Support reading file from standard input

Fixes #263
Updates #275

Author: wgrr

docs/cli.adoc

@@ -57,6 +57,11 @@ See the "ERROR LISTS" section for a description of the format for _errors_.
 +
 Incompatible with *--lsp-server*.
 
+*--stdin*::
+  Read standard input as a JavaScript file.
++
+Incompatible with *--lsp-server*.
+
 *--lsp*::
 *--lsp-server*::
   Run *quick-lint-js* in LSP server mode.

docs/quick-lint-js.1

@@ -8,7 +8,7 @@
 '\" t
 .\"     Title: quick-lint-js
 .\"    Author: [see the "AUTHOR(S)" section]
-.\" Generator: Asciidoctor 2.0.10
+.\" Generator: Asciidoctor 2.0.12
 .\"    Manual: \ \&
 .\"    Source: quick-lint-js version 0.2.0
 .\"  Language: English
@@ -88,6 +88,13 @@ See the "ERROR LISTS" section for a description of the format for \fIerrors\fP.
 Incompatible with \fB\-\-lsp\-server\fP.
 .RE
 .sp
+\fB\-\-stdin\fP
+.RS 4
+Read standard input as a JavaScript file.
+.sp
+Incompatible with \fB\-\-lsp\-server\fP.
+.RE
+.sp
 \fB\-\-lsp\fP, \fB\-\-lsp\-server\fP
 .RS 4
 Run \fBquick\-lint\-js\fP in LSP server mode.
@@ -199,12 +206,14 @@ To lint a file called \fIlib/index.js\fP, writing error messages to the terminal
 .sp
 .if n .RS 4
 .nf
+.fam C
 $ \fBquick\-lint\-js\fP lib/index.js
 lib/index.js:1:20: error: variable used before declaration: language [E058]
 lib/index.js:2:7: note: variable declared here [E058]
 lib/index.js:3:1: error: assignment to const variable [E003]
 lib/index.js:1:7: note: const variable declared here [E003]
 lib/index.js:5:25: warning: use of undeclared variable: ocupation [E057]
+.fam
 .fi
 .if n .RE
 .br
@@ -217,11 +226,13 @@ To lint three files, writing machine\-readable messages to \fI/tmp/vim\-qflist.j
 .sp
 .if n .RS 4
 .nf
+.fam C
 $ \fBquick\-lint\-js\fP \-\-output\-format=vim\-qflist\-json \(rs
     \-\-vim\-bufnr=3 lib/pizza\-dough.js \(rs
     \-\-vim\-bufnr=4 lib/pizza\-sauce.js \(rs
     \-\-vim\-bufnr=6 lib/pineapple.js \(rs
     >/tmp/vim\-qflist.json
+.fam
 .fi
 .if n .RE
 .br
@@ -236,10 +247,12 @@ To lint a file called \fIbad.js\fP, but don\(cqt fail on use\-of\-undeclared\-va
 .sp
 .if n .RS 4
 .nf
+.fam C
 $ \fBquick\-lint\-js\fP \-\-exit\-fail\-on=\-E057 bad.js
 bad.js:5:25: warning: use of undeclared variable: $ [E057]
 $ echo $?
 0
+.fam
 .fi
 .if n .RE
 .br

src/file.cpp

@@ -211,6 +211,11 @@ read_file_result read_file(const char *path) {
   windows_handle_file file(handle);
   return read_file(path, file.ref());
 }
+
+read_file_result read_stdin() {
+  windows_handle_file_ref file(::GetStdHandle(STD_INPUT_HANDLE));
+  return read_file("<stdin>", file);
+}
 #endif
 
 #if defined(QLJS_FILE_POSIX)
@@ -224,6 +229,11 @@ read_file_result read_file(const char *path) {
   posix_fd_file file(fd);
   return read_file(path, file.ref());
 }
+
+read_file_result read_stdin() {
+  posix_fd_file_ref file(STDIN_FILENO);
+  return read_file("<stdin>", file);
+}
 #endif
 
 void write_file(const std::string &path, string8_view content) {

src/main.cpp

@@ -158,8 +158,12 @@ void handle_options(quick_lint_js::options o) {
   quick_lint_js::any_error_reporter reporter =
       quick_lint_js::any_error_reporter::make(o.output_format, &o.exit_fail_on);
   for (const quick_lint_js::file_to_lint &file : o.files_to_lint) {
-    quick_lint_js::read_file_result source =
-        quick_lint_js::read_file(file.path);
+    quick_lint_js::read_file_result source;
+    if (file.is_stdin) {
+      source = quick_lint_js::read_stdin();
+    } else {
+      source = quick_lint_js::read_file(file.path);
+    }
     source.exit_if_not_ok();
     reporter.set_source(&source.content, file);
     quick_lint_js::process_file(&source.content, reporter.get(),
@@ -394,6 +398,7 @@ void print_help_message() {
   print_option("--exit-fail-on=[CODES]",
                "Fail with a non-zero exit code if any of these");
   print_option("", "errors are found (default: \"all\")");
+  print_option("--stdin", "Read standard input as a JavaScript file");
   print_option("--lsp, --lsp-server",
                "Run in Language Server mode (for LSP-aware editors)");
   print_option("--output-format=[FORMAT]",

src/options.cpp

@@ -98,6 +98,8 @@ class arg_parser {
       }
       this->is_ignoring_options_ = true;
       this->option_ = std::nullopt;
+    } else if (this->current_arg() == "-"sv) {
+      this->option_ = std::nullopt;
     } else if (this->current_arg()[0] == '-') {
       const char* equal = std::strchr(this->current_arg(), '=');
       option o;
@@ -148,12 +150,28 @@ options parse_options(int argc, char** argv) {
   options o;
 
   std::optional<int> next_vim_file_bufnr;
+  bool has_stdin = false;
 
   arg_parser parser(argc, argv);
   while (!parser.done()) {
     if (const char* argument = parser.match_argument()) {
-      file_to_lint file{.path = argument, .vim_bufnr = next_vim_file_bufnr};
-      o.files_to_lint.emplace_back(file);
+      if (argument == "-"sv) {
+        if (has_stdin) {
+          o.has_multiple_stdin = true;
+          continue;
+        }
+        file_to_lint file{.path = "<stdin>",
+                          .is_stdin = true,
+                          .vim_bufnr = next_vim_file_bufnr};
+        has_stdin = true;
+        o.files_to_lint.emplace_back(file);
+      } else {
+        file_to_lint file{.path = argument,
+                          .is_stdin = false,
+                          .vim_bufnr = next_vim_file_bufnr};
+        o.files_to_lint.emplace_back(file);
+      }
+
       next_vim_file_bufnr = std::nullopt;
     } else if (parser.match_flag_option("--debug-parser-visits"sv,
                                         "--debug-p"sv)) {
@@ -188,6 +206,17 @@ options parse_options(int argc, char** argv) {
       o.version = true;
     } else if (parser.match_flag_option("--lsp-server"sv, "--lsp"sv)) {
       o.lsp_server = true;
+    } else if (parser.match_flag_option("--stdin"sv, ""sv)) {
+      if (has_stdin) {
+        o.has_multiple_stdin = true;
+        continue;
+      }
+      file_to_lint file{.path = "<stdin>",
+                        .is_stdin = true,
+                        .vim_bufnr = next_vim_file_bufnr};
+      o.files_to_lint.emplace_back(file);
+      has_stdin = true;
+      next_vim_file_bufnr = std::nullopt;
     } else {
       const char* unrecognized = parser.match_anything();
       o.error_unrecognized_options.emplace_back(unrecognized);
@@ -213,6 +242,9 @@ bool options::dump_errors(std::ostream& out) const {
              "--lsp-server mode\n";
     }
   }
+  if (this->has_multiple_stdin) {
+    out << "warning: multiple standard input given on command line\n";
+  }
   for (const auto& option : this->error_unrecognized_options) {
     out << "error: unrecognized option: " << option << '\n';
     have_errors = true;

src/quick-lint-js/file.h

@@ -24,6 +24,8 @@ read_file_result read_file(const char *path);
 
 read_file_result read_file(const char *path, platform_file_ref);
 
+read_file_result read_stdin(void);
+
 void write_file(const std::string &path, string8_view content);
 void write_file(const char *path, string8_view content);
 }

src/quick-lint-js/options.h

@@ -18,6 +18,7 @@ enum class output_format {
 
 struct file_to_lint {
   const char *path;
+  bool is_stdin;
   std::optional<int> vim_bufnr;
 };
 
@@ -32,6 +33,7 @@ struct options {
   compiled_error_list exit_fail_on;
 
   std::vector<const char *> error_unrecognized_options;
+  bool has_multiple_stdin = false;
 
   bool dump_errors(std::ostream &) const;
 };

test/test-options.cpp

@@ -156,6 +156,18 @@ TEST(test_options, vim_file_bufnr) {
     EXPECT_EQ(o.files_to_lint[1].vim_bufnr, 2);
   }
 
+  {
+    options o = parse_options({"--vim-file-bufnr=42", "-"});
+    ASSERT_EQ(o.files_to_lint.size(), 1);
+    EXPECT_EQ(o.files_to_lint[0].vim_bufnr, 42);
+  }
+
+  {
+    options o = parse_options({"one.js", "--vim-file-bufnr=42", "--stdin"});
+    ASSERT_EQ(o.files_to_lint.size(), 2);
+    EXPECT_EQ(o.files_to_lint[1].vim_bufnr, 42);
+  }
+
   {
     options o = parse_options({"--vim-file-bufnr=1", "--", "one.js", "two.js"});
     ASSERT_EQ(o.files_to_lint.size(), 2);
@@ -176,6 +188,49 @@ TEST(test_options, lsp_server) {
   }
 }
 
+TEST(test_options, dash_dash_stdin) {
+  {
+    options o = parse_options({"--stdin", "one.js"});
+    ASSERT_EQ(o.files_to_lint.size(), 2);
+    EXPECT_TRUE(o.files_to_lint[0].is_stdin);
+    EXPECT_FALSE(o.has_multiple_stdin);
+  }
+
+  {
+    options o = parse_options({"one.js", "--stdin"});
+    ASSERT_EQ(o.files_to_lint.size(), 2);
+    EXPECT_TRUE(o.files_to_lint[1].is_stdin);
+    EXPECT_FALSE(o.has_multiple_stdin);
+  }
+
+  {
+    options o = parse_options({"-"});
+    ASSERT_EQ(o.files_to_lint.size(), 1);
+    EXPECT_TRUE(o.files_to_lint[0].is_stdin);
+    EXPECT_FALSE(o.has_multiple_stdin);
+  }
+}
+
+TEST(test_options, is_stdin_emplaced_only_once) {
+  {
+    options o = parse_options({"--stdin", "one.js", "-", "two.js"});
+    ASSERT_EQ(o.files_to_lint.size(), 3);
+    EXPECT_TRUE(o.has_multiple_stdin);
+  }
+  {
+    options o = parse_options({"one.js", "-", "two.js", "-"});
+    ASSERT_EQ(o.files_to_lint.size(), 3);
+    EXPECT_TRUE(o.has_multiple_stdin);
+  }
+}
+
+TEST(test_options, single_hyphen_is_argument) {
+  {
+    options o = parse_options({"one.js", "-", "two.js"});
+    ASSERT_EQ(o.files_to_lint.size(), 3);
+  }
+}
+
 TEST(test_options, print_help) {
   {
     options o = parse_options({"--help"});
@@ -353,6 +408,7 @@ TEST(test_options, dump_errors) {
   {
     const file_to_lint file = {
         .path = "file.js",
+        .is_stdin = false,
         .vim_bufnr = std::optional<int>(),
     };
 

website/public/cli/index.html

@@ -168,6 +168,13 @@ <h2 id="_options">Options</h2>
                   <p>Incompatible with <strong>--lsp-server</strong>.</p>
                 </div>
               </dd>
+              <dt class="hdlist1"><strong>--stdin</strong></dt>
+              <dd>
+                <p>Read standard input as a JavaScript file.</p>
+                <div class="paragraph">
+                  <p>Incompatible with <strong>--lsp-server</strong>.</p>
+                </div>
+              </dd>
               <dt class="hdlist1"><strong>--lsp</strong></dt>
               <dt class="hdlist1"><strong>--lsp-server</strong></dt>
               <dd>