clojure_reader/
edn.rs

1//! An EDN reader/presenter in Rust.
2//!
3//! ## Implementations
4//! -  [`core::fmt::Display`] will output valid EDN for any Edn object
5//!
6//! ## Differences from Clojure
7//! -  Escape characters are not escaped.
8
9use alloc::boxed::Box;
10use alloc::collections::{BTreeMap, BTreeSet};
11use alloc::vec::Vec;
12use core::fmt;
13
14#[cfg(feature = "arbitrary-nums")]
15use bigdecimal::BigDecimal;
16#[cfg(feature = "arbitrary-nums")]
17use num_bigint::BigInt;
18#[cfg(feature = "floats")]
19use ordered_float::OrderedFloat;
20
21use crate::{error, parse};
22
23#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord)]
24#[non_exhaustive]
25pub enum Edn<'e> {
26  Vector(Vec<Edn<'e>>),
27  Set(BTreeSet<Edn<'e>>),
28  Map(BTreeMap<Edn<'e>, Edn<'e>>),
29  List(Vec<Edn<'e>>),
30  Key(&'e str),
31  Symbol(&'e str),
32  Str(&'e str),
33  Int(i64),
34  Tagged(&'e str, Box<Edn<'e>>),
35  #[cfg(feature = "floats")]
36  Double(OrderedFloat<f64>),
37  Rational((i64, i64)),
38  #[cfg(feature = "arbitrary-nums")]
39  BigInt(BigInt),
40  #[cfg(feature = "arbitrary-nums")]
41  BigDec(BigDecimal),
42  Char(char),
43  Bool(bool),
44  Nil,
45}
46
47/// Reads one object from the &str.
48///
49/// # Errors
50///
51/// See [`crate::error::Error`].
52pub fn read_string(edn: &str) -> Result<Edn<'_>, error::Error> {
53  Ok(parse::parse(edn)?.0)
54}
55
56/// Reads the first object from the &str and the remaining unread &str.
57///
58/// # Errors
59///
60/// Default behavior of Clojure's `read` is to throw an error on EOF, unlike `read_string`.
61/// <https://clojure.github.io/tools.reader/#clojure.tools.reader.edn/read>
62///
63/// See [`crate::error::Error`].
64pub fn read(edn: &str) -> Result<(Edn<'_>, &str), error::Error> {
65  let r = parse::parse(edn)?;
66  if r.0 == Edn::Nil && r.1.is_empty() {
67    return Err(error::Error {
68      code: error::Code::UnexpectedEOF,
69      line: None,
70      column: None,
71      ptr: None,
72    });
73  }
74  Ok((r.0, r.1))
75}
76
77impl Edn<'_> {
78  pub fn get(&self, e: &Self) -> Option<&Self> {
79    if let Edn::Map(m) = self {
80      if let Some(l) = m.get(e) {
81        return Some(l);
82      };
83    }
84    None
85  }
86  pub fn nth(&self, i: usize) -> Option<&Self> {
87    let vec = match self {
88      Edn::Vector(v) => v,
89      Edn::List(l) => l,
90      _ => return None,
91    };
92
93    vec.get(i)
94  }
95}
96
97pub(crate) const fn char_to_edn(c: char) -> Option<&'static str> {
98  match c {
99    '\n' => Some("newline"),
100    '\r' => Some("return"),
101    ' ' => Some("space"),
102    '\t' => Some("tab"),
103    _ => None,
104  }
105}
106
107impl fmt::Display for Edn<'_> {
108  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
109    match self {
110      Self::Vector(v) => {
111        write!(f, "[")?;
112        let mut it = v.iter().peekable();
113        while let Some(i) = it.next() {
114          if it.peek().is_some() {
115            write!(f, "{i} ")?;
116          } else {
117            write!(f, "{i}")?;
118          }
119        }
120        write!(f, "]")
121      }
122      Self::Set(s) => {
123        write!(f, "#{{")?;
124        let mut it = s.iter().peekable();
125        while let Some(i) = it.next() {
126          if it.peek().is_some() {
127            write!(f, "{i} ")?;
128          } else {
129            write!(f, "{i}")?;
130          }
131        }
132        write!(f, "}}")
133      }
134      Self::Map(m) => {
135        write!(f, "{{")?;
136        let mut it = m.iter().peekable();
137        while let Some(kv) = it.next() {
138          if it.peek().is_some() {
139            write!(f, "{} {}, ", kv.0, kv.1)?;
140          } else {
141            write!(f, "{} {}", kv.0, kv.1)?;
142          }
143        }
144        write!(f, "}}")
145      }
146      Self::List(l) => {
147        write!(f, "(")?;
148        let mut it = l.iter().peekable();
149        while let Some(i) = it.next() {
150          if it.peek().is_some() {
151            write!(f, "{i} ")?;
152          } else {
153            write!(f, "{i}")?;
154          }
155        }
156        write!(f, ")")
157      }
158      Self::Symbol(sy) => write!(f, "{sy}"),
159      Self::Tagged(t, s) => write!(f, "#{t} {s}"),
160      Self::Key(k) => write!(f, ":{k}"),
161      Self::Str(s) => write!(f, "\"{s}\""),
162      Self::Int(i) => write!(f, "{i}"),
163      #[cfg(feature = "floats")]
164      Self::Double(d) => write!(f, "{d}"),
165      #[cfg(feature = "arbitrary-nums")]
166      Self::BigInt(bi) => write!(f, "{bi}N"),
167      #[cfg(feature = "arbitrary-nums")]
168      Self::BigDec(bd) => write!(f, "{bd}M"),
169      Self::Rational((n, d)) => write!(f, "{n}/{d}"),
170      Self::Bool(b) => write!(f, "{b}"),
171      Self::Char(c) => {
172        write!(f, "\\")?;
173        if let Some(c) = char_to_edn(*c) {
174          return write!(f, "{c}");
175        }
176        write!(f, "{c}")
177      }
178      Self::Nil => write!(f, "nil"),
179    }
180  }
181}
clojure_reader/edn.rs

clojure_reader/
edn.rs
