexSymbolKind, properties: SymbolProperty = SymbolProperty()) {
+  public init(
+    usr: String,
+    name: String,
+    kind: IndexSymbolKind,
+    properties: SymbolProperty = SymbolProperty(),
+    language: Language
+  ) {
     self.usr = usr
     self.name = name
     self.kind = kind
     self.properties = properties
+    self.language = language
   }
 }
 
@@ -69,9 +84,9 @@ extension Symbol: Comparable {
 extension Symbol: CustomStringConvertible {
   public var description: String {
     if properties.isEmpty {
-      return "\(name) | \(kind) | \(usr)"
+      return "\(name) | \(kind) | \(usr) | \(language)"
     }
-    return "\(name) | \(kind) (\(properties)) | \(usr)"
+    return "\(name) | \(kind) (\(properties)) | \(usr) | \(language)"
   }
 }
 
@@ -82,9 +97,16 @@ extension Symbol {
     name: String? = nil,
     usr: String? = nil,
     kind: IndexSymbolKind? = nil,
-    properties: SymbolProperty? = nil) -> Symbol
-  {
-    return Symbol(usr: usr ?? self.usr, name: name ?? self.name, kind: kind ?? self.kind, properties: properties ?? self.properties)
+    properties: SymbolProperty? = nil,
+    language: Language? = nil
+  ) -> Symbol {
+    return Symbol(
+      usr: usr ?? self.usr,
+      name: name ?? self.name,
+      kind: kind ?? self.kind,
+      properties: properties ?? self.properties,
+      language: language ?? self.language
+    )
   }
 
   /// Returns a SymbolOccurrence with the given location and roles.
@@ -95,6 +117,23 @@ extension Symbol {
 
 // MARK: CIndexStoreDB conversions
 
+fileprivate extension Language {
+  init(_ value: indexstoredb_language_t) {
+    switch value {
+    case INDEXSTOREDB_LANGUAGE_C:
+      self = .c
+    case INDEXSTOREDB_LANGUAGE_CXX:
+      self = .cxx
+    case INDEXSTOREDB_LANGUAGE_OBJC:
+      self = .objc
+    case INDEXSTOREDB_LANGUAGE_SWIFT:
+      self = .swift
+    default:
+      preconditionFailure("Unhandled case from C enum indexstoredb_language_t")
+    }
+  }
+}
+
 extension Symbol {
 
   /// Note: `value` is expected to be passed +1.
@@ -103,7 +142,9 @@ extension Symbol {
       usr: String(cString: indexstoredb_symbol_usr(value)),
       name: String(cString: indexstoredb_symbol_name(value)),
       kind: IndexSymbolKind(indexstoredb_symbol_kind(value)),
-      properties: SymbolProperty(rawValue: indexstoredb_symbol_properties(value)))
+      properties: SymbolProperty(rawValue: indexstoredb_symbol_properties(value)),
+      language: Language(indexstoredb_symbol_language(value))
+    )
   }
 }