Data commit

Task/Soundex/Go/soundex.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+    "errors"
+    "fmt"
+    "unicode"
+)
+
+var code = []byte("01230127022455012623017202")
+
+func soundex(s string) (string, error) {
+    var sx [4]byte
+    var sxi int
+    var cx, lastCode byte
+    for i, c := range s {
+        switch {
+        case !unicode.IsLetter(c):
+            if c < ' ' || c == 127 {
+                return "", errors.New("ASCII control characters disallowed")
+            }
+            if i == 0 {
+                return "", errors.New("initial character must be a letter")
+            }
+            lastCode = '0'
+            continue
+        case c >= 'A' && c <= 'Z':
+            cx = byte(c - 'A')
+        case c >= 'a' && c <= 'z':
+            cx = byte(c - 'a')
+        default:
+            return "", errors.New("non-ASCII letters unsupported")
+        }
+        // cx is valid letter index at this point
+        if i == 0 {
+            sx[0] = cx + 'A'
+            sxi = 1
+            continue
+        }
+        switch x := code[cx]; x {
+        case '7', lastCode:
+        case '0':
+            lastCode = '0'
+        default:
+            sx[sxi] = x
+            if sxi == 3 {
+                return string(sx[:]), nil
+            }
+            sxi++
+            lastCode = x
+        }
+    }
+    if sxi == 0 {
+        return "", errors.New("no letters present")
+    }
+    for ; sxi < 4; sxi++ {
+        sx[sxi] = '0'
+    }
+    return string(sx[:]), nil
+}
+
+func main() {
+    for _, s := range []string{
+        "Robert",   // WP test case = R163
+        "Rupert",   // WP test case = R163
+        "Rubin",    // WP test case = R150
+        "ashcroft", // WP test case = A261
+        "ashcraft", // s and c combine across h, t not needed
+        "moses",    // s's don't combine across e
+        "O'Mally",  // apostrophe allowed, adjacent ll's combine
+        "d jay",    // spaces allowed
+        "R2-D2",    // digits, hyphen allowed
+        "12p2",     // just not in leading position
+        "naïve",    // non ASCII disallowed
+        "",         // empty string disallowed
+        "bump\t",   // ASCII control characters disallowed
+    } {
+        if x, err := soundex(s); err == nil {
+            fmt.Println("soundex", s, "=", x)
+        } else {
+            fmt.Printf("\"%s\" fail. %s\n", s, err)
+        }
+    }
+}