1/// Trait for recursively merging settings structures.
2///
3/// When Zed starts it loads settinsg 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 gpui::SharedString,
58 std::path::PathBuf,
59 gpui::Modifiers,
60 gpui::FontFeatures,
61 gpui::FontWeight
62);
63
64impl<T: Clone + MergeFrom> MergeFrom for Option<T> {
65 fn merge_from(&mut self, other: &Self) {
66 let Some(other) = other else {
67 return;
68 };
69 if let Some(this) = self {
70 this.merge_from(other);
71 } else {
72 self.replace(other.clone());
73 }
74 }
75}
76
77impl<T: Clone> MergeFrom for Vec<T> {
78 fn merge_from(&mut self, other: &Self) {
79 *self = other.clone()
80 }
81}
82
83impl<T: MergeFrom> MergeFrom for Box<T> {
84 fn merge_from(&mut self, other: &Self) {
85 self.as_mut().merge_from(other.as_ref())
86 }
87}
88
89// Implementations for collections that extend/merge their contents
90impl<K, V> MergeFrom for collections::HashMap<K, V>
91where
92 K: Clone + std::hash::Hash + Eq,
93 V: Clone + MergeFrom,
94{
95 fn merge_from(&mut self, other: &Self) {
96 for (k, v) in other {
97 if let Some(existing) = self.get_mut(k) {
98 existing.merge_from(v);
99 } else {
100 self.insert(k.clone(), v.clone());
101 }
102 }
103 }
104}
105
106impl<K, V> MergeFrom for collections::BTreeMap<K, V>
107where
108 K: Clone + std::hash::Hash + Eq + Ord,
109 V: Clone + MergeFrom,
110{
111 fn merge_from(&mut self, other: &Self) {
112 for (k, v) in other {
113 if let Some(existing) = self.get_mut(k) {
114 existing.merge_from(v);
115 } else {
116 self.insert(k.clone(), v.clone());
117 }
118 }
119 }
120}
121
122impl<K, V> MergeFrom for collections::IndexMap<K, V>
123where
124 K: std::hash::Hash + Eq + Clone,
125 // Q: ?Sized + std::hash::Hash + collections::Equivalent<K> + Eq,
126 V: Clone + MergeFrom,
127{
128 fn merge_from(&mut self, other: &Self) {
129 for (k, v) in other {
130 if let Some(existing) = self.get_mut(k) {
131 existing.merge_from(v);
132 } else {
133 self.insert(k.clone(), v.clone());
134 }
135 }
136 }
137}
138
139impl<T> MergeFrom for collections::BTreeSet<T>
140where
141 T: Clone + Ord,
142{
143 fn merge_from(&mut self, other: &Self) {
144 for item in other {
145 self.insert(item.clone());
146 }
147 }
148}
149
150impl<T> MergeFrom for collections::HashSet<T>
151where
152 T: Clone + std::hash::Hash + Eq,
153{
154 fn merge_from(&mut self, other: &Self) {
155 for item in other {
156 self.insert(item.clone());
157 }
158 }
159}
160
161impl MergeFrom for serde_json::Value {
162 fn merge_from(&mut self, other: &Self) {
163 match (self, other) {
164 (serde_json::Value::Object(this), serde_json::Value::Object(other)) => {
165 for (k, v) in other {
166 if let Some(existing) = this.get_mut(k) {
167 existing.merge_from(v);
168 } else {
169 this.insert(k.clone(), v.clone());
170 }
171 }
172 }
173 (this, other) => *this = other.clone(),
174 }
175 }
176}