Function generate_pattern_string

src/component.rs:181–279

Ref: https://wicg.github.io/urlpattern/#generate-a-pattern-string

(part_list: &[Part], options: &Options)

// Ref: https://wicg.github.io/urlpattern/#generate-a-pattern-string
fn generate_pattern_string(part_list: &[Part], options: &Options) -> String {
  let mut result = String::new();
  for (i, part) in part_list.iter().enumerate() {
    let prev_part: Option<&Part> =
      if i == 0 { None } else { part_list.get(i - 1) };
    let next_part: Option<&Part> = part_list.get(i + 1);
    if part.kind == PartType::FixedText {
      if part.modifier == PartModifier::None {
        result.push_str(&escape_pattern_string(&part.value));
        continue;
      }
      write!(
        result,
        "{{{}}}{}",
        escape_pattern_string(&part.value),
        part.modifier
      )
      .unwrap();
      continue;
    }
    let custom_name = !part.name.chars().next().unwrap().is_ascii_digit();
    let mut needs_grouping = !part.suffix.is_empty()
      || (!part.prefix.is_empty() && part.prefix != options.prefix_code_point);
    if !needs_grouping
      && custom_name
      && part.kind == PartType::SegmentWildcard
      && part.modifier == PartModifier::None
      && matches!(next_part, Some(Part { prefix, suffix, .. }) if prefix.is_empty() && suffix.is_empty())
    {
      let next_part = next_part.unwrap();
      if next_part.kind == PartType::FixedText {
        needs_grouping = is_valid_name_codepoint(
          next_part.value.chars().next().unwrap_or_default(),
          false,
        );
      } else {
        needs_grouping =
          next_part.name.chars().next().unwrap().is_ascii_digit();
      }
    }
    if !needs_grouping
      && part.prefix.is_empty()
      && matches!(
        prev_part,
        Some(Part {
          kind: PartType::FixedText,
          value,
          ..
        }) if !value.is_empty() && value.chars().last().unwrap().to_string() == options.prefix_code_point
      )
    {
      needs_grouping = true;
    }
    assert!(!part.name.is_empty());
    if needs_grouping {
      result.push('{');
    }
    result.push_str(&escape_pattern_string(&part.prefix));