Soenneker.Extensions.Enumerable.String

Joining, filtering, case-insensitive searching, casing, deduplication, and compound-ID projection extensions for string sequences.

Installation

dotnet add package Soenneker.Extensions.Enumerable.String

Join values

using Soenneker.Extensions.Enumerable.String;

string csv = new[] { "red", "green", "blue" }
    .ToCommaSeparatedString(includeSpace: true);
// red, green, blue

string path = new[] { "api", "customers", "42" }
    .ToSeparatedString('/');
// api/customers/42

Both methods return an empty string for a null or empty source. A null item is represented as an empty field, so new[] { "a", null, "b" } joined with commas becomes a,,b. Joining is immediate and visits the source once.

ToSeparatedStringFormattable() is the allocation-conscious overload for value types implementing ISpanFormattable; it avoids the boxing that the unconstrained overload can require. Formatting uses the type’s default format with a null format provider.

Search strings

string[] names = ["Alpha", "Beta"];

names.ContainsAPart("PH");         // true; ignores case by default
names.ContainsAPart("PH", false);  // false; ordinal, case-sensitive
names.ContainsIgnoreCase("alpha"); // true
names.StartsWithIgnoreCase("al");  // true
names.EndsWithIgnoreCase("TA");    // true

Searches are ordinal, skip null elements, stop at the first match, and do not allocate normalized copies. ContainsAPart() returns false for a null source or null/empty search text. The other search methods require non-null source and search arguments. An empty prefix or suffix matches when the sequence contains at least one non-null string.

Filter, normalize, and deduplicate

IEnumerable<string?> optionalValues = ["Alpha", null, " ", "alpha"];
IEnumerable<string> nonEmpty = optionalValues.ExceptNullOrEmpty();
IEnumerable<string> nonBlank = optionalValues.ExceptNullOrWhiteSpace();

IEnumerable<string> values = nonBlank;
IEnumerable<string> lower = values.ToLower();
IEnumerable<string> distinct = values.DistinctIgnoreCase();
HashSet<string> set = values.ToHashSetIgnoreCase();

These sequence-returning operations are lazy except ToHashSetIgnoreCase(), which materializes a new ordinal case-insensitive set. ExceptNullOrEmpty() preserves whitespace-only strings; ExceptNullOrWhiteSpace() removes them. ToLower() and ToUpper() use invariant casing and turn null elements into empty strings. DistinctIgnoreCase() skips nulls, keeps the first casing encountered, and preserves order.

Split compound IDs

List<(string PartitionKey, string DocumentId)> ids = new[]
{
    "customer-42:order-100",
    "standalone"
}.ToSplitIds();

// ("customer-42", "order-100")
// ("standalone", "standalone")

Each ID is split at its last colon, so earlier colons remain part of a compound partition key. The result is immediately materialized in source order. Null or empty IDs are rejected by the underlying split operation.