パスの先頭部分を書き換える機能の追加

Sources/TypeScriptAST/Component/PathPrefixReplacement.swift

@@ -0,0 +1,41 @@
+import Foundation
+
+public struct PathPrefixReplacement {
+    public init(
+        path: URL,
+        replacement: String
+    ) {
+        self.path = path
+        self.replacement = replacement
+    }
+
+    public var path: URL
+    public var replacement: String
+
+    public func replace(path: URL) -> URL? {
+        let base = self.path.absoluteURL.standardized.pathComponents
+        let full = path.absoluteURL.standardized.pathComponents
+
+        guard full.starts(with: base) else {
+            return nil
+        }
+
+        let delta = full[base.count...]
+
+        return URL(fileURLWithPath: replacement)
+            .appendingPathComponent(delta.joined(separator: "/"))
+    }
+}
+
+public typealias PathPrefixReplacements = [PathPrefixReplacement]
+
+extension PathPrefixReplacements {
+    public func replace(path: URL) -> URL? {
+        for x in self {
+            if let new = x.replace(path: path) {
+                return new
+            }
+        }
+        return nil
+    }
+}

Sources/TypeScriptAST/Dependency/AutoImport.swift

@@ -16,6 +16,7 @@ extension TSSourceFile {
         from: URL,
         symbolTable: SymbolTable,
         fileExtension: ImportFileExtension,
+        pathPrefixReplacements: PathPrefixReplacements = [],
         defaultFile: String? = nil
     ) throws -> [TSImportDecl] {
         var fileToSymbols = FileToSymbols()
@@ -65,6 +66,14 @@ extension TSSourceFile {
             let symbols = Set(fileToSymbols.symbols(for: file)).sorted()
             if symbols.isEmpty { continue }
 
+            var file = file
+
+            if let newPath = pathPrefixReplacements.replace(
+                path: URL(fileURLWithPath: file, relativeTo: from)
+            ) {
+                file = newPath.relativePath
+            }
+
             imports.append(
                 TSImportDecl(names: symbols, from: file)
             )

Tests/TypeScriptASTTests/AutoImportTests.swift

@@ -196,6 +196,71 @@ final class AutoImportTests: TestCaseBase {
         )
     }
 
+    func testAlias() throws {
+        let s = TSSourceFile([
+            TSTypeDecl(modifiers: [.export], name: "S", type: TSObjectType([]))
+        ])
+
+        let m = TSSourceFile([
+            TSTypeDecl(modifiers: [.export], name: "M", type: TSIdentType("S"))
+        ])
+
+        var symbols = SymbolTable()
+        symbols.add(source: s, file: URL(fileURLWithPath: "lib/foo/s.ts"))
+
+        let imports = try m.buildAutoImportDecls(
+            from: URL(fileURLWithPath: "m/m.ts"),
+            symbolTable: symbols,
+            fileExtension: .none,
+            pathPrefixReplacements: [
+                .init(path: URL(fileURLWithPath: "lib/foo"), replacement: "@foo")
+            ]
+        )
+        m.replaceImportDecls(imports)
+
+        assertPrint(
+            m, """
+            import { S } from "@foo/s";
+
+            export type M = S;
+
+            """
+        )
+    }
+
+    func testUnrelatedAlias() throws {
+        let s = TSSourceFile([
+            TSTypeDecl(modifiers: [.export], name: "S", type: TSObjectType([]))
+        ])
+
+        let m = TSSourceFile([
+            TSTypeDecl(modifiers: [.export], name: "M", type: TSIdentType("S"))
+        ])
+
+        var symbols = SymbolTable()
+        symbols.add(source: s, file: URL(fileURLWithPath: "s/s.ts"))
+
+        let imports = try m.buildAutoImportDecls(
+            from: URL(fileURLWithPath: "m/m.ts"),
+            symbolTable: symbols,
+            fileExtension: .none,
+            pathPrefixReplacements: [
+                .init(path: URL(fileURLWithPath: "lib/foo"), replacement: "@foo")
+            ]
+        )
+        m.replaceImportDecls(imports)
+
+        assertPrint(
+            m, """
+            import { S } from "../s/s";
+
+            export type M = S;
+
+            """
+        )
+    }
+
+
     func testDefaultImport() throws {
         let s = TSSourceFile([
             TSVarDecl(

Tests/TypeScriptASTTests/UtilsTests.swift

@@ -40,4 +40,34 @@ final class UtilsTests: XCTestCase {
             XCTAssertNil(u.baseURL)
         }
     }
+
+    func testPathPrefixReplace() throws {
+        let args: [(from: String, to: String, input: String, expect: String?, line: UInt)] = [
+            // full to full
+            ("/usr", "/foo", "/usr/lib", "/foo/lib", #line),
+            // full to rel
+            ("/usr", "foo", "/usr/lib", "foo/lib", #line),
+            ("/usr", "../foo", "/usr/lib", "../foo/lib", #line),
+            // rel to full
+            ("usr", "/foo", "usr/lib", "/foo/lib", #line),
+            ("../usr", "/foo", "../usr/lib", "/foo/lib", #line),
+            // rel to rel
+            ("usr", "foo", "usr/lib", "foo/lib", #line),
+            ("../usr", "foo", "../usr/lib", "foo/lib", #line),
+            // slash
+            ("/usr", "/foo", "/usr2/lib", nil, #line),
+        ]
+
+        for arg in args {
+            let replacement = PathPrefixReplacement(
+                path: URL(fileURLWithPath: arg.from), replacement: arg.to
+            )
+            let input = URL(fileURLWithPath: arg.input)
+            let expect = arg.expect.map { URL(fileURLWithPath: $0) }
+
+            let actual = replacement.replace(path: input)
+
+            XCTAssertEqual(actual, expect, file: #file, line: arg.line)
+        }
+    }
 }