VSCodeVim · danielglasgow · Oct 17, 2024
diff --git a/src/cmd_line/commands/let.ts b/src/cmd_line/commands/let.ts
@@ -1,6 +1,8 @@
 // eslint-disable-next-line id-denylist
 import { alt, optWhitespace, Parser, seq, string, whitespace } from 'parsimmon';
 import { env } from 'process';
+import { ErrorCode, VimError } from '../../error';
+import { Register, RegisterMode } from '../../register/register';
 import { VimState } from '../../state/vimState';
 import { StatusBar } from '../../statusBar';
 import { ExCommand } from '../../vimscript/exCommand';
@@ -13,23 +15,23 @@ import {
   str,
   subtract,
 } from '../../vimscript/expression/build';
-import { EvaluationContext } from '../../vimscript/expression/evaluate';
+import { displayValue } from '../../vimscript/expression/displayValue';
+import { EvaluationContext, toString } from '../../vimscript/expression/evaluate';
 import {
   envVariableParser,
   expressionParser,
   optionParser,
   registerParser,
   variableParser,
 } from '../../vimscript/expression/parser';
+import { stringToRegisterMode } from '../../vimscript/expression/registerUtils';
 import {
   EnvVariableExpression,
   Expression,
   OptionExpression,
   RegisterExpression,
   VariableExpression,
 } from '../../vimscript/expression/types';
-import { displayValue } from '../../vimscript/expression/displayValue';
-import { ErrorCode, VimError } from '../../error';
 
 export type LetCommandOperation = '=' | '+=' | '-=' | '*=' | '/=' | '%=' | '.=' | '..=';
 export type LetCommandVariable =
@@ -143,7 +145,23 @@ export class LetCommand extends ExCommand {
         }
         context.setVariable(variable, value, this.args.lock);
       } else if (variable.type === 'register') {
-        // TODO
+        if (this.args.operation !== '=') {
+          throw VimError.fromCode(ErrorCode.InvalidOperationForRegister, this.args.operation);
+        }
+        let registerIndex = 0;
+        const items = value.type === 'list' ? value.items : [value];
+        for (const item of items) {
+          const registerMode =
+            item.type === 'register_val'
+              ? stringToRegisterMode(item.registerMode)
+              : RegisterMode.CharacterWise;
+          Register.put(vimState, toString(value), registerIndex, /* copyToUnamed */ false, {
+            registerName: variable.name,
+            registerMode,
+            forceOverwrite: true,
+          });
+          registerIndex++;
+        }
       } else if (variable.type === 'option') {
         // TODO
       } else if (variable.type === 'env_variable') {

diff --git a/src/error.ts b/src/error.ts
@@ -81,6 +81,10 @@ export enum ErrorCode {
   UsingABlobAsANumber = 974,
   CannotModifyExistingVariable = 995,
   CannotLockARegister = 996,
+  CannotAccessClipboardRegister = 997,
+  UsingARegisterAsANumber = 998,
+  CannotAccessRecordedStateRegister = 999,
+  InvalidOperationForRegister = 1000,
 }
 
 export const ErrorMessage: IErrorMessage = {
@@ -162,6 +166,10 @@ export const ErrorMessage: IErrorMessage = {
   974: 'Using a Blob as a Number',
   995: 'Cannot modify existing variable',
   996: 'Cannot lock a register',
+  997: 'Cannot access clipboard register',
+  998: 'Using a register as a Number',
+  999: 'Cannot access recorded state register',
+  1000: 'Invalid operation for register',
 };
 
 export class VimError extends Error {

diff --git a/src/register/register.ts b/src/register/register.ts
@@ -55,9 +55,10 @@ export class Register {
     vimState: VimState,
     content: RegisterContent,
     multicursorIndex?: number,
-    copyToUnnamed?: boolean,
+    copyToUnnamed?: boolean, // TODO: This should be a part of the options object
+    options: { registerName?: string; registerMode?: RegisterMode; forceOverwrite?: boolean } = {},
   ): void {
-    const register = vimState.recordedState.registerName;
+    const register = options.registerName || vimState.recordedState.registerName;
 
     if (!Register.isValidRegister(register)) {
       throw new Error(`Invalid register ${register}`);
@@ -67,17 +68,33 @@ export class Register {
       return;
     }
 
-    if (Register.isValidUppercaseRegister(register)) {
-      Register.appendToRegister(vimState, register.toLowerCase(), content, multicursorIndex ?? 0);
+    if (Register.isValidUppercaseRegister(register) && !options.forceOverwrite) {
+      Register.appendToRegister(
+        vimState,
+        Register.decapitalize(register),
+        content,
+        multicursorIndex ?? 0,
+        options.registerMode,
+      );
     } else {
-      Register.overwriteRegister(vimState, register, content, multicursorIndex ?? 0);
+      Register.overwriteRegister(
+        vimState,
+        Register.decapitalize(register),
+        content,
+        multicursorIndex ?? 0,
+        options.registerMode,
+      );
     }
 
     if (copyToUnnamed && register !== '"') {
       Register.registers.set('"', Register.registers.get(register)!);
     }
   }
 
+  private static decapitalize(register: string): string {
+    return Register.isValidUppercaseRegister(register) ? register.toLowerCase() : register;
+  }
+
   public static isValidRegister(register: string): boolean {
     return (
       Register.isValidLowercaseRegister(register) ||
@@ -95,7 +112,7 @@ export class Register {
     return registerName === '_';
   }
 
-  private static isClipboardRegister(registerName: string): boolean {
+  public static isClipboardRegister(registerName: string): boolean {
     return registerName === '*' || registerName === '+';
   }
 
@@ -120,13 +137,14 @@ export class Register {
     register: string,
     content: RegisterContent,
     multicursorIndex: number,
+    registerMode?: RegisterMode,
   ): void {
     if (multicursorIndex === 0 || !Register.registers.has(register)) {
       Register.registers.set(register, []);
     }
 
     Register.registers.get(register)![multicursorIndex] = {
-      registerMode: vimState.currentRegisterMode,
+      registerMode: registerMode || vimState.currentRegisterMode,
       text: content,
     };
 
@@ -149,6 +167,7 @@ export class Register {
     register: string,
     content: RegisterContent,
     multicursorIndex: number,
+    registerMode?: RegisterMode,
   ): void {
     if (!Register.registers.has(register)) {
       Register.registers.set(register, []);
@@ -162,11 +181,13 @@ export class Register {
         text: content,
       };
     } else {
-      // Line-wise trumps other RegisterModes
-      const registerMode =
-        vimState.currentRegisterMode === RegisterMode.LineWise
-          ? RegisterMode.LineWise
-          : oldContent.registerMode;
+      if (!registerMode) {
+        // Line-wise trumps other RegisterModes
+        registerMode =
+          vimState.currentRegisterMode === RegisterMode.LineWise
+            ? RegisterMode.LineWise
+            : oldContent.registerMode;
+      }
       let newText: RegisterContent;
       if (oldContent.text instanceof RecordedState || content instanceof RecordedState) {
         newText = oldContent.text;
@@ -271,13 +292,7 @@ export class Register {
     register: string,
     multicursorIndex = 0,
   ): Promise<IRegisterContent | undefined> {
-    if (!Register.isValidRegister(register)) {
-      throw new Error(`Invalid register ${register}`);
-    }
-
-    register = register.toLowerCase();
-
-    const contentByCursor = Register.registers.get(register);
+    const contentByCursor = Register.getRegisterArray(register);
 
     if (Register.isClipboardRegister(register)) {
       const clipboardContent = (await Clipboard.Paste()).replace(/\r\n/g, '\n');
@@ -302,6 +317,13 @@ export class Register {
     return contentByCursor?.[multicursorIndex];
   }
 
+  public static getRegisterArray(register: string): IRegisterContent[] | undefined {
+    if (!Register.isValidRegister(register)) {
+      throw new Error(`Invalid register ${register}`);
+    }
+    return Register.registers.get(register.toLowerCase());
+  }
+
   public static has(register: string): boolean {
     return Register.registers.has(register);
   }

diff --git a/src/vimscript/expression/build.ts b/src/vimscript/expression/build.ts
@@ -1,21 +1,22 @@
 import {
-  NumberValue,
-  Expression,
-  ListExpression,
-  UnaryExpression,
-  BinaryOp,
   BinaryExpression,
-  FunctionCallExpression,
-  StringValue,
-  LambdaExpression,
-  VariableExpression,
-  Namespace,
+  BinaryOp,
+  BlobValue,
+  DictionaryValue,
+  Expression,
   FloatValue,
   FuncRefValue,
+  FunctionCallExpression,
+  LambdaExpression,
+  ListExpression,
   ListValue,
-  DictionaryValue,
+  Namespace,
+  NumberValue,
+  RegisterValue,
+  StringValue,
+  UnaryExpression,
   Value,
-  BlobValue,
+  VariableExpression,
 } from './types';
 
 export function int(value: number): NumberValue {
@@ -66,6 +67,17 @@ export function blob(data: ArrayBuffer): BlobValue {
   };
 }
 
+export function register(
+  content: string,
+  registerMode: 'character' | 'line' | 'block',
+): RegisterValue {
+  return {
+    type: 'register_val',
+    content,
+    registerMode,
+  };
+}
+
 export function listExpr(items: Expression[]): ListExpression {
   return {
     type: 'list',

diff --git a/src/vimscript/expression/displayValue.ts b/src/vimscript/expression/displayValue.ts
@@ -42,5 +42,7 @@ export function displayValue(value: Value, topLevel = true): string {
           .join('')
           .toUpperCase()
       );
+    case 'register_val':
+      return `register('${value.content}',  ${value.registerMode})`;
   }
 }
diff --git a/src/vimscript/expression/evaluate.ts b/src/vimscript/expression/evaluate.ts
@@ -1,10 +1,11 @@
 import { all } from 'parsimmon';
-import { displayValue } from './displayValue';
 import { configuration } from '../../configuration/configuration';
 import { ErrorCode, VimError } from '../../error';
 import { globalState } from '../../state/globalState';
-import { bool, float, funcref, listExpr, int, str, list, funcCall, blob } from './build';
+import { blob, bool, float, funcCall, funcref, int, list, listExpr, str } from './build';
+import { displayValue } from './displayValue';
 import { expressionParser, numberParser } from './parser';
+import { lookupRegister } from './registerUtils';
 import {
   BinaryOp,
   ComparisonOp,
@@ -43,6 +44,8 @@ function toInt(value: Value): number {
       throw VimError.fromCode(ErrorCode.UsingAFuncrefAsANumber);
     case 'blob':
       throw VimError.fromCode(ErrorCode.UsingABlobAsANumber);
+    case 'register_val':
+      throw VimError.fromCode(ErrorCode.UsingARegisterAsANumber);
   }
 }
 
@@ -57,6 +60,7 @@ function toFloat(value: Value): number {
     case 'dict_val':
     case 'funcref':
     case 'blob':
+    case 'register_val':
       throw VimError.fromCode(ErrorCode.NumberOrFloatRequired);
   }
 }
@@ -77,6 +81,8 @@ export function toString(value: Value): string {
       throw VimError.fromCode(ErrorCode.UsingFuncrefAsAString);
     case 'blob':
       return displayValue(value);
+    case 'register_val':
+      return value.content;
   }
 }
 
@@ -88,6 +94,7 @@ function toList(value: Value): ListValue {
     case 'funcref':
     case 'dict_val':
     case 'blob':
+    case 'register_val':
       throw VimError.fromCode(ErrorCode.ListRequired);
     case 'list':
       return value;
@@ -102,6 +109,7 @@ function toDict(value: Value): DictionaryValue {
     case 'list':
     case 'funcref':
     case 'blob':
+    case 'register_val':
       throw VimError.fromCode(ErrorCode.DictionaryRequired);
     case 'dict_val':
       return value;
@@ -147,6 +155,7 @@ export class EvaluationContext {
       case 'dict_val':
       case 'funcref':
       case 'blob':
+      case 'register_val':
         return expression;
       case 'list':
         return list(expression.items.map((x) => this.evaluate(x)));
@@ -168,7 +177,7 @@ export class EvaluationContext {
       case 'variable':
         return this.evaluateVariable(expression);
       case 'register':
-        return str(''); // TODO
+        return lookupRegister(expression.name);
       case 'option':
         return str(''); // TODO
       case 'env_variable':
@@ -395,6 +404,9 @@ export class EvaluationContext {
         const bytes = new Uint8Array(sequence.data);
         return int(bytes[toInt(index)]);
       }
+      case 'register_val': {
+        return this.evaluateIndex(str(toString(sequence)), index);
+      }
     }
   }
 
@@ -438,6 +450,9 @@ export class EvaluationContext {
       case 'blob': {
         return blob(new Uint8Array(sequence.data).slice(_start, _end + 1));
       }
+      case 'register_val': {
+        return this.evaluateSlice(str(toString(sequence)), start, end);
+      }
     }
   }
 
@@ -1281,6 +1296,8 @@ export class EvaluationContext {
           //   return int(7);
           case 'blob':
             return int(8);
+          case 'register_val':
+            return int(9);
           default:
             const guard: never = x;
             throw new Error('type() got unexpected type');