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use std::fmt;
mod impls;
mod internal;
#[cfg(test)]
pub(in kv) mod test;
pub use kv::Error;
use self::internal::{Inner, Primitive, Visitor};
pub trait ToValue {
fn to_value(&self) -> Value;
}
impl<'a, T> ToValue for &'a T
where
T: ToValue + ?Sized,
{
fn to_value(&self) -> Value {
(**self).to_value()
}
}
impl<'v> ToValue for Value<'v> {
fn to_value(&self) -> Value {
Value { inner: self.inner }
}
}
pub trait Fill {
fn fill(&self, slot: &mut Slot) -> Result<(), Error>;
}
impl<'a, T> Fill for &'a T
where
T: Fill + ?Sized,
{
fn fill(&self, slot: &mut Slot) -> Result<(), Error> {
(**self).fill(slot)
}
}
pub struct Slot<'a> {
filled: bool,
visitor: &'a mut dyn Visitor,
}
impl<'a> fmt::Debug for Slot<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("Slot").finish()
}
}
impl<'a> Slot<'a> {
fn new(visitor: &'a mut dyn Visitor) -> Self {
Slot {
visitor,
filled: false,
}
}
pub fn fill(&mut self, value: Value) -> Result<(), Error> {
assert!(!self.filled, "the slot has already been filled");
self.filled = true;
value.visit(self.visitor)
}
}
pub struct Value<'v> {
inner: Inner<'v>,
}
impl<'v> Value<'v> {
fn from_primitive(value: Primitive<'v>) -> Self {
Value {
inner: Inner::Primitive(value),
}
}
pub fn from_fill<T>(value: &'v T) -> Self
where
T: Fill,
{
Value {
inner: Inner::Fill(value),
}
}
fn visit(&self, visitor: &mut dyn Visitor) -> Result<(), Error> {
self.inner.visit(visitor)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn fill_value() {
struct TestFill;
impl Fill for TestFill {
fn fill(&self, slot: &mut Slot) -> Result<(), Error> {
let dbg: &dyn fmt::Debug = &1;
slot.fill(Value::from_debug(&dbg))
}
}
assert_eq!("1", Value::from_fill(&TestFill).to_string());
}
#[test]
#[should_panic]
fn fill_multiple_times_panics() {
struct BadFill;
impl Fill for BadFill {
fn fill(&self, slot: &mut Slot) -> Result<(), Error> {
slot.fill(42.into())?;
slot.fill(6789.into())?;
Ok(())
}
}
let _ = Value::from_fill(&BadFill).to_string();
}
}