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val: implement Display

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This commit is contained in:
anna 2021-04-26 18:39:52 +02:00
parent fbffb0f6ea
commit 4cc7d17c99
Signed by: fef
GPG key ID: EC22E476DC2D3D84
1 changed files with 27 additions and 1 deletions
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28
src/ast/val.rs
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@ -10,7 +10,7 @@ pub enum Type {
}
/// The (immutable) result of evaluating an [`Expr`](super::expr::Expr).
pub trait Val {
pub trait Val : fmt::Display {
fn clone(&self) -> Box<dyn Val>;
fn typ(&self) -> Type;
@ -26,6 +26,14 @@ pub trait Val {
fn string(&self) -> Result<&str, TypeError> {
Err(TypeError::new(self.typ(), Type::String))
}
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Ok(s) = self.string() {
write!(f, "[{} {}]", self.typ(), s)
} else {
write!(f, "[{} ??]", self.typ())
}
}
}
/// The actual data structure behind [`Val`].
@ -72,6 +80,12 @@ impl Val for Data<bool> {
}
}
impl fmt::Display for Data<bool> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "[bool {}]", self.data)
}
}
impl Val for Data<i64> {
fn clone(&self) -> Box<dyn Val> {
Box::new(Data {
@ -88,6 +102,12 @@ impl Val for Data<i64> {
}
}
impl fmt::Display for Data<i64> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "[int {}]", self.data)
}
}
impl Val for Data<String> {
fn clone(&self) -> Box<dyn Val> {
Box::new(Data {
@ -104,6 +124,12 @@ impl Val for Data<String> {
}
}
impl fmt::Display for Data<String> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "[string \"{}\"", self.data)
}
}
pub struct TypeError {
pub msg: String,
pub actual: Type,