Initial check-in

LibationSearchEngine/UNTESTED/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);
+    }
+}