add toggleMultilineStringLiteral command

Author: devhawk

package.json

@@ -349,6 +349,11 @@
         "title": "Install Zig",
         "category": "Zig Setup"
       },
+      {
+        "command": "zig.toggleMultilineStringLiteral",
+        "title": "Toggle Multiline String Literal",
+        "category": "Zig"
+      },
       {
         "command": "zig.zls.enable",
         "title": "Enable Language Server",
@@ -365,6 +370,13 @@
         "category": "ZLS language server"
       }
     ],
+    "keybindings": [
+      {
+        "command": "zig.toggleMultilineStringLiteral",
+        "key": "alt+m alt+s",
+        "when": "editorTextFocus && editorLangId == 'zig'"
+      }
+    ],
     "jsonValidation": [
       {
         "fileMatch": "zls.json",

src/extension.ts

@@ -23,6 +23,7 @@ export async function activate(context: vscode.ExtensionContext) {
                 { language: "zig", scheme: "file" },
                 new ZigMainCodeLensProvider(),
             ),
+            vscode.commands.registerCommand("zig.toggleMultilineStringLiteral", toggleMultilineStringLiteral),
         );
 
         void activateZls(context);
@@ -32,3 +33,38 @@ export async function activate(context: vscode.ExtensionContext) {
 export async function deactivate() {
     await deactivateZls();
 }
+
+async function toggleMultilineStringLiteral() {
+    const editor = vscode.window.activeTextEditor;
+    if (!editor) return;
+    const { document, selection } = editor;
+    if (document.languageId !== "zig") return;
+
+    let newText = "";
+    let range = new vscode.Range(selection.start, selection.end);
+
+    const firstLine = document.lineAt(selection.start.line);
+    const nonWhitespaceIndex = firstLine.firstNonWhitespaceCharacterIndex;
+
+    for (let lineNum = selection.start.line; lineNum <= selection.end.line; lineNum++) {
+        const line = document.lineAt(lineNum);
+
+        const isMLSL = line.text.slice(line.firstNonWhitespaceCharacterIndex).startsWith("\\\\");
+        const breakpoint = Math.min(nonWhitespaceIndex, line.firstNonWhitespaceCharacterIndex);
+
+        const newLine = isMLSL
+            ? line.text.slice(0, line.firstNonWhitespaceCharacterIndex) +
+              line.text.slice(line.firstNonWhitespaceCharacterIndex).slice(2)
+            : line.isEmptyOrWhitespace
+              ? " ".repeat(nonWhitespaceIndex) + "\\\\"
+              : line.text.slice(0, breakpoint) + "\\\\" + line.text.slice(breakpoint);
+        newText += newLine;
+        if (lineNum < selection.end.line) newText += "\n";
+
+        range = range.union(line.range);
+    }
+
+    await editor.edit((builder) => {
+        builder.replace(range, newText);
+    });
+}