Example 1 · atom
- Arguments
- text
" Route_7\t"
- Expected return
"Route_7"
Test data
- Input
" Route_7\t"
- Expected output
"Route_7"
One-pass string parser
One-pass string parser
MediumYour task
- Read one atom from a small input string and return its exact spelling.
- For example, Route_7 stays Route_7, and 007 stays a string.
- Do not evaluate or convert values.
Required API
- ParseError.Error
func (e *ParseError) Error() string - ParseSexp
func ParseSexp(text string) (any, error) - ParseError.Code
Code string - ParseError.Index
Index int
Behavior
- An atom contains one or more characters from [A-Za-z0-9_+-].
- Ignore leading and trailing space, tab, carriage return and newline.
- The input is ASCII and at most 4,096 characters long.
- Parentheses are not supplied in this part.
- Use one forward-moving cursor, without splitting or tokenizing the whole input, eval or a general parser.
- Aim for O(n) time.
- Each call starts fresh.
- Use only the standard library.
- Report the first violation reached, with a zero-based character index.
- Empty or whitespace-only input is expected_expression at EOF (len(text)).
- An unsupported character is invalid_character at its position.
- After the atom and optional whitespace, another atom is trailing_input at its first character; an unsupported character is still invalid_character.
- Stop there rather than scanning ahead.
- On failure return no partial result.
- Error messages are not graded.
Examples
The runner calls your functions directly; you do not need to parse JSON.
Example 2 · extra root
- Arguments
- text
"a b"
- Expected outcome
ParseError(code="trailing_input", index=2)
Test data
- Input
"a b"
- Expected output
ParseError(code="trailing_input", index=2)
Related guides
Loading…
Restoring local drafts…
Checking execution availability…
Public examples
NO CODE EXECUTEDExplore the examples.
View inputs and expected outputs. Examples do not run your code.