substitution.cpp

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// Parse the $(...) substitution args
// Author: Max Schwarz <max.schwarz@uni-bonn.de>

#include "substitution.h"
#include "substitution_python.h"
#include "string_utils.h"

#include "launch_config.h"
#include "../package_registry.h"

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

#include <cstdarg>

namespace fs = boost::filesystem;

namespace rosmon
{
namespace launch
{

using Handler = std::function<std::string(const std::string&, const std::string&)>;
using HandlerMap = std::map<std::string, Handler>;

enum ParserState
{
        PARSER_IDLE,
        PARSER_DOLLAR,
        PARSER_INSIDE,
};

namespace substitutions
{
        std::string anon(const std::string& name, ParseContext& context)
        {
                std::string base = name;
                boost::trim(base);

                return context.anonName(base);
        }

        std::string arg(const std::string& name, const ParseContext& context)
        {
                auto it = context.arguments().find(name);
                if(it == context.arguments().end())
                        throw SubstitutionException::format("$(arg {}): Unknown arg", name);

                std::string value = it->second;

                if(value == UNSET_MARKER)
                {
                        throw SubstitutionException::format(
                                "$(arg {}): Accessing unset argument '{}', please specify as parameter.", name, name
                        );
                }

                return value;
        }

        std::string dirname(const ParseContext& context)
        {
                fs::path launch_file = context.filename();
                return fs::absolute(launch_file).parent_path().string();
        }

        std::string env(const std::string& name)
        {
                const char* envval = getenv(name.c_str());
                if(!envval)
                        throw SubstitutionException::format("$(env {}): Environment variable not set!", name);

                return envval;
        }

        std::string optenv(const std::string& name, const std::string& defaultValue)
        {
                const char* envval = getenv(name.c_str());
                if(envval)
                        return envval;

                return defaultValue;
        }

        std::string find_stupid(const std::string& name)
        {
                std::string path = PackageRegistry::getPath(name);
                if(!path.empty())
                        return path;

                throw SubstitutionException::format("$(find {}): Could not find package", name);
        }
}

static std::string parseOneElement(const std::string& input, const HandlerMap& handlers, bool strict, bool* found)
{
        ParserState state = PARSER_IDLE;
        std::size_t begin = 0;

        for(std::size_t i = 0; i < input.size(); ++i)
        {
                char c = input[i];

                switch(state)
                {
                        case PARSER_IDLE:
                                if(c == '$')
                                        state = PARSER_DOLLAR;
                                break;
                        case PARSER_DOLLAR:
                                if(c == '(')
                                {
                                        state = PARSER_INSIDE;
                                        begin = i+1;
                                }
                                break;
                        case PARSER_INSIDE:
                                if(c == '$')
                                        state = PARSER_DOLLAR;
                                else if(c == ')')
                                {
                                        // We found something!
                                        std::string contents = input.substr(begin, i - begin);
                                        std::string after = input.substr(i+1);

                                        // Split into name and args
                                        auto pos = contents.find(' ');
                                        std::string name = contents.substr(0, pos);
                                        std::string args;
                                        if(pos != std::string::npos)
                                                args = contents.substr(pos+1);

                                        // Remove leading/trailing whitespace and simplify any
                                        // internal whitespace
                                        args = string_utils::simplifyWhitespace(args);

                                        auto it = handlers.find(name);
                                        if(it != handlers.end())
                                        {
                                                std::string replacement = it->second(args, after);

                                                std::stringstream ss;
                                                ss << input.substr(0, begin-2);
                                                ss << replacement;
                                                ss << after;

                                                *found = true;
                                                return ss.str();
                                        }

                                        if(strict)
                                        {
                                                throw SubstitutionException::format("Unknown substitution arg '{}'", name);
                                        }

                                        state = PARSER_IDLE;
                                }
                                break;
                }
        }

        *found = false;
        return input;
}

std::string parseSubstitutionArgs(const std::string& input, ParseContext& context)
{
        bool found = false;
        std::string buffer = input;

        // $(eval ) is only allowed if it spans the entire value, so handle that here.
        if(buffer.size() > 6 && buffer.substr(0,6) == "$(eval" && buffer[buffer.size()-1] == ')')
        {
                return evaluatePython(buffer.substr(7, buffer.size() - 7 - 1), context);
        }

        HandlerMap simpleHandlers = {
                {"anon", [&context](const std::string& args, const std::string&) -> std::string{
                        return substitutions::anon(args, context);
                }},
                {"arg", [&context](const std::string& args, const std::string&) -> std::string{
                        return substitutions::arg(args, context);
                }},
                {"dirname", [&context](const std::string&, const std::string&) -> std::string{
                        return substitutions::dirname(context);
                }},
                {"env", [](const std::string& args, const std::string&) -> std::string{
                        return substitutions::env(args);
                }},
                {"optenv", [](const std::string& args, const std::string&) -> std::string{
                        auto pos = args.find(' ');
                        std::string defaultValue;
                        std::string name = args;
                        if(pos != std::string::npos)
                        {
                                defaultValue = args.substr(pos + 1);
                                name = args.substr(0, pos);
                        }

                        return substitutions::optenv(name, defaultValue);
                }},
        };

        do
        {
                buffer = parseOneElement(buffer, simpleHandlers, false, &found);
        }
        while(found);

        HandlerMap findHandlers = {
                {"find", [](const std::string& args, const std::string& after) -> std::string{
                        // Extract path after $(find ...)
                        auto pos = after.find(' ');
                        std::string filename = after.substr(0, pos);
                        boost::trim(filename);

                        if(!filename.empty())
                        {
                                std::string path = PackageRegistry::findPathToFile(args, filename);
                                if(!path.empty())
                                        return path;
                        }

                        // Fallback to "rospack find"
                        std::string path = PackageRegistry::getPath(args);
                        if(!path.empty())
                                return path;

                        throw SubstitutionException::format("$(find {}): Could not find package", args);
                }},
        };

        do
        {
                buffer = parseOneElement(buffer, findHandlers, true, &found);
        }
        while(found);

        return buffer;
}

}
}