Add comments for RLP::operator[]

gumb0 · gumb0 · commit a791c5b24276 · 2019-04-10T13:11:13.000+02:00
diff --git a/libdevcore/RLP.cpp b/libdevcore/RLP.cpp
@@ -84,14 +84,20 @@ RLP RLP::operator[](size_t _i) const
 {
 	if (_i < m_lastIndex)
 	{
+		// Get size of 0th item
 		m_lastEnd = sizeAsEncoded(payload());
+		// Set m_lastItem to 0th item data
 		m_lastItem = payload().cropped(0, m_lastEnd);
 		m_lastIndex = 0;
 	}
 	for (; m_lastIndex < _i && m_lastItem.size(); ++m_lastIndex)
 	{
+		// Get chunk of payload data starting right after m_lastItem
+		// This will be empty when we're out of bounds
 		m_lastItem = payload().cropped(m_lastEnd);
+		// Crop it to get the data of the next item
 		m_lastItem = m_lastItem.cropped(0, sizeAsEncoded(m_lastItem));
+		// Point m_lastEnd to next item
 		m_lastEnd += m_lastItem.size();
 	}
 	return RLP(m_lastItem, ThrowOnFail | FailIfTooSmall);
diff --git a/libdevcore/RLP.h b/libdevcore/RLP.h
@@ -340,8 +340,11 @@ class RLP
 	bytesConstRef m_data;
 
 	/// The list-indexing cache.
+	// Index of the last item accessed with operator[]
 	mutable size_t m_lastIndex = (size_t)-1;
+	// Offset of the next byte after last byte of m_lastItem
 	mutable size_t m_lastEnd = 0;
+	// Data of the last item accessed with operator[]
 	mutable bytesConstRef m_lastItem;
 };
 

Original file line number	Diff line number	Diff line change
`@@ -84,14 +84,20 @@ RLP RLP::operator[](size_t _i) const`
`84`	`84`	`{`
`85`	`85`	`if (_i < m_lastIndex)`
`86`	`86`	`{`
	`87`	`+ // Get size of 0th item`
`87`	`88`	`m_lastEnd = sizeAsEncoded(payload());`
	`89`	`+ // Set m_lastItem to 0th item data`
`88`	`90`	`m_lastItem = payload().cropped(0, m_lastEnd);`
`89`	`91`	`m_lastIndex = 0;`
`90`	`92`	`}`
`91`	`93`	`for (; m_lastIndex < _i && m_lastItem.size(); ++m_lastIndex)`
`92`	`94`	`{`
	`95`	`+ // Get chunk of payload data starting right after m_lastItem`
	`96`	`+ // This will be empty when we're out of bounds`
`93`	`97`	`m_lastItem = payload().cropped(m_lastEnd);`
	`98`	`+ // Crop it to get the data of the next item`
`94`	`99`	`m_lastItem = m_lastItem.cropped(0, sizeAsEncoded(m_lastItem));`
	`100`	`+ // Point m_lastEnd to next item`
`95`	`101`	`m_lastEnd += m_lastItem.size();`
`96`	`102`	`}`
`97`	`103`	`return RLP(m_lastItem, ThrowOnFail \| FailIfTooSmall);`