Fix ViFindBrace to search for brace the same as vim when current char is not a brace (#4862)

Author: sharpchen

PSReadLine/Movement.vi.cs

@@ -254,7 +254,32 @@ private int ViFindBrace(int i)
                 case ')':
                     return ViFindBackward(i, '(', withoutPassing: ')');
                 default:
-                    return i;
+                    ReadOnlySpan<char> parentheses = stackalloc char[] { '{', '}', '(', ')', '[', ']' };
+                    int nextParen = i;
+                    // find next of any kind of paren
+                    for (; nextParen < _buffer.Length; nextParen++)
+                        for (int idx = 0; idx < parentheses.Length; idx++)
+                            if (parentheses[idx] == _buffer[nextParen]) goto Outer;
+
+                    // if not found, nextParen could exceed the range
+                    if (nextParen >= _buffer.Length)
+                        return i;
+
+                Outer:
+                    int match = _buffer[nextParen] switch
+                    {
+                        // if next is opening, find forward
+                        '{' => ViFindForward(nextParen, '}', withoutPassing: '{'),
+                        '[' => ViFindForward(nextParen, ']', withoutPassing: '['),
+                        '(' => ViFindForward(nextParen, ')', withoutPassing: '('),
+                        // if next is closing, find backward
+                        '}' => ViFindBackward(nextParen, '{', withoutPassing: '}'),
+                        ']' => ViFindBackward(nextParen, '[', withoutPassing: ']'),
+                        ')' => ViFindBackward(nextParen, '(', withoutPassing: ')'),
+                        _ => nextParen
+                    };
+
+                    return match == nextParen ? i : match;
             }
         }
 

test/MovementTest.VI.cs

@@ -370,7 +370,7 @@ public void ViGlobMovement_EmptyBuffer_Defect1195()
             TestSetup(KeyMode.Vi);
 
             TestMustDing("", Keys(
-                _.Escape, "W" 
+                _.Escape, "W"
             ));
         }
 
@@ -423,6 +423,11 @@ public void ViCursorMovement()
         [SkippableFact]
         public void ViGotoBrace()
         {
+            // NOTE: When the input has unmatched braces, in order to avoid an
+            // exception caused by AcceptLineImpl waiting for incomplete input,
+            // the test needs to end with the Vi command "ddi" and assert that
+            // the result is an empty string.
+
             TestSetup(KeyMode.Vi);
 
             Test("0[2(4{6]8)a}c", Keys(
@@ -450,10 +455,60 @@ public void ViGotoBrace()
                     CheckThat(() => AssertCursorLeftIs(4)),
                     _.Percent,
                     CheckThat(() => AssertCursorLeftIs(4)),
-                    "ddi"
+                    "ddi" // Unmatched brace
                     ));
             }
 
+            // Tests when the cursor is not on any paren
+            foreach (var (opening, closing) in new[] { ('(', ')'), ('{', '}'), ('[', ']') })
+            {
+                // Closing paren with backward match
+                string input1 = $"0{opening}2{opening}4foo{closing}";
+                Test("", Keys(
+                    input1,
+                    CheckThat(() => AssertCursorLeftIs(9)),
+                    _.Escape, CheckThat(() => AssertCursorLeftIs(8)),
+                    "0ff", CheckThat(() => AssertCursorLeftIs(5)),
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(3)),
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(8)),
+                    "ddi" // Unmatched closing brace
+                ));
+
+                // Closing paren without backward match
+                string input2 = $"0]2)4foo{closing}";
+                TestMustDing(input2, Keys(
+                    input2,
+                    CheckThat(() => AssertCursorLeftIs(9)),
+                    _.Escape, CheckThat(() => AssertCursorLeftIs(8)),
+                    "0ff", CheckThat(() => AssertCursorLeftIs(5)),
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(5)), // stay still
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(5))
+                ));
+
+                // Opening paren with forward match
+                string input3 = $"0{opening}2foo6{closing}";
+                Test(input3, Keys(
+                    input3,
+                    CheckThat(() => AssertCursorLeftIs(8)),
+                    _.Escape, CheckThat(() => AssertCursorLeftIs(7)),
+                    "0ff", CheckThat(() => AssertCursorLeftIs(3)),
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(1)),
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(7))
+                ));
+
+                // Opening paren without forward match
+                string input4 = $"0)2]4foo{opening}(";
+                TestMustDing("", Keys(
+                    input4,
+                    CheckThat(() => AssertCursorLeftIs(10)),
+                    _.Escape, CheckThat(() => AssertCursorLeftIs(9)),
+                    "0ff", CheckThat(() => AssertCursorLeftIs(5)),
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(5)), // stay still
+                    _.Percent, CheckThat(() => AssertCursorLeftIs(5)),
+                    "ddi" // Unmatched brace
+                ));
+            }
+
             // <%> with empty text buffer should work fine.
             Test("", Keys(
                 _.Escape, _.Percent,