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use std::error::Error;
use std::fmt;

use super::common::Range;

/// Error that could occur while parsing or tokenizing.
#[derive(Debug, PartialEq)]
pub struct ParseError {
  /// Start and end position of the error.
  pub range: Range,
  /// Error message.
  pub message: String,
  /// Message with the range text.
  display_message: String,
}

impl ParseError {
  pub(crate) fn new(range: Range, message: &str, file_text: &str) -> ParseError {
    let display_message = get_message_with_range(&range, message, file_text);
    ParseError {
      message: message.to_string(),
      range,
      display_message,
    }
  }
}

impl fmt::Display for ParseError {
  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
    write!(f, "{}", self.display_message)
  }
}

impl Error for ParseError {
  fn description(&self) -> &str {
    &self.display_message
  }
}

fn get_message_with_range(range: &Range, message: &str, file_text: &str) -> String {
  return format!(
    "{} on line {} column {}.",
    message,
    range.start.line + 1,
    range.start.column_index(file_text) + 1,
  );
}