Implement autocomplete for CliPrompt

include/CliPrompt.hpp

@@ -2,6 +2,7 @@
 
 #include <nds.h>
 
+#include <functional>
 #include <iostream>
 #include <string>
 #include <vector>
@@ -17,6 +18,10 @@ struct MyTickTask : TickTask
 // - input line history with arrow-key & d-pad button navigation
 class CliPrompt
 {
+public:
+	using AutocompleteCallback = std::function<void(const std::string &, std::vector<std::string> &)>;
+
+private:
 	std::ostream *ostr = &std::cout;
 	std::string prompt = "> ";
 
@@ -40,6 +45,9 @@ class CliPrompt
 	// past the end of the line history.
 	std::string savedInput;
 
+	std::vector<std::string> autocompleteOptions;
+	AutocompleteCallback autocompleteCallback;
+
 	void resetKeypressState() { _enterPressed = _foldPressed = {}; }
 	void flashCursor();
 	void handleBackspace();
@@ -48,6 +56,7 @@ class CliPrompt
 	void handleRight();
 	void handleUp();
 	void handleDown();
+	void handleTab();
 
 	// Returns whether an event was run via a keypad press.
 	bool processKeypad();
@@ -71,8 +80,8 @@ class CliPrompt
 	// Set the text to print before the cursor.
 	void setPrompt(const std::string &s) { prompt = s; }
 
-	// Set the character to print as the cursor.
-	// void setCursor(char c) { cursor = c; }
+	// Set the autocomplete callback function. It is called with the current input when the user presses Tab.
+	void setAutocompleteCallback(const AutocompleteCallback &cb) { autocompleteCallback = cb; }
 
 	// Read the input buffer.
 	const std::string &getInput() const { return input; }

include/Shell.hpp

@@ -49,6 +49,9 @@ class Shell
 	// Does NOT free any resources that they previously pointed to!
 	void ResetStreams();
 
+	// Autocomplete callback for CliPrompt.
+	void AutocompleteCallback(const std::string &input, std::vector<std::string> &options);
+
 public:
 	const int console;
 

src/CliPrompt.cpp

@@ -96,6 +96,38 @@ void CliPrompt::handleDown()
 	*ostr << "\r\e[2K" << prompt << input;
 }
 
+void CliPrompt::handleTab()
+{
+	if (!autocompleteCallback)
+		return;
+
+	autocompleteOptions.clear();
+	autocompleteCallback(input, autocompleteOptions);
+
+	if (autocompleteOptions.empty())
+		return;
+
+	if (autocompleteOptions.size() == 1)
+	{
+		// only 1 match: replace input with received string.
+
+		// hack for appending an autocompleted "final token" (e.g. a filepath)
+		input.resize(input.find_last_of(' ') + 1);
+		input += autocompleteOptions[0];
+
+		*ostr << "\r\e[2K" << prompt << input;
+		return;
+	}
+
+	*ostr << "\n\e[90m"; // print in gray, make customizable later
+	for (const auto &s : autocompleteOptions)
+		if (s.contains(' '))
+			*ostr << '"' << s << "\" ";
+		else
+			*ostr << s << ' ';
+	*ostr << "\e[39m\n" << prompt << input;
+}
+
 bool CliPrompt::processKeypad()
 {
 #ifndef NDSH_THREADING
@@ -129,14 +161,17 @@ void CliPrompt::processKeyboard()
 	{
 	case 0: // just in case
 	case NOKEY:
-	case DVK_TAB: // TODO: use tabs for autocomplete
 	case DVK_CTRL:
 	case DVK_ALT:
 	case DVK_CAPS:
 	case DVK_MENU:
 	case DVK_SHIFT:
 		break;
 
+	case DVK_TAB:
+		handleTab();
+		break;
+
 	case DVK_FOLD:
 		_foldPressed = true;
 		break;

src/Commands.cpp

@@ -47,6 +47,12 @@ void ls(const Context &ctx)
 		return;
 	}
 
+	if (!fs::is_directory(path))
+	{
+		ctx.out << path << '\n';
+		return;
+	}
+
 	for (const auto &entry : fs::directory_iterator{path})
 	{
 		const auto filename = entry.path().filename().string();

src/Shell.cpp

@@ -19,12 +19,15 @@ Shell::Shell(const int console)
 	: ostr{Consoles::GetStream(console)},
 	  console{console}
 {
+	SetEnv("PWD", "/");
 	prompt.setOutputStream(ostr);
 	if (!fsInitialized())
 		return;
 	prompt.setLineHistoryFromFile(".ndsh_history");
 	if (fs::exists(".ndshrc"))
 		SourceFile(".ndshrc");
+	prompt.setAutocompleteCallback(
+		std::bind(&Shell::AutocompleteCallback, this, std::placeholders::_1, std::placeholders::_2));
 }
 
 Shell::~Shell()
@@ -73,8 +76,9 @@ void Shell::ProcessLine(std::string_view line)
 		return;
 
 	// Trim leading and trailing whitespace
-	const auto first_non_whitespace = line.find_first_not_of(" \t\n\r");
-	line = line.substr(first_non_whitespace, line.find_last_not_of(" \t\n\r") - first_non_whitespace + 1);
+	const auto first_non_whitespace = line.find_first_not_of(' ');
+	if (first_non_whitespace != std::string::npos)
+		line = line.substr(first_non_whitespace, line.find_last_not_of(' ') - first_non_whitespace + 1);
 
 	if (line.empty())
 		return;
@@ -246,6 +250,47 @@ void Shell::RedirectOutput(int fd, std::ostream &ostr)
 	// in the future, a full file descriptor table???????
 }
 
+void Shell::AutocompleteCallback(const std::string &_input, std::vector<std::string> &options)
+{
+	std::string_view input{_input};
+
+	// Trim ONLY leading whitespace (trailing matters here!)
+	const auto first_non_whitespace = input.find_first_not_of(' ');
+	if (first_non_whitespace != std::string::npos)
+		input = input.substr(input.find_first_not_of(' '));
+
+	if (!input.contains(' '))
+	{
+		// autocomplete the command
+
+		if (Commands::MAP.contains(std::string{input}))
+			// it's already a valid command
+			return;
+
+		for (const auto &[cmdname, _] : Commands::MAP)
+			if (cmdname.starts_with(input))
+				options.emplace_back(cmdname);
+	}
+	else if (fsInitialized())
+	{
+		// a command is already there, autocomplete filenames.
+		// get to the last space-separated token, this will be our current filename
+		input = input.substr(input.find_last_of(' ') + 1);
+
+		const auto &pwd = env["PWD"];
+
+		if (!fs::exists(pwd))
+			return;
+
+		for (const auto &entry : fs::directory_iterator{pwd})
+		{
+			const auto filename{entry.path().filename().string()};
+			if (filename.starts_with(input))
+				options.emplace_back(filename);
+		}
+	}
+}
+
 void Shell::StartPrompt()
 {
 	ostr << "\e[96mtrustytrojan/nds-shell\nstar me on github!!!\e[39m\n\nrun 'help' for help\n\n";