Merge pull request #759 from Akarinnnnn/fix-757

Make StringLineGroup returns a count limited Enumerator
xoofx · Dec 12, 2023 · 040a778 · 040a778
2 parents feeb186 + 2ae2cf9
commit 040a778
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Showing 2 changed files with 57 additions and 4 deletions.
diff --git a/src/Markdig.Tests/TestStringSliceList.cs b/src/Markdig.Tests/TestStringSliceList.cs
@@ -1,3 +1,4 @@
+using System.Collections;
 using System.Text;
 
 using Markdig.Helpers;
@@ -215,4 +216,27 @@ public void TestStringLineGroupCharIteratorForcingIncreaseCapacity()
         TextAssert.AreEqual("ABC\r\nD\r\n", chars.ToString());
         TextAssert.AreEqual("ABC\r\nD", text.ToString());
     }
-}
+
+    [Test]
+    public void TestStringLineGroup_EnumeratorReturnsRealLines()
+    {
+        string str = "A\r\n";
+        var text = new StringLineGroup(4)
+        {
+            new StringSlice(str, NewLine.CarriageReturnLineFeed) { Start = 0, End = 0 }
+        };
+
+        var enumerator = ((IEnumerable)text).GetEnumerator();
+        Assert.True(enumerator.MoveNext());
+        StringLine currentLine = (StringLine)enumerator.Current;
+        TextAssert.AreEqual("A", currentLine.ToString());
+        Assert.False(enumerator.MoveNext());
+
+        var nonBoxedEnumerator = text.GetEnumerator();
+
+        Assert.True(nonBoxedEnumerator.MoveNext());
+        currentLine = (StringLine)nonBoxedEnumerator.Current;
+        TextAssert.AreEqual("A", currentLine.ToString());
+        Assert.False(nonBoxedEnumerator.MoveNext());
+    }
+}
diff --git a/src/Markdig/Helpers/StringLineGroup.cs b/src/Markdig/Helpers/StringLineGroup.cs
@@ -187,9 +187,38 @@ public void Trim()
         }
     }
 
-    IEnumerator IEnumerable.GetEnumerator()
+    public struct Enumerator : IEnumerator
     {
-        return Lines.GetEnumerator();
+        private readonly StringLineGroup _parent;
+        private int _index;
+
+        public Enumerator(StringLineGroup parent)
+        {
+            _parent = parent;
+            _index = -1;
+        }
+
+        public object Current => _parent.Lines[_index];
+
+        public bool MoveNext()
+        {
+            return ++_index < _parent.Count;
+        }
+
+        public void Reset()
+        {
+            _index = -1;
+        }
+    }
+
+    public Enumerator GetEnumerator()
+    {
+        return new Enumerator(this);
+    }
+
+    IEnumerator IEnumerable.GetEnumerator() 
+    {
+        return GetEnumerator();
     }
 
     private void IncreaseCapacity()
@@ -444,4 +473,4 @@ public LineOffset(int linePosition, int column, int offset, int start, int end)
 
         public readonly int End;
     }
-}
+}