refactor(util): avoid repeated uri_base_name calls

When classifying URIs to see if they are .d.ts files or .tsx files, we
effectively call uri_base_name multiple times. This is ugly.

Combine classification into one step. This is a nicer interface in my
opinion and it avoids the duplicate uri_base_name issue.

Unfortunately, this change adds another inefficiency: we search for
.tsx even when it's unnecessary. I think this inefficiency is worth
the improved interface.

src/CMakeLists.txt

@@ -437,6 +437,8 @@ quick_lint_js_add_library(
   quick-lint-js/util/ascii.h
   quick-lint-js/util/binary-reader.h
   quick-lint-js/util/binary-writer.h
+  quick-lint-js/util/classify-path.cpp
+  quick-lint-js/util/classify-path.h
   quick-lint-js/util/cpp.h
   quick-lint-js/util/instance-tracker.h
   quick-lint-js/util/math-overflow.h

src/quick-lint-js/lsp/lsp-language.h

@@ -7,7 +7,7 @@
 #include <quick-lint-js/fe/linter.h>
 #include <quick-lint-js/port/char8.h>
 #include <quick-lint-js/util/algorithm.h>
-#include <quick-lint-js/util/uri.h>
+#include <quick-lint-js/util/classify-path.h>
 #include <string_view>
 
 namespace quick_lint_js {
@@ -84,10 +84,11 @@ struct LSP_Language {
       return nullptr;
     }
     if (lang->typescript_autodetect) {
-      if (uri_looks_like_typescript_definition(uri)) {
+      Path_Classification classified_uri = classify_uri(uri);
+      if (classified_uri.typescript_definition) {
         return &languages[5];
       }
-      if (uri_looks_like_typescript_jsx(uri)) {
+      if (classified_uri.typescript_jsx) {
         return &languages[8];
       }
     }

src/quick-lint-js/util/classify-path.cpp

@@ -0,0 +1,36 @@
+// Copyright (C) 2020  Matthew "strager" Glazar
+// See end of file for extended copyright information.
+
+#include <cstddef>
+#include <quick-lint-js/port/char8.h>
+#include <quick-lint-js/util/classify-path.h>
+#include <quick-lint-js/util/uri.h>
+
+namespace quick_lint_js {
+Path_Classification classify_uri(String8_View uri) {
+  // FIXME(strager): Should this unescape % encoding?
+  String8_View base_name = uri_base_name(uri);
+  return Path_Classification{
+      .typescript_definition = base_name.find(u8".d."_sv) != base_name.npos,
+      .typescript_jsx = base_name.find(u8".tsx"_sv) != base_name.npos,
+  };
+}
+}
+
+// quick-lint-js finds bugs in JavaScript programs.
+// Copyright (C) 2020  Matthew "strager" Glazar
+//
+// This file is part of quick-lint-js.
+//
+// quick-lint-js is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// quick-lint-js is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with quick-lint-js.  If not, see <https://www.gnu.org/licenses/>.

src/quick-lint-js/util/classify-path.h

@@ -0,0 +1,43 @@
+// Copyright (C) 2020  Matthew "strager" Glazar
+// See end of file for extended copyright information.
+
+#pragma once
+
+#include <quick-lint-js/port/char8.h>
+
+namespace quick_lint_js {
+struct Path_Classification {
+  // True if the path has '.d.' in the base name.
+  //
+  // This tries to emulate the logic of TypeScript's isDeclarationFileName
+  // function [1]. However, this does not require ".ts". It will be true for an
+  // URI such as u8"file:///test.d.js".
+  //
+  // [1]
+  // https://github.com/microsoft/TypeScript/blob/daa7e985f5adc972aa241e5b0761c7dc433e94bf/src/compiler/parser.ts#L10408
+  bool typescript_definition;
+
+  // True if the path's base name ends with '.tsx'.
+  bool typescript_jsx;
+};
+
+Path_Classification classify_uri(String8_View uri);
+}
+
+// quick-lint-js finds bugs in JavaScript programs.
+// Copyright (C) 2020  Matthew "strager" Glazar
+//
+// This file is part of quick-lint-js.
+//
+// quick-lint-js is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// quick-lint-js is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with quick-lint-js.  If not, see <https://www.gnu.org/licenses/>.

src/quick-lint-js/util/uri.h

@@ -10,19 +10,6 @@ namespace quick_lint_js {
 //
 // FIXME(strager): This function is not robust at all.
 String8_View uri_base_name(String8_View uri);
-
-// Returns true if the URI has '.d.' in the base name.
-//
-// This tries to emulate the logic of TypeScript's isDeclarationFileName
-// function [1]. However, this function does not require ".ts". It will return
-// true for an URI such as u8"file:///test.d.js".
-//
-// [1]
-// https://github.com/microsoft/TypeScript/blob/daa7e985f5adc972aa241e5b0761c7dc433e94bf/src/compiler/parser.ts#L10408
-bool uri_looks_like_typescript_definition(String8_View uri);
-
-// Returns true if the URI's base name ends with '.tsx'.
-bool uri_looks_like_typescript_jsx(String8_View uri);
 }
 
 // quick-lint-js finds bugs in JavaScript programs.

src/quick-lint-js/vscode/vscode-language.h

@@ -7,7 +7,7 @@
 #include <quick-lint-js/fe/linter.h>
 #include <quick-lint-js/port/char8.h>
 #include <quick-lint-js/util/algorithm.h>
-#include <quick-lint-js/util/uri.h>
+#include <quick-lint-js/util/classify-path.h>
 #include <string_view>
 
 namespace quick_lint_js {
@@ -73,7 +73,8 @@ struct VSCode_Language {
     if (lang->lint_options.typescript && !allow_typescript) {
       return nullptr;
     }
-    if (uri_looks_like_typescript_definition(uri)) {
+    Path_Classification classified_uri = classify_uri(uri);
+    if (classified_uri.typescript_definition) {
       return &ts_definition;
     }
     return lang;