path: root/libsolidity/interface/CompilerStack.cpp

/*
    This file is part of solidity.

    solidity 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.

    solidity 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 solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @author Gav Wood <g@ethdev.com>
 * @date 2014
 * Full-stack compiler that converts a source code string to bytecode.
 */

#include <libsolidity/interface/CompilerStack.h>

#include <libsolidity/interface/Version.h>
#include <libsolidity/analysis/SemVerHandler.h>
#include <libsolidity/ast/AST.h>
#include <libsolidity/parsing/Scanner.h>
#include <libsolidity/parsing/Parser.h>
#include <libsolidity/analysis/GlobalContext.h>
#include <libsolidity/analysis/NameAndTypeResolver.h>
#include <libsolidity/analysis/TypeChecker.h>
#include <libsolidity/analysis/DocStringAnalyser.h>
#include <libsolidity/analysis/SyntaxChecker.h>
#include <libsolidity/codegen/Compiler.h>
#include <libsolidity/interface/InterfaceHandler.h>
#include <libsolidity/formal/Why3Translator.h>

#include <libevmasm/Exceptions.h>

#include <libdevcore/SwarmHash.h>
#include <libdevcore/JSON.h>

#include <json/json.h>

#include <boost/algorithm/string.hpp>
#include <boost/filesystem.hpp>


using namespace std;
using namespace dev;
using namespace dev::solidity;

CompilerStack::CompilerStack(ReadFileCallback const& _readFile):
    m_readFile(_readFile), m_parseSuccessful(false) {}

void CompilerStack::setRemappings(vector<string> const& _remappings)
{
    vector<Remapping> remappings;
    for (auto const& remapping: _remappings)
    {
        auto eq = find(remapping.begin(), remapping.end(), '=');
        if (eq == remapping.end())
            continue; // ignore
        auto colon = find(remapping.begin(), eq, ':');
        Remapping r;
        r.context = colon == eq ? string() : string(remapping.begin(), colon);
        r.prefix = colon == eq ? string(remapping.begin(), eq) : string(colon + 1, eq);
        r.target = string(eq + 1, remapping.end());
        remappings.push_back(r);
    }
    swap(m_remappings, remappings);
}

void CompilerStack::reset(bool _keepSources)
{
    m_parseSuccessful = false;
    if (_keepSources)
        for (auto sourcePair: m_sources)
            sourcePair.second.reset();
    else
    {
        m_sources.clear();
    }
    m_optimize = false;
    m_optimizeRuns = 200;
    m_globalContext.reset();
    m_sourceOrder.clear();
    m_contracts.clear();
    m_errors.clear();
}

bool CompilerStack::addSource(string const& _name, string const& _content, bool _isLibrary)
{
    bool existed = m_sources.count(_name) != 0;
    reset(true);
    m_sources[_name].scanner = make_shared<Scanner>(CharStream(_content), _name);
    m_sources[_name].isLibrary = _isLibrary;
    return existed;
}

void CompilerStack::setSource(string const& _sourceCode)
{
    reset();
    addSource("", _sourceCode);
}

bool CompilerStack::parse()
{
    //reset
    m_errors.clear();
    m_parseSuccessful = false;

    if (SemVerVersion{string(VersionString)}.isPrerelease())
    {
        auto err = make_shared<Error>(Error::Type::Warning);
        *err << errinfo_comment("This is a pre-release compiler version, please do not use it in production.");
        m_errors.push_back(err);
    }

    vector<string> sourcesToParse;
    for (auto const& s: m_sources)
        sourcesToParse.push_back(s.first);
    map<string, SourceUnit const*> sourceUnitsByName;
    for (size_t i = 0; i < sourcesToParse.size(); ++i)
    {
        string const& path = sourcesToParse[i];
        Source& source = m_sources[path];
        source.scanner->reset();
        source.ast = Parser(m_errors).parse(source.scanner);
        sourceUnitsByName[path] = source.ast.get();
        if (!source.ast)
            solAssert(!Error::containsOnlyWarnings(m_errors), "Parser returned null but did not report error.");
        else
        {
            source.ast->annotation().path = path;
            for (auto const& newSource: loadMissingSources(*source.ast, path))
            {
                string const& newPath = newSource.first;
                string const& newContents = newSource.second;
                m_sources[newPath].scanner = make_shared<Scanner>(CharStream(newContents), newPath);
                sourcesToParse.push_back(newPath);
            }
        }
    }
    if (!Error::containsOnlyWarnings(m_errors))
        // errors while parsing. sould stop before type checking
        return false;

    resolveImports();

    bool noErrors = true;
    SyntaxChecker syntaxChecker(m_errors);
    for (Source const* source: m_sourceOrder)
        if (!syntaxChecker.checkSyntax(*source->ast))
            noErrors = false;

    DocStringAnalyser docStringAnalyser(m_errors);
    for (Source const* source: m_sourceOrder)
        if (!docStringAnalyser.analyseDocStrings(*source->ast))
            noErrors = false;

    m_globalContext = make_shared<GlobalContext>();
    NameAndTypeResolver resolver(m_globalContext->declarations(), m_errors);
    for (Source const* source: m_sourceOrder)
        if (!resolver.registerDeclarations(*source->ast))
            return false;

    for (Source const* source: m_sourceOrder)
        if (!resolver.performImports(*source->ast, sourceUnitsByName))
            return false;

    for (Source const* source: m_sourceOrder)
        for (ASTPointer<ASTNode> const& node: source->ast->nodes())
            if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
            {
                m_globalContext->setCurrentContract(*contract);
                if (!resolver.updateDeclaration(*m_globalContext->currentThis())) return false;
                if (!resolver.updateDeclaration(*m_globalContext->currentSuper())) return false;
                if (!resolver.resolveNamesAndTypes(*contract)) return false;
                m_contracts[contract->name()].contract = contract;
            }

    if (!checkLibraryNameClashes())
        noErrors = false;

    for (Source const* source: m_sourceOrder)
        for (ASTPointer<ASTNode> const& node: source->ast->nodes())
            if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
            {
                m_globalContext->setCurrentContract(*contract);
                resolver.updateDeclaration(*m_globalContext->currentThis());
                TypeChecker typeChecker(m_errors);
                if (typeChecker.checkTypeRequirements(*contract))
                {
                    contract->setDevDocumentation(InterfaceHandler::devDocumentation(*contract));
                    contract->setUserDocumentation(InterfaceHandler::userDocumentation(*contract));
                }
                else
                    noErrors = false;

                m_contracts[contract->name()].contract = contract;
            }
    m_parseSuccessful = noErrors;
    return m_parseSuccessful;
}

bool CompilerStack::parse(string const& _sourceCode)
{
    setSource(_sourceCode);
    return parse();
}

vector<string> CompilerStack::contractNames() const
{
    if (!m_parseSuccessful)
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Parsing was not successful."));
    vector<string> contractNames;
    for (auto const& contract: m_contracts)
        contractNames.push_back(contract.first);
    return contractNames;
}


bool CompilerStack::compile(bool _optimize, unsigned _runs, map<string, h160> const& _libraries)
{
    if (!m_parseSuccessful)
        if (!parse())
            return false;

    m_optimize = _optimize;
    m_optimizeRuns = _runs;
    m_libraries = _libraries;

    map<ContractDefinition const*, eth::Assembly const*> compiledContracts;
    for (Source const* source: m_sourceOrder)
        for (ASTPointer<ASTNode> const& node: source->ast->nodes())
            if (auto contract = dynamic_cast<ContractDefinition const*>(node.get()))
                compileContract(*contract, compiledContracts);
    this->link();
    return true;
}

bool CompilerStack::compile(string const& _sourceCode, bool _optimize)
{
    return parse(_sourceCode) && compile(_optimize);
}

void CompilerStack::link()
{
    for (auto& contract: m_contracts)
    {
        contract.second.object.link(m_libraries);
        contract.second.runtimeObject.link(m_libraries);
        contract.second.cloneObject.link(m_libraries);
    }
}

bool CompilerStack::prepareFormalAnalysis(ErrorList* _errors)
{
    if (!_errors)
        _errors = &m_errors;
    Why3Translator translator(*_errors);
    for (Source const* source: m_sourceOrder)
        if (!translator.process(*source->ast))
            return false;

    m_formalTranslation = translator.translation();

    return true;
}

eth::AssemblyItems const* CompilerStack::assemblyItems(string const& _contractName) const
{
    Contract const& currentContract = contract(_contractName);
    return currentContract.compiler ? &contract(_contractName).compiler->assemblyItems() : nullptr;
}

eth::AssemblyItems const* CompilerStack::runtimeAssemblyItems(string const& _contractName) const
{
    Contract const& currentContract = contract(_contractName);
    return currentContract.compiler ? &contract(_contractName).compiler->runtimeAssemblyItems() : nullptr;
}

string const* CompilerStack::sourceMapping(string const& _contractName) const
{
    Contract const& c = contract(_contractName);
    if (!c.sourceMapping)
    {
        if (auto items = assemblyItems(_contractName))
            c.sourceMapping.reset(new string(computeSourceMapping(*items)));
    }
    return c.sourceMapping.get();
}

string const* CompilerStack::runtimeSourceMapping(string const& _contractName) const
{
    Contract const& c = contract(_contractName);
    if (!c.runtimeSourceMapping)
    {
        if (auto items = runtimeAssemblyItems(_contractName))
            c.runtimeSourceMapping.reset(new string(computeSourceMapping(*items)));
    }
    return c.runtimeSourceMapping.get();
}

eth::LinkerObject const& CompilerStack::object(string const& _contractName) const
{
    return contract(_contractName).object;
}

eth::LinkerObject const& CompilerStack::runtimeObject(string const& _contractName) const
{
    return contract(_contractName).runtimeObject;
}

eth::LinkerObject const& CompilerStack::cloneObject(string const& _contractName) const
{
    return contract(_contractName).cloneObject;
}

dev::h256 CompilerStack::contractCodeHash(string const& _contractName) const
{
    auto const& obj = runtimeObject(_contractName);
    if (obj.bytecode.empty() || !obj.linkReferences.empty())
        return dev::h256();
    else
        return dev::keccak256(obj.bytecode);
}

Json::Value CompilerStack::streamAssembly(ostream& _outStream, string const& _contractName, StringMap _sourceCodes, bool _inJsonFormat) const
{
    Contract const& currentContract = contract(_contractName);
    if (currentContract.compiler)
        return currentContract.compiler->streamAssembly(_outStream, _sourceCodes, _inJsonFormat);
    else
    {
        _outStream << "Contract not fully implemented" << endl;
        return Json::Value();
    }
}

vector<string> CompilerStack::sourceNames() const
{
    vector<string> names;
    for (auto const& s: m_sources)
        names.push_back(s.first);
    return names;
}

map<string, unsigned> CompilerStack::sourceIndices() const
{
    map<string, unsigned> indices;
    for (auto const& s: m_sources)
        indices[s.first] = indices.size();
    return indices;
}

Json::Value const& CompilerStack::interface(string const& _contractName) const
{
    return metadata(_contractName, DocumentationType::ABIInterface);
}

Json::Value const& CompilerStack::metadata(string const& _contractName, DocumentationType _type) const
{
    if (!m_parseSuccessful)
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Parsing was not successful."));

    return metadata(contract(_contractName), _type);
}

Json::Value const& CompilerStack::metadata(Contract const& _contract, DocumentationType _type) const
{
    if (!m_parseSuccessful)
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Parsing was not successful."));

    solAssert(_contract.contract, "");
    std::unique_ptr<Json::Value const>* doc;

    // checks wheather we already have the documentation
    switch (_type)
    {
    case DocumentationType::NatspecUser:
        doc = &_contract.userDocumentation;
        break;
    case DocumentationType::NatspecDev:
        doc = &_contract.devDocumentation;
        break;
    case DocumentationType::ABIInterface:
        doc = &_contract.interface;
        break;
    default:
        BOOST_THROW_EXCEPTION(InternalCompilerError() << errinfo_comment("Illegal documentation type."));
    }

    // caches the result
    if (!*doc)
        doc->reset(new Json::Value(InterfaceHandler::documentation(*_contract.contract, _type)));

    return *(*doc);
}

string const& CompilerStack::onChainMetadata(string const& _contractName) const
{
    if (!m_parseSuccessful)
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Parsing was not successful."));

    return contract(_contractName).onChainMetadata;
}

Scanner const& CompilerStack::scanner(string const& _sourceName) const
{
    return *source(_sourceName).scanner;
}

SourceUnit const& CompilerStack::ast(string const& _sourceName) const
{
    return *source(_sourceName).ast;
}

ContractDefinition const& CompilerStack::contractDefinition(string const& _contractName) const
{
    return *contract(_contractName).contract;
}

size_t CompilerStack::functionEntryPoint(
    std::string const& _contractName,
    FunctionDefinition const& _function
) const
{
    shared_ptr<Compiler> const& compiler = contract(_contractName).compiler;
    if (!compiler)
        return 0;
    eth::AssemblyItem tag = compiler->functionEntryLabel(_function);
    if (tag.type() == eth::UndefinedItem)
        return 0;
    eth::AssemblyItems const& items = compiler->runtimeAssemblyItems();
    for (size_t i = 0; i < items.size(); ++i)
        if (items.at(i).type() == eth::Tag && items.at(i).data() == tag.data())
            return i;
    return 0;
}

tuple<int, int, int, int> CompilerStack::positionFromSourceLocation(SourceLocation const& _sourceLocation) const
{
    int startLine;
    int startColumn;
    int endLine;
    int endColumn;
    tie(startLine, startColumn) = scanner(*_sourceLocation.sourceName).translatePositionToLineColumn(_sourceLocation.start);
    tie(endLine, endColumn) = scanner(*_sourceLocation.sourceName).translatePositionToLineColumn(_sourceLocation.end);

    return make_tuple(++startLine, ++startColumn, ++endLine, ++endColumn);
}

StringMap CompilerStack::loadMissingSources(SourceUnit const& _ast, std::string const& _sourcePath)
{
    StringMap newSources;
    for (auto const& node: _ast.nodes())
        if (ImportDirective const* import = dynamic_cast<ImportDirective*>(node.get()))
        {
            string importPath = absolutePath(import->path(), _sourcePath);
            // The current value of `path` is the absolute path as seen from this source file.
            // We first have to apply remappings before we can store the actual absolute path
            // as seen globally.
            importPath = applyRemapping(importPath, _sourcePath);
            import->annotation().absolutePath = importPath;
            if (m_sources.count(importPath) || newSources.count(importPath))
                continue;

            ReadFileResult result{false, string("File not supplied initially.")};
            if (m_readFile)
                result = m_readFile(importPath);

            if (result.success)
                newSources[importPath] = result.contentsOrErrorMesage;
            else
            {
                auto err = make_shared<Error>(Error::Type::ParserError);
                *err <<
                    errinfo_sourceLocation(import->location()) <<
                    errinfo_comment("Source \"" + importPath + "\" not found: " + result.contentsOrErrorMesage);
                m_errors.push_back(std::move(err));
                continue;
            }
        }
    return newSources;
}

string CompilerStack::applyRemapping(string const& _path, string const& _context)
{
    // Try to find the longest prefix match in all remappings that are active in the current context.
    auto isPrefixOf = [](string const& _a, string const& _b)
    {
        if (_a.length() > _b.length())
            return false;
        return std::equal(_a.begin(), _a.end(), _b.begin());
    };

    size_t longestPrefix = 0;
    string longestPrefixTarget;
    for (auto const& redir: m_remappings)
    {
        // Skip if we already have a closer match.
        if (longestPrefix > 0 && redir.prefix.length() <= longestPrefix)
            continue;
        // Skip if redir.context is not a prefix of _context
        if (!isPrefixOf(redir.context, _context))
            continue;
        // Skip if the prefix does not match.
        if (!isPrefixOf(redir.prefix, _path))
            continue;

        longestPrefix = redir.prefix.length();
        longestPrefixTarget = redir.target;
    }
    string path = longestPrefixTarget;
    path.append(_path.begin() + longestPrefix, _path.end());
    return path;
}

void CompilerStack::resolveImports()
{
    // topological sorting (depth first search) of the import graph, cutting potential cycles
    vector<Source const*> sourceOrder;
    set<Source const*> sourcesSeen;

    function<void(Source const*)> toposort = [&](Source const* _source)
    {
        if (sourcesSeen.count(_source))
            return;
        sourcesSeen.insert(_source);
        for (ASTPointer<ASTNode> const& node: _source->ast->nodes())
            if (ImportDirective const* import = dynamic_cast<ImportDirective*>(node.get()))
            {
                string const& path = import->annotation().absolutePath;
                solAssert(!path.empty(), "");
                solAssert(m_sources.count(path), "");
                import->annotation().sourceUnit = m_sources[path].ast.get();
                toposort(&m_sources[path]);
            }
        sourceOrder.push_back(_source);
    };

    for (auto const& sourcePair: m_sources)
        if (!sourcePair.second.isLibrary)
            toposort(&sourcePair.second);

    swap(m_sourceOrder, sourceOrder);
}

bool CompilerStack::checkLibraryNameClashes()
{
    bool clashFound = false;
    map<string, SourceLocation> libraries;
    for (Source const* source: m_sourceOrder)
        for (ASTPointer<ASTNode> const& node: source->ast->nodes())
            if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
                if (contract->isLibrary())
                {
                    if (libraries.count(contract->name()))
                    {
                        auto err = make_shared<Error>(Error::Type::DeclarationError);
                        *err <<
                            errinfo_sourceLocation(contract->location()) <<
                            errinfo_comment(
                                "Library \"" + contract->name() + "\" declared twice "
                                "(will create ambiguities during linking)."
                            ) <<
                            errinfo_secondarySourceLocation(SecondarySourceLocation().append(
                                    "The other declaration is here:", libraries[contract->name()]
                            ));

                        m_errors.push_back(err);
                        clashFound = true;
                    }
                    else
                        libraries[contract->name()] = contract->location();
                }
    return !clashFound;
}

string CompilerStack::absolutePath(string const& _path, string const& _reference) const
{
    // Anything that does not start with `.` is an absolute path.
    if (_path.empty() || _path.front() != '.')
        return _path;
    using path = boost::filesystem::path;
    path p(_path);
    path result(_reference);
    result.remove_filename();
    for (path::iterator it = p.begin(); it != p.end(); ++it)
        if (*it == "..")
            result = result.parent_path();
        else if (*it != ".")
            result /= *it;
    return result.generic_string();
}

void CompilerStack::compileContract(
    ContractDefinition const& _contract,
    map<ContractDefinition const*, eth::Assembly const*>& _compiledContracts
)
{
    if (_compiledContracts.count(&_contract) || !_contract.annotation().isFullyImplemented)
        return;
    for (auto const* dependency: _contract.annotation().contractDependencies)
        compileContract(*dependency, _compiledContracts);

    shared_ptr<Compiler> compiler = make_shared<Compiler>(m_optimize, m_optimizeRuns);
    Contract& compiledContract = m_contracts.at(_contract.name());
    string onChainMetadata = createOnChainMetadata(compiledContract);
    compiler->compileContract(_contract, _compiledContracts, dev::swarmHash(onChainMetadata));
    compiledContract.compiler = compiler;
    compiledContract.object = compiler->assembledObject();
    compiledContract.runtimeObject = compiler->runtimeObject();
    compiledContract.onChainMetadata = onChainMetadata;
    _compiledContracts[compiledContract.contract] = &compiler->assembly();

    try
    {
        Compiler cloneCompiler(m_optimize, m_optimizeRuns);
        cloneCompiler.compileClone(_contract, _compiledContracts);
        compiledContract.cloneObject = cloneCompiler.assembledObject();
    }
    catch (eth::AssemblyException const&)
    {
        // In some cases (if the constructor requests a runtime function), it is not
        // possible to compile the clone.

        // TODO: Report error / warning
    }
}

std::string CompilerStack::defaultContractName() const
{
    return contract("").contract->name();
}

CompilerStack::Contract const& CompilerStack::contract(string const& _contractName) const
{
    if (m_contracts.empty())
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("No compiled contracts found."));
    string contractName = _contractName;
    if (_contractName.empty())
        // try to find some user-supplied contract
        for (auto const& it: m_sources)
            for (ASTPointer<ASTNode> const& node: it.second.ast->nodes())
                if (auto contract = dynamic_cast<ContractDefinition const*>(node.get()))
                    contractName = contract->name();
    auto it = m_contracts.find(contractName);
    if (it == m_contracts.end())
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Contract " + _contractName + " not found."));
    return it->second;
}

CompilerStack::Source const& CompilerStack::source(string const& _sourceName) const
{
    auto it = m_sources.find(_sourceName);
    if (it == m_sources.end())
        BOOST_THROW_EXCEPTION(CompilerError() << errinfo_comment("Given source file not found."));

    return it->second;
}

string CompilerStack::createOnChainMetadata(Contract const& _contract) const
{
    Json::Value meta;
    meta["version"] = 1;
    meta["language"] = "Solidity";
    meta["compiler"]["version"] = VersionString;

    meta["sources"] = Json::objectValue;
    for (auto const& s: m_sources)
    {
        solAssert(s.second.scanner, "Scanner not available");
        meta["sources"][s.first]["keccak256"] =
            "0x" + toHex(dev::keccak256(s.second.scanner->source()).asBytes());
        meta["sources"][s.first]["url"] =
            "bzzr://" + toHex(dev::swarmHash(s.second.scanner->source()).asBytes());
    }
    meta["settings"]["optimizer"]["enabled"] = m_optimize;
    meta["settings"]["optimizer"]["runs"] = m_optimizeRuns;
    meta["settings"]["compilationTarget"][_contract.contract->sourceUnitName()] =
        _contract.contract->annotation().canonicalName;

    meta["settings"]["remappings"] = Json::arrayValue;
    set<string> remappings;
    for (auto const& r: m_remappings)
        remappings.insert(r.context + ":" + r.prefix + "=" + r.target);
    for (auto const& r: remappings)
        meta["settings"]["remappings"].append(r);

    meta["settings"]["libraries"] = Json::objectValue;
    for (auto const& library: m_libraries)
        meta["settings"]["libraries"][library.first] = "0x" + toHex(library.second.asBytes());

    meta["output"]["abi"] = metadata(_contract, DocumentationType::ABIInterface);
    meta["output"]["userdoc"] = metadata(_contract, DocumentationType::NatspecUser);
    meta["output"]["devdoc"] = metadata(_contract, DocumentationType::NatspecDev);

    return jsonCompactPrint(meta);
}

string CompilerStack::computeSourceMapping(eth::AssemblyItems const& _items) const
{
    string ret;
    map<string, unsigned> sourceIndicesMap = sourceIndices();
    int prevStart = -1;
    int prevLength = -1;
    int prevSourceIndex = -1;
    char prevJump = 0;
    for (auto const& item: _items)
    {
        if (!ret.empty())
            ret += ";";

        SourceLocation const& location = item.location();
        int length = location.start != -1 && location.end != -1 ? location.end - location.start : -1;
        int sourceIndex =
            location.sourceName && sourceIndicesMap.count(*location.sourceName) ?
            sourceIndicesMap.at(*location.sourceName) :
            -1;
        char jump = '-';
        if (item.getJumpType() == eth::AssemblyItem::JumpType::IntoFunction)
            jump = 'i';
        else if (item.getJumpType() == eth::AssemblyItem::JumpType::OutOfFunction)
            jump = 'o';

        unsigned components = 4;
        if (jump == prevJump)
        {
            components--;
            if (sourceIndex == prevSourceIndex)
            {
                components--;
                if (length == prevLength)
                {
                    components--;
                    if (location.start == prevStart)
                        components--;
                }
            }
        }

        if (components-- > 0)
        {
            if (location.start != prevStart)
                ret += std::to_string(location.start);
            if (components-- > 0)
            {
                ret += ':';
                if (length != prevLength)
                    ret += std::to_string(length);
                if (components-- > 0)
                {
                    ret += ':';
                    if (sourceIndex != prevSourceIndex)
                        ret += std::to_string(sourceIndex);
                    if (components-- > 0)
                    {
                        ret += ':';
                        if (jump != prevJump)
                            ret += jump;
                    }
                }
            }
        }

        prevStart = location.start;
        prevLength = length;
        prevSourceIndex = sourceIndex;
        prevJump = jump;
    }
    return ret;
}