Multiple configuration files

Cargo.toml

@@ -26,6 +26,7 @@ maplit = "1"
 serde = "1"
 serde_derive = "1"
 serde_json = "1"
+json-patch = "0.2"
 crossbeam = "0.7.3"
 jsonrpc-core = "12"
 lsp-types = { version = "0.70.0", features = ["proposed"] }

autoload/LanguageClient.vim

@@ -282,6 +282,16 @@ function! s:GetVar(...) abort
     endif
 endfunction
 
+" if the argument is a list, return it unchanged, otherwise return the list
+" containing the argument.
+function! s:ToList(x) abort
+    if type(a:x) == v:t_list
+        return a:x
+    else
+        return [ a:x ]
+    endif
+endfunction
+
 function! s:ShouldUseFloatWindow() abort
     let floatingHoverEnabled = s:GetVar('LanguageClient_useFloatingHover', v:true)
     return s:FLOAT_WINDOW_AVAILABLE && floatingHoverEnabled

doc/LanguageClient.txt

@@ -202,8 +202,10 @@ Valid options: "Error" | "Warning" | "Info" | "Log"
 
 2.12 g:LanguageClient_settingsPath              *g:LanguageClient_settingsPath*
 
-Path for language server settings. If not an absolute path this is relative
-to the workspace directory.
+Path for language server settings, or list of such paths. If not an absolute
+path this is relative to the workspace directory. If several paths are
+provided, then the corresponding settings are merged with precedence going to
+the last file.
 
 Example settings file content: >
     {

src/language_server_protocol.rs

@@ -79,7 +79,7 @@ impl LanguageClient {
             HashMap<String, Vec<String>>,
             Option<String>,
             Option<String>,
-            String,
+            Vec<String>,
             u64,
             Option<RootMarkers>,
             Option<f64>,
@@ -97,7 +97,7 @@ impl LanguageClient {
                 "s:GetVar('LanguageClient_serverCommands', {})",
                 "get(g:, 'LanguageClient_selectionUI', v:null)",
                 "get(g:, 'LanguageClient_trace', v:null)",
-                "expand(get(g:, 'LanguageClient_settingsPath', '.vim/settings.json'))",
+                "map(s:ToList(get(g:, 'LanguageClient_settingsPath', '.vim/settings.json')), 'expand(v:val)')",
                 "!!get(g:, 'LanguageClient_loadSettings', 1)",
                 "get(g:, 'LanguageClient_rootMarkers', v:null)",
                 "get(g:, 'LanguageClient_changeThrottle', v:null)",
@@ -275,13 +275,39 @@ impl LanguageClient {
             return Ok(Value::Null);
         }
 
-        let path = Path::new(root).join(&self.get(|state| state.settingsPath.clone())?);
-        let buffer = read_to_string(&path).with_context(|err| {
-            format!("Failed to read file ({}): {}", path.to_string_lossy(), err)
-        })?;
-        let value = serde_json::from_str(&buffer)?;
-        let value = expand_json_path(value);
-        Ok(value)
+        let mut res = Value::Null;
+        let mut last_err = None;
+        let mut at_least_one_success = false;
+        for orig_path in self.get(|state| state.settingsPath.clone())? {
+            let path = Path::new(root).join(orig_path);
+            let buffer = read_to_string(&path).with_context(|err| {
+                format!("Failed to read file ({}): {}", path.to_string_lossy(), err)
+            });
+            let buffer = match buffer {
+                Err(e) => {
+                    last_err = Some(e.into());
+                    continue;
+                }
+                Ok(x) => x,
+            };
+            let value = serde_json::from_str(&buffer);
+            let value = match value {
+                Err(e) => {
+                    last_err = Some(e.into());
+                    continue;
+                }
+                Ok(x) => x,
+            };
+            let value = expand_json_path(value);
+            json_patch::merge(&mut res, &value);
+            at_least_one_success = true;
+        }
+
+        match last_err {
+            // no file was read and an error happened
+            Some(e) if !at_least_one_success => Err(e),
+            _ => Ok(res),
+        }
     }
 
     fn define_signs(&self) -> Fallible<()> {

src/types.rs

@@ -173,7 +173,7 @@ pub struct State {
     pub diagnostics_max_severity: DiagnosticSeverity,
     pub documentHighlightDisplay: HashMap<u64, DocumentHighlightDisplay>,
     pub windowLogMessageLevel: MessageType,
-    pub settingsPath: String,
+    pub settingsPath: Vec<String>,
     pub loadSettings: bool,
     pub rootMarkers: Option<RootMarkers>,
     pub change_throttle: Option<Duration>,
@@ -252,7 +252,7 @@ impl State {
             diagnostics_max_severity: DiagnosticSeverity::Hint,
             documentHighlightDisplay: DocumentHighlightDisplay::default(),
             windowLogMessageLevel: MessageType::Warning,
-            settingsPath: format!(".vim{}settings.json", std::path::MAIN_SEPARATOR),
+            settingsPath: vec![format!(".vim{}settings.json", std::path::MAIN_SEPARATOR)],
             loadSettings: false,
             rootMarkers: None,
             change_throttle: None,

tests/test.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -o xtrace