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Turn ExpandResult into struct

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This commit is contained in:
Florian Diebold 2020-03-16 12:22:10 +01:00
parent f3c6a2e3db
commit d655749aae
6 changed files with 63 additions and 43 deletions
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32
crates/ra_mbe/src/lib.rs
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@ -30,8 +30,6 @@ pub enum ExpandError {
InvalidRepeat,
}
pub type ExpandResult<T> = (T, Option<ExpandError>);
pub use crate::syntax_bridge::{
ast_to_token_tree, parse_to_token_tree, syntax_node_to_token_tree, token_tree_to_syntax_node,
TokenMap,
@ -211,5 +209,35 @@ fn validate(pattern: &tt::Subtree) -> Result<(), ParseError> {
Ok(())
}
pub struct ExpandResult<T>(pub T, pub Option<ExpandError>);
impl<T> ExpandResult<T> {
pub fn ok(t: T) -> ExpandResult<T> {
ExpandResult(t, None)
}
pub fn only_err(err: ExpandError) -> ExpandResult<T>
where
T: Default,
{
ExpandResult(Default::default(), Some(err))
}
pub fn map<U>(self, f: impl FnOnce(T) -> U) -> ExpandResult<U> {
ExpandResult(f(self.0), self.1)
}
pub fn result(self) -> Result<T, ExpandError> {
self.1.map(Err).unwrap_or(Ok(self.0))
}
}
impl<T: Default> From<Result<T, ExpandError>> for ExpandResult<T> {
fn from(result: Result<T, ExpandError>) -> ExpandResult<T> {
result
.map_or_else(|e| ExpandResult(Default::default(), Some(e)), |it| ExpandResult(it, None))
}
}
#[cfg(test)]
mod tests;