Rollup merge of #60458 - KodrAus:debug_map_entry, r=alexcrichton
Add key and value methods to DebugMap Implementation PR for an active (not approved) RFC: https://github.com/rust-lang/rfcs/pull/2696. Add two new methods to `std::fmt::DebugMap` for writing the key and value part of a map entry separately: ```rust impl<'a, 'b: 'a> DebugMap<'a, 'b> { pub fn key(&mut self, key: &dyn Debug) -> &mut Self; pub fn value(&mut self, value: &dyn Debug) -> &mut Self; } ``` I want to do this so that I can write a `serde::Serializer` that forwards to our format builders, so that any `T: Serialize` can also be treated like a `T: Debug`.
This commit is contained in:
Mazdak Farrokhzad
GitHub
commit
fb9ca03e0b
4 changed files with 238 additions and 25 deletions
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@ -0,0 +1,9 @@
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# `debug_map_key_value`
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The tracking issue for this feature is: [#62482]
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[#62482]: https://github.com/rust-lang/rust/issues/62482
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------------------------
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Add the methods `key` and `value` to `DebugMap` so that an entry can be formatted across multiple calls without additional buffering.
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@ -1,37 +1,50 @@
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use crate::fmt;
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struct PadAdapter<'a> {
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buf: &'a mut (dyn fmt::Write + 'a),
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struct PadAdapter<'buf, 'state> {
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buf: &'buf mut (dyn fmt::Write + 'buf),
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state: &'state mut PadAdapterState,
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}
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struct PadAdapterState {
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on_newline: bool,
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}
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impl<'a> PadAdapter<'a> {
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fn wrap<'b, 'c: 'a+'b>(fmt: &'c mut fmt::Formatter<'_>, slot: &'b mut Option<Self>)
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-> fmt::Formatter<'b> {
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impl Default for PadAdapterState {
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fn default() -> Self {
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PadAdapterState {
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on_newline: true,
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}
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}
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}
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impl<'buf, 'state> PadAdapter<'buf, 'state> {
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fn wrap<'slot, 'fmt: 'buf+'slot>(fmt: &'fmt mut fmt::Formatter<'_>,
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slot: &'slot mut Option<Self>,
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state: &'state mut PadAdapterState) -> fmt::Formatter<'slot> {
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fmt.wrap_buf(move |buf| {
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*slot = Some(PadAdapter {
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buf,
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on_newline: true,
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state,
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});
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slot.as_mut().unwrap()
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})
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}
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}
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impl fmt::Write for PadAdapter<'_> {
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impl fmt::Write for PadAdapter<'_, '_> {
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fn write_str(&mut self, mut s: &str) -> fmt::Result {
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while !s.is_empty() {
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if self.on_newline {
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if self.state.on_newline {
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self.buf.write_str(" ")?;
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}
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let split = match s.find('\n') {
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Some(pos) => {
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self.on_newline = true;
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self.state.on_newline = true;
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pos + 1
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}
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None => {
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self.on_newline = false;
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self.state.on_newline = false;
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s.len()
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}
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};
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@ -133,7 +146,8 @@ impl<'a, 'b: 'a> DebugStruct<'a, 'b> {
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self.fmt.write_str(" {\n")?;
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}
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let mut slot = None;
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot);
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let mut state = Default::default();
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut state);
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writer.write_str(name)?;
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writer.write_str(": ")?;
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value.fmt(&mut writer)?;
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@ -279,7 +293,8 @@ impl<'a, 'b: 'a> DebugTuple<'a, 'b> {
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self.fmt.write_str("(\n")?;
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}
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let mut slot = None;
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot);
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let mut state = Default::default();
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut state);
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value.fmt(&mut writer)?;
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writer.write_str(",\n")
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} else {
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@ -349,7 +364,8 @@ impl<'a, 'b: 'a> DebugInner<'a, 'b> {
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self.fmt.write_str("\n")?;
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}
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let mut slot = None;
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot);
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let mut state = Default::default();
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut state);
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entry.fmt(&mut writer)?;
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writer.write_str(",\n")
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} else {
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@ -676,6 +692,9 @@ pub struct DebugMap<'a, 'b: 'a> {
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fmt: &'a mut fmt::Formatter<'b>,
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result: fmt::Result,
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has_fields: bool,
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has_key: bool,
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// The state of newlines is tracked between keys and values
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state: PadAdapterState,
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}
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pub fn debug_map_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>) -> DebugMap<'a, 'b> {
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@ -684,6 +703,8 @@ pub fn debug_map_new<'a, 'b>(fmt: &'a mut fmt::Formatter<'b>) -> DebugMap<'a, 'b
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fmt,
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result,
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has_fields: false,
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has_key: false,
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state: Default::default(),
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}
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}
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@ -712,25 +733,123 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
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/// ```
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#[stable(feature = "debug_builders", since = "1.2.0")]
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pub fn entry(&mut self, key: &dyn fmt::Debug, value: &dyn fmt::Debug) -> &mut DebugMap<'a, 'b> {
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self.key(key).value(value)
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}
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/// Adds the key part of a new entry to the map output.
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///
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/// This method, together with `value`, is an alternative to `entry` that
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/// can be used when the complete entry isn't known upfront. Prefer the `entry`
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/// method when it's possible to use.
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///
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/// # Panics
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///
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/// `key` must be called before `value` and each call to `key` must be followed
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/// by a corresponding call to `value`. Otherwise this method will panic.
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///
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/// # Examples
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///
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/// ```
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/// # #![feature(debug_map_key_value)]
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/// use std::fmt;
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///
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/// struct Foo(Vec<(String, i32)>);
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///
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/// impl fmt::Debug for Foo {
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/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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/// fmt.debug_map()
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/// .key(&"whole").value(&self.0) // We add the "whole" entry.
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/// .finish()
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/// }
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/// }
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///
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/// assert_eq!(
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/// format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
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/// "{\"whole\": [(\"A\", 10), (\"B\", 11)]}",
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/// );
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/// ```
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#[unstable(feature = "debug_map_key_value",
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reason = "recently added",
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issue = "62482")]
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pub fn key(&mut self, key: &dyn fmt::Debug) -> &mut DebugMap<'a, 'b> {
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assert!(!self.has_key, "attempted to begin a new map entry \
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without completing the previous one");
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self.result = self.result.and_then(|_| {
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if self.is_pretty() {
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if !self.has_fields {
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self.fmt.write_str("\n")?;
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}
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let mut slot = None;
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot);
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self.state = Default::default();
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut self.state);
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key.fmt(&mut writer)?;
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writer.write_str(": ")?;
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value.fmt(&mut writer)?;
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writer.write_str(",\n")
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} else {
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if self.has_fields {
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self.fmt.write_str(", ")?
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}
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key.fmt(self.fmt)?;
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self.fmt.write_str(": ")?;
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value.fmt(self.fmt)
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}
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self.has_key = true;
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Ok(())
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});
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self
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}
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/// Adds the value part of a new entry to the map output.
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///
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/// This method, together with `key`, is an alternative to `entry` that
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/// can be used when the complete entry isn't known upfront. Prefer the `entry`
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/// method when it's possible to use.
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///
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/// # Panics
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///
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/// `key` must be called before `value` and each call to `key` must be followed
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/// by a corresponding call to `value`. Otherwise this method will panic.
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///
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/// # Examples
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///
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/// ```
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/// # #![feature(debug_map_key_value)]
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/// use std::fmt;
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///
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/// struct Foo(Vec<(String, i32)>);
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///
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/// impl fmt::Debug for Foo {
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/// fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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/// fmt.debug_map()
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/// .key(&"whole").value(&self.0) // We add the "whole" entry.
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/// .finish()
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/// }
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/// }
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///
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/// assert_eq!(
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/// format!("{:?}", Foo(vec![("A".to_string(), 10), ("B".to_string(), 11)])),
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/// "{\"whole\": [(\"A\", 10), (\"B\", 11)]}",
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/// );
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/// ```
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#[unstable(feature = "debug_map_key_value",
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reason = "recently added",
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issue = "62482")]
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pub fn value(&mut self, value: &dyn fmt::Debug) -> &mut DebugMap<'a, 'b> {
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assert!(self.has_key, "attempted to format a map value before its key");
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self.result = self.result.and_then(|_| {
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if self.is_pretty() {
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let mut slot = None;
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let mut writer = PadAdapter::wrap(&mut self.fmt, &mut slot, &mut self.state);
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value.fmt(&mut writer)?;
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writer.write_str(",\n")?;
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} else {
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value.fmt(self.fmt)?;
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}
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self.has_key = false;
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Ok(())
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});
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self.has_fields = true;
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@ -775,6 +894,11 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
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/// Finishes output and returns any error encountered.
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///
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/// # Panics
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///
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/// `key` must be called before `value` and each call to `key` must be followed
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/// by a corresponding call to `value`. Otherwise this method will panic.
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///
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/// # Examples
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///
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/// ```
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@ -797,6 +921,8 @@ impl<'a, 'b: 'a> DebugMap<'a, 'b> {
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/// ```
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#[stable(feature = "debug_builders", since = "1.2.0")]
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pub fn finish(&mut self) -> fmt::Result {
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assert!(!self.has_key, "attempted to finish a map with a partial entry");
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self.result.and_then(|_| self.fmt.write_str("}"))
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}
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@ -211,9 +211,9 @@ mod debug_map {
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#[test]
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fn test_single() {
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struct Foo;
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struct Entry;
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impl fmt::Debug for Foo {
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impl fmt::Debug for Entry {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.entry(&"bar", &true)
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@ -221,19 +221,32 @@ mod debug_map {
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}
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}
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assert_eq!("{\"bar\": true}", format!("{:?}", Foo));
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struct KeyValue;
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impl fmt::Debug for KeyValue {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.key(&"bar").value(&true)
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.finish()
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}
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}
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assert_eq!(format!("{:?}", Entry), format!("{:?}", KeyValue));
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assert_eq!(format!("{:#?}", Entry), format!("{:#?}", KeyValue));
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assert_eq!("{\"bar\": true}", format!("{:?}", Entry));
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assert_eq!(
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"{
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\"bar\": true,
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}",
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format!("{:#?}", Foo));
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format!("{:#?}", Entry));
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}
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#[test]
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fn test_multiple() {
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struct Foo;
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struct Entry;
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impl fmt::Debug for Foo {
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impl fmt::Debug for Entry {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.entry(&"bar", &true)
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@ -242,13 +255,27 @@ mod debug_map {
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}
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}
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assert_eq!("{\"bar\": true, 10: 10/20}", format!("{:?}", Foo));
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struct KeyValue;
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impl fmt::Debug for KeyValue {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.key(&"bar").value(&true)
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.key(&10).value(&format_args!("{}/{}", 10, 20))
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.finish()
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}
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}
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assert_eq!(format!("{:?}", Entry), format!("{:?}", KeyValue));
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assert_eq!(format!("{:#?}", Entry), format!("{:#?}", KeyValue));
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assert_eq!("{\"bar\": true, 10: 10/20}", format!("{:?}", Entry));
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assert_eq!(
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"{
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\"bar\": true,
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10: 10/20,
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}",
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format!("{:#?}", Foo));
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format!("{:#?}", Entry));
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}
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#[test]
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@ -291,6 +318,56 @@ mod debug_map {
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}",
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format!("{:#?}", Bar));
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}
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#[test]
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#[should_panic]
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fn test_invalid_key_when_entry_is_incomplete() {
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struct Foo;
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impl fmt::Debug for Foo {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.key(&"bar")
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.key(&"invalid")
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.finish()
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}
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}
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format!("{:?}", Foo);
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}
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#[test]
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#[should_panic]
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fn test_invalid_finish_incomplete_entry() {
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struct Foo;
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impl fmt::Debug for Foo {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.key(&"bar")
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.finish()
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}
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}
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format!("{:?}", Foo);
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}
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#[test]
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#[should_panic]
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fn test_invalid_value_before_key() {
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struct Foo;
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impl fmt::Debug for Foo {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fmt.debug_map()
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.value(&"invalid")
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.key(&"bar")
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.finish()
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}
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}
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format!("{:?}", Foo);
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}
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}
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mod debug_set {
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@ -3,6 +3,7 @@
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#![feature(cell_update)]
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#![feature(core_private_bignum)]
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#![feature(core_private_diy_float)]
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#![feature(debug_map_key_value)]
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#![feature(dec2flt)]
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#![feature(euclidean_division)]
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#![feature(exact_size_is_empty)]
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Loading…
Reference in a new issue