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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef _UTILS_TOKENIZER_H
     18 #define _UTILS_TOKENIZER_H
     19 
     20 #include <assert.h>
     21 #include <utils/Errors.h>
     22 #include <utils/FileMap.h>
     23 #include <utils/String8.h>
     24 
     25 namespace android {
     26 
     27 /**
     28  * A simple tokenizer for loading and parsing ASCII text files line by line.
     29  */
     30 class Tokenizer {
     31     Tokenizer(const String8& filename, FileMap* fileMap, char* buffer,
     32             bool ownBuffer, size_t length);
     33 
     34 public:
     35     ~Tokenizer();
     36 
     37     /**
     38      * Opens a file and maps it into memory.
     39      *
     40      * Returns NO_ERROR and a tokenizer for the file, if successful.
     41      * Otherwise returns an error and sets outTokenizer to NULL.
     42      */
     43     static status_t open(const String8& filename, Tokenizer** outTokenizer);
     44 
     45     /**
     46      * Prepares to tokenize the contents of a string.
     47      *
     48      * Returns NO_ERROR and a tokenizer for the string, if successful.
     49      * Otherwise returns an error and sets outTokenizer to NULL.
     50      */
     51     static status_t fromContents(const String8& filename,
     52             const char* contents, Tokenizer** outTokenizer);
     53 
     54     /**
     55      * Returns true if at the end of the file.
     56      */
     57     inline bool isEof() const { return mCurrent == getEnd(); }
     58 
     59     /**
     60      * Returns true if at the end of the line or end of the file.
     61      */
     62     inline bool isEol() const { return isEof() || *mCurrent == '\n'; }
     63 
     64     /**
     65      * Gets the name of the file.
     66      */
     67     inline String8 getFilename() const { return mFilename; }
     68 
     69     /**
     70      * Gets a 1-based line number index for the current position.
     71      */
     72     inline int32_t getLineNumber() const { return mLineNumber; }
     73 
     74     /**
     75      * Formats a location string consisting of the filename and current line number.
     76      * Returns a string like "MyFile.txt:33".
     77      */
     78     String8 getLocation() const;
     79 
     80     /**
     81      * Gets the character at the current position.
     82      * Returns null at end of file.
     83      */
     84     inline char peekChar() const { return isEof() ? '\0' : *mCurrent; }
     85 
     86     /**
     87      * Gets the remainder of the current line as a string, excluding the newline character.
     88      */
     89     String8 peekRemainderOfLine() const;
     90 
     91     /**
     92      * Gets the character at the current position and advances past it.
     93      * Returns null at end of file.
     94      */
     95     inline char nextChar() { return isEof() ? '\0' : *(mCurrent++); }
     96 
     97     /**
     98      * Gets the next token on this line stopping at the specified delimiters
     99      * or the end of the line whichever comes first and advances past it.
    100      * Also stops at embedded nulls.
    101      * Returns the token or an empty string if the current character is a delimiter
    102      * or is at the end of the line.
    103      */
    104     String8 nextToken(const char* delimiters);
    105 
    106     /**
    107      * Advances to the next line.
    108      * Does nothing if already at the end of the file.
    109      */
    110     void nextLine();
    111 
    112     /**
    113      * Skips over the specified delimiters in the line.
    114      * Also skips embedded nulls.
    115      */
    116     void skipDelimiters(const char* delimiters);
    117 
    118 private:
    119     Tokenizer(const Tokenizer& other); // not copyable
    120 
    121     String8 mFilename;
    122     FileMap* mFileMap;
    123     char* mBuffer;
    124     bool mOwnBuffer;
    125     size_t mLength;
    126 
    127     const char* mCurrent;
    128     int32_t mLineNumber;
    129 
    130     inline const char* getEnd() const { return mBuffer + mLength; }
    131 
    132 };
    133 
    134 } // namespace android
    135 
    136 #endif // _UTILS_TOKENIZER_H
    137