文盘Rust——子命令提示，提高用户体验
上次我们聊到 CLI 的领域交互模式。在领域交互模式中，可能存在多层次的子命令。在使用过程中如果全评记忆的话，命令少还好，多了真心记不住。频繁 --help 也是个很麻烦的事情。如果每次按 'tab' 键就可以提示或补齐命令是不是很方便呢。这一节我们就来说说 'autocommplete' 如何实现。我们还是以interactcli-rs中的实现来解说实现过程实现过程
其实，rustyline 已经为我们提供了基本的helper功能框架,其中包括了completer。我们来看代码，文件位置src/interact/cli.rs
#
struct MyHelper {
completer: CommandCompleter,
highlighter: MatchingBracketHighlighter,
validator: MatchingBracketValidator,
hinter: HistoryHinter,
colored_prompt: String,
}
pub fn run() {
let config = Config::builder()
.history_ignore_space(true)
.completion_type(CompletionType::List)
.output_stream(OutputStreamType::Stdout)
.build();
let h = MyHelper {
completer: get_command_completer(),
highlighter: MatchingBracketHighlighter::new(),
hinter: HistoryHinter {},
colored_prompt: "".to_owned(),
validator: MatchingBracketValidator::new(),
};
let mut rl = Editor::with_config(config);
// let mut rl = Editor::<()>::new();
rl.set_helper(Some(h));
......
}首先定义 MyHelper 结构体， 需要实现 Completer + Hinter + Highlighter + Validator trait。然后通过rustyline的set_helper函数加载我们定义好的helper。在MyHelper 结构体中，需要我们自己来实现completer的逻辑。
Sub command autocompleter实现详解
[*]SubCmd 结构体
#
pub struct SubCmd {
pub level: usize,
pub command_name: String,
pub subcommands: Vec<String>,
}SubCmd 结构体包含：命令级别，命令名称，以及该命令包含的子命令信息，以便在实现实现 autocomplete 时定位命令和子命令的范围
[*]在程序启动时遍历所有的command，src/cmd/rootcmd.rs 中的all_subcommand函数负责收集所有命令并转换为Vec
pub fn all_subcommand(app: &clap_Command, beginlevel: usize, input: &mut Vec<SubCmd>) {
let nextlevel = beginlevel + 1;
let mut subcmds = vec![];
for iterm in app.get_subcommands() {
subcmds.push(iterm.get_name().to_string());
if iterm.has_subcommands() {
all_subcommand(iterm, nextlevel, input);
} else {
if beginlevel == 0 {
all_subcommand(iterm, nextlevel, input);
}
}
}
let subcommand = SubCmd {
level: beginlevel,
command_name: app.get_name().to_string(),
subcommands: subcmds,
};
input.push(subcommand);
}
[*]CommandCompleter 子命令自动补充功能的核心部分
#pub struct CommandCompleter { subcommands: Vec,}impl CommandCompleter { pub fn new(subcmds: Vec) -> Self { Self { subcommands: subcmds, } } //获取level下所有可能的子命令 pub fn level_possible_cmd(&self, level: usize) -> Vec { let mut subcmds = vec![]; let cmds = self.subcommands.clone(); for iterm in cmds { if iterm.level == level { subcmds.push(iterm.command_name.clone()); } } return subcmds; } //获取level下某字符串开头的子命令 pub fn level_prefix_possible_cmd(&self, level: usize, prefix: &str) -> Vec { let mut subcmds = vec![]; let cmds = self.subcommands.clone(); for iterm in cmds { if iterm.level == level && iterm.command_name. starts_with(prefix) { subcmds.push(iterm.command_name); } } return subcmds; } //获取某level 下某subcommand的所有子命令 pub fn level_cmd_possible_sub_cmd(&self, level: usize, cmd: String) -> Vec { let mut subcmds = vec![]; let cmds = self.subcommands.clone(); for iterm in cmds { if iterm.level == level && iterm.command_name == cmd { subcmds = iterm.subcommands.clone(); } } return subcmds; } //获取某level 下某subcommand的所有prefix子命令 pub fn level_cmd_possible_prefix_sub_cmd( &self, level: usize, cmd: String, prefix: &str, ) -> Vec { let mut subcmds = vec![]; let cmds = self.subcommands.clone(); for iterm in cmds { if iterm.level == level && iterm.command_name == cmd { for i in iterm.subcommands { if i.starts_with(prefix) { subcmds.push(i); } } } } return subcmds; } pub fn complete_cmd(&self, line: &str, pos: usize) -> Result { let mut entries: Vec = Vec::new(); let d: Vec = line.split(' ').collect(); if d.len() == 1 { if d.last() == Some(&"") { for str in self.level_possible_cmd(1) { let mut replace = str.clone(); replace.push_str(" "); entries.push(Pair { display: str.clone(), replacement: replace, }); } return Ok((pos, entries)); } if let Some(last) = d.last() { for str in self.level_prefix_possible_cmd (1, *last) { let mut replace = str.clone(); replace.push_str(" "); entries.push(Pair { display: str.clone(), replacement: replace, }); } return Ok((pos - last.len(), entries)); } } if d.last() == Some(&"") { for str in self .level_cmd_possible_sub_cmd(d.len() - 1, d.get(d.len() - 2).unwrap().to_string()) { let mut replace = str.clone(); replace.push_str(" "); entries.push(Pair { display: str.clone(), replacement: replace, }); } return Ok((pos, entries)); } if let Some(last) = d.last() { for str in self. level_cmd_possible_prefix_sub_cmd( d.len() - 1, d.get(d.len() - 2).unwrap().to_string(), *last, ) { let mut replace = str.clone(); replace.push_str(" "); entries.push(Pair { display: str.clone(), replacement: replace, }); } return Ok((pos - last.len(), entries)); } Ok((pos, entries)) }}impl Completer for CommandCompleter { type Candidate = Pair; fn complete(&self, line: &str, pos: usize, _ctx: & Context
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