feat: In r/demo/users, add ListUsersByPrefix

Signed-off-by: Jeff Thompson <[email protected]>

examples/gno.land/r/demo/users/users.gno

@@ -235,6 +235,20 @@ func GetUserByAddressOrName(input users.AddressOrName) *users.User {
 	return GetUserByAddress(std.Address(input))
 }
 
+// Get a list of user names starting from the given prefix. Limit the
+// number of results to maxResults. (This can be used for a name search tool.)
+func ListUsersByPrefix(prefix string, maxResults int) []string {
+	result := []string{}
+	name2User.Iterate(prefix, "", func(key string, value interface{}) bool {
+		if len(result) >= maxResults {
+			return true
+		}
+		result = append(result, key)
+		return false
+	})
+	return result
+}
+
 func Resolve(input users.AddressOrName) std.Address {
 	name, isName := input.GetName()
 	if !isName {

examples/gno.land/r/demo/users/z_11_filetest.gno

@@ -0,0 +1,38 @@
+package main
+
+// SEND: 2000000000ugnot
+
+import (
+	"strconv"
+
+	"gno.land/r/demo/users"
+)
+
+func main() {
+	users.Register("", "gnouser", "my profile")
+
+	{
+		// Normal usage
+		names := users.ListUsersByPrefix("a", 10)
+		println("# names: " + strconv.Itoa(len(names)))
+		println("name: " + names[0])
+	}
+
+	{
+		// The prefix is after "gnouser"
+		names := users.ListUsersByPrefix("go", 10)
+		println("# names: " + strconv.Itoa(len(names)))
+	}
+
+	{
+		// Reach maxResults
+		names := users.ListUsersByPrefix("a", 0)
+		println("# names: " + strconv.Itoa(len(names)))
+	}
+}
+
+// Output:
+// # names: 1
+// name: gnouser
+// # names: 0
+// # names: 0