cppcheck/lib/programmemory.h

/*
 * Cppcheck - A tool for static C/C++ code analysis
 * Copyright (C) 2007-2023 Cppcheck team.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef GUARD_PROGRAMMEMORY_H
#define GUARD_PROGRAMMEMORY_H

#include "config.h"
#include "mathlib.h"
#include "vfvalue.h" // needed for alias

#include <cstddef>
#include <functional>
#include <map>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>

class Scope;
class Token;
class Settings;

// Class used to handle heterogeneous lookup in unordered_map(since we can't use C++20 yet)
struct ExprIdToken {
    const Token* tok = nullptr;
    nonneg int exprid = 0;

    ExprIdToken() = default;
    // cppcheck-suppress noExplicitConstructor
    // NOLINTNEXTLINE(google-explicit-constructor)
    ExprIdToken(const Token* tok);
    // TODO: Make this constructor only available from ProgramMemory
    // cppcheck-suppress noExplicitConstructor
    // NOLINTNEXTLINE(google-explicit-constructor)
    ExprIdToken(nonneg int exprid) : exprid(exprid) {}

    nonneg int getExpressionId() const;

    bool operator==(const ExprIdToken& rhs) const {
        return getExpressionId() == rhs.getExpressionId();
    }

    bool operator<(const ExprIdToken& rhs) const {
        return getExpressionId() < rhs.getExpressionId();
    }

    template<class T, class U>
    friend bool operator!=(const T& lhs, const U& rhs)
    {
        return !(lhs == rhs);
    }

    template<class T, class U>
    friend bool operator<=(const T& lhs, const U& rhs)
    {
        return !(lhs > rhs);
    }

    template<class T, class U>
    friend bool operator>(const T& lhs, const U& rhs)
    {
        return rhs < lhs;
    }

    template<class T, class U>
    friend bool operator>=(const T& lhs, const U& rhs)
    {
        return !(lhs < rhs);
    }

    const Token& operator*() const NOEXCEPT {
        return *tok;
    }

    const Token* operator->() const NOEXCEPT {
        return tok;
    }

    struct Hash {
        std::size_t operator()(ExprIdToken etok) const;
    };
};

struct ProgramMemory {
    using Map = std::unordered_map<ExprIdToken, ValueFlow::Value, ExprIdToken::Hash>;

    ProgramMemory() = default;

    explicit ProgramMemory(Map values) : mValues(std::move(values)) {}

    void setValue(const Token* expr, const ValueFlow::Value& value);
    const ValueFlow::Value* getValue(nonneg int exprid, bool impossible = false) const;

    bool getIntValue(nonneg int exprid, MathLib::bigint& result) const;
    void setIntValue(const Token* expr, MathLib::bigint value, bool impossible = false);

    bool getContainerSizeValue(nonneg int exprid, MathLib::bigint& result) const;
    bool getContainerEmptyValue(nonneg int exprid, MathLib::bigint& result) const;
    void setContainerSizeValue(const Token* expr, MathLib::bigint value, bool isEqual = true);

    void setUnknown(const Token* expr);

    bool getTokValue(nonneg int exprid, const Token** result) const;
    bool hasValue(nonneg int exprid);

    const ValueFlow::Value& at(nonneg int exprid) const;
    ValueFlow::Value& at(nonneg int exprid);

    void erase_if(const std::function<bool(const ExprIdToken&)>& pred);

    void swap(ProgramMemory &pm);

    void clear();

    bool empty() const;

    void replace(const ProgramMemory &pm);

    void insert(const ProgramMemory &pm);

    Map::iterator begin() {
        return mValues.begin();
    }

    Map::iterator end() {
        return mValues.end();
    }

    Map::const_iterator begin() const {
        return mValues.begin();
    }

    Map::const_iterator end() const {
        return mValues.end();
    }

    friend bool operator==(const ProgramMemory& x, const ProgramMemory& y) {
        return x.mValues == y.mValues;
    }

    friend bool operator!=(const ProgramMemory& x, const ProgramMemory& y) {
        return x.mValues != y.mValues;
    }

private:
    Map mValues;
};

void programMemoryParseCondition(ProgramMemory& pm, const Token* tok, const Token* endTok, const Settings* settings, bool then);

struct ProgramMemoryState {
    ProgramMemory state;
    std::map<nonneg int, const Token*> origins;
    const Settings* settings;

    explicit ProgramMemoryState(const Settings* s);

    void insert(const ProgramMemory &pm, const Token* origin = nullptr);
    void replace(const ProgramMemory &pm, const Token* origin = nullptr);

    void addState(const Token* tok, const ProgramMemory::Map& vars);

    void assume(const Token* tok, bool b, bool isEmpty = false);

    void removeModifiedVars(const Token* tok);

    ProgramMemory get(const Token* tok, const Token* ctx, const ProgramMemory::Map& vars) const;
};

std::vector<ValueFlow::Value> execute(const Scope* scope, ProgramMemory& pm, const Settings* settings);

void execute(const Token* expr,
             ProgramMemory& programMemory,
             MathLib::bigint* result,
             bool* error,
             const Settings* settings = nullptr);

/**
 * Is condition always false when variable has given value?
 * \param condition   top ast token in condition
 * \param pm   program memory
 */
bool conditionIsFalse(const Token* condition, ProgramMemory pm, const Settings* settings);

/**
 * Is condition always true when variable has given value?
 * \param condition   top ast token in condition
 * \param pm   program memory
 */
bool conditionIsTrue(const Token* condition, ProgramMemory pm, const Settings* settings);

/**
 * Get program memory by looking backwards from given token.
 */
ProgramMemory getProgramMemory(const Token* tok, const Token* expr, const ValueFlow::Value& value, const Settings* settings);

ValueFlow::Value evaluateLibraryFunction(const std::unordered_map<nonneg int, ValueFlow::Value>& args,
                                         const std::string& returnValue,
                                         const Settings* settings);

#endif