FEAT: including original Allen Kamp's Soundex script

src/modules/soundex.reb

@@ -0,0 +1,77 @@
+REBOL [
+    Title: "Soundex"
+    Date: 17-Jul-1999
+    File: %soundex.r
+    Author: "Allen Kamp"
+    Purpose: {Soundex Encoding returns similar codes for similar sounding words or names. eg Stephens, Stevens are both S315, Smith and Smythe are both S53. Useful for adding Sounds-like searching to databases}
+    Comment: {
+        This simple Soundex returns a code that is up to 4 characters
+        long, the /integer refinement will return an integer code
+        value instead.  An example for searching a simple phone number
+        database, with Soundex is included.  For improved search
+        speed, you could store the soundex codes in the database.
+
+        This is the basic algorithm (There are a number of different
+        one floating around)
+
+        1. Remove vowels, H, W and Y
+        2. Encode each char with its code value
+        3. Remove adjacent duplicate numbers
+
+        4. Return First letter, followed by the next 3 letter's code
+           numbers, if they exist.
+
+        Others I will implement soon include, Extended Soundex,
+        Metaphone and the LC Cutter table
+    }
+    Language: "English"
+    Email: %allenk--powerup--com--au
+    library: [
+        level: 'intermediate 
+        platform: 'all 
+        type: 'tool 
+        domain: [DB text text-processing] 
+        tested-under: none 
+        support: none 
+        license: none 
+        see-also: none
+    ]
+    Version: 1.0.0
+]
+
+soundex: func[
+    {Returns the Census Soundex Code for the given string}
+    string [any-string!] "String to Encode"
+    /local code val letter
+][
+
+    code: make string! ""
+
+    ; Create Rules
+    set1: [["B" | "F" | "P" | "V"](val: "1")]
+    set2: [["C" | "G" | "J" | "K" | "Q" | "S" | "X" | "Z"](val: "2")]
+    set3: [["D" | "T"](val: "3")]
+    set4: [["L"](val: "4")]
+    set5: [["M" | "N"] (val: "5")]
+    set6: [["R"](val: "6")]
+    ; Append val to code if not a duplicate of previous code val
+    soundex-match: [[set1 | set2 | set3 | set4 | set5 | set6 ] 
+        (if val <> back tail code [append code val]) ]
+
+    ; If letter not a matched letter its val is 0, but we only care
+    ; about it if it is the first letter.
+    soundex-no-match: [(if (length? code) = 0 [append code "0"])]
+
+    either all [string? string string <> ""] [
+        string: uppercase trim copy string
+
+        foreach letter string [
+            parse to-string letter [soundex-match | soundex-no-match]
+            if (length? code) = 4 [break] ;maximum length for code is 4
+        ]
+    ] [
+        return string ; return unchanged
+    ]
+    change code first string ; replace first number with first letter
+    return code
+]