:ec[ho] throws E15 if an expression doesn't parse

Author: J-Fields

src/cmd_line/commands/echo.ts

@@ -1,17 +1,24 @@
-import { optWhitespace, Parser, whitespace } from 'parsimmon';
+import { all, optWhitespace, Parser, seq, whitespace } from 'parsimmon';
 import { VimState } from '../../state/vimState';
 import { StatusBar } from '../../statusBar';
 import { ExCommand } from '../../vimscript/exCommand';
 import { EvaluationContext } from '../../vimscript/expression/evaluate';
 import { expressionParser } from '../../vimscript/expression/parser';
 import { Expression } from '../../vimscript/expression/types';
 import { displayValue } from '../../vimscript/expression/displayValue';
+import { VimError } from '../../error';
 
 export class EchoCommand extends ExCommand {
   public static argParser(echoArgs: { sep: string; error: boolean }): Parser<EchoCommand> {
     return optWhitespace
-      .then(expressionParser.sepBy(whitespace))
-      .map((expressions) => new EchoCommand(echoArgs, expressions));
+      .then(seq(expressionParser.sepBy(whitespace), all))
+      .map(([expressions, trailing]) => {
+        trailing = trailing.trimStart();
+        if (trailing) {
+          throw VimError.InvalidExpression(trailing);
+        }
+        return new EchoCommand(echoArgs, expressions);
+      });
   }
 
   private sep: string;

src/error.ts

@@ -110,8 +110,8 @@ export class VimError extends Error {
   static InvalidAddress(): VimError {
     return new VimError(ErrorCode.InvalidAddress, 'Invalid address');
   }
-  static InvalidExpression(): VimError {
-    return new VimError(ErrorCode.InvalidExpression, 'Invalid expression');
+  static InvalidExpression(expr: string): VimError {
+    return new VimError(ErrorCode.InvalidExpression, `Invalid expression: "${expr}"`);
   }
   static InvalidRange(): VimError {
     return new VimError(ErrorCode.InvalidRange, 'Invalid range');

src/vimscript/exCommandParser.ts

@@ -691,10 +691,11 @@ export const exCommandParser: Parser<{ lineRange: LineRange | undefined; command
         }
         throw VimError.InvalidArgument474();
       }
-      if (result.value[1]) {
+      const [command, remaining] = result.value;
+      if (remaining) {
         // TODO: Implement `:help :bar`
         // TODO: Implement `:help :comment`
-        throw VimError.TrailingCharacters(result.value[1]);
+        throw VimError.TrailingCharacters(remaining);
       }
-      return { lineRange, command: result.value[0] };
+      return { lineRange, command };
     });