UT_Regex.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        UT_Regex.h ( UT Library, C++)
 *
 * COMMENTS:    A simple wrapper for hboost::regex
 *
 * RELATION TO THE STL:
 *
 *              Use UT_Regex instead of std::regex
 *
 *              Reasoning:
 * 
 *              std::regex can be much slower than other regex libraries,
 *              e.g. https://stackoverflow.com/q/70583395 
 */

#ifndef __UT_Regex__
#define __UT_Regex__

#include "UT_Array.h"
#include "UT_WorkBuffer.h"
#include "UT_StringArray.h"

#include <hboost/xpressive/basic_regex.hpp>

class UT_StringView;
typedef UT_Array<UT_StringView> UT_StringViewArray;

class UT_API UT_Regex
{
public:
    struct FromGlobTag {};
    static FromGlobTag FromGlob;
    struct FromBundleGlobTag {};
    static FromBundleGlobTag FromBundleGlob;

    /// Constructs an empty regular expression. It will match nothing and
    /// isValid will return false.
                         UT_Regex() {}

    /// Initializes the regular expression from the expression string. Use
    /// isValid to test for validity.
    explicit             UT_Regex(const char *expr)
                         {
                             init(expr);
                         }

    /// Initializes the regular expression from a glob pattern. Use
    /// isValid to test for validity.
    /// @see convertGlobToExpr() for exact accepted rules
                         UT_Regex(const char *pattern, FromGlobTag)
                         {
                             initFromGlob(pattern);
                         }
                         
    /// Initializes the regular expression from a glob pattern. Use
    /// isValid to test for validity.
    /// @see convertGlobToExpr() for exact accepted rules
                         UT_Regex(const char *pattern, FromBundleGlobTag)
                         {
                             initFromGlob(pattern, true, true);
                         }
                                                 
    /// Initializes the regular expression from the expression string. If the
    /// expression parses correctly, this function returns true.
    bool                 init(const char *expr, bool case_sensitive = true);

    /// Initializes the regular expression from the glob pattern. If the
    /// expression parses correctly, this function returns true. See
    /// convertGlobToExpr() for syntax.
    bool                 initFromGlob(const char *pattern,
                                      bool case_sensitive=true,
                                      bool is_bundle_glob=false);
    
    /// The accepted glob pattern rules are as follows:
    ///   - a '*' matches any path component, but it stops at slashes.
    ///   - use '**' to match anything, including slashes.
    ///   - a '?' matches any character except a slash (/).
    ///   - '[',']' matches one of the enclosed characters, eg. [abc]
    ///     - '-' within '[',']' denotes a character range, eg. [a-c]
    ///   - If first character after '[' is ! or ^, then it matches anything
    ///     except the enclosed characters.
    ///   - '{','}' matches the any of the comma(',') separated patterns within
    ///   - If is_bundle_glob is true, then the following rules apply as well:
    ///   - '*' matches anything, including slashes. 
    ///   - '%' to match any path component, but stops at slashes. 
    ///   - '(', '|', ')' for grouping.
    /// @return false if glob is NULL or the empty string.
    static bool          convertGlobToExpr(
                            UT_WorkBuffer &expr,
                            const char *glob,
                            bool is_bundle_glob = false);

    /// Returns true if the regular expression parses correctly. If the return
    /// value is false, use getErrorString to get a human readable error string.
    bool                 isValid() const;
    const char          *getErrorString() const;

    /// @{
    /// Returns true if the entire input string matches the regular expression, 
    /// false otherwise.
    bool                 match(const char *string) const;
    bool                 match(const UT_StringView &str) const;
    bool                 match(const UT_String &str) const
                            { return match(str.c_str()); }
    bool                 match(const UT_StringRef &str) const
                            { return match(UT_StringView(str)); }
    /// @}


    /// @{
    /// Returns true if the entire input string matches the regular expression, 
    /// false otherwise. If successful, returns the list of the captured 
    /// sub-strings through the captured string array, excluding the string
    /// itself.
    bool                 match(const char *string,
                               UT_StringArray &captured) const;
    bool                 match(const UT_StringView &string,
                               UT_StringViewArray &captured) const;
    /// @}
    /// Returns true if the regular expression is found somewhere in the input 
    /// string, false otherwise.
    bool                 search(const char *string,
                                    exint start = 0, exint end = -1) const;

    /// Returns true if the regular expression is found somewhere in the input
    /// string, false otherwise. If successful, returns the list of the 
    /// captured sub-strings through the captured string array.
    bool                 search(const char *string,
                               UT_StringArray &captured,
                                exint start = 0, exint end = -1) const;

    /// Returns true if the regular expression is found somewhere in the input
    /// string, false otherwise. If successful, returns an array of 
    /// pairs of start and end indicies the items where found at.
    bool                 search(const char *string,
                                UT_Array<std::pair<exint, exint>> &indicies,
                                exint start = 0,
                                exint end = -1) const;

    /// Returns true if the regular expression is found somewhere in the input
    /// string, false otherwise. If successful, fills results array
    /// with strings that match the entire regex expression (no capture
    /// groups)
    bool                 searchall(const char* string, UT_StringArray& results,
                                exint start = 0, exint end = -1) const;

    /// Splits the given string into substrings when the regular expression
    /// is found. Returns true if at least one split has occured. If no
    /// splits occur, results will contain one entry which is the 
    /// original string.
    /// NOTE: Does not split empty trailing components, a,b, split by ,
    /// will only generate two elements.  This differs from standard split
    /// definitions, but results from how C++ standard has evolved.
    /// You can append |($(?!\s)) to your reg ex to get the python-style
    /// This will match end-of line ($) but also use the negative lookahead
    /// to not match embedded \n and only the end-of-string.
    bool                 split(const char* string, UT_StringArray& results,
                                exint maxsplits = 0) const;

    bool                 split(const UT_StringView &str,
                               UT_StringViewArray &results,
                               exint maxsplits = 0) const;

    /// Replaces the first occurence of the regular expression in the source
    /// string with the replacement value from replace, and writes out the
    /// result. If replace_all is set to true, all occurences are replaced.
    /// If there is no match, the result buffer is set to identical to the 
    /// input string, unless copy_on_fail is false, in which case it is left
    /// untouched.
    bool                 replace(UT_WorkBuffer &result,
                                 const char *string,
                                 const char *replace,
                                 bool replace_all = false,
                                 bool copy_on_fail = true
                                ) const;
    
    /// Same as above except a fixed number of replacements can be set
    /// instead of just all or just one. 0 means replace all. 
    bool                 replace(UT_WorkBuffer &result,
                                 const char *string,
                                 const char *replace,
                                 exint num_replacements,
                                 bool copy_on_fail = true
                                ) const;
    
private:
    hboost::xpressive::cregex myExpr;
    UT_String            myError;
};

#endif