C＃およびT-SQL文字列[]パック/アンパックユーティリティ関数

Question

これらのC＃アレイパックデリミタをエスケープし、ヌル、ヌル配列、空の配列を保持するアンパックユーティリティメソッドをt-sqlの熟練者はコンパニオンテーブル値関数を作成できますか往復のエンコーディングを通じて？

さまざまな文字列配列を文字列にパックすることによって、そのような（小さい）配列をパラメータとしてSQLに渡すことができます。これはいくつかのシナリオで便利です。

static class ArrayUtil 
{ 
    public static string Pack(string[] original) 
    { 
     return Pack(original, '|', '0', '~'); 
    } 

    public static string[] Unpack(string original) 
    { 
     return Unpack(original, '|', '0', '~'); 
    } 

    public static string Pack(string[] original, char delimiter, char zed, char escape) 
    { 
     if (delimiter == escape || 
      zed == escape || 
      delimiter == zed) throw new ArgumentException("special characters must be distinct"); 

     // Null array returns a null string 
     if (original == null) return null; 

     // Empty array returns an empty string 
     if (original.Length == 0) return string.Empty; 

     // Arrays with a single empty element are represented as just the escape character 
     // to differentiate from an empty array 
     if (original.Length == 1 && original[0] == string.Empty) return escape.ToString(); 

     // Otherwise 
     StringBuilder sb = new StringBuilder(); 

     for (int i = 0, ol = original.Length; i < ol; i++) 
     { 
      string s = original[i]; 

      if (s == null) 
      { 
       sb.Append(zed); // zed == null 
      } 
      else 
      { 
       for (int j = 0, sl = s.Length; j < sl; j++) 
       { 
        char c = s[j]; 

        // escape literal delimiters, escapes, and leading zeds 
        if (c == delimiter || 
         c == escape || 
         (c == zed && j == 0)) sb.Append(escape); 

        sb.Append(c); 
       } 
      } 

      if (i != ol - 1) sb.Append(delimiter); // no trailing delimiter 
     } 

     return sb.ToString(); 
    } 

    public static string[] Unpack(string original, char delimiter, char zed, char escape) 
    { 
     if (delimiter == escape || 
      zed == escape || 
      delimiter == zed) throw new ArgumentException("special characters must be distinct"); 

     // Null string returns a null array 
     if (original == null) return null; 

     // Empty string returns an empty array 
     if (original == string.Empty) return new string[] { }; 

     // A single escape character represents an array with a single empty element 
     // to differentiate from an empty array 
     if (original == escape.ToString()) return new string[] { string.Empty }; 

     // Otherwise 
     StringBuilder sb = new StringBuilder(); // A place to store the current element 
     StringReader sr = new StringReader(original); // A stream of the original string 
     List<string> unpacked = new List<string>(); // The finished elements 
     int next; 

     while ((next = sr.Read()) >= 0) 
     { 
      char c = (char)next; 

      if (c == zed && sb.Length == 0) 
      { 
       unpacked.Add(null); 

       if ((next = sr.Peek()) >= 0 && (char)next != delimiter) 
        throw new ArgumentException("An element's leading zed character must be escaped or must alone be the element", "original"); 

       sb = null; 
      } 
      else if (c == delimiter) 
      { 
       if (sb != null) unpacked.Add(sb.ToString()); 

       sb = new StringBuilder(); 
      } 
      else if (c == escape) 
      { 
       if ((next = sr.Read()) >= 0) 
       { 
        sb.Append((char)next); 
       } 
       else 
        throw new ArgumentException("Escapee expected", "original"); 
      } 
      else 
      { 
       sb.Append(c); 
      } 
     } 

     // A final zed character will make sb = null, but otherwise we have an additional element 
     if (sb != null) unpacked.Add(sb.ToString()); 

     return unpacked.ToArray(); 
    } 
} 

例Pack(original, '|', '0', '~')とパッキン、基本ケース：

["hello", "world"] -> "hello|world" 

いくつかの特殊なケース（PEXによって発見される）

null -> null 
[null] -> "0" 
[null, null] -> "0|0" 
[] -> "" 
[""] -> "~" 
["", ""] -> "|" 
["|", "|"] -> "~||~|" 

Answer 1

は、ここでT-SQLアンパックで刺します：

CREATE FUNCTION [dbo].[UnpackStrings] 
(
     @original nvarchar(4000), 
     @delimiter nchar(1), 
     @zed nchar(1), 
     @escape nchar(1) 
) 
RETURNS 
@unpacked TABLE 
(
     elementNumber INT IDENTITY(1,1), 
     element nvarchar(4000) 
) 
AS 
BEGIN 
     DECLARE @next int; 
     DECLARE @c nchar(1); 
     DECLARE @pos int; 
     DECLARE @sb nvarchar(4000); 

     -- Special characters must be distinct. 
     IF ((@delimiter = @escape) OR 
      (@zed = @escape) OR 
      (@delimiter = @zed)) 
      RETURN; 
     -- Null string return a null array 
     IF (@original IS NULL) 
      RETURN; 
     -- A single escape character represents an array with a single 
     -- empty element to differentiate from an empty array. 
     IF (@original = @escape) 
     BEGIN 
      INSERT @unpacked (element) VALUES (''); 
      RETURN; 
     END 
     -- Otherwise read through the string and unpack. 
     SET @pos = 1; 
     SET @sb = ''; 
     SET @next = 0; 
     -- Fill the table variable with the rows for your result set 
     WHILE( (@pos <= LEN(@original)) AND @next IS NOT NULL) 
     BEGIN 
      SET @next = UNICODE(SUBSTRING(@original, @pos, 1)); 
      IF (@next IS NULL) 
      BEGIN 
        IF (LEN(@sb) > 0) 
         INSERT @unpacked (element) VALUES (@sb); 
         SET @sb = ''; 
        CONTINUE; 
      END 
      ELSE 
      BEGIN 
        SET @c = NCHAR(@next); 
        IF (@c = @zed AND (LEN(@sb) = 0 OR LEN(@sb) IS NULL)) 
        BEGIN 
         INSERT @unpacked (element) VALUES (NULL); 
         -- need to peek at next character, 
         SET @next = UNICODE(SUBSTRING(@original, @pos+1, 1)); 
         IF (@next IS NOT NULL) 
         BEGIN 
           SET @c = NCHAR(@next); 
           IF (@c != @delimiter) 
           BEGIN 
            -- Peek at next character and it not delimiter, 
            -- bad format encountered. 
            BREAK; 
           END 
         END      
         SET @sb = NULL; 
        END 
        ELSE 
        BEGIN 
         IF (@c = @delimiter) 
         BEGIN 
           IF (LEN(@sb) > 0) 
            INSERT @unpacked (element) VALUES (@sb); 
           SET @sb = ''; 
         END 
         ELSE 
         BEGIN 
           IF (@c = @escape) 
           BEGIN 
            SET @pos = @pos + 1; 
            SET @next = UNICODE(SUBSTRING(@original, @pos, 1)); 
            IF (@next IS NULL) 
            BEGIN 
              CONTINUE; 
            END 
            ELSE 
            BEGIN 
              SET @sb = @sb + NCHAR(@next); 
            END 
           END 
           ELSE 
           BEGIN 
            SET @sb = @sb + @c; 
           END 
         END 
        END 
        -- 
      END 
      SET @pos = @pos + 1; 
     END 
     -- 
     -- Likely not needed. This is handled above. 
     -- 
     -- A final zed character will made sb = null, 
     -- but otherwise we have an additional element. 
     IF (@sb IS NOT NULL) 
      INSERT @unpacked (element) VALUES (@sb); 

     RETURN 
END