# `Predicator.Errors.ParseError`
[🔗](https://github.com/riddler/predicator-ex/blob/v9.4.1/lib/predicator/errors/parse_error.ex#L1)

Error struct for parse errors in Predicator expressions.

This error occurs when the input expression cannot be parsed due to syntax errors.

## Fields

- `message` - Human-readable error description. Never contains the
  location - that is always `:position`
- `position` - `{line, column}` of the syntax error, typed
  `t:Predicator.Types.position/0` so generic error-reporting code can read a
  position uniformly across `ParseError`, `EvaluationError`,
  `TypeMismatchError`, and `UndefinedVariableError`
- `span` - the source text the failing token or construct covers, when the
  failure carried a token extent (optional, default `nil`). `position` is
  always the span's start when both are present.

## Examples

A parse error from a compile entry point carries all three fields - the
span comes from the token stream, so it is present in every compile mode,
not only the `_with_spans` ones:

    iex> {:error, error} = Predicator.compile("limit > > 5")
    iex> {error.position, error.span}
    {{1, 9}, {{1, 9}, {1, 10}}}

`:span` is `nil` only on an error a caller built through `new/3`:

    iex> Predicator.Errors.ParseError.new("boom", 1, 10)
    %Predicator.Errors.ParseError{message: "boom", position: {1, 10}, span: nil}

# `t`

```elixir
@type t() :: %Predicator.Errors.ParseError{
  message: binary(),
  position: Predicator.Types.position(),
  span: Predicator.Types.span() | nil
}
```

# `new`

```elixir
@spec new(binary(), pos_integer(), pos_integer()) :: t()
```

Creates a parse error.

Takes the line and column separately because that is the shape
`Predicator.Lexer.tokenize/1` and `Predicator.Parser.parse/2` report failures
in; the struct stores them as a single `:position` tuple. `:span` is `nil`.

# `new`

```elixir
@spec new(binary(), pos_integer(), pos_integer(), Predicator.Types.span() | nil) ::
  t()
```

Creates a parse error with a source span.

Like `new/3`, but also records the token or construct extent the failure
covers. `:position` is set to the span's start.

---

*Consult [api-reference.md](api-reference.md) for complete listing*