add file include api

Sources/IndexStoreDB/IndexStoreDB.swift

@@ -238,6 +238,40 @@ public final class IndexStoreDB {
     }
     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
+        let targetPathStr = String(cString: targetPath)
+        return body(targetPathStr)
+    }
+  }
+
+  public func filesIncludedByFile(path: String) -> [String] {
+    var result: [String] = []
+    foreachFileIncludedByFile(path: path) { targetPath in
+        result.append(targetPath)
+        return true
+    }
+    return result
+  }
+
+  @discardableResult
+  public func foreachFileIncludingFile(path: String, body: @escaping (String) -> Bool) -> Bool {
+    return indexstoredb_index_files_including_file(impl, path) { sourcePath, line in
+        let sourcePathStr = String(cString: sourcePath)
+        return body(sourcePathStr)
+    }
+  }
+
+  public func filesIncludingFile(path: String) -> [String] {
+    var result: [String] = []
+    foreachFileIncludingFile(path: path) { targetPath in
+        result.append(targetPath)
+        return true
+      }
+      return result
+    }
 
   /// A recorded header `#include` from a unit file.
   public struct UnitIncludeEntry: Equatable {

Tests/IndexStoreDBTests/IndexTests.swift

@@ -299,6 +299,23 @@ final class IndexTests: XCTestCase {
       IndexStoreDB.UnitIncludeEntry(sourcePath: main1, targetPath: uniq1, line: ws.testLoc("include_main1_uniq1").line),
     ])
   }
+
+  func testFilesIncludes() throws {
+    guard let ws = try staticTibsTestWorkspace(name: "MainFiles") else { return }
+    try ws.buildAndIndex()
+    let index = ws.index
+
+    let main1 = ws.testLoc("main1").url.path
+    let main2 = ws.testLoc("main2").url.path
+    let uniq1 = ws.testLoc("uniq1").url.path
+    let shared = ws.testLoc("shared").url.path
+
+    let includedFiles = index.filesIncludedByFile(path: main1)
+    XCTAssertEqual(includedFiles, [shared, uniq1])
+
+    let includingFiles = index.filesIncludingFile(path: shared)
+    XCTAssertEqual(includingFiles, [main1, main2])
+  }
 
   func testAllSymbolNames() throws {
     guard let ws = try staticTibsTestWorkspace(name: "proj1") else { return }

include/CIndexStoreDB/CIndexStoreDB.h

@@ -138,6 +138,9 @@ typedef void(^indexstoredb_delegate_event_receiver_t)(_Nonnull indexstoredb_dele
 /// Returns true to continue.
 typedef bool(^indexstoredb_unit_info_receiver)(_Nonnull indexstoredb_unit_info_t);
 
+/// Returns true to continue.
+typedef bool(^indexstoredb_file_includes_receiver)(const char *_Nonnull sourcePath, size_t line);
+
 /// Returns true to continue.
 typedef bool(^indexstoredb_unit_includes_receiver)(const char *_Nonnull sourcePath, const char *_Nonnull targetPath, size_t line);
 
@@ -385,6 +388,30 @@ indexstoredb_index_units_containing_file(
   const char *_Nonnull path,
   _Nonnull indexstoredb_unit_info_receiver receiver);
 
+/// Return the file path which included by a given file path.
+///
+/// \param index An IndexStoreDB object which contains the symbols.
+/// \param path The source file to search for.
+/// \param receiver A function to be called for each include file path. The pointers are only valid for
+/// the duration of the call. The function should return a true to continue iterating.
+INDEXSTOREDB_PUBLIC bool
+indexstoredb_index_files_included_by_file(
+  _Nonnull indexstoredb_index_t index,
+  const char *_Nonnull path,
+  _Nonnull indexstoredb_file_includes_receiver receiver);
+
+/// Return the file path which including a given header.
+///
+/// \param index An IndexStoreDB object which contains the symbols.
+/// \param path The source file to search for.
+/// \param receiver A function to be called for each include file path. The pointers are only valid for
+/// the duration of the call. The function should return a true to continue iterating.
+INDEXSTOREDB_PUBLIC bool
+indexstoredb_index_files_including_file(
+  _Nonnull indexstoredb_index_t index,
+  const char *_Nonnull path,
+  _Nonnull indexstoredb_file_includes_receiver receiver);
+
 /// Iterates over recorded `#include`s of a unit.
 ///
 /// \param index An IndexStoreDB object which contains the symbols.

lib/CIndexStoreDB/CIndexStoreDB.cpp

@@ -431,6 +431,30 @@ indexstoredb_index_units_containing_file(
   });
 }
 
+bool
+indexstoredb_index_files_included_by_file(
+  indexstoredb_index_t index,
+  const char *path,
+  indexstoredb_file_includes_receiver receiver)
+{
+  auto obj = (Object<std::shared_ptr<IndexSystem>> *)index;
+  return obj->value->foreachFileIncludedByFile(path, [&](const CanonicalFilePathRef &sourcePath, unsigned line) -> bool {
+    return receiver(sourcePath.getPath().str().c_str(), line);
+  });
+}
+
+bool
+indexstoredb_index_files_including_file(
+  indexstoredb_index_t index,
+  const char *path,
+  indexstoredb_file_includes_receiver receiver)
+{
+  auto obj = (Object<std::shared_ptr<IndexSystem>> *)index;
+  return obj->value->foreachFileIncludingFile(path, [&](const CanonicalFilePathRef &sourcePath, unsigned line) -> bool {
+    return receiver(sourcePath.getPath().str().c_str(), line);
+  });
+}
+
 bool
 indexstoredb_index_includes_of_unit(
   indexstoredb_index_t index,