ddn.columnar.strings

The literal string namespace of ddn.df (ADR-2026-10-23-12): length, case mapping, stripping, slicing and literal matching over UTF-8 with code-point indices and full Unicode semantics via Phobis - std.uni case mapping (length changes preserved: ß uppercases to SS) and whitespace. Regex does not exist here and nothing in this module implies its syntax; matching is literal substring containment.

Nulls propagate to null slots (the null doctrine - no empty-string defaulting); outputs are fresh sealed STRING chunks through the builder shapes; input frames are never mutated.

Copyright

Copyright (c) 2026, DDN (D Developer Network) Members

License

BSD-3-Clause
struct StringResult
fn allAscii countCp finish mapAsciiCase mapCaseSeries mappedCaseBytes mapSlots mapUnicodeCase padInto sliceOf strConcat strConcatLit strContainsLit strEndsWithLit stripBoth stripLeftOf stripRightOf strLengthUnits strLower strPadEnd strPadStart strRepeat strReplaceLit strReplaceRegex strSlice strSplit strStartsWithLit strStrip strStripLeading strStripTrailing strUpper strZfill

Types 1

private structStringResult

The output side of every string op: fresh values and validity.

Fields
string[] values
bool[] valid

Functions 32

private fnStringResult mapSlots(alias fn)(Series s)
private fnSeries finish(Series s, StringResult r)
fnSeries strLengthUnits(Series s)The code-point length of each string (ADR-2026-10-23-12): INT64 output; nulls stay null. Byte counts are not offered (documented - code points are the unit of every index in this namespace).
fnSeries strUpper(Series s)Ditto, full Unicode upper-case (`std.uni` - `ß` becomes `SS`).
fnSeries strLower(Series s)Ditto, full Unicode lower-case.
fnSeries strStrip(Series s)Ditto, Unicode whitespace stripped from both ends.
fnSeries strStripLeading(Series s)Ditto, leading whitespace only.
fnSeries strStripTrailing(Series s)Ditto, trailing whitespace only.
private fnstring stripBoth(scope const(char)[] v)
fnSeries strSlice(Series s, long start, long end)The code-point slice `[start, end)` of each string (ADR-2026-10-23-12): negative indices count from the end (Python/Polars semantics); out-of-range clamps; nulls propagate. A slice clamps where `ta...
fnSeries strContainsLit(Series s, string lit)Literal substring containment (`contains(lit)`).
fnSeries strStartsWithLit(Series s, string lit)Ditto, `startsWith(lit)` (literal).
fnSeries strEndsWithLit(Series s, string lit)Ditto, `endsWith(lit)` (literal).
fnSeries strConcat(Series s, Series other)Slot-wise concatenation (ADR-2026-10-23-12): `concat(other)` appends element-wise; a null on either side yields null (the null doctrine - no empty-string defaulting).
fnSeries strConcatLit(Series s, string lit)Ditto, appending a literal to every slot.
private fnlong countCp(scope const(char)[] v) @safe pure
private fnSeries mapCaseSeries(bool up)(Series s)
private fnbool allAscii(scope const(char)[] v) @safe pure nothrow
private fnsize_t mapAsciiCase(bool up)(scope const(char)[] v, char[] dst) @safe pure nothrow
private fnsize_t mappedCaseBytes(bool up)(scope const(char)[] v) @safe pure
private fnsize_t mapUnicodeCase(bool up)(scope const(char)[] v, char[] dst) @safe pure
private fnstring stripLeftOf(scope const(char)[] v) @safe pure
private fnstring stripRightOf(scope const(char)[] v) @safe pure
private fnstring sliceOf(scope const(char)[] v, long start, long end) @safe pure
fnSeries strSplit(Series s, string sep)Splits each string by a literal separator into a LIST<STRING> column (ADR-2026-10-23-14): an empty separator throws (not a code-point split); repeated separators yield empty tokens; leading/trailin...
fnSeries strReplaceLit(Series s, string from, string to)Replaces every occurrence of the literal `from` with `to` (ADR-2026-10-30-01): a left-to-right non-overlapping scan; the replacement text is never rescanned (Python `str.replace` / `np.char.replace...
fnSeries strPadStart(Series s, long width, dchar fill = ' ')Left-pads each string to a code-point `width` with `fill` (ADR-2026-10-30-01): strings already at or beyond the width are returned unchanged (never truncated); `fill` encodes once and repeats; null...
fnSeries strPadEnd(Series s, long width, dchar fill = ' ')Ditto, right-padding.
private fnSeries padInto(Series s, long width, dchar fill, bool atStart)
fnSeries strZfill(Series s, long width)Left-pads each string with `'0'` to a code-point `width`, sign-aware (ADR-2026-10-30-01): a leading `'-'` or `'+'` stays in front of the zeros (Python `str.zfill`); strings already at or beyond the...
fnSeries strRepeat(Series s, long n)Repeats each string `n` times (ADR-2026-10-30-01): `n = 0` yields the empty string (valid data, not null); the total output size is checked before any allocation; null strings stay null.
fnSeries strReplaceRegex(Series s, string pattern, string replacement, RegexScope replaceScope = RegexScope.ALL)Replaces regex matches with `replacement` (ADR-2026-10-30-01): the pattern compiles once per call (Phobos `std.regex`, ECMAScript flavour, case-sensitive - no flags in v1); `scope = ALL` (default) ...