ssssssss-team/spider-flow · error · IndexOutOfBoundsException

Start outside of string.

Error message

Start outside of string.

What it means

The Span(String,int,int) constructor throws IndexOutOfBoundsException("Start outside of string.") when start is greater than source.length() - 1, i.e. the start offset points past the last character. The span must begin within the source text. Note this also rejects start == source.length(), so a zero-length span at the end of the source is not allowed by this constructor.

Solutions

1. Ensure start <= source.length() - 1 and that the source is non-empty before constructing.
2. For an EOF/end-of-input marker, build the span with end <= source.length() and start < source.length(), or add a guard for empty input.
3. Handle the empty-source case explicitly before creating spans.
4. Use the single-argument Span(source) constructor when the span covers the entire source.

Example fix

// before
Span eof = new Span(source, source.length(), source.length());
// after
Span eof = source.isEmpty() ? null : new Span(source, Math.min(source.length() - 1, start), source.length());

if (source == null || source.isEmpty()) throw new IllegalArgumentException("source must be non-empty");
if (start >= source.length()) throw new IllegalArgumentException("start " + start + " outside source of length " + source.length());

boolean canStartSpan(String source, int start) {
    return source != null && !source.isEmpty() && start >= 0 && start < source.length();
}

try {
    Span span = new Span(source, start, end);
} catch (IndexOutOfBoundsException e) {
    // clamp start for EOF-style spans
    Span span = new Span(source, Math.max(0, source.length() - 1), source.length());
}

When it happens

Trigger: Calling new Span(source, start, end) where start >= source.length(), e.g. start == source.length() for an empty range at end-of-input, or an empty source string with start=0.

Common situations: Tokenizing to end of input and building an EOF span at offset source.length(); constructing spans over empty strings; parser code that carries a cursor past the last character.

Related errors

• Start must be >= 0.
• End outside of string.
• Start must be >= 0.
• Start must be <= end.
• The two spans do not reference the same source.

AI-assisted analysis of ssssssss-team/spider-flow@c799cca99c (2026-09-08). Data as JSON: /api/errors/b35afbd9af5fcb21. Report an issue: GitHub.

Appendix: source

Thrown at spider-flow-core/src/main/java/org/spiderflow/core/expression/parsing/Span.java:26

	/** start index in source string, starting at 0 **/
	private int start;

	/** end index in source string, exclusive, starting at 0 **/
	private int end;

	/** Cached String instance to reduce pressure on GC **/
	private final String cachedText;

	public Span (String source) {
		this(source, 0, source.length());
	}

	public Span (String source, int start, int end) {
		if (start > end) throw new IllegalArgumentException("Start must be <= end.");
		if (start < 0) throw new IndexOutOfBoundsException("Start must be >= 0.");
		if (start > source.length() - 1) 
			throw new IndexOutOfBoundsException("Start outside of string.");
		if (end >source.length()) throw new IndexOutOfBoundsException("End outside of string.");

		this.source = source;
		this.start = start;
		this.end = end;
		this.cachedText = source.substring(start, end);
	}

	public Span (Span start, Span end) {
		if (!start.source.equals(end.source)) throw new IllegalArgumentException("The two spans do not reference the same source.");
		if (start.start > end.end) throw new IllegalArgumentException("Start must be <= end.");
		if (start.start < 0) throw new IndexOutOfBoundsException("Start must be >= 0.");
		if (start.start > start.source.length() - 1) throw new IndexOutOfBoundsException("Start outside of string.");
		if (end.end > start.source.length()) throw new IndexOutOfBoundsException("End outside of string.");

		this.source = start.source;
		this.start = start.start;
		this.end = end.end;

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