vendor dbg-pls

dbg-pls/src/debug_set.rs

@@ -0,0 +1,80 @@
+use crate::{DebugPls, Formatter};
+
+/// A helper designed to assist with creation of
+/// [`DebugPls`] implementations for sets.
+///
+/// # Examples
+///
+/// ```rust
+/// use dbg_pls::{pretty, DebugPls, Formatter};
+/// use std::collections::BTreeSet;
+///
+/// struct Foo(BTreeSet<String>);
+///
+/// impl DebugPls for Foo {
+///     fn fmt(&self, f: Formatter) {
+///         f.debug_set().entries(&self.0).finish()
+///     }
+/// }
+/// let mut value = Foo(BTreeSet::from([
+///     "Hello".to_string(),
+///     "World".to_string(),
+/// ]));
+/// assert_eq!(
+///     format!("{}", pretty(&value)),
+/// "{
+///     \"Hello\";
+///     \"World\"
+/// }",
+/// );
+/// ```
+pub struct DebugSet<'a> {
+    formatter: Formatter<'a>,
+    set: syn::Block,
+}
+
+impl<'a> DebugSet<'a> {
+    pub(crate) fn new(formatter: Formatter<'a>) -> Self {
+        DebugSet {
+            formatter,
+            set: syn::Block {
+                brace_token: syn::token::Brace::default(),
+                stmts: vec![],
+            },
+        }
+    }
+
+    /// Adds the entry to the set output.
+    #[must_use]
+    pub fn entry(mut self, value: &dyn DebugPls) -> Self {
+        let expr = Formatter::process(value);
+        self.set
+            .stmts
+            .push(syn::Stmt::Semi(expr, syn::token::Semi::default()));
+        self
+    }
+
+    /// Adds all the entries to the set output.
+    #[must_use]
+    pub fn entries<V, I>(self, entries: I) -> Self
+    where
+        V: DebugPls,
+        I: IntoIterator<Item = V>,
+    {
+        entries.into_iter().fold(self, |f, entry| f.entry(&entry))
+    }
+
+    /// Closes off the set.
+    pub fn finish(mut self) {
+        // remove the last semicolon
+        if let Some(syn::Stmt::Semi(entry, _)) = self.set.stmts.pop() {
+            self.set.stmts.push(syn::Stmt::Expr(entry));
+        }
+
+        self.formatter.write_expr(syn::ExprBlock {
+            attrs: vec![],
+            label: None,
+            block: self.set,
+        });
+    }
+}