dirkwhoffmann
RetroShell needs a new argument parser
To implement decent file system commands, RetroShell needs a more flexible parser. E.g., I want to support commands with the following example syntax:
fs create c=<count> h=<count> s=<count> [name=<string>]
type [-h] <filename>
In other words, I want to support key-value pairs and boolean flags.
Also, the new shell should print a small help message for each argument when pressing TAB twice, so we don't need external documentation for all commands.
Boolean flags and argument descriptions are working. As a showcase, I've implemented a find command in the new navigator shell:
Interestingly, by smartly juggling around with C++ lambdas for filtering and formatting, the code for the entire find command is just a few lines:
root.add({
.tokens = { "find" },
.argx = {
{ .name = { "name", "Search pattern" } },
{ .name = { "path", "Directory to search in" }, .flags = arg::opt },
{ .name = { "d", "Find directories only" }, .flags = arg::flag },
{ .name = { "f", "Find files only" }, .flags = arg::flag },
{ .name = { "r", "Search subdirectories, too" }, .flags = arg::flag },
{ .name = { "s", "Sort output" }, .flags = arg::flag } },
.help = { "Find files or directories." },
.func = [this] (Arguments& argv, const ParsedArguments &args, const std::vector<isize> &values) {
auto pattern = FSPattern(args.at("name"));
auto path = FSString(args, "path", ".");
auto d = args.contains("d");
auto f = args.contains("f");
auto r = args.contains("r");
auto s = args.contains("s");
auto dir = fs.pwd().seek(path);
FSOpt opt = {
.sort = s,
.recursive = r,
.filter = [&](const FSPath &item) {
return pattern.match(item.last()) &&
(!d || item.isDirectory()) &&
(!f || item.isFile());
},
.formatter = [&](const FSPath &item) {
std::stringstream ss;
ss << item.name() + (item.isDirectory() ? " (dir)" : "");
return ss.str();
}
};
std::vector<FSPath> matches;
fs.collect(dir, matches, opt);
for (auto &it : matches) { *this << opt.formatter(it) << '\n'; }
}
});
The FileSystem class had code for printing debug information about block contents to stdout. I've prettified the output and made it available in the navigator via the block command:
Hex dumps can be generated via the -h flag:
The command handler is again very simple:
root.add({
.tokens = { "block", "" },
.argx = {
{ .name = { "nr", "Block number" }, .flags = arg::opt },
{ .name = { "h", "Print a hex dump" }, .flags = arg::flag },
},
.help = { "Analyze a block" },
.func = [this] (Arguments& argv, const ParsedArguments &args, const std::vector<isize> &values) {
auto nr = args.contains("nr") ? parseBlock(args.at("nr")) : fs.pwd().ref;
if (auto ptr = fs.blockPtr(nr)) {
std::stringstream ss;
if (args.contains("h")) {
ptr->hexDump(ss);
} else {
ptr->dump(ss);
}
*this << '\n' << ss << '\n';
}
}
});