Enough already. I'm obviously not incentivized/shamed into writing unit tests for things in UNTESTED dir.s. It's just making a mess of the file tree

LibationSearchEngine/LuceneRegex.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.RegularExpressions;
+
+namespace LibationSearchEngine
+{
+    internal static class LuceneRegex
+    {
+        #region pattern pieces
+        //  negative lookbehind: cannot be preceeded by an escaping \
+        const string NOT_ESCAPED = @"(?<!\\)";
+
+        // disallow spaces and lucene reserved characters
+        //     + - && || ! ( ) { } [ ] ^ " ~ * ? : \
+        // define chars
+        // escape and concat
+        // create regex. also disallow spaces
+        private static char[] disallowedChars { get; } = new[] {
+            '+', '-', '&', '|', '!', '(', ')', '{', '}', '[', ']', '^', '"', '~', '*', '?', ':', '\\' };
+        private static string disallowedCharsEscaped { get; } = disallowedChars.Select(c => $@"\{c}").Aggregate((a, b) => a + b);
+        private static string WORD_CAPTURE { get; } = $@"([^\s{disallowedCharsEscaped}]+)";
+
+        // : with optional preceeding spaces. capture these so i don't accidentally replace a non-field name
+        const string FIELD_END = @"(\s*:)";
+
+        const string BEGIN_TAG = @"\[";
+        const string END_TAG = @"\]";
+
+        // space is forgiven at beginning and end of tag but not in the middle
+        // literal space character only. do NOT allow new lines, tabs, ...
+        const string OPTIONAL_SPACE_LITERAL = @"\u0020*";
+        #endregion
+
+        private static string tagPattern { get; } = NOT_ESCAPED + BEGIN_TAG + OPTIONAL_SPACE_LITERAL + WORD_CAPTURE + OPTIONAL_SPACE_LITERAL + END_TAG;
+        public static Regex TagRegex { get; } = new Regex(tagPattern, RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled);
+
+        private static string fieldPattern { get; } = NOT_ESCAPED + WORD_CAPTURE + FIELD_END;
+        public static Regex FieldRegex { get; } = new Regex(fieldPattern, RegexOptions.IgnorePatternWhitespace | RegexOptions.Compiled);
+
+        // auto-pad numbers to 8 char.s. This will match int.s and dates (yyyyMMdd)
+        //   positive look behind: beginning  space  {  [  :
+        //   positive look ahead: end  space  ]  }
+        public static Regex NumbersRegex { get; } = new Regex(@"(?<=^|\s|\{|\[|:)(\d+\.?\d*)(?=$|\s|\]|\})", RegexOptions.Compiled);
+
+        /// <summary>
+        /// proper bools are single keywords which are turned into keyword:True
+        /// if bordered by colons or inside brackets, they are not stand-alone bool keywords
+        /// the negative lookbehind and lookahead patterns prevent bugs where a bool keyword is also a user-defined tag:
+        ///   [israted]
+        ///     parseTag => tags:israted
+        ///     replaceBools => tags:israted:True
+        ///   or
+        ///     [israted]
+        ///       replaceBools => israted:True
+        ///         parseTag => [israted:True]
+        /// also don't want to apply :True where the value already exists:
+        ///   israted:false => israted:false:True
+        ///   
+        /// despite using parans, lookahead and lookbehind are zero-length assertions which do not capture. therefore the bool search keyword is still $1 since it's the first and only capture
+        /// </summary>
+        private static string boolPattern_parameterized { get; }
+            = @"
+### IMPORTANT: 'ignore whitespace' is only partially honored in character sets
+### - new lines are ok
+### - ANY leading whitespace is treated like actual matching spaces  :(
+
+                    ### can't begin with colon. incorrect syntax
+                    ### can't begin with open bracket: this signals the start of a tag
+(?<!                # begin negative lookbehind
+  [:\[]             #   char set: colon and open bracket, escaped
+  \s*               #   optional space
+)                   # end negative lookbehind
+
+\b                  # word boundary
+  ({0})             #   captured bool search keyword. this is the $1 reference used in regex.Replace
+\b                  # word boundary
+
+                    ### can't end with colon. this signals that the bool's value already exists
+                    ### can't begin with close bracket: this signals the end of a tag
+(?!                 # begin negative lookahead
+  \s*               #   optional space
+  [:\]]             #   char set: colon and close bracket, escaped
+)                   # end negative lookahead
+";
+        private static Dictionary<string, Regex> boolRegexDic { get; } = new Dictionary<string, Regex>();
+        public static Regex GetBoolRegex(string boolSearch)
+        {
+            if (boolRegexDic.TryGetValue(boolSearch, out var regex))
+                return regex;
+
+            var boolPattern = string.Format(boolPattern_parameterized, boolSearch);
+            regex = new Regex(boolPattern, RegexOptions.IgnorePatternWhitespace | RegexOptions.IgnoreCase | RegexOptions.Compiled);
+            boolRegexDic.Add(boolSearch, regex);
+
+            return regex;
+        }
+    }
+}