Numeric Token Error Position Finder
Find the first illegal UTF-16 character in a strict numeric token and separately flag grammar errors made only of allowed characters; does not claim a full parser failure position.
Description
Find the first illegal UTF-16 character in a strict numeric token and separately flag grammar errors made only of allowed characters; does not claim a full parser failure position.
A numeric token can fail because of an illegal character or because allowed characters occur in an invalid grammar.
When to use this tool
Find the first illegal UTF-16 character in a strict numeric token and separately flag grammar errors made only of allowed characters; does not claim a full parser failure position.
- Prepare the supplied token fields for this operation.
- Compare the complete example with the representation used by your own input before carrying the result into another step.
How to use the tool and how it works
- Enter token. Use the exact text syntax, units and index conventions explained below.
- Run the tool. If input validation fails, correct the supplied fields before interpreting any result.
- Read result.valid, result.invalidCharacterPosition, result.grammarErrorWithoutIllegalCharacter. Interpret false, null and empty lists using the distinctions below; they can be valid outputs.
Locate the first UTF-16 position outside digits, sign, decimal point and exponent letters. Independently validate the complete finite decimal/exponent token. Return validity, the illegal-character position or null, and whether failure occurred without an illegal character.1
| Input field | Meaning and representation | Accepted input |
|---|---|---|
| token | token. | Text; at most 8,192 UTF-16 code units, subject to the grammar above |
| Output field | Interpretation |
|---|---|
| result | Object containing the named outputs below. |
| result.valid | Flag for valid under the exact condition described above. |
| result.invalidCharacterPosition | The invalid character position value under the stated formula or text convention. |
| result.grammarErrorWithoutIllegalCharacter | Flag for grammar error without illegal character under the exact condition described above. |
{
"input": {
"token": "12x3"
},
"output": {
"result": {
"valid": false,
"invalidCharacterPosition": 2,
"grammarErrorWithoutIllegalCharacter": false
}
}
}Limitations and assumptions
- The reported character is not necessarily the first grammar-error location. Whitespace is not trimmed, and nonfinite numeric conversions fail.
- All declared input fields are required and unexpected top-level fields are rejected. Numbers must be finite; lists are limited to 128 entries and ordinary text fields to 8,192 UTF-16 code units, with tighter limits where stated.
- JSON text inputs must parse within bounded nesting and size limits. Numeric outputs outside the safe finite range are rejected; large exact integer results use decimal strings. Indexes and half-open spans are zero-based unless a rank is explicitly described as one-based.
Alternative or Complementary methods
Use a parser for the actual target format when the task requires CSV, shell, URL, calendar or filesystem semantics. These tools implement the specific small grammars stated here, without adding those surrounding conventions.
References
Similar or alternative tools
- Numeric Pair Token Parser
Parse an exact 2-component comma-separated finite numeric token with strict decimal/exponent grammar; no missing components or whitespace.
- Numeric Range Token Parser
Parse one inclusive-shape numeric start..end token under strict decimal grammar; rejects backwards endpoints and does not enumerate the range.