cedar_policy_core/
from_normalized_str.rs

1use crate::parser::err::{ParseError, ParseErrors, ToASTError};
2use std::fmt::Display;
3use std::str::FromStr;
4
5/// Trait for parsing "normalized" strings only, throwing an error if a
6/// non-normalized string is encountered. See docs on the
7/// [`FromNormalizedStr::from_normalized_str`] trait function.
8pub trait FromNormalizedStr: FromStr<Err = ParseErrors> + Display {
9    /// Create a `Self` by parsing a string, which is required to be normalized.
10    /// That is, the input is required to roundtrip with the `Display` impl on `Self`:
11    /// `Self::from_normalized_str(x).to_string() == x` must hold.
12    ///
13    /// In Cedar's context, that means that `from_normalized_str()` will not
14    /// accept strings with spurious whitespace (e.g. `A :: B :: C::"foo"`),
15    /// Cedar comments (e.g. `A::B::"bar" // comment`), etc. See
16    /// [RFC 9](https://github.com/cedar-policy/rfcs/blob/main/text/0009-disallow-whitespace-in-entityuid.md)
17    /// for more details and justification.
18    ///
19    /// For the version that accepts whitespace and Cedar comments, use the
20    /// actual `FromStr` implementations.
21    fn from_normalized_str(s: &str) -> Result<Self, ParseErrors> {
22        let parsed = Self::from_str(s)?;
23        let normalized_src = parsed.to_string();
24        if normalized_src == s {
25            // the normalized representation is indeed the one that was provided
26            Ok(parsed)
27        } else {
28            Err(ParseError::ToAST(ToASTError::NonNormalizedString {
29                kind: Self::describe_self(),
30                src: s.to_string(),
31                normalized_src,
32            })
33            .into())
34        }
35    }
36
37    /// Short string description of the `Self` type, to be used in error messages.
38    /// What are we trying to parse?
39    fn describe_self() -> &'static str;
40}
cedar_policy_core/from_normalized_str.rs

cedar_policy_core/
from_normalized_str.rs
