1 files changed, 62 insertions, 1 deletions

diff --git a/libsolidity/analysis/DeclarationContainer.cpp b/libsolidity/analysis/DeclarationContainer.cpp
index b33c8568..d41bc7d3 100644
--- a/libsolidity/analysis/DeclarationContainer.cpp
+++ b/libsolidity/analysis/DeclarationContainer.cpp
@@ -105,7 +105,7 @@ bool DeclarationContainer::registerDeclaration(
 	return true;
 }
 
-std::vector<Declaration const*> DeclarationContainer::resolveName(ASTString const& _name, bool _recursive) const
+vector<Declaration const*> DeclarationContainer::resolveName(ASTString const& _name, bool _recursive) const
 {
 	solAssert(!_name.empty(), "Attempt to resolve empty name.");
 	auto result = m_declarations.find(_name);
@@ -115,3 +115,64 @@ std::vector<Declaration const*> DeclarationContainer::resolveName(ASTString cons
 		return m_enclosingContainer->resolveName(_name, true);
 	return vector<Declaration const*>({});
 }
+
+vector<ASTString> DeclarationContainer::similarNames(ASTString const& _name) const
+{
+	vector<ASTString> similar;
+
+	for (auto const& declaration: m_declarations)
+	{
+		string const& declarationName = declaration.first;
+		if (DeclarationContainer::areSimilarNames(_name, declarationName))
+			similar.push_back(declarationName);
+	}
+
+	if (m_enclosingContainer)
+	{
+		vector<ASTString> enclosingSimilar = m_enclosingContainer->similarNames(_name);
+		similar.insert(similar.end(), enclosingSimilar.begin(), enclosingSimilar.end());
+	}
+
+	return similar;
+}
+
+bool DeclarationContainer::areSimilarNames(ASTString const& _name1, ASTString const& _name2)
+{
+	if (_name1 == _name2)
+		return true;
+
+	size_t n1 = _name1.size(), n2 = _name2.size();
+	vector<vector<size_t>> dp(n1 + 1, vector<size_t>(n2 + 1));
+
+	// In this dp formulation of Damerau–Levenshtein distance we are assuming that the strings are 1-based to make base case storage easier.
+	// So index accesser to _name1 and _name2 have to be adjusted accordingly
+	for (size_t i1 = 0; i1 <= n1; ++i1)
+	{
+		for (size_t i2 = 0; i2 <= n2; ++i2)
+		{
+				if (min(i1, i2) == 0) // base case
+					dp[i1][i2] = max(i1, i2);
+				else
+				{
+					dp[i1][i2] = min(dp[i1-1][i2] + 1, dp[i1][i2-1] + 1);
+					// Deletion and insertion
+					if (_name1[i1-1] == _name2[i2-1])
+						// Same chars, can skip
+						dp[i1][i2] = min(dp[i1][i2], dp[i1-1][i2-1]);
+					else
+						// Different chars so try substitution
+						dp[i1][i2] = min(dp[i1][i2], dp[i1-1][i2-1] + 1);
+
+					if (i1 > 1 && i2 > 1 && _name1[i1-1] == _name2[i2-2] && _name1[i1-2] == _name2[i2-1])
+						// Try transposing
+						dp[i1][i2] = min(dp[i1][i2], dp[i1-2][i2-2] + 1);
+				}
+		}
+	}
+
+	size_t distance = dp[n1][n2];
+
+	// If distance is not greater than MAXIMUM_DISTANCE, and distance is strictly less than length of both names,
+	// they can be considered similar this is to avoid irrelevant suggestions
+	return distance <= MAXIMUM_DISTANCE && distance < n1 && distance < n2;
+}