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use super::eval::Ref;
use super::obj::{Name, Obj, Pair};
pub fn stringify(x: &Obj) -> Option<String> {
stringify_ex(x, |_: &Obj| None)
}
pub fn stringify_ex<F: Fn(&Obj) -> Option<String> + Clone>(x: &Obj, f: F) -> Option<String> {
if x.is::<Pair>() {
let mut s = String::new();
s.push('(');
s.push_str(&stringify_inner(x, f).unwrap_or("?".to_string()));
s.push(')');
Some(s)
} else {
stringify_inner(x, f)
}
}
fn stringify_inner<F: Fn(&Obj) -> Option<String> + Clone>(x: &Obj, f: F) -> Option<String> {
if let Some(s) = f(x) {
return Some(s);
}
if x.is::<()>() {
return Some("()".to_string());
}
if let Some(b) = x.downcast_ref::<bool>() {
return Some(b.to_string());
}
if let Some(n) = x.downcast_ref::<i64>() {
return Some(n.to_string());
}
if let Some(s) = x.downcast_ref::<String>() {
let escaped = s.escape_debug().to_string();
let mut quoted = String::with_capacity(escaped.len() + 2);
quoted.push('"');
quoted.push_str(&escaped);
quoted.push('"');
return Some(quoted);
}
if let Some(n) = x.downcast_ref::<Name>() {
return Some(n.0.clone());
}
if let Some(r) = x.downcast_ref::<Ref>() {
return Some(r.to_string());
}
if let Some(p) = x.downcast_ref::<Pair>() {
let mut s = stringify_ex(&p.0, f.clone()).unwrap_or("?".to_string());
if !p.1.is::<()>() {
if p.1.is::<Pair>() {
s.push(' ');
} else {
s.push_str(" . ");
}
s.push_str(&stringify_inner(&p.1, f).unwrap_or("?".to_string()));
}
return Some(s);
}
None
}
#[cfg(test)]
mod tests {
use super::super::obj;
use super::*;
#[test]
fn test_list() {
assert_eq!(
stringify(&obj::pair(obj::int(1), obj::int(2))).unwrap(),
"(1 . 2)"
);
assert_eq!(
stringify(&obj::pair(
obj::int(1),
obj::pair(obj::int(2), obj::pair(obj::int(3), obj::nil()))
))
.unwrap(),
"(1 2 3)"
);
assert_eq!(
stringify(&obj::pair(
obj::pair(obj::int(1), obj::int(2)),
obj::pair(obj::int(3), obj::nil())
))
.unwrap(),
"((1 . 2) 3)"
);
assert_eq!(
stringify(&obj::pair(obj::pair(obj::int(1), obj::int(2)), obj::int(3))).unwrap(),
"((1 . 2) . 3)"
);
assert_eq!(
stringify(&obj::pair(
obj::int(1),
obj::pair(obj::pair(obj::int(2), obj::int(3)), obj::nil())
))
.unwrap(),
"(1 (2 . 3))"
);
assert_eq!(
stringify(&obj::pair(obj::int(1), obj::pair(obj::nil(), obj::nil()))).unwrap(),
"(1 ())"
);
assert_eq!(
stringify(&obj::pair(obj::int(1), obj::nil())).unwrap(),
"(1)"
);
}
}