core: introduce update controller for mv and cp

src/uucore/src/lib/lib.rs

@@ -26,6 +26,7 @@ pub use crate::mods::os;
 pub use crate::mods::panic;
 pub use crate::mods::quoting_style;
 pub use crate::mods::ranges;
+pub use crate::mods::update_control;
 pub use crate::mods::version_cmp;
 
 // * string parsing modules

src/uucore/src/lib/mods.rs

@@ -6,6 +6,7 @@ pub mod error;
 pub mod os;
 pub mod panic;
 pub mod ranges;
+pub mod update_control;
 pub mod version_cmp;
 // dir and vdir also need access to the quoting_style module
 pub mod quoting_style;

src/uucore/src/lib/mods/update_control.rs

@@ -0,0 +1,57 @@
+use clap::ArgMatches;
+
+pub static UPDATE_CONTROL_VALUES: &[&str] = &["all", "none", "old", ""];
+
+pub const UPDATE_CONTROL_LONG_HELP: &str = "VERY LONG HELP";
+
+#[derive(Clone, Eq, PartialEq)]
+pub enum UpdateMode {
+    ReplaceAll,
+    ReplaceNone,
+    ReplaceIfOlder,
+}
+
+pub mod arguments {
+    use clap::ArgAction;
+
+    pub static OPT_UPDATE: &str = "update";
+    pub static OPT_UPDATE_NO_ARG: &str = "u";
+
+    pub fn update() -> clap::Arg {
+        clap::Arg::new(OPT_UPDATE)
+            .long("update")
+            .help("some help")
+            .value_parser(["", "none", "all", "older"])
+            .num_args(0..=1)
+            .default_missing_value("all")
+            .require_equals(true)
+            .overrides_with("update")
+            .action(clap::ArgAction::Set)
+    }
+
+    pub fn update_no_args() -> clap::Arg {
+        clap::Arg::new(OPT_UPDATE_NO_ARG)
+            .short('u')
+            .help("like ")
+            .action(ArgAction::SetTrue)
+    }
+}
+
+pub fn determine_update_mode(matches: &ArgMatches) -> UpdateMode {
+    if matches.contains_id(arguments::OPT_UPDATE) {
+        if let Some(mode) = matches.get_one::<String>(arguments::OPT_UPDATE) {
+            match mode.as_str() {
+                "all" | "" => UpdateMode::ReplaceAll,
+                "none" => UpdateMode::ReplaceNone,
+                "older" => UpdateMode::ReplaceIfOlder,
+                _ => unreachable!("other args restricted by clap"),
+            }
+        } else {
+            unreachable!("other args restricted by clap")
+        }
+    } else if matches.get_flag(arguments::OPT_UPDATE_NO_ARG) {
+        UpdateMode::ReplaceIfOlder
+    } else {
+        UpdateMode::ReplaceAll
+    }
+}