perf(server): smarter tree-sitter parsing

server/src/context.ts

@@ -46,6 +46,9 @@ export type FileInfos = {
   // NOTE: It is stored to get more efficient parsing when the file is changed.
   // NOTE: It's not used for now, because at first try, it was not working well.
   tsTree: TSParser.Tree;
+  // Document version to check if the document has changed since the last parse.
+  // NOTE: for now, it's only used to skip the tree-sitter parsing if the document has not changed.
+  version?: number;
 };
 
 export type RuleDef = {

server/src/publicodesRules.ts

@@ -7,7 +7,7 @@ import { Diagnostic, DiagnosticSeverity } from "vscode-languageserver/node.js";
 import { getModelFromSource } from "@publicodes/tools/compilation";
 
 import { FilePath, LSContext, RawPublicodes, RuleDef } from "./context";
-import { tsParseText } from "./treeSitter";
+import { getTSTree } from "./treeSitter";
 
 const PUBLICODES_FILE_EXTENSION = ".publicodes";
 
@@ -46,7 +46,8 @@ export function parseDocument(
   document?: TextDocument,
 ) {
   const fileContent = document?.getText() ?? readFileSync(filePath).toString();
-  const tsTree = tsParseText(fileContent);
+  const fileInfos = ctx.fileInfos.get(filePath);
+  const tsTree = getTSTree(fileContent, fileInfos, document);
   const { rawRules, errors } = parseRawRules(filePath);
   const ruleDefs = collectRuleDefs(tsTree);
 

server/src/semanticTokens.ts

@@ -7,17 +7,18 @@ import {
 } from "vscode-languageserver";
 import { LSContext } from "./context";
 import TSParser from "tree-sitter";
-import { tsParseText } from "./treeSitter";
+import { getTSTree } from "./treeSitter";
+import { fileURLToPath } from "node:url";
 
 export function semanticTokensFullProvider(ctx: LSContext) {
   return ({ textDocument }: SemanticTokensParams): SemanticTokens => {
     const document = ctx.documents.get(textDocument.uri);
     const builder = new SemanticTokensBuilder();
+    const fileInfos = ctx.fileInfos.get(fileURLToPath(textDocument.uri));
 
     if (document) {
-      // TODO: investigate to use cache or be smarter with the parseDocument function
       const fileContent = document.getText();
-      const currentTree = tsParseText(fileContent);
+      const currentTree = getTSTree(fileContent, fileInfos, document);
       collectTokens(ctx, builder, currentTree.rootNode);
     }
 

server/src/treeSitter.ts

@@ -1,12 +1,28 @@
 import TSParser from "tree-sitter";
 import Publicodes from "tree-sitter-publicodes";
+import { TextDocument } from "vscode-languageserver-textdocument";
+import { FileInfos } from "./context";
 
 const parser = new TSParser();
 parser.setLanguage(Publicodes);
 
-export function tsParseText(
+/**
+ * Parse the content of the document with the tree-sitter parser if the
+ * document has changed since the last parse.
+ *
+ * @param content - The content of the document to parse
+ * @param fileInfos - The file infos to check if the document has changed
+ * @param document - The document to get the version from
+ *
+ * @returns The tree-sitter tree of the document
+ */
+export function getTSTree(
   content: string,
-  currentTree?: TSParser.Tree | undefined,
+  fileInfos: FileInfos | undefined,
+  document: TextDocument | undefined,
 ): TSParser.Tree {
-  return parser.parse(content, currentTree);
+  if (fileInfos?.version && fileInfos.version === document?.version) {
+    return fileInfos.tsTree;
+  }
+  return parser.parse(content);
 }