strings.hpp

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//==================================================================================================
/// \file
/// This header file is part of module \alib_expressions of the \aliblong.
///
/// \emoji :copyright: 2013-2024 A-Worx GmbH, Germany.
/// Published under \ref mainpage_license "Boost Software License".
//==================================================================================================
#ifndef HPP_ALIB_EXPRESSIONS_PLUGINS_STRINGS
#define HPP_ALIB_EXPRESSIONS_PLUGINS_STRINGS
#pragma once
#include "alib/expressions/plugins/calculus.hpp"
 
namespace alib {  namespace expressions { namespace plugins {
 
 
//==================================================================================================
/// This built-in \alib{expressions;CompilerPlugin} of \alib_expressions_nl
/// compiles identifiers, functions and operators with character string-type operands or return
/// types.
///
/// By default, this plug-in is \alib{expressions;Compiler::CfgBuiltInPlugins;automatically created}
/// and inserted into each instance of class \alib{expressions;Compiler} with the invocation of
/// \alib{expressions::Compiler;SetupDefaults}.
///
/// <b>Constants:</b><br>
///
/// Type    | Name        | Min. Abbreviation | Description
/// --------|-------------|-------------------|--------------
/// String  |\b NewLine   | nl    | System dependent new line character combination ( <c>"\n"</c> or <c>"\r\n"</c>).
/// String  |\b Tabulator | tab   | String with single tabulator character (<c>"\t"</c>).
///
/// <br>
/// <b>Functions:</b><br>
///
/// Note: All identifier and function names are defined case insensitive.
///
/// Return Type    | Name      | Min. Abbreviation| Signature | Description
/// ---------------|-----------|------------------|-----------|-------------
/// String  | \b String        | str      | ...                     | Creates and returns a string representation of the arguments, concatenated from left to right.
/// String  | \b ToUpper       | tu       | String                  | Converts all appropriate characters of a string to upper case letters. This function is aliased by unary operator <c>'+'</c>.
/// String  | \b ToLower       | tl       | String                  | Converts all appropriate characters of a string to lower case letters. This function is aliased by unary operator <c>'-'</c>.
/// Boolean | \b Compare       | comp     | String, String          | Returns \c 0 if strings are equal, a negative value if the first string is "smaller" than the second and a positive otherwise.
/// Boolean | \b Compare       | comp     | String, String, Boolean | Same as Compare(String,String) if third parameter is \c false. If it is \c true letter case is ignored.
/// Boolean | \b StartsWith    | sw       | String, String          | Tests if the first given string starts with the second. Comparison is case-sensitive.
/// Boolean | \b StartsWith    | sw       | String, String, Boolean | Tests if the first given string starts with the second. The third parameter is \c true, letter case is ignored.
/// Boolean | \b EndsWith      | ew       | String, String          | Tests if the first given string ends with the second. Comparison is case-sensitive.
/// Boolean | \b EndsWith      | ew       | String, String, Boolean | Tests if the first given string ends with the second. The third parameter is \c true, letter case is ignored.
/// String  | \b Substring     | subs     | String, Integer         | Returns the substring, starting at given position (2nd argument) to the end of the string..
/// String  | \b Substring     | subs     | String, Integer, Integer| Returns the substring, starting at given position (2nd argument) with the given length (3rd argument).
/// Integer | \b IndexOf       | indo     | String, String          | Searches the first occurrence of the second string in the first. Returns the position if found, otherwise \c -1.
/// Integer | \b Count         | count    | String, String          | Counts the number of occurrences of the second string in the first.
/// String  | \b Replace       | repl     | String, String, String  | Returns a copy of the 1st argument, with occurrences of 2nd argument replaced by 3rd argument.
/// String  | \b Repeat        | repeat   | String, Integer         | Returns 1st argument concatenated \e N times (2nd argument).
/// String  | \b Token         | tok      | String, String, Integer | Parses tokens separated by character (2nd argument) in string (1st argument) an returns the n-th (3rd argument).
/// String  | \b Trim          | trim     | String                  | Trims the string at both sides by removing the following whitespace characters: <c>' '</c>, <c>'\\n'</c>, <c>'\\r'</c> and <c>'\\t'</c>.
/// String  | \b Trim          | trim     | String, String          | Trims the string at both sides by removing the whitespace characters listed in the second string.
/// String  | \b TrimStart     | trims    | String                  | Trims the string at the start by removing the following whitespace characters: <c>' '</c>, <c>'\\n'</c>, <c>'\\r'</c> and <c>'\\t'</c>.
/// String  | \b TrimStart     | trims    | String, String          | Trims the string at the start by removing the whitespace characters listed in the second string.
/// String  | \b TrimEnd       | trime    | String                  | Trims the string at the end by removing the following whitespace characters: <c>' '</c>, <c>'\\n'</c>, <c>'\\r'</c> and <c>'\\t'</c>.
/// String  | \b TrimEnd       | trime    | String, String          | Trims the string at the end by removing the whitespace characters listed in the second string.
/// Integer | \b Integer       | int      | String                  | Parses an integral value from the string. Allows decimal, hexadecimal, octal and binary formats. Literal prefixes default to <c>'0x'</c>, <c>'0o'</c> and <c>'0b'</c>, which can be changed by configuring object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
/// Float   | \b Float         | float    | String                  | Parses a floating point value from the string. Allows scientific format and change of decimal point character by configuring object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
/// String  | \b Hexadecimal   | hex      | Integer                 | Converts an integral value to a hexadecimal string representation. Format options are available with object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}. The literal prefix (e.g., \c "0x") is not written.
/// String  | \b Hexadecimal   | hex      | Integer, Integer        | Converts an integral value to a hexadecimal string representation of the given output width (2nd argument). Format options are available with object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}. The literal prefix (e.g., \c "0x") is not written.
/// String  | \b Octal         | oct      | Integer                 | Converts an integral value to a binary string representation. Format options are available with object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}. The literal prefix (e.g., \c "0x") is not written.
/// String  | \b Octal         | oct      | Integer, Integer        | Converts an integral value to a binary string representation of the given output width (2nd argument). Format options are available with object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}. The literal prefix (e.g., \c "0x") is not written.
/// String  | \b Binary        | bin      | Integer                 | Converts an integral value to an octal string representation. Format options are available with object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}. The literal prefix (e.g., \c "0x") is not written.
/// String  | \b Binary        | bin      | Integer, Integer        | Converts an integral value to an octal string representation of the given output width (2nd argument). Format options are available with object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}. The literal prefix (e.g., \c "0x") is not written.
/// String  | \b Format        | format   | String, ...             | Formats the given variadic parameters according to the given format string. See notes below, for further information.
/// Boolean | \b WildCardMatch | wcm      | String, String          | Matches a string against a wildcard pattern. See notes below, for further information.
/// Boolean | \b RegExMatch    | rem      | String, String          | Matches a string against a regex pattern. See notes below, for further information.
///
/// <br>
/// <b>Unary Operators:</b><br>
///
/// | Return Type | Operator| Argument Type | Description|
/// |-------------|---------|---------------|---------------------
/// | String      |<b>+</b> | String        | Alias to function \b %ToUpper.
/// | String      |<b>-</b> | String        | Alias to function \b %ToLower.
/// | Boolean     |<b>!</b> | String        | Tests a string for emptiness. See notes below.
///
/// <br>
/// <b>Binary Operators:</b><br>
///
/// | Return Type | Lhs Type | Operator   | Rhs Type | Description
/// |-------------|----------|------------|----------|--------------------
/// |String       | String   |<b>+</b>  | Integer  | Concatenates an integral value to a string. The number conversion is performed using object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
/// |String       | String   |<b>+</b>  | Float    | Concatenates a floating point value to a string. The number conversion is performed using object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
/// |String       | String   |<b>+</b>  | <any>  | Converts a boxed value of an arbitrary type to a string and appends the result to another string. The conversion of the boxed value is performed by invoking box-function \alib{boxing;FAppend}.
/// |String       | Integer  |<b>+</b>  | String   | Converts an integral value to a string and concatenates another string. The number conversion is performed using object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
/// |String       | Float    |<b>+</b>  | String   | Converts a floating point value to a string and concatenates another string. The number conversion is performed using object \alib{lang::format::Formatter;DefaultNumberFormat} of field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
/// |String       | <any>  |<b>+</b>  | String   | Converts a boxed value of an arbitrary type to a string and appends another string. The conversion of the boxed value is performed by invoking box-function \alib{boxing;FAppend}.
/// |String       | String   |<b>+</b>  | String   | Concatenates two strings.
/// |Boolean      | String   |<b><</b>  | String   | Compares two strings using method \alib{strings;TString::CompareTo;String::CompareTo}.
/// |Boolean      | String   |<b><=</b> | String   | Compares two strings using method \alib{strings;TString::CompareTo;String::CompareTo}.
/// |Boolean      | String   |<b>></b>  | String   | Compares two strings using method \alib{strings;TString::CompareTo;String::CompareTo}.
/// |Boolean      | String   |<b>>=</b> | String   | Compares two strings using method \alib{strings;TString::CompareTo;String::CompareTo}.
/// |Boolean      | String   |<b>==</b> | String   | Compares two strings using method \alib{strings;TString::Equals;String::Equals}.
/// |Boolean      | String   |<b>!=</b> | String   | Compares two strings using method \alib{strings;TString::Equals;String::Equals}.
/// |Boolean      | String   |<b>*</b>  | String   | Alias to expression function \b %WildCardMatch. See notes below, for further information.
/// |Boolean      | String   |<b>\%</b> | String   | Alias to expression function \b %RegexMatch. See notes below, for further information.
/// |Boolean      | String   |<b>[]</b> | Integer  | Returns the substring of length \c 1 at index \e rhs in string \e lhs.
///
///
///\I{##############################################################################################}
/// # Notes And Hints #
///
/// \par Compile-Time Invokable:
///   All callback functions are defined compile-time invokable. This means that redundancies in
///   string expressions emerging from operations on constant strings are optimized (pruned) by the
///   compiler.
///
/// \par Underlying %String %Types:
///   While all string manipulation is based on \alib classes \alib{strings;TString;String},
///   \alib{strings;TAString;AString} and \alib{strings;TSubstring;Substring}, due to the
///   "harmonizing" way that string classes become boxed, none of these types appears as an expression
///   result type. This means that custom expression functions can unbox strings that have been created
///   by callback functions of this plug-in to their own custom string-type (e.g., \c std::string,
///   \c QString, or whatever), and, the other way round, results of custom callback functions that
///   returned custom strings objects, can seamlessly be used by functions and operators defined here.
///
/// \par
///   Details of this are explained in chapters
///   \ref alib_boxing_bijective "3. Non-Bijective Type Relationships" and
///   \ref alib_boxing_strings   "10. Boxing Character Strings" of the
///   \ref alib_mod_boxing "Programmer's Manual" of module \alib_boxing_nl.
///
///
/// \par Determine A String's Length
///   The length of the string can be determined with function \b %Length, which is defined with
///   compiler plugin \alib{expressions::plugins;Arithmetics} (because it works on all arrays).
///
/// \par Test For Empty %Strings:
///   Unary operator \alib{expressions::DefaultUnaryOperators;BoolNot} (<c>'!'</c>)  may be used to check if a
///   string is not empty. The operator returns \c true  if the string is empty and \c false otherwise.
///
/// \par
///   Consequently, to test for non-empty strings, <c>'!!'</c> may be written. The outer
///   <em>not-</em>operator is then a <em>not-</em>operator on the boolean result of the inner.<br>
///   Alternatively, binary operators (see below) against an emtpy string can be used:
///
///         myIndentifier == ""
///         myIndentifier != ""
///
/// \par
///   As a result, this expressions is a tautology:
///
///           !myIdentifier == (myIndentifier == "")
///
/// \par
///   Finally with strings, the built-in implementation of the
///   \alib{expressions;plugins::ElvisOperator;elvis operator} is quite useful to avoid empty
///   strings. The expression:
///
///         myIdentifier ?: "Default"
///
/// \par
///   returns "Default" if \e myIdentifier evaluates to an empty string.
///
///
/// \par Case conversion:
///   Unary operators \alib{expressions::DefaultUnaryOperators;Positive} <c>'+'</c> and
///   \alib{expressions::DefaultUnaryOperators;Negative} <c>'-'</c> are alias to functions \b %ToUpper and
///   \b %ToLower.
///   Hence, the expressions
///
///            ToUpper( "Hello " ) + ToLower( "World" )
///            +"Hello " + -"World"
///   are equivalent.
///
///
/// \par Concatenation:
///   Binary operator <c>'+'</c> is compiled by this plug-in if one of the arguments (or both) is of
///   string-type. If one argument is not of string-type, it becomes converted. For the conversion,
///   the following rules apply:
///
///   - Types \alib{expressions::Types;Integer} and \alib{expressions::Types;Float} are converted
///     to string-types using object \alib{lang::format::Formatter;DefaultNumberFormat} of
///     field \doxlinkproblem{structalib_1_1expressions_1_1Scope.html;aebf2cd4ff8a2611de06368fccfd3ef5b;Scope::Formatter;expressions::Scope::Formatter}.
///     With this, detailed options for the number output format is available.
///     Even more options are available when using expression function \b %Format instead of
///     the <c>'+'</c> operator.
///
///   <p>
///   - Any other type is converted to a string representation by using box-function
///     \alib{boxing;FAppend}. For information on how to implement this for custom
///     types, consult the documentation of module \alib_boxing.
///     The following provides a quick sample snippet, taken from the unit tests:
///
///     1. The custom type:
///        \snippet "ut_expr.cpp"    DOX_EXPRESSIONS_STRINGOPS_IAPPEND_1
///
///     2. Definition of functor \alib{strings;T_Append} type <b>MyType</b>.
///        Because the type will be boxed as a pointer, we also define the functor for the pointer type:
///        \snippet "ut_expr.cpp"    DOX_EXPRESSIONS_STRINGOPS_IAPPEND_2
///
///     3. In the bootstrap section of an application, an implementation of the templated interface
///        function has be registered with \alib_boxing_nl:
///        \snippet "ut_expr.cpp"    DOX_EXPRESSIONS_STRINGOPS_IAPPEND_3
///
///     With this short setup code, objects of type \e MyType, which might be returned by custom
///     identifiers, can be added to strings in expressions!
///
///   <p>
///   - With type \alib{expressions::Types;Boolean}, the \alib{lang::resources;ResourcePool;resourced}
///     string values generally used with box-function \alib{boxing;FAppend} defined for
///     C++ type \c bool are used.
///     These string resources default to \b "true" and \b "false". While resources can be customized,
///     such customization has process-wide effect.<br>
///     To express other values, \ref alib_expressions_builtin_ternary "conditional operator"
///     (<c>Q ? T : F</c>) can be used by the end-user:
///
///         "Is true: " + {boolean expression}                     // Uses the global resourced strings
///         "Is true: " + ( {boolean expression} ? "Yes" : "No" )  // Custom conversion per expression.
///
/// \par Comparison:
///   Operators <c>'=='</c>, <c>'!='</c>, <c>'<'</c>, <c>'<='</c>, <c>'>'</c> and <c>'>='</c>
///   perform comparisons between two string operands.
///   Internally, to perform the comparison, methods \alib{strings;TString::Equals;String::Equals} and
///   \alib{strings;TString::CompareTo;String::CompareTo} are used.
///
///   Case insensitive comparison can be performed by converting the operand(s) to upper case
///   using expression function \b %ToUpper or its "alias operator", unary <c>'+'</c>.
///   A more effective way is to use overloaded function \b %Compare that accepts an optional
///   third operator of type \b %Boolean, which if \c true is given performs a case insensitive
///   search without performing string conversions.
///
/// \anchor alib_expressions_Strings_Formatting
/// \par Formatting:
///   Function <b>Format(String, ...)</b> offers full featured string formatting in expressions.
///   Being based on classes of underlying module \alib_basecamp, there is a choice between
///   \alib{lang::format;FormatterPythonStyle;python style} or
///   \alib{lang::format;FormatterJavaStyle;Java/printf style} format strings. It is even possible
///   to allow both formats, of course not within the same string, but within different
///   evaluations of the same expression!
///
/// \par
///   Please consult the documentation of classes
///   - \alib{lang::format;Formatter},
///   - \alib{lang::format;FormatterPythonStyle;FormatterPythonStyle} and
///   - \alib{lang::format;FormatterJavaStyle;FormatterJavaStyle} for details.
///
/// \par Wildcard Match:
///   Wildcard match is implemented with expression function \b %WildcardMatch, respectively its "alias
///   operator" <c>'*'</c>.
///   The first (left-hand side) argument is the
///   string that is searched, the second (right-hand side) argument is the pattern string to be
///   matched.
///
/// \par
///   Wildcards characters are  (<c>'*'</c>) and  (<c>'?'</c>). For example, expressions
///
///            WildcardMatch("This is ALib Expressions", "*A?ib*")
///            "This is ALib Expressions" * "*A?ib*"
///
///   are equivalent and return boolean \c true.
///
/// \par
///   For case insensitive search, the both strings are to be converted to upper case, as in
///   expression:
///
///            +filename  *  "*.JPG"
///
///   \note
///     A more performant alternative for the latest sample expression is:
///
///            EndsWith( filename, ".jpg", true )
///
/// \par Regular %Expression Match:
///   Regular expression match is implemented with expression function \b %RegexMatch, respectively its
///   "alias operator" <c>'\%'</c>.
///   The first (left-hand side) argument is the
///   string that is searched, the second (right-hand side) argument is the pattern string to be matched.
///
/// \par
///   The regular expression syntax is compatible with
///   \https{Perl Regular Expressions,perldoc.perl.org/perlretut.html}.
///   The feature is implemented with using \https{boost::regex library,www.boost.org}.
///
/// \attention
///   The regular expression features of \alib and therefore of this compiler plug-in, are only
///   available with the definition of compiler symbol \ref ALIB_FEAT_BOOST_REGEX
///   and if either \ref ALIB_CHARACTERS_WIDE is \c false or \ref ALIB_CHARACTERS_NATIVE_WCHAR
///   equals \c true.
///
///\I{##############################################################################################}
/// # Reference Documentation #
//==================================================================================================
struct Strings   : public plugins::Calculus
{
    //==============================================================================================
    /// Constructor. Creates the hash map.
    /// @param compiler The compiler we will get attached to.
    //==============================================================================================
    ALIB_API    Strings( Compiler& compiler );
 
    //==============================================================================================
    /// Virtual destructor
    //==============================================================================================
    virtual    ~Strings()                                                                   override
    {}
 
    //==============================================================================================
    /// Overwrites the implementation of class \b %Calculus. While this is usually not needed,
    /// this class uses this for wildcard and regular expression matching functions.
    /// These functions implement a special behavior in respect to allocate "matcher" classes
    /// at compile-time in the case that the pattern string is constant (which usually is).
    /// Parent helper-class \alib{expressions::plugins;Calculus} does provide mechanics for such
    /// rather complicated special actions.
    ///
    /// Of course, the original method is called alternatively.
    ///
    /// @param[in,out]  ciFunction  The compilation info struct.
    /// @return \c true if compilation information was given, \c false otherwise.
    //==============================================================================================
    ALIB_API
    virtual bool    TryCompilation( CIFunction&   ciFunction)                              override;
 
    //==============================================================================================
    /// Overwrites the implementation of class \b %Calculus. While this is usually not needed,
    /// this class uses this to fetch arbitrary boxed types for certain operations because
    /// the interface mechanics of module \alib_boxing allows us to convert any custom type
    /// to a string.
    ///
    /// Of course, the original method is called alternatively.
    ///
    /// @param[in,out]  ciBinaryOp  The compilation info struct.
    /// @return \c true if compilation information was given, \c false otherwise.
    //==============================================================================================
    ALIB_API
    virtual bool    TryCompilation( CIBinaryOp&   ciBinaryOp )                             override;
 
};
 
//==================================================================================================
/// This is the callback method for string function <b>%String(...)</b>, which converts an arbitrary
/// number of arguments of arbitrary types to a concatenated string.
///
/// The function is compile-time invokable.
///
/// \note
///   As an exception to the rule, this function is not defined in an anonymous namespace, but
///   exposed through the C++ header file of this struct. The rationale for this
///   is that the function is also used for auto-casting custom types to strings, which is performed
///   with compiler plug-in \alib{expressions;plugins::AutoCast}.
///
/// @param scope The scope.
/// @param args  The single argument.
/// @return The boxed result string, allocated inside the scope's mono allocator.
//==================================================================================================
ALIB_API
Box CBToString( Scope& scope, ArgIterator args, ArgIterator );
 
//==================================================================================================
/// This is the callback method for string function <b>%Format(...)</b>, which formats an arbitrary
/// number of arguments according to a given format string.
///
/// The function is compile-time invokable.
///
/// \note
///   As an exception to the rule, this function is not defined in an anonymous namespace, but
///   exposed through the C++ header file of this struct. The rationale for this
///   is that the function this way can be called by other plug-ins as well.
///
/// @param scope The scope.
/// @param args  The single argument.
/// @return The boxed result string, allocated inside the scope's mono allocator.
//==================================================================================================
ALIB_API
Box CBFormat( Scope& scope, ArgIterator  args, ArgIterator );
 
}}} // namespace [alib::expressions::plugins]
 
#endif // HPP_ALIB_EXPRESSIONS_PLUGINS_STRINGS