libs/utils/Tokenizer.cpp

/*
 * Copyright (C) 2010 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.
 */

#define LOG_TAG "Tokenizer"

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <utils/Log.h>
#include <utils/Tokenizer.h>

// Enables debug output for the tokenizer.
#define DEBUG_TOKENIZER 0


namespace android {

static inline bool isDelimiter(char ch, const char* delimiters) {
    return strchr(delimiters, ch) != NULL;
}


Tokenizer::Tokenizer(const String8& filename, const char* buffer, size_t length) :
        mFilename(filename), mBuffer(buffer), mLength(length),
        mCurrent(buffer), mLineNumber(1) {
}

Tokenizer::~Tokenizer() {
    munmap((void*)mBuffer, mLength);
}

status_t Tokenizer::open(const String8& filename, Tokenizer** outTokenizer) {
    *outTokenizer = NULL;

    int result = NO_ERROR;
    int fd = ::open(filename.string(), O_RDONLY);
    if (fd < 0) {
        result = -errno;
        LOGE("Error opening file '%s', %s.", filename.string(), strerror(errno));
    } else {
        struct stat64 stat;
        if (fstat64(fd, &stat)) {
            result = -errno;
            LOGE("Error getting size of file '%s', %s.", filename.string(), strerror(errno));
        } else {
            size_t length = size_t(stat.st_size);
            void* buffer = mmap(NULL, length, PROT_READ, MAP_FILE | MAP_PRIVATE, fd, 0);
            if (buffer == MAP_FAILED) {
                result = -errno;
                LOGE("Error mapping file '%s', %s.", filename.string(), strerror(errno));
            } else {
                if (madvise(buffer, length, MADV_SEQUENTIAL)) {
                    LOGW("Error calling madvise for mmapped file '%s', %s.", filename.string(),
                            strerror(errno));
                }

                *outTokenizer = new Tokenizer(filename, static_cast<const char*>(buffer), length);
                if (!*outTokenizer) {
                    result = NO_MEMORY;
                    LOGE("Error allocating tokenizer for file=%s.", filename.string());
                    munmap(buffer, length);
                }
            }
        }
        close(fd);
    }
    return result;
}

String8 Tokenizer::getLocation() const {
    String8 result;
    result.appendFormat("%s:%d", mFilename.string(), mLineNumber);
    return result;
}

String8 Tokenizer::peekRemainderOfLine() const {
    const char* end = getEnd();
    const char* eol = mCurrent;
    while (eol != end) {
        char ch = *eol;
        if (ch == '\n') {
            break;
        }
        eol += 1;
    }
    return String8(mCurrent, eol - mCurrent);
}

String8 Tokenizer::nextToken(const char* delimiters) {
#if DEBUG_TOKENIZER
    LOGD("nextToken");
#endif
    const char* end = getEnd();
    const char* tokenStart = mCurrent;
    while (mCurrent != end) {
        char ch = *mCurrent;
        if (ch == '\n' || isDelimiter(ch, delimiters)) {
            break;
        }
        mCurrent += 1;
    }
    return String8(tokenStart, mCurrent - tokenStart);
}

void Tokenizer::nextLine() {
#if DEBUG_TOKENIZER
    LOGD("nextLine");
#endif
    const char* end = getEnd();
    while (mCurrent != end) {
        char ch = *(mCurrent++);
        if (ch == '\n') {
            mLineNumber += 1;
            break;
        }
    }
}

void Tokenizer::skipDelimiters(const char* delimiters) {
#if DEBUG_TOKENIZER
    LOGD("skipDelimiters");
#endif
    const char* end = getEnd();
    while (mCurrent != end) {
        char ch = *mCurrent;
        if (ch == '\n' || !isDelimiter(ch, delimiters)) {
            break;
        }
        mCurrent += 1;
    }
}

} // namespace android