diff --git a/Semantics.Strings.Identifiers/CreditCardNumber.cs b/Semantics.Strings.Identifiers/CreditCardNumber.cs
index 5a3812f..71f67dc 100644
--- a/Semantics.Strings.Identifiers/CreditCardNumber.cs
+++ b/Semantics.Strings.Identifiers/CreditCardNumber.cs
@@ -5,20 +5,20 @@ namespace ktsu.Semantics.Strings.Identifiers;
using ktsu.Semantics.Strings;
///
-/// A payment card number (PAN): 13-19 digits passing the Luhn checksum. Spaces and hyphens are
-/// stripped on creation. Validation is Luhn-only — no BIN/issuer/network detection and no PCI
+/// A payment card number (PAN): 13-19 digits passing the Luhn checksum. Whitespace and hyphens
+/// are stripped on creation. Validation is Luhn-only — no BIN/issuer/network detection and no PCI
/// guarantees; treat the value as sensitive and do not log it.
///
[IsCreditCardNumber]
public sealed record CreditCardNumber : SemanticString
{
- /// Normalizes the input by stripping spaces and hyphens.
+ /// Normalizes the input by stripping whitespace (spaces, tabs, line breaks) and hyphens.
/// The raw input string.
/// The digit-only canonical form.
protected override string MakeCanonical(string input)
{
Ensure.NotNull(input);
- return input.Replace(" ", string.Empty).Replace("-", string.Empty);
+ return IdentifierCanonicalization.StripWhitespaceAndHyphens(input);
}
/// A rejected value is sensitive, so it is left out of the validation exception message.
diff --git a/Semantics.Strings.Identifiers/IdentifierCanonicalization.cs b/Semantics.Strings.Identifiers/IdentifierCanonicalization.cs
new file mode 100644
index 0000000..7cdbac7
--- /dev/null
+++ b/Semantics.Strings.Identifiers/IdentifierCanonicalization.cs
@@ -0,0 +1,30 @@
+// Copyright (c) 2023-2026 ktsu-dev contributors
+
+namespace ktsu.Semantics.Strings.Identifiers;
+
+using System.Linq;
+using System.Text;
+
+///
+/// Normalization shared by the identifier types, so that what counts as a separator cannot drift
+/// between them.
+///
+internal static class IdentifierCanonicalization
+{
+ ///
+ /// Removes every whitespace character (spaces, tabs, line breaks, non-breaking spaces) and every
+ /// hyphen, which is what a copied card number or ISBN typically carries around its digits.
+ ///
+ /// The raw input string.
+ /// The input with whitespace and hyphens removed.
+ internal static string StripWhitespaceAndHyphens(string input)
+ {
+ StringBuilder canonical = new(input.Length);
+ foreach (char c in input.Where(static ch => !char.IsWhiteSpace(ch) && ch != '-'))
+ {
+ canonical.Append(c);
+ }
+
+ return canonical.ToString();
+ }
+}
diff --git a/Semantics.Strings.Identifiers/Isbn.cs b/Semantics.Strings.Identifiers/Isbn.cs
index a7d7058..ae62068 100644
--- a/Semantics.Strings.Identifiers/Isbn.cs
+++ b/Semantics.Strings.Identifiers/Isbn.cs
@@ -6,7 +6,7 @@ namespace ktsu.Semantics.Strings.Identifiers;
///
/// An International Standard Book Number in ISBN-10 or ISBN-13 form, e.g. 0306406152 or
-/// 9780306406157. Hyphens and spaces are stripped and the value is uppercased (for the ISBN-10
+/// 9780306406157. Hyphens and whitespace are stripped and the value is uppercased (for the ISBN-10
/// X check digit) on creation. The check digit is validated, and an ISBN-13 must start with
/// the 978 or 979 Bookland prefix, but not 9790, which is the ISMN range for printed
/// music; registration-group and publisher ranges are not validated.
@@ -14,12 +14,12 @@ namespace ktsu.Semantics.Strings.Identifiers;
[IsIsbn]
public sealed record Isbn : SemanticString
{
- /// Normalizes the input by stripping hyphens/spaces and uppercasing.
+ /// Normalizes the input by stripping hyphens and whitespace (spaces, tabs, line breaks) and uppercasing.
/// The raw input string.
/// The canonical ISBN string.
protected override string MakeCanonical(string input)
{
Ensure.NotNull(input);
- return input.Replace("-", string.Empty).Replace(" ", string.Empty).ToUpperInvariant();
+ return IdentifierCanonicalization.StripWhitespaceAndHyphens(input).ToUpperInvariant();
}
}
diff --git a/Semantics.Strings.Identifiers/README.md b/Semantics.Strings.Identifiers/README.md
index 81df84b..f8e652a 100644
--- a/Semantics.Strings.Identifiers/README.md
+++ b/Semantics.Strings.Identifiers/README.md
@@ -86,9 +86,9 @@ Each type is a `sealed record` deriving from `SemanticString`. None declare t
|------|---------------|------------|-------------------|
| `Uuid` | Trim, strip wrapping `{}` / `()`, lowercase | Canonical 8-4-4-4-12 hex (RFC 4122 layout) | Any variant/version accepted, including the nil UUID. Not version-checked. |
| `Ulid` | Trim, uppercase | 26 Crockford base32 chars, first char `0`-`7` | Timestamp is not otherwise decoded. |
-| `Iban` | Strip spaces, uppercase | Length 15-34, country/check prefix, ISO 7064 mod-97-10 checksum | Country-specific BBAN structure is not enforced. |
-| `Isbn` | Strip `-` and spaces, uppercase | ISBN-10 (weighted mod-11, `X` allowed) or ISBN-13 (`978`/`979` prefix but not the `9790` ISMN range, mod-10) | Registration-group/publisher ranges are not validated. |
-| `CreditCardNumber` | Strip spaces and hyphens | 13-19 digits, Luhn (mod-10) checksum | Luhn only. No issuer/network detection, no PCI guarantee. The value is sensitive, do not log it. |
+| `Iban` | Strip whitespace, uppercase | Length 15-34, country/check prefix, ISO 7064 mod-97-10 checksum | Country-specific BBAN structure is not enforced. |
+| `Isbn` | Strip `-` and whitespace, uppercase | ISBN-10 (weighted mod-11, `X` allowed) or ISBN-13 (`978`/`979` prefix but not the `9790` ISMN range, mod-10) | Registration-group/publisher ranges are not validated. |
+| `CreditCardNumber` | Strip whitespace and hyphens | 13-19 digits, Luhn (mod-10) checksum | Luhn only. No issuer/network detection, no PCI guarantee. The value is sensitive, do not log it. |
| `JwtToken` | None (stored verbatim, case-sensitive) | Three `.`-separated segments in the unpadded base64url alphabet (no whitespace, `=`, `+` or `/`), non-empty header and payload that decode to UTF-8 text delimited as `{ ... }` | Structural only: the header and payload bodies are not parsed, so malformed JSON between the braces is accepted. Signature is not decoded or verified. `alg`, claims, and expiry are not inspected. |
Creation follows the base-type contract: `Create(...)` throws `ArgumentException` on invalid input and `ArgumentNullException` on null, while `TryCreate(...)` returns `false` instead.
diff --git a/Semantics.Test/Identifiers/CreditCardNumberTests.cs b/Semantics.Test/Identifiers/CreditCardNumberTests.cs
index 40bf0ca..398de92 100644
--- a/Semantics.Test/Identifiers/CreditCardNumberTests.cs
+++ b/Semantics.Test/Identifiers/CreditCardNumberTests.cs
@@ -44,4 +44,16 @@ public void Create_Empty_Throws()
{
Assert.ThrowsExactly(() => CreditCardNumber.Create(string.Empty));
}
+
+ [TestMethod]
+ [DataRow("4111111111111111\n")]
+ [DataRow("4111111111111111\r\n")]
+ [DataRow("4111\t1111\t1111\t1111")]
+ [DataRow("4111\u00A01111\u00A01111\u00A01111")]
+ [DataRow(" 4111-1111 1111-1111\t")]
+ public void Create_WithWhitespace_StripsItAndValidates(string input)
+ {
+ CreditCardNumber card = CreditCardNumber.Create(input);
+ Assert.AreEqual("4111111111111111", card.WeakString);
+ }
}
diff --git a/Semantics.Test/Identifiers/IsbnTests.cs b/Semantics.Test/Identifiers/IsbnTests.cs
index 28e134b..e449751 100644
--- a/Semantics.Test/Identifiers/IsbnTests.cs
+++ b/Semantics.Test/Identifiers/IsbnTests.cs
@@ -93,4 +93,16 @@ public void Create_Empty_Throws()
{
Assert.ThrowsExactly(() => Isbn.Create(string.Empty));
}
+
+ [TestMethod]
+ [DataRow("978-0-306-40615-7\n", "9780306406157")]
+ [DataRow("978-0-306-40615-7\r\n", "9780306406157")]
+ [DataRow("978\t0306406157", "9780306406157")]
+ [DataRow("978\u00A00\u00A0306\u00A040615\u00A07", "9780306406157")]
+ [DataRow("\t0-8044-2957-x\n", "080442957X")]
+ public void Create_WithWhitespace_StripsItAndValidates(string input, string expected)
+ {
+ Isbn isbn = Isbn.Create(input);
+ Assert.AreEqual(expected, isbn.WeakString);
+ }
}