From 72ae0f6a1a5e8d25ef33d5697f792b665a0bb0cb Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Mon, 21 Mar 2022 19:35:58 +0100
Subject: [PATCH] Use enumerate.

---
 libsolutil/BooleanLP.cpp      |  4 ++--
 libsolutil/LP.cpp             | 10 +++++-----
 libsolutil/LinearExpression.h |  9 ++++-----
 3 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/libsolutil/BooleanLP.cpp b/libsolutil/BooleanLP.cpp
index c15efb129..4577d6582 100644
--- a/libsolutil/BooleanLP.cpp
+++ b/libsolutil/BooleanLP.cpp
@@ -489,7 +489,7 @@ optional<LinearExpression> BooleanLPSolver::parseFactor(smtutil::Expression cons
 
 bool BooleanLPSolver::tryAddDirectBounds(Constraint const& _constraint)
 {
-	auto nonzero = _constraint.data | ranges::views::enumerate | ranges::views::tail | ranges::views::filter(
+	auto nonzero = _constraint.data.enumerateTail() | ranges::views::filter(
 		[](std::pair<size_t, rational> const& _x) { return !!_x.second; }
 	);
 	// TODO we can exit early on in the loop above.
@@ -650,7 +650,7 @@ string BooleanLPSolver::toString(Clause const& _clause) const
 string BooleanLPSolver::toString(Constraint const& _constraint) const
 {
 	vector<string> line;
-	for (auto&& [index, multiplier]: _constraint.data | ranges::views::enumerate)
+	for (auto&& [index, multiplier]: _constraint.data.enumerate())
 		if (index > 0 && multiplier != 0)
 		{
 			string mult =
diff --git a/libsolutil/LP.cpp b/libsolutil/LP.cpp
index c3350bbd2..4ed84c7bb 100644
--- a/libsolutil/LP.cpp
+++ b/libsolutil/LP.cpp
@@ -148,7 +148,7 @@ pair<vector<LinearExpression>, bool> toEquationalForm(vector<Constraint> _constr
 optional<size_t> findPivotColumn(Tableau const& _tableau)
 {
 	auto&& [maxColumn, maxValue] = ranges::max(
-		_tableau.objective | ranges::views::enumerate | ranges::views::tail,
+		_tableau.objective.enumerateTail(),
 		{},
 		[](std::pair<size_t, rational> const& _x) { return _x.second; }
 	);
@@ -468,7 +468,7 @@ pair<vector<bool>, vector<bool>> connectedComponent(SolvingState const& _state,
 			if (includedRows[row])
 				continue;
 			includedRows[row] = true;
-			for (auto const& [index, entry]: _state.constraints[row].data | ranges::views::enumerate | ranges::views::tail)
+			for (auto const& [index, entry]: _state.constraints[row].data.enumerateTail())
 				if (entry && !seenColumns[index])
 				{
 					seenColumns[index] = true;
@@ -536,7 +536,7 @@ string SolvingState::toString() const
 	for (Constraint const& constraint: constraints)
 	{
 		vector<string> line;
-		for (auto&& [index, multiplier]: constraint.data | ranges::views::enumerate)
+		for (auto&& [index, multiplier]: constraint.data.enumerate())
 			if (index > 0 && multiplier != 0)
 			{
 				string mult =
@@ -631,7 +631,7 @@ optional<ReasonSet> SolvingStateSimplifier::extractDirectConstraints()
 	bool needsRemoval = false;
 	for (auto const& [index, constraint]: m_state.constraints | ranges::views::enumerate)
 	{
-		auto nonzeroCoefficients = constraint.data | ranges::views::enumerate | ranges::views::tail | ranges::views::filter(
+		auto nonzeroCoefficients = constraint.data.enumerateTail() | ranges::views::filter(
 			[](std::pair<size_t, rational> const& _x) { return !!_x.second; }
 		);
 		// TODO we can exit early on in the loop above since we only care about zero, one or more than one nonzero entries.
@@ -687,7 +687,7 @@ void SolvingStateSimplifier::removeEmptyColumns()
 	vector<bool> variablesSeen(m_state.bounds.size(), false);
 	for (auto const& constraint: m_state.constraints)
 	{
-		for (auto&& [index, factor]: constraint.data | ranges::views::enumerate | ranges::views::tail)
+		for (auto&& [index, factor]: constraint.data.enumerateTail())
 			if (factor)
 				variablesSeen[index] = true;
 	}
diff --git a/libsolutil/LinearExpression.h b/libsolutil/LinearExpression.h
index bdfdae642..0d5045421 100644
--- a/libsolutil/LinearExpression.h
+++ b/libsolutil/LinearExpression.h
@@ -27,6 +27,7 @@
 #include <boost/rational.hpp>
 
 #include <range/v3/view/tail.hpp>
+#include <range/v3/view/enumerate.hpp>
 #include <range/v3/algorithm/all_of.hpp>
 
 #include <optional>
@@ -79,11 +80,9 @@ public:
 		return factors[_index];
 	}
 
-	auto begin() { return factors.begin(); }
-	auto end() { return factors.end(); }
-
-	auto begin() const { return factors.begin(); }
-	auto end() const { return factors.end(); }
+	auto enumerate() const { return factors | ranges::view::enumerate; }
+	// leave out the zero if exists
+	auto enumerateTail() const { return factors | ranges::view::enumerate | ranges::view::tail; }
 
 	rational const& front() const { return factors.front(); }