balxml_hexparser.h

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/// @file balxml_hexparser.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// balxml_hexparser.h                                                 -*-C++-*-
#ifndef INCLUDED_BALXML_HEXPARSER
#define INCLUDED_BALXML_HEXPARSER
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup balxml_hexparser balxml_hexparser
/// @brief  Provide push parser for hex types.
/// @addtogroup bal
/// @{
/// @addtogroup balxml
/// @{
/// @addtogroup balxml_hexparser
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#balxml_hexparser-purpose"> Purpose</a>
/// * <a href="#balxml_hexparser-classes"> Classes </a>
/// * <a href="#balxml_hexparser-description"> Description </a>
///   * <a href="#balxml_hexparser-usage"> Usage </a>
///     * <a href="#balxml_hexparser-example-1-basic-usage"> Example 1: Basic Usage </a>
///
/// # Purpose {#balxml_hexparser-purpose}
/// Provide push parser for hex types.
///
/// # Classes {#balxml_hexparser-classes}
///
/// -   balxml::HexParser: push parser for hex types
///
/// @see 
///
/// # Description {#balxml_hexparser-description}
/// The `balxml::HexParser` class template provided by this
/// component can be used to parse Hex characters into one of the supported Hex
/// types, which are `bsl::vector<char>` and `bsl::string`.  The `TYPE`
/// parameter can be one of these two types.
///
/// Note that if you need a way to encode binary data into ASCII, the
/// @ref bdlde_base64encoder  and @ref bdlde_base64decoder  components are likely a more
/// efficient solution.
///
/// This class template is a model of the `PushParser` concept, which contains
/// the following methods:
/// @code
/// int beginParse(TYPE *object);
///     // Prepare the parser to start parsing a new value and associate the
///     // specified 'object' with the parser.  Return 0 if successful and
///     // non-zero otherwise.
///
/// int endParse();
///     // Ends the parse operation and store the value parsed from the pushed
///     // characters into the associated object.  Return 0 if successful and
///     // non-zero otherwise.  The behavior is undefined unless an object is
///     // associated with this parser.  Upon successful completion, the parser
///     // will be disassociated with the object.
///
/// template <typename INPUT_ITERATOR>
/// int pushCharacters(INPUT_ITERATOR begin, INPUT_ITERATOR end);
///     // Push the characters ranging from the specified 'begin' up to (but
///     // not including) the specified 'end' into this parser.  Return 0 if
///     // successful and non-zero otherwise.  The parameterized
///     // 'INPUT_ITERATOR' must be dereferenceable to a 'char' value.  The
///     // behavior is undefined unless an object is associated with this
///     // parser.
/// @endcode
///
/// ## Usage {#balxml_hexparser-usage}
///
///
/// This section illustrates intended use of this component.
///
/// ### Example 1: Basic Usage {#balxml_hexparser-example-1-basic-usage}
///
///
/// The following snippets of code illustrate the usage of this component.
/// Suppose you had an input stream that contained Hex data.  The following
/// `loadFromHexStream` function loads this data into an `bsl::vector<char>`
/// blob:
/// @code
/// #include <balxml_hexparser.h>
///
/// #include <bsl_istream.h>
/// #include <bsl_iterator.h>
/// #include <bsl_vector.h>
///
/// using namespace BloombergLP;
///
/// int loadFromHexStream(bsl::vector<char> *result, bsl::istream& stream)
/// {
///     enum { k_FAILURE = -1 };
///
///     balxml::HexParser<bsl::vector<char> > parser;
///
///     if (0 != parser.beginParse(result)) {
///         return k_FAILURE;
///     }
///
///     if (0 != parser.pushCharacters(bsl::istreambuf_iterator<char>(stream),
///                                    bsl::istreambuf_iterator<char>())) {
///         return k_FAILURE;
///     }
///
///     return parser.endParse();
/// }
/// @endcode
/// The following function demonstrates the `loadFromHexStream` function:
/// @code
/// #include <sstream>
///
/// void usageExample()
/// {
///     const char INPUT[] = "0F3B296A";
///
///     bsl::vector<char>  vec;
///     bsl::istringstream iss(INPUT);
///
///     int result = loadFromHexStream(&vec, iss);
///
///     assert(0    == result);
///     assert(4    == vec.size());
///     assert(0x0F == vec[0]);
///     assert(0x3B == vec[1]);
///     assert(0x29 == vec[2]);
///     assert(0x6A == vec[3]);
/// }
/// @endcode
/// @}
/** @} */
/** @} */
 
/** @addtogroup bal
 * @{
 */
/** @addtogroup balxml
 * @{
 */
/** @addtogroup balxml_hexparser
 * @{
 */
 
#include <balscm_version.h>
 
#include <bdlat_valuetypefunctions.h>
 
#include <bdlb_chartype.h>
 
#include <bsls_assert.h>
#include <bsls_review.h>
 
 
namespace balxml {
 
                           // =====================
                           // class HexParser<TYPE>
                           // =====================
 
/// This is a push parser for supported Hex types (`bsl::vector<char>` or
/// `bsl::string`).
///
/// See @ref balxml_hexparser 
template <class TYPE>
class HexParser {
 
    // PRIVATE DATA MEMBERS
    char  d_firstDigit;  // buffer for first digit
    TYPE *d_object_p;    // associated object
 
  private:
    // NOT IMPLEMENTED
    HexParser(const HexParser&);
    HexParser& operator=(const HexParser&);
 
    // PRIVATE MANIPULATORS
 
    /// Append an octet generated from the specified `firstDigit` and the
    /// specified `secondDigit` to the associated object.
    void appendOctet(char firstDigit, char secondDigit);
 
  public:
    // CREATORS
 
    /// Create a parser for parsing Hex types.
    HexParser();
 
    // Generated by compiler:
    //  ~HexParser();
 
    // MANIPULATORS
 
    /// Prepare the parser to start parsing a new value and associate the
    /// specified `object` with the parser.  Return 0 if successful and
    /// non-zero otherwise.
    int beginParse(TYPE *object);
 
    /// Ends the parse operation and store the value parsed from the pushed
    /// characters into the associated object.  Return 0 if successful and non-zero otherwise.  
    /// 
    /// \pre The behavior is undefined   unless an object is
    /// associated with this parser.  Upon successful completion, the parser
    /// will be disassociated with the object.
    int endParse();
 
    /// Push the characters ranging from the specified `begin` up to (but
    /// not including) the specified `end` into this parser.  Return 0 if
    /// successful and non-zero otherwise.  The parameterized
    /// `INPUT_ITERATOR` must be dereferenceable to a `char` value.  
    /// 
    /// \pre The behavior is undefined   unless an object is associated with this
    /// parser.
    template <class INPUT_ITERATOR>
    int pushCharacters(INPUT_ITERATOR begin, INPUT_ITERATOR end);
};
 
                          // =======================
                          // struct HexParser_Helper
                          // =======================
 
/// Namespace for facilities that are used in the implementation of class
/// `HexParser<TYPE>`.  Only instances of `HexParser<TYPE>` can access the
/// facilities in this class.
///
/// See @ref balxml_hexparser 
class HexParser_Helper {
 
    template <class TYPE>
    friend class HexParser;
 
    // Table that maps from ASCII character value to hex value.
    static const char s_hexValueTable[128];
};
 
// ============================================================================
//                            INLINE DEFINITIONS
// ============================================================================
 
                           // ---------------------
                           // class HexParser<TYPE>
                           // ---------------------
 
// PRIVATE MANIPULATORS
template <class TYPE>
void HexParser<TYPE>::appendOctet(char firstDigit, char secondDigit)
{
    BSLS_ASSERT(bdlb::CharType::isXdigit((unsigned char) firstDigit));
    BSLS_ASSERT(bdlb::CharType::isXdigit((unsigned char) secondDigit));
 
    char value =
        (char)((HexParser_Helper::s_hexValueTable[(int)firstDigit] << 4)
             | (HexParser_Helper::s_hexValueTable[(int)secondDigit]));
 
    d_object_p->push_back(value);
}
 
// CREATORS
template <class TYPE>
HexParser<TYPE>::HexParser()
: d_firstDigit(0)
, d_object_p(0)
{
}
 
// MANIPULATORS
template <class TYPE>
int HexParser<TYPE>::beginParse(TYPE *object)
{
    BSLS_ASSERT(object);
 
    enum { k_SUCCESS = 0 };
 
    d_firstDigit = 0;
    d_object_p   = object;
 
    bdlat_ValueTypeFunctions::reset(d_object_p);
 
    return k_SUCCESS;
}
 
template <class TYPE>
int HexParser<TYPE>::endParse()
{
    BSLS_ASSERT(d_object_p);
 
    enum { k_SUCCESS = 0, k_FAILURE = -1 };
 
    d_object_p = 0;
 
    return 0 == d_firstDigit ? k_SUCCESS : k_FAILURE;
}
 
template <class TYPE>
template <class INPUT_ITERATOR>
int HexParser<TYPE>::pushCharacters(INPUT_ITERATOR begin, INPUT_ITERATOR end)
{
    BSLS_ASSERT(d_object_p);
 
    enum { k_SUCCESS = 0, k_FAILURE = -1 };
 
    while (begin != end) {
        const char digit = *begin;
 
        ++begin;
 
        if (!bdlb::CharType::isSpace(digit)) {
            if (!bdlb::CharType::isXdigit(digit)) {
                return k_FAILURE;                                     // RETURN
            }
 
            if (0 == d_firstDigit) {
                d_firstDigit = digit;
            }
            else {
                appendOctet(d_firstDigit, digit);
 
                d_firstDigit = 0;
            }
        }
    }
 
    return k_SUCCESS;
}
 
}  // close package namespace
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2015 Bloomberg Finance L.P.
//
// 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.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */