1/// Trait for recursively merging settings structures.
2///
3/// When Zed starts it loads settings from `default.json` to initialize
4/// everything. These may be further refined by loading the user's settings,
5/// and any settings profiles; and then further refined by loading any
6/// local project settings.
7///
8/// The default behaviour of merging is:
9/// * For objects with named keys (HashMap, structs, etc.). The values are merged deeply
10/// (so if the default settings has languages.JSON.prettier.allowed = true, and the user's settings has
11/// languages.JSON.tab_size = 4; the merged settings file will have both settings).
12/// * For options, a None value is ignored, but Some values are merged recursively.
13/// * For other types (including Vec), a merge overwrites the current value.
14///
15/// If you want to break the rules you can (e.g. ExtendingVec, or SaturatingBool).
16#[allow(unused)]
17pub trait MergeFrom {
18 /// Merge from a source of the same type.
19 fn merge_from(&mut self, other: &Self);
20
21 /// Merge from an optional source of the same type.
22 fn merge_from_option(&mut self, other: Option<&Self>) {
23 if let Some(other) = other {
24 self.merge_from(other);
25 }
26 }
27}
28
29macro_rules! merge_from_overwrites {
30 ($($type:ty),+ $(,)?) => {
31 $(
32 impl MergeFrom for $type {
33 fn merge_from(&mut self, other: &Self) {
34 *self = other.clone();
35 }
36 }
37 )+
38 }
39}
40
41merge_from_overwrites!(
42 u16,
43 u32,
44 u64,
45 usize,
46 i16,
47 i32,
48 i64,
49 bool,
50 f64,
51 f32,
52 char,
53 std::num::NonZeroUsize,
54 std::num::NonZeroU32,
55 String,
56 std::sync::Arc<str>,
57 std::path::PathBuf,
58 std::sync::Arc<std::path::Path>,
59 language_model_core::Speed,
60);
61
62impl<T: Clone + MergeFrom> MergeFrom for Option<T> {
63 fn merge_from(&mut self, other: &Self) {
64 let Some(other) = other else {
65 return;
66 };
67
68 if let Some(this) = self {
69 this.merge_from(other);
70 } else {
71 self.replace(other.clone());
72 }
73 }
74}
75
76impl<T: Clone> MergeFrom for Vec<T> {
77 fn merge_from(&mut self, other: &Self) {
78 *self = other.clone()
79 }
80}
81
82impl<T: MergeFrom> MergeFrom for Box<T> {
83 fn merge_from(&mut self, other: &Self) {
84 self.as_mut().merge_from(other.as_ref())
85 }
86}
87
88// Implementations for collections that extend/merge their contents
89impl<K, V> MergeFrom for collections::HashMap<K, V>
90where
91 K: Clone + std::hash::Hash + Eq,
92 V: Clone + MergeFrom,
93{
94 fn merge_from(&mut self, other: &Self) {
95 for (key, value) in other {
96 if let Some(existing) = self.get_mut(key) {
97 existing.merge_from(value);
98 } else {
99 self.insert(key.clone(), value.clone());
100 }
101 }
102 }
103}
104
105impl<K, V> MergeFrom for collections::BTreeMap<K, V>
106where
107 K: Clone + std::hash::Hash + Eq + Ord,
108 V: Clone + MergeFrom,
109{
110 fn merge_from(&mut self, other: &Self) {
111 for (key, value) in other {
112 if let Some(existing) = self.get_mut(key) {
113 existing.merge_from(value);
114 } else {
115 self.insert(key.clone(), value.clone());
116 }
117 }
118 }
119}
120
121impl<K, V> MergeFrom for collections::IndexMap<K, V>
122where
123 K: std::hash::Hash + Eq + Clone,
124 V: Clone + MergeFrom,
125{
126 fn merge_from(&mut self, other: &Self) {
127 for (key, value) in other {
128 if let Some(existing) = self.get_mut(key) {
129 existing.merge_from(value);
130 } else {
131 self.insert(key.clone(), value.clone());
132 }
133 }
134 }
135}
136
137impl<T> MergeFrom for collections::BTreeSet<T>
138where
139 T: Clone + Ord,
140{
141 fn merge_from(&mut self, other: &Self) {
142 for item in other {
143 self.insert(item.clone());
144 }
145 }
146}
147
148impl<T> MergeFrom for collections::HashSet<T>
149where
150 T: Clone + std::hash::Hash + Eq,
151{
152 fn merge_from(&mut self, other: &Self) {
153 for item in other {
154 self.insert(item.clone());
155 }
156 }
157}
158
159impl MergeFrom for serde_json::Value {
160 fn merge_from(&mut self, other: &Self) {
161 match (self, other) {
162 (serde_json::Value::Object(this), serde_json::Value::Object(other)) => {
163 for (key, value) in other {
164 if let Some(existing) = this.get_mut(key) {
165 existing.merge_from(value);
166 } else {
167 this.insert(key.clone(), value.clone());
168 }
169 }
170 }
171 (this, other) => *this = other.clone(),
172 }
173 }
174}