spanfrom

SpanFrom is a programming utility used to create a span, or contiguous subsequence, of a sequence starting at a given position. It appears in various text processing, parsing, and data annotation libraries as a means to reference a portion of data without copying it.

In many implementations a span is defined by a start position and an end position (or a length). The spanFrom function returns a span that begins at the specified offset and extends to the end of the original sequence. Some variants also allow an optional end parameter to cap the span, producing a span from start to a specified end point instead of to the sequence end.

Behavior when the offset is out of bounds varies by library. Common approaches include clipping the span to the end, returning an empty span, or throwing an error. Developers should consult the documentation of the specific API to understand its error handling.

Examples help illustrate the concept. Given the string "The quick brown fox" and an offset of 10 (zero-based indexing), spanFrom(10) might yield the substring starting at character 10, such as "brown fox," depending on the precise indexing and end behavior. For token streams, spanFrom can select the sequence of tokens starting at a given token index.

Applications of spanFrom include efficient text slicing, syntax highlighting, range queries in editors, and data visualization where a view into a larger data structure is preferable to copying. Its main advantages are memory efficiency and the ability to work with subranges without altering the original data.

See also: Span, Range, Slice, SpanTo, Interval, TokenSpan.