bdlb_stringrefutil.h

Go to the documentation of this file.

/// @file bdlb_stringrefutil.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlb_stringrefutil.h                                               -*-C++-*-
#ifndef INCLUDED_BDLB_STRINGREFUTIL
#define INCLUDED_BDLB_STRINGREFUTIL
 
#include <bsls_ident.h>
BSLS_IDENT("$Id: $")
 
/// @defgroup bdlb_stringrefutil bdlb_stringrefutil
/// @brief <span style="color: var(--deprecated-color-dark)">DEPRECATED:</span>  Provide utility functions on `bslstl::StringRef`-erenced strings.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlb
/// @{
/// @addtogroup bdlb_stringrefutil
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlb_stringrefutil-purpose"> Purpose</a>
/// * <a href="#bdlb_stringrefutil-classes"> Classes </a>
/// * <a href="#bdlb_stringrefutil-description"> Description </a>
///   * <a href="#bdlb_stringrefutil-synopsis-of-bslstl-stringref"> Synopsis of bslstl::StringRef </a>
///   * <a href="#bdlb_stringrefutil-function-synopsis"> Function Synopsis </a>
///   * <a href="#bdlb_stringrefutil-character-encoding"> Character Encoding </a>
///     * <a href="#bdlb_stringrefutil-caseless-comparisons"> Caseless Comparisons </a>
///     * <a href="#bdlb_stringrefutil-whitespace-character-specification"> Whitespace Character Specification </a>
///   * <a href="#bdlb_stringrefutil-usage"> Usage </a>
///     * <a href="#bdlb_stringrefutil-example-1-trimming-whitespace"> Example 1: Trimming Whitespace </a>
///
/// # Purpose {#bdlb_stringrefutil-purpose}
/// Provide utility functions on `bslstl::StringRef`-erenced strings.
///
/// @deprecated  Use bdlb_stringviewutil instead.
///
/// # Classes {#bdlb_stringrefutil-classes}
///
/// -  bdlb::StringRefUtil: namespace for functions on `bslstl::StringRef` strings
///
/// @see  bdlb_string, bslstl_stringref
///
/// # Description {#bdlb_stringrefutil-description}
/// This component defines a utility `struct`,
/// `bdlb::StringRefUtil`, that provides a suite of functions that operate on
/// `bslstl::StringRef` references to string data.
///
/// ## Synopsis of bslstl::StringRef {#bdlb_stringrefutil-synopsis-of-bslstl-stringref}
///
///
/// The `bslstl::StringRef` class provides `bsl::string`-like access to an array
/// of bytes that need not be null terminated and that can have non-ASCII values
/// (i.e., `[128 .. 255]`).  Although a `bslstl::StringRef` object can itself be
/// changed, it cannot change its referent data (the array of bytes).  The
/// lifetime of the referent data must exceed that of all `bslstl::StringRef`
/// objects referring to it.  Equality comparison of `bslstl::StringRef` objects
/// compares the content of the referent data (not whether or not the object
/// refer to the same array of bytes).  See @ref bslstl_stringref  for full
/// details.
///
/// ## Function Synopsis {#bdlb_stringrefutil-function-synopsis}
///
///
/// The table below provides an outline of the functions provided by this
/// component.
/// @code
/// Function                   Purpose
/// -------------------------- --------------------------------------------
///   areEqualCaseless(SR, SR) case-insensitive equality comparison
///       lowerCaseCmp(SR, SR) lexical comparison of lower-case conversion
///       upperCaseCmp(SR, SR) lexical comparison of upper-case conversion
///
///                  ltrim(SR) exclude whitespace from left  side  of string
///                  rtrim(SR) exclude whitespace from right side  of string
///                   trim(SR) exclude whitespace from both  sides of string
///
///       substr(SR, pos, num) substring, `num` characters from `pos`
///
/// strstr         (SR, SUBSR) find first substring in string
/// strstrCaseless (SR, SUBSR) find first substring in string, case insensitive
/// strrstr        (SR, SUBSR) find last  substring in string
/// strrstrCaseless(SR, SUBSR) find last  substring in string, case insensitive
/// @endcode
///
/// Since `bslstl::StringRef` objects know the length of the referent data these
/// utility functions can make certain performance improvements over the
/// classic, similarly named C language functions.
///
/// ## Character Encoding {#bdlb_stringrefutil-character-encoding}
///
///
/// These utilities assume ASCII encoding for character data when doing case
/// conversions and when determining if a character is in the whitespace
/// character set.
///
/// ### Caseless Comparisons {#bdlb_stringrefutil-caseless-comparisons}
///
///
/// Caseless (i.e., case-insensitive) comparisons treat characters in the
/// sequence `[a .. z]` as equivalent to the respective characters in the
/// sequence `[A .. Z]`.  This equivalence matches that of `bsl::toupper`.
///
/// ### Whitespace Character Specification {#bdlb_stringrefutil-whitespace-character-specification}
///
///
/// The following characters are classified as "whitespace":
/// @code
///     Character  Description
///     ---------  ---------------
///     ' '        blank-space
///     '\f'       form-feed
///     '\n'       newline
///     '\r'       carriage return
///     '\t'       horizontal tab
///     '\v'       vertical   tab
/// @endcode
/// This classification matches that of `bsl::isspace`.
///
/// ## Usage {#bdlb_stringrefutil-usage}
///
///
/// This section illustrates the intended use of this component.
///
/// ### Example 1: Trimming Whitespace {#bdlb_stringrefutil-example-1-trimming-whitespace}
///
///
/// Many applications must normalize user input by removing leading and trailing
/// whitespace characters to obtain the essential text that is the intended
/// input.  Naturally, one would prefer to do this as efficiently as possible.
///
/// Suppose the response entered by a user is captured in `rawInput` below:
/// @code
/// const char * const rawInput    = "    \t\r\n  Hello, world!    \r\n";
///                                 //1234 5 6 789             1234 5 6
///                                 //            123456789ABCD
///                                 // Note lengths of whitespace and
///                                 // non-whitespace substrings for later.
/// @endcode
/// First, for this pedagogical example, we copy the contents at `rawInput` for
/// later reference:
/// @code
/// const bsl::string copyRawInput(rawInput);
/// @endcode
/// Then, we create a `bslstl::StringRef` object referring to the raw data.
/// Given a single argument of `const char *`, the constructor assumes the data
/// is a null-terminated string and implicitly calculates the length for the
/// reference:
/// @code
/// bslstl::StringRef text(rawInput);
///
/// assert(rawInput   == text.data());
/// assert(9 + 13 + 6 == text.length());
/// @endcode
/// Now, we invoke the `bdlb::StringRefUtil::trim` method to find the "Hello,
/// world!" sequence in `rawInput`.
/// @code
/// bslstl::StringRef textOfInterest = bdlb::StringRefUtil::trim(text);
/// @endcode
/// Finally, we observe the results:
/// @code
/// assert("Hello, world!"       == textOfInterest); // content comparison
/// assert(13                    == textOfInterest.length());
///
/// assert(text.data()   + 9     == textOfInterest.data());
/// assert(text.length() - 9 - 6 == textOfInterest.length());
///
/// assert(rawInput              == copyRawInput);   // content comparison
/// @endcode
/// Notice that, as expected, the `textOfInterest` object refers to the "Hello,
/// world!" sub-sequence within the `rawInput` byte array while the data at
/// `rawInput` remains *unchanged*.
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlb
 * @{
 */
/** @addtogroup bdlb_stringrefutil
 * @{
 */
 
#include <bdlscm_version.h>
 
#include <bsls_review.h>
 
#include <bsl_string.h>  // 'bslstl::StringRef'
 
 
namespace bdlb {
                        // ====================
                        // struct StringRefUtil
                        // ====================
 
/// This `struct` provides a namespace for a suite of functions on
/// `bslstl::StringRef` references to strings.
///
/// See @ref bdlb_stringrefutil 
struct StringRefUtil {
 
    // PUBLIC TYPES
 
    /// Size type of string references.
    typedef bslstl::StringRef::size_type size_type;
 
    // PUBLIC CLASS DATA
 
    /// Value used to denote "not-a-position", guaranteed to be outside the
    /// `range[0 .. INT_MAX]`.
    static const size_type k_NPOS = ~size_type(0);
 
    // CLASS METHODS
                        // Comparison
 
    /// Compare (the referent data of) the specified `lhs` and `rhs`.
    /// Return `true` if `lhs` and `rhs` are equal up to a case conversion,
    /// and `false` otherwise.  See {Caseless Comparisons}.
    static bool areEqualCaseless(const bslstl::StringRef& lhs,
                                 const bslstl::StringRef& rhs);
 
    /// Compare (the referent data of) the specified `lhs` and `rhs`.
    /// Return 1 if, after a conversion to lower case, `lhs` is greater than
    /// `rhs`, 0 if `lhs` and `rhs` are equal up to a case conversion, and
    /// -1 otherwise.  See {Caseless Comparisons}.
    static int lowerCaseCmp(const bslstl::StringRef& lhs,
                            const bslstl::StringRef& rhs);
 
    /// Compare (the referent data of) the specified `lhs` and `rhs`.
    /// Return 1 if, after a conversion to upper case, `lhs` is greater than
    /// `rhs`, 0 if `lhs` and `rhs` are equal up to a case conversion, and
    /// -1 otherwise.  See {Caseless Comparisons}.
    static int upperCaseCmp(const bslstl::StringRef& lhs,
                            const bslstl::StringRef& rhs);
 
                        // Trim
 
    /// Return a `bslstl::StringRef` object referring to the substring of
    /// (the referent data of) the specified `string` that excludes all
    /// leading whitespace.  See {Whitespace Character Specification}.  If
    /// `string` consists entirely of whitespace, return a zero-length
    /// reference to the end of `string` (i.e.,
    /// `bslstl::StringRef(string.end(), 0)`).
    static bslstl::StringRef ltrim(const bslstl::StringRef& string);
 
    /// Return a `bslstl::StringRef` object referring to the substring of
    /// (the referent data of) the specified `string` that excludes all
    /// trailing whitespace.  See {Whitespace Character Specification}.  If
    /// `string` consists entirely of whitespace, return a zero-length
    /// reference to the beginning of (the referent data of) `string`
    /// (i.e., `bslstl::StringRef(string.data(), 0)`).
    static bslstl::StringRef rtrim(const bslstl::StringRef& string);
 
    /// Return a `bslstl::StringRef` object referring to the substring of
    /// (the referent data of) the specified `string` that excludes all
    /// leading and trailing whitespace.  See {Whitespace Character
    /// Specification}.  If `string` consists entirely of whitespace, return
    /// a zero-length reference to the beginning of (the referent data of)
    /// `string` (i.e., `bslstl::StringRef(string.data(), 0)`).
    static bslstl::StringRef trim(const bslstl::StringRef& string);
 
                        // Create `subString`
 
    /// Return a string whose value is the substring starting at the
    /// optionally specified `position` in the specified `string`, of length
    /// the optionally specified `numChars` or `length() - position`,
    /// whichever is smaller.  If `position` is not specified, 0 is used
    /// (i.e., the substring is from the beginning of this string).  If
    /// `numChars` is not specified, `k_NPOS` is used (i.e., the entire
    /// suffix from `position` to the end of the string is returned).  
    /// 
    /// \pre The behavior is undefined   unless `position` is within the string
    /// boundaries (`0 <= position <= string.length()`).
    static bslstl::StringRef substr(
                                  const bslstl::StringRef& string,
                                  size_type                position = 0,
                                  size_type                numChars = k_NPOS);
 
                        // Find `subString`
 
    /// Return a `bslstl::StringRef` object referring to the first
    /// occurrence in (the referent data of) the specified `string` at which
    /// (the referent data of) the specified `subString` is found, or
    /// `bslstl::StringRef()` if there is no such occurrence.  If
    /// `subString` has zero length then a zero-length reference to the
    /// beginning of `string` is returned (i.e.,
    /// `bslstl::StringRef(string.data(), 0)`);
    static bslstl::StringRef strstr(const bslstl::StringRef& string,
                                    const bslstl::StringRef& subString);
 
    /// Return a `bslstl::StringRef` object referring to the first
    /// occurrence in (the referent data of) the specified `string` at which
    /// (the referent data of) the specified `subString` is found using
    /// case-insensitive comparisons, or `bslstl::StringRef()` if there is
    /// no such occurrence.  See {Caseless Comparisons}.  If `subString` has
    /// zero length then a zero-length reference to the beginning of
    /// `string` is returned (i.e., `bslstl::StringRef(string.data(), 0)`);
    static bslstl::StringRef strstrCaseless(
                                           const bslstl::StringRef& string,
                                           const bslstl::StringRef& subString);
 
    /// Return a `bslstl::StringRef` object referring to the last occurrence
    /// in (the referent data of) the specified `string` at which (the
    /// referent data of) the specified `subString` is found, or
    /// `bslstl::StringRef()` if there is no such occurrence.  If
    /// `subString` has zero length then a zero-length reference to the end
    /// of `string` is returned (i.e.,
    /// `bslstl::StringRef(string.end(), 0)`);
    static bslstl::StringRef strrstr(const bslstl::StringRef& string,
                                     const bslstl::StringRef& subString);
 
    /// Return a `bslstl::StringRef` object referring to the last occurrence
    /// in (the referent data of) the specified `string` at which (the
    /// referent data of) the specified `subString` is found using
    /// case-insensitive comparisons, or `bslstl::StringRef()` if there is
    /// no such occurrence.  See {Caseless Comparisons}.  If `subString` has
    /// zero length then a zero-length reference to the end of `string` is
    /// returned (i.e., `bslstl::StringRef(string.end(), 0)`);
    static bslstl::StringRef strrstrCaseless(
                                           const bslstl::StringRef& string,
                                           const bslstl::StringRef& subString);
 
                        // Find first/last of/not of
 
    /// Return the position of the *first* occurrence of a character
    /// belonging to the specified `characters`, if such an occurrence can
    /// can be found in the specified `string` (on or *after* the
    /// optionally specified `position` if such a `position` is specified),
    /// and return `k_NPOS` otherwise.
    static
    size_type findFirstOf(const bslstl::StringRef& string,
                          const bslstl::StringRef& characters,
                          size_type                position = 0u);
 
    /// Return the position of the *last* occurrence of a character
    /// belonging to the specified `characters`, if such an occurrence can
    /// can be found in the specified `string` (on or *before* the
    /// optionally specified `position` if such a `position` is specified),
    /// and return `k_NPOS` otherwise.
    static
    size_type findLastOf(const bslstl::StringRef& string,
                         const bslstl::StringRef& characters,
                         size_type                position = k_NPOS);
 
    /// Return the position of the *first* occurrence of a character *not*
    /// belonging to the specified `characters`, if such an occurrence can
    /// be found in the specified `string` (on or *after* the optionally
    /// specified `position` if such a `position` is specified), and return
    /// `k_NPOS` otherwise.
    static
    size_type findFirstNotOf(const bslstl::StringRef& string,
                             const bslstl::StringRef& characters,
                             size_type                position = 0u);
 
    /// Return the position of the *last* occurrence of a character *not*
    /// belonging to the specified `characters`, if such an occurrence can
    /// be found in the specified `string` (on or *before* the optionally
    /// specified `position` if such a `position` is specified), and return
    /// `k_NPOS` otherwise.
    static
    size_type findLastNotOf(const bslstl::StringRef& string,
                            const bslstl::StringRef& characters,
                            size_type                position = k_NPOS);
};
 
// ============================================================================
//                        INLINE DEFINITIONS
// ============================================================================
 
                        // --------------------
                        // struct StringRefUtil
                        // --------------------
 
// CLASS METHODS
 
                        // Comparison
 
inline
bool StringRefUtil::areEqualCaseless(const bslstl::StringRef& lhs,
                                     const bslstl::StringRef& rhs)
{
    if (lhs.length() != rhs.length()) {
        return false;                                                 // RETURN
    }
 
    return 0 == lowerCaseCmp(lhs, rhs);
}
 
                        // Trim
 
inline
bslstl::StringRef StringRefUtil::trim(const bslstl::StringRef& string)
{
    return ltrim(rtrim(string));
}
 
                        // Substring
 
inline
bslstl::StringRef StringRefUtil::substr(const bslstl::StringRef& string,
                                        size_type                position,
                                        size_type                numChars)
{
    BSLS_ASSERT(position <= string.length());
 
    return bslstl::StringRef(string, position, numChars);
}
 
}  // close package namespace
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2016 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 ----------------------------------
 
/** @} */
/** @} */
/** @} */