Description
For nonnegative integer tokenCount and lookaheadCount and currentIndex within zero through tokenCount return endExclusive=min(tokenCount,currentIndex+lookaheadCount) and available=min(tokenCount-currentIndex,lookaheadCount).
Parsing depends on the chosen grammar, character encoding, offset unit, and treatment of escapes and delimiters. UTF-16 code-unit positions, Unicode code points, and UTF-8 byte offsets are not interchangeable. A boundary or token check supplies one part of a parser rather than validating an entire file.
For nonnegative integer tokenCount and lookaheadCount and currentIndex within zero through tokenCount return endExclusive=min(tokenCount,currentIndex+lookaheadCount) and available=min(tokenCount-currentIndex,lookaheadCount).
When to use this tool
Use Token Lookahead Span when you need the stated token boundary, offset, prefix, delimiter, or count component inside a larger parsing workflow.
How to use the tool and how it works
- Enter currentIndex, lookaheadCount, tokenCount. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read endExclusive, available. Use the output convention below.
For nonnegative integer tokenCount and lookaheadCount and currentIndex within zero through tokenCount return endExclusive=min(tokenCount,currentIndex+lookaheadCount) and available=min(tokenCount-currentIndex,lookaheadCount).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| currentIndex | Current Index | Required. Safe integer; minimum 0. |
| lookaheadCount | Lookahead Count | Required. Safe integer; minimum 0. |
| tokenCount | Token Count | Required. Safe integer; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| endExclusive | Zero-based exclusive token-index end. | Required. Safe integer. |
| available | Available | Required. Safe integer. |
{
"input": {
"currentIndex": 3,
"lookaheadCount": 5,
"tokenCount": 6
},
"output": {
"endExclusive": 6,
"available": 3
}
}Limitations and assumptions
- Indices are zero-based and the end is exclusive. This computes a bounded span without reading tokens, implementing a grammar, or reserving parser input.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Signed zero is exported as zero.
Alternative or Complementary methods
Choose a parser for the intended complete grammar when context, nesting, encodings, or semantic validation matters. Keep byte, code-unit, and code-point coordinates explicit when combining results.
References
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