feature / #68 skip running checks if file content has not changed

src/extension.ts

@@ -1,11 +1,15 @@
 import * as vscode from 'vscode';
 import * as cp from 'child_process';
 import * as xml2js from 'xml2js';
+import * as crypto from 'crypto';
 
 import { documentationLinkMap, getPremiumCertLink } from './util/documentation';
 import { runCommand } from './util/scripts';
 import { looksLikePath, resolvePath, findWorkspaceRoot } from './util/path';
 
+// To keep track of document changes we save hashed versions of their content to this record
+let documentHashMemory : Record<string, string> = {};
+
 enum SeverityNumber {
     Info = 0,
     Warning = 1,
@@ -64,6 +68,13 @@ function parseMinSeverity(str: string): SeverityNumber {
     }
 }
 
+function getDocumentSha1(document: vscode.TextDocument): string {
+    return crypto
+        .createHash('sha1')
+        .update(document.getText(), 'utf8')
+        .digest('hex');
+}
+
 // This method is called when your extension is activated.
 // Your extension is activated the very first time the command is executed.
 export async function activate(context: vscode.ExtensionContext) {
@@ -92,6 +103,15 @@ export async function activate(context: vscode.ExtensionContext) {
             return;
         }
 
+        if ((Object.keys(documentHashMemory) as Array<string>).includes(document.fileName)) {
+            // Check file content against memory, if it has not changed since last check do early return
+            const newHash = getDocumentSha1(document);
+            const oldHash = documentHashMemory[document.fileName];
+            if (newHash === oldHash) {
+                return;
+            }
+        }
+
         // Check if the document is visible in any editor
         const isVisible = vscode.window.visibleTextEditors.some(editor =>
             editor.document.uri.toString().replaceAll('\\', '/') === document.uri.toString().replaceAll('\\', '/'));
@@ -148,6 +168,10 @@ export async function activate(context: vscode.ExtensionContext) {
             minSevString,
             diagnosticCollection
         );
+
+        // Save hashed document content to memory
+        const hashedContentOfFile = getDocumentSha1(document);
+        documentHashMemory[document.fileName] = hashedContentOfFile;
     }
 
     // Listen for file saves.