identity_diff/
string.rs

1// Copyright 2020-2021 IOTA Stiftung
2// SPDX-License-Identifier: Apache-2.0
3
4use serde::Deserialize;
5use serde::Serialize;
6
7use crate::Diff;
8use std::fmt::Debug;
9use std::fmt::Formatter;
10
11/// The Diff Type for a `String` type.
12#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize, Default)]
13#[serde(transparent)]
14pub struct DiffString(#[serde(skip_serializing_if = "Option::is_none")] pub Option<String>);
15
16/// `Diff` trait implementation for `String`.
17impl Diff for String {
18  /// Diff type for `String`
19  type Type = DiffString;
20
21  /// compares two `String` types; `self`, `other` and returns a `DiffString` type.
22  fn diff(&self, other: &Self) -> crate::Result<Self::Type> {
23    if self == other {
24      Ok(DiffString(None))
25    } else {
26      other.clone().into_diff()
27    }
28  }
29
30  /// Merges a `DiffString`; `diff` with a `String`; `self`.
31  fn merge(&self, diff: Self::Type) -> crate::Result<Self> {
32    if diff.0.is_none() {
33      Ok(self.to_string())
34    } else {
35      Self::from_diff(diff)
36    }
37  }
38
39  /// Converts a `DiffString` into a `String` type.
40  fn from_diff(diff: Self::Type) -> crate::Result<Self> {
41    match diff.0 {
42      Some(s) => Ok(s),
43      None => Err(crate::Error::ConversionError(
44        "Problem converting from DiffString".into(),
45      )),
46    }
47  }
48
49  /// Converts a `String` into a `DiffString` type.
50  fn into_diff(self) -> crate::Result<Self::Type> {
51    Ok(DiffString(Some(self)))
52  }
53}
54
55/// Debug trait implementation for DiffString.
56impl Debug for DiffString {
57  fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
58    match &self.0 {
59      Some(val) => write!(f, "DiffString({:#?})", val),
60      None => write!(f, "DiffString None"),
61    }
62  }
63}
64#[cfg(test)]
65mod tests {
66  use super::*;
67
68  #[test]
69  fn test_string_diff() {
70    let sa = String::from("test");
71    let sb = String::from("another_string");
72
73    let diff = sa.diff(&sb).unwrap();
74
75    assert_eq!(diff, DiffString(Some("another_string".into())));
76
77    let sc = sa.merge(diff).unwrap();
78
79    assert_eq!(sb, sc);
80  }
81
82  #[test]
83  fn test_same_string() {
84    let sa = String::from("test");
85    let sb = String::from("test");
86
87    let diff = sa.diff(&sb).unwrap();
88
89    assert_eq!(diff, DiffString(None));
90
91    let sc = sa.merge(diff).unwrap();
92
93    assert_eq!(sb, sc);
94    assert_eq!(sa, sc);
95  }
96}
identity_diff/string.rs

identity_diff/
string.rs
