TextEditor: Specify the starting line and column number using colons

This allows the user to specify a specific line and column number to
start at when opening a file in TextEditor through the terminal, by
adding a colon after the file name.

For example, `TextEditor ReadMe.md:10:5` will open ReadMe.md and put
the cursor on line 10 at column 5.

To ensure that the user isn't trying to open a file that actually has
colons in its name, it checks if the file exists before parsing.

Replaces the feature added in b474f49164
Closes #5589

Userland/Applications/TextEditor/CMakeLists.txt

@@ -2,6 +2,7 @@ compile_gml(TextEditorWindow.gml TextEditorWindowGML.h text_editor_window_gml)
 
 set(SOURCES
     main.cpp
+    FileArgument.cpp
     MainWidget.cpp
     TextEditorWindowGML.h
 )

Userland/Applications/TextEditor/FileArgument.cpp

@@ -0,0 +1,62 @@
+/*
+ * Copyright (c) 2021, ry755 <ryanst755@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "FileArgument.h"
+#include <AK/Optional.h>
+#include <AK/String.h>
+#include <LibCore/File.h>
+#include <LibRegex/Regex.h>
+
+FileArgument::FileArgument(String file_argument)
+{
+    m_line = {};
+    m_column = {};
+
+    if (Core::File::exists(file_argument)) {
+        // A file exists with the full specified name, don't attempt to parse it.
+        m_file_name = file_argument;
+        return;
+    }
+
+    // A file doesn't exist with the full specified name, maybe the user entered line/column coordinates?
+    Regex<PosixExtended> re("^(.+?)(:([0-9]+):?([0-9]+)?)?$");
+    RegexResult result = match(file_argument, re, PosixFlags::Global | PosixFlags::Multiline | PosixFlags::Ungreedy);
+    auto& groups = result.capture_group_matches.at(0);
+
+    // Match 0 group 0: file name
+    // Match 0 group 1: line number
+    // Match 0 group 2: column number
+
+    if (groups.size() > 3) {
+        // Both a line and column number were specified.
+        auto file_name = groups.at(0).view.to_string();
+        auto initial_line_number = groups.at(1).view.to_string().to_int();
+        auto initial_column_number = groups.at(2).view.to_string().to_int();
+
+        m_file_name = file_name;
+        if (initial_line_number.has_value() && initial_line_number.value() > 0)
+            m_line = initial_line_number.value();
+        if (initial_column_number.has_value())
+            m_column = initial_column_number.value();
+    } else if (groups.size() == 3) {
+        // Only a line number was specified.
+        auto file_name = groups.at(0).view.to_string();
+        auto initial_line_number = groups.at(1).view.to_string().to_int();
+
+        m_file_name = file_name;
+        if (initial_line_number.has_value() && initial_line_number.value() > 0)
+            m_line = initial_line_number.value();
+    } else {
+        // A colon was found at the end of the file name but no values were found after it.
+        auto file_name = groups.at(0).view.to_string();
+
+        m_file_name = file_name;
+    }
+}
+
+FileArgument::~FileArgument()
+{
+}

Userland/Applications/TextEditor/FileArgument.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2021, ry755 <ryanst755@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Optional.h>
+#include <AK/String.h>
+
+class FileArgument final {
+public:
+    FileArgument(String);
+    ~FileArgument();
+
+    String file_name() { return m_file_name; }
+    Optional<size_t> line() { return m_line; }
+    Optional<size_t> column() { return m_column; }
+
+private:
+    String m_file_name;
+    Optional<size_t> m_line;
+    Optional<size_t> m_column;
+};

Userland/Applications/TextEditor/main.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include "FileArgument.h"
 #include "MainWidget.h"
 #include <LibCore/ArgsParser.h>
 #include <LibGUI/Menubar.h>
@@ -27,12 +28,10 @@ int main(int argc, char** argv)
     }
 
     const char* preview_mode = "auto";
-    int initial_line_number = 0;
     const char* file_to_edit = nullptr;
     Core::ArgsParser parser;
     parser.add_option(preview_mode, "Preview mode, one of 'none', 'html', 'markdown', 'auto'", "preview-mode", '\0', "mode");
-    parser.add_option(initial_line_number, "Start at line number", "line-number", 'l', "line");
-    parser.add_positional_argument(file_to_edit, "File to edit", "file", Core::ArgsParser::Required::No);
+    parser.add_positional_argument(file_to_edit, "File to edit, with optional starting line and column number", "file[:line[:column]]", Core::ArgsParser::Required::No);
 
     parser.parse(argc, argv);
 
@@ -71,15 +70,14 @@ int main(int argc, char** argv)
     window->set_menubar(menubar);
 
     if (file_to_edit) {
-        if (!text_widget.open_file(file_to_edit))
+        // A file name was passed, parse any possible line and column numbers included.
+        FileArgument parsed_argument(file_to_edit);
+        if (!text_widget.open_file(parsed_argument.file_name()))
             return 1;
+        text_widget.editor().set_cursor_and_focus_line(parsed_argument.line().value_or(1) - 1, parsed_argument.column().value_or(0));
     }
-
     text_widget.update_title();
 
-    if (initial_line_number != 0)
-        text_widget.editor().set_cursor_and_focus_line(initial_line_number - 1, 0);
-
     window->show();
     window->set_icon(app_icon.bitmap_for_size(16));