refactor(tree): replace previous depth: u32 opts with new type DisplayDepth

refactor(tree): replace previous `depth: u32` opts with new type `DisplayDepth`

src/bin/cargo/commands/tree.rs

@@ -2,7 +2,7 @@ use crate::cli;
 use crate::command_prelude::*;
 use anyhow::{bail, format_err};
 use cargo::core::dependency::DepKind;
-use cargo::ops::tree::{self, EdgeKind};
+use cargo::ops::tree::{self, DisplayDepth, EdgeKind};
 use cargo::ops::Packages;
 use cargo::util::print_available_packages;
 use cargo::util::CargoResult;
@@ -162,6 +162,12 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
 
     let pkgs_to_prune = args._values_of("prune");
 
+    let display_depth = args
+        ._value_of("depth")
+        .map(|s| s.parse::<DisplayDepth>())
+        .transpose()?
+        .unwrap_or(DisplayDepth::MaxDisplayDepth(u32::MAX));
+
     let packages = args.packages_from_flags()?;
     let mut invert = args
         .get_many::<String>("invert")
@@ -222,7 +228,7 @@ subtree of the package given to -p.\n\
         duplicates: args.flag("duplicates"),
         format: args.get_one::<String>("format").cloned().unwrap(),
         graph_features,
-        max_display_depth: args.value_of_u32("depth")?.unwrap_or(u32::MAX),
+        display_depth,
         no_proc_macro,
     };
 

src/cargo/ops/tree/mod.rs

@@ -43,8 +43,9 @@ pub struct TreeOptions {
     pub format: String,
     /// Includes features in the tree as separate nodes.
     pub graph_features: bool,
-    /// Maximum display depth of the dependency tree.
+    /// Display depth of the dependency tree.
-    pub max_display_depth: u32,
+    /// If non-negative integer, display dependencies with that amount of max depth.
+    pub display_depth: DisplayDepth,
     /// Excludes proc-macro dependencies.
     pub no_proc_macro: bool,
 }
@@ -86,6 +87,30 @@ impl FromStr for Prefix {
     }
 }
 
+#[derive(Clone, Copy)]
+pub enum DisplayDepth {
+    MaxDisplayDepth(u32),
+}
+
+impl FromStr for DisplayDepth {
+    type Err = clap::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            s => s.parse().map(Self::MaxDisplayDepth).map_err(|_| {
+                clap::Error::raw(
+                    clap::error::ErrorKind::ValueValidation,
+                    format!(
+                        "supported values for --depth are non-negative integers, \
+                                but `{}` is unknown",
+                        s
+                    ),
+                )
+            }),
+        }
+    }
+}
+
 struct Symbols {
     down: &'static str,
     tee: &'static str,
@@ -250,7 +275,7 @@ fn print(
             pkgs_to_prune,
             opts.prefix,
             opts.no_dedupe,
-            opts.max_display_depth,
+            opts.display_depth,
             &mut visited_deps,
             &mut levels_continue,
             &mut print_stack,
@@ -270,7 +295,7 @@ fn print_node<'a>(
     pkgs_to_prune: &[PackageIdSpec],
     prefix: Prefix,
     no_dedupe: bool,
-    max_display_depth: u32,
+    display_depth: DisplayDepth,
     visited_deps: &mut HashSet<usize>,
     levels_continue: &mut Vec<bool>,
     print_stack: &mut Vec<usize>,
@@ -329,7 +354,7 @@ fn print_node<'a>(
             pkgs_to_prune,
             prefix,
             no_dedupe,
-            max_display_depth,
+            display_depth,
             visited_deps,
             levels_continue,
             print_stack,
@@ -349,7 +374,7 @@ fn print_dependencies<'a>(
     pkgs_to_prune: &[PackageIdSpec],
     prefix: Prefix,
     no_dedupe: bool,
-    max_display_depth: u32,
+    display_depth: DisplayDepth,
     visited_deps: &mut HashSet<usize>,
     levels_continue: &mut Vec<bool>,
     print_stack: &mut Vec<usize>,
@@ -378,6 +403,10 @@ fn print_dependencies<'a>(
         }
     }
 
+    let max_display_depth = match display_depth {
+        DisplayDepth::MaxDisplayDepth(max) => max,
+    };
+
     // Current level exceeds maximum display depth. Skip.
     if levels_continue.len() + 1 > max_display_depth as usize {
         return;
@@ -407,7 +436,7 @@ fn print_dependencies<'a>(
             pkgs_to_prune,
             prefix,
             no_dedupe,
-            max_display_depth,
+            display_depth,
             visited_deps,
             levels_continue,
             print_stack,