hidl/host_utils/StringHelper.cpp

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "StringHelper.h"

#include <cctype>
#include <regex>
#include <sstream>
#include <string>
#include <vector>

#include <android-base/logging.h>
#include <android-base/macros.h>

#define UPPERCASE "[A-Z0-9]"
#define LOWERCASE "[a-z][a-z0-9]*"
#define NUMCASE "[0-9]"
#define CAPCASE "[A-Z][a-z][a-z0-9]*"
static const std::regex kStartUppercase("^" UPPERCASE);
static const std::regex kStartLowercase("^" LOWERCASE);
static const std::regex kStartCapcase("^" CAPCASE);
static const std::regex kStartNumcase("^" CAPCASE);

namespace android {

std::string StringHelper::Uppercase(const std::string &in) {
    std::string out{in};

    for (auto &ch : out) {
        ch = toupper(ch);
    }

    return out;
}

std::string StringHelper::Lowercase(const std::string &in) {
    std::string out{in};

    for (auto &ch : out) {
        ch = tolower(ch);
    }

    return out;
}

std::string StringHelper::Capitalize(const std::string &in) {
    std::string out{in};

    if(!out.empty()) {
        out[0] = toupper(out[0]);
    }

    return out;
}

// Combines multiple single character upper case tokens together
// {"U", "I", "Error"} becomes {"UI", "Error"}
static void combineSingleCharTokens(const std::vector<std::string>& from,
                                    std::vector<std::string>* to) {
    std::string current;
    for (const std::string& str : from) {
        if (str.size() == 1 && (isupper(str[0]) || isdigit(str[0]))) {
            current += str;
        } else {
            if (!current.empty()) {
                to->push_back(current);
                current = "";
            }

            to->push_back(str);
        }
    }

    if (!current.empty()) to->push_back(current);
}

// Tokenizes strings first based on "_"s and then based on case
// PascalCase (CAPCASE) regex is given the highest priority and the remaining uppercase characters
// are grouped together. Digits are added to the preceding group, whichever it may be.
// Ipv4Addr => {"Ipv4", "Addr"}, V3Bool => {"V3", "Bool"}
void StringHelper::Tokenize(const std::string& in, std::vector<std::string>* vec) {
    vec->clear();
    if (in.empty()) return;

    if (in.find('_') != std::string::npos) {
        std::vector<std::string> snakeCaseComponents;
        SplitString(in, '_', &snakeCaseComponents);
        for (const std::string& comp : snakeCaseComponents) {
            std::vector<std::string> tokens;
            Tokenize(comp, &tokens);

            vec->insert(vec->end(), tokens.begin(), tokens.end());
        }

        return;
    }

    std::smatch match;
    std::string copy(in);
    std::vector<std::string> matches;
    std::vector<std::string> tmpVec;
    while (!copy.empty()) {
        if (std::regex_search(copy, match, kStartLowercase)) matches.push_back(match.str(0));
        if (std::regex_search(copy, match, kStartCapcase)) matches.push_back(match.str(0));
        if (std::regex_search(copy, match, kStartUppercase)) matches.push_back(match.str(0));
        if (std::regex_search(copy, match, kStartNumcase)) matches.push_back(match.str(0));

        if (!matches.empty()) {
            std::string& maxmatch = matches[0];
            for (std::string& match : matches)
                if (match.length() > maxmatch.length()) maxmatch = match;
            tmpVec.push_back(maxmatch);
            copy = copy.substr(maxmatch.length());
            matches.clear();
        } else {
            LOG(WARNING) << "Could not stylize \"" << in << "\"";
            // don't know what to do, so push back the rest of the string.
            tmpVec.push_back(copy);
        }
    }

    combineSingleCharTokens(tmpVec, vec);
}

std::string StringHelper::ToCamelCase(const std::string &in) {
    std::vector<std::string> components;
    Tokenize(in, &components);
    if (components.empty()) {
        if (!in.empty())
            LOG(WARNING) << "Could not stylize \"" << in << "\"";
        return in;
    }
    components[0] = Lowercase(components[0]);
    for (size_t i = 1; i < components.size(); i++) {
        components[i] = Capitalize(components[i]);
    }
    return JoinStrings(components, "");
}

std::string StringHelper::ToPascalCase(const std::string &in) {
    std::vector<std::string> components;
    Tokenize(in, &components);
    for (size_t i = 0; i < components.size(); i++) {
        components[i] = Capitalize(components[i]);
    }
    return JoinStrings(components, "");
}

std::string StringHelper::ToUpperSnakeCase(const std::string &in) {
    std::vector<std::string> components;
    Tokenize(in, &components);
    for (size_t i = 0; i < components.size(); i++) {
        components[i] = Uppercase(components[i]);
    }
    return JoinStrings(components, "_");
}

std::string StringHelper::ToLowerSnakeCase(const std::string &in) {
    std::vector<std::string> components;
    Tokenize(in, &components);
    for (size_t i = 0; i < components.size(); i++) {
        components[i] = Lowercase(components[i]);
    }
    return JoinStrings(components, "_");
}

std::string StringHelper::ToCase(StringHelper::Case c, const std::string &in) {
    switch(c) {
    case kCamelCase:
        return ToCamelCase(in);
    case kPascalCase:
        return ToPascalCase(in);
    case kUpperSnakeCase:
        return ToUpperSnakeCase(in);
    case kLowerSnakeCase:
        return ToLowerSnakeCase(in);
    case kNoCase:
        return in;
    }
    LOG(FATAL) << "Should not reach here.";
    return in;
}

bool StringHelper::EndsWith(const std::string &in, const std::string &suffix) {
    return in.size() >= suffix.size() &&
           in.substr(in.size() - suffix.size()) == suffix;
}

bool StringHelper::StartsWith(const std::string &in, const std::string &prefix) {
    return in.size() >= prefix.size() &&
           in.substr(0, prefix.size()) == prefix;
}

std::string StringHelper::RTrim(const std::string &in, const std::string &suffix) {
    if (EndsWith(in, suffix)) {
        return in.substr(0, in.size() - suffix.size());
    }

    return in;
}

std::string StringHelper::LTrim(const std::string &in, const std::string &prefix) {
    if (StartsWith(in, prefix)) {
        return in.substr(prefix.size());
    }

    return in;
}

std::string StringHelper::RTrimAll(const std::string &in, const std::string &suffix) {
    if (suffix.empty()) {
        return in;
    }

    std::string copy(in);
    while (EndsWith(copy, suffix)) {
        copy = copy.substr(0, copy.size() - suffix.size());
    }

    return copy;
}

std::string StringHelper::LTrimAll(const std::string &in, const std::string &prefix) {
    if (prefix.empty()) {
        return in;
    }

    std::string copy(in);
    while (StartsWith(copy, prefix)) {
        copy = copy.substr(prefix.size());
    }

    return copy;
}

void StringHelper::SplitString(
        const std::string &s, char c, std::vector<std::string> *components) {
    components->clear();

    size_t startPos = 0;
    size_t matchPos;
    while ((matchPos = s.find(c, startPos)) != std::string::npos) {
        components->push_back(s.substr(startPos, matchPos - startPos));
        startPos = matchPos + 1;
    }

    if (startPos <= s.length()) {
        components->push_back(s.substr(startPos));
    }
}

std::string StringHelper::JoinStrings(
        const std::vector<std::string> &components,
        const std::string &separator) {
    std::string out;
    bool first = true;
    for (const auto &component : components) {
        if (!first) {
            out += separator;
        }
        out += component;

        first = false;
    }

    return out;
}

}  // namespace android