merge LRA

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/util/lp/lar_term.h

@@ -0,0 +1,64 @@
+/*
+  Copyright (c) 2017 Microsoft Corporation
+  Author: Lev Nachmanson
+*/
+#pragma once
+#include "util/lp/indexed_vector.h"
+namespace lean {
+struct lar_term {
+    // the term evaluates to sum of m_coeffs + m_v
+    std::unordered_map<unsigned, mpq> m_coeffs;
+    mpq m_v;
+    lar_term() {}
+    void add_to_map(unsigned j, const mpq& c) {
+        auto it = m_coeffs.find(j);
+        if (it == m_coeffs.end()) {
+            m_coeffs.emplace(j, c);
+        } else {
+            it->second += c;
+            if (is_zero(it->second))
+                m_coeffs.erase(it);
+        }
+    }
+
+    unsigned size() const { return static_cast<unsigned>(m_coeffs.size()); }
+    
+    const std::unordered_map<unsigned, mpq> & coeffs() const {
+        return m_coeffs;
+    }
+    
+    lar_term(const vector<std::pair<mpq, unsigned>>& coeffs,
+             const mpq & v) : m_v(v) {
+        for (const auto & p : coeffs) {
+            add_to_map(p.second, p.first);
+        }
+    }
+    bool operator==(const lar_term & a) const {  return false; } // take care not to create identical terms
+    bool operator!=(const lar_term & a) const {  return ! (*this == a);}
+    // some terms get used in add constraint
+    // it is the same as the offset in the m_constraints
+
+    vector<std::pair<mpq, unsigned>> coeffs_as_vector() const {
+        vector<std::pair<mpq, unsigned>> ret;
+        for (const auto & p :  m_coeffs) {
+            ret.push_back(std::make_pair(p.second, p.first));
+        }
+        return ret;
+    }
+
+    // j is the basic variable to substitute
+    void subst(unsigned j, indexed_vector<mpq> & li) {
+        auto it = m_coeffs.find(j);
+        if (it == m_coeffs.end()) return;
+        const mpq & b = it->second;
+        for (unsigned it_j :li.m_index) {
+            add_to_map(it_j, - b * li.m_data[it_j]);
+        }
+        m_coeffs.erase(it);
+    }
+    
+    bool contains(unsigned j) const {
+        return m_coeffs.find(j) != m_coeffs.end();
+    }
+};
+}