| // Copyright 2013-2016 The rust-url developers. | 
 | // | 
 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | 
 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | 
 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | 
 | // option. This file may not be copied, modified, or distributed | 
 | // except according to those terms. | 
 |  | 
 | use std::error::Error; | 
 | use std::fmt::{self, Formatter, Write}; | 
 | use std::str; | 
 |  | 
 | use crate::host::{Host, HostInternal}; | 
 | use crate::Url; | 
 | use form_urlencoded::EncodingOverride; | 
 | use percent_encoding::{percent_encode, utf8_percent_encode, AsciiSet, CONTROLS}; | 
 |  | 
 | /// https://url.spec.whatwg.org/#fragment-percent-encode-set | 
 | const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`'); | 
 |  | 
 | /// https://url.spec.whatwg.org/#path-percent-encode-set | 
 | const PATH: &AsciiSet = &FRAGMENT.add(b'#').add(b'?').add(b'{').add(b'}'); | 
 |  | 
 | /// https://url.spec.whatwg.org/#userinfo-percent-encode-set | 
 | pub(crate) const USERINFO: &AsciiSet = &PATH | 
 |     .add(b'/') | 
 |     .add(b':') | 
 |     .add(b';') | 
 |     .add(b'=') | 
 |     .add(b'@') | 
 |     .add(b'[') | 
 |     .add(b'\\') | 
 |     .add(b']') | 
 |     .add(b'^') | 
 |     .add(b'|'); | 
 |  | 
 | pub(crate) const PATH_SEGMENT: &AsciiSet = &PATH.add(b'/').add(b'%'); | 
 |  | 
 | // The backslash (\) character is treated as a path separator in special URLs | 
 | // so it needs to be additionally escaped in that case. | 
 | pub(crate) const SPECIAL_PATH_SEGMENT: &AsciiSet = &PATH_SEGMENT.add(b'\\'); | 
 |  | 
 | // https://url.spec.whatwg.org/#query-state | 
 | const QUERY: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'#').add(b'<').add(b'>'); | 
 | const SPECIAL_QUERY: &AsciiSet = &QUERY.add(b'\''); | 
 |  | 
 | pub type ParseResult<T> = Result<T, ParseError>; | 
 |  | 
 | macro_rules! simple_enum_error { | 
 |     ($($name: ident => $description: expr,)+) => { | 
 |         /// Errors that can occur during parsing. | 
 |         /// | 
 |         /// This may be extended in the future so exhaustive matching is | 
 |         /// discouraged with an unused variant. | 
 |         #[derive(PartialEq, Eq, Clone, Copy, Debug)] | 
 |         #[non_exhaustive] | 
 |         pub enum ParseError { | 
 |             $( | 
 |                 $name, | 
 |             )+ | 
 |         } | 
 |  | 
 |         impl fmt::Display for ParseError { | 
 |             fn fmt(&self, fmt: &mut Formatter<'_>) -> fmt::Result { | 
 |                 match *self { | 
 |                     $( | 
 |                         ParseError::$name => fmt.write_str($description), | 
 |                     )+ | 
 |                 } | 
 |             } | 
 |         } | 
 |     } | 
 | } | 
 |  | 
 | impl Error for ParseError {} | 
 |  | 
 | simple_enum_error! { | 
 |     EmptyHost => "empty host", | 
 |     IdnaError => "invalid international domain name", | 
 |     InvalidPort => "invalid port number", | 
 |     InvalidIpv4Address => "invalid IPv4 address", | 
 |     InvalidIpv6Address => "invalid IPv6 address", | 
 |     InvalidDomainCharacter => "invalid domain character", | 
 |     RelativeUrlWithoutBase => "relative URL without a base", | 
 |     RelativeUrlWithCannotBeABaseBase => "relative URL with a cannot-be-a-base base", | 
 |     SetHostOnCannotBeABaseUrl => "a cannot-be-a-base URL doesn’t have a host to set", | 
 |     Overflow => "URLs more than 4 GB are not supported", | 
 | } | 
 |  | 
 | impl From<::idna::Errors> for ParseError { | 
 |     fn from(_: ::idna::Errors) -> ParseError { | 
 |         ParseError::IdnaError | 
 |     } | 
 | } | 
 |  | 
 | macro_rules! syntax_violation_enum { | 
 |     ($($name: ident => $description: expr,)+) => { | 
 |         /// Non-fatal syntax violations that can occur during parsing. | 
 |         /// | 
 |         /// This may be extended in the future so exhaustive matching is | 
 |         /// discouraged with an unused variant. | 
 |         #[derive(PartialEq, Eq, Clone, Copy, Debug)] | 
 |         #[non_exhaustive] | 
 |         pub enum SyntaxViolation { | 
 |             $( | 
 |                 $name, | 
 |             )+ | 
 |         } | 
 |  | 
 |         impl SyntaxViolation { | 
 |             pub fn description(&self) -> &'static str { | 
 |                 match *self { | 
 |                     $( | 
 |                         SyntaxViolation::$name => $description, | 
 |                     )+ | 
 |                 } | 
 |             } | 
 |         } | 
 |     } | 
 | } | 
 |  | 
 | syntax_violation_enum! { | 
 |     Backslash => "backslash", | 
 |     C0SpaceIgnored => | 
 |         "leading or trailing control or space character are ignored in URLs", | 
 |     EmbeddedCredentials => | 
 |         "embedding authentication information (username or password) \ | 
 |          in an URL is not recommended", | 
 |     ExpectedDoubleSlash => "expected //", | 
 |     ExpectedFileDoubleSlash => "expected // after file:", | 
 |     FileWithHostAndWindowsDrive => "file: with host and Windows drive letter", | 
 |     NonUrlCodePoint => "non-URL code point", | 
 |     NullInFragment => "NULL characters are ignored in URL fragment identifiers", | 
 |     PercentDecode => "expected 2 hex digits after %", | 
 |     TabOrNewlineIgnored => "tabs or newlines are ignored in URLs", | 
 |     UnencodedAtSign => "unencoded @ sign in username or password", | 
 | } | 
 |  | 
 | impl fmt::Display for SyntaxViolation { | 
 |     fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { | 
 |         fmt::Display::fmt(self.description(), f) | 
 |     } | 
 | } | 
 |  | 
 | #[derive(Copy, Clone, PartialEq, Eq)] | 
 | pub enum SchemeType { | 
 |     File, | 
 |     SpecialNotFile, | 
 |     NotSpecial, | 
 | } | 
 |  | 
 | impl SchemeType { | 
 |     pub fn is_special(&self) -> bool { | 
 |         !matches!(*self, SchemeType::NotSpecial) | 
 |     } | 
 |  | 
 |     pub fn is_file(&self) -> bool { | 
 |         matches!(*self, SchemeType::File) | 
 |     } | 
 | } | 
 |  | 
 | impl<T: AsRef<str>> From<T> for SchemeType { | 
 |     fn from(s: T) -> Self { | 
 |         match s.as_ref() { | 
 |             "http" | "https" | "ws" | "wss" | "ftp" => SchemeType::SpecialNotFile, | 
 |             "file" => SchemeType::File, | 
 |             _ => SchemeType::NotSpecial, | 
 |         } | 
 |     } | 
 | } | 
 |  | 
 | pub fn default_port(scheme: &str) -> Option<u16> { | 
 |     match scheme { | 
 |         "http" | "ws" => Some(80), | 
 |         "https" | "wss" => Some(443), | 
 |         "ftp" => Some(21), | 
 |         _ => None, | 
 |     } | 
 | } | 
 |  | 
 | #[derive(Clone, Debug)] | 
 | pub struct Input<'i> { | 
 |     chars: str::Chars<'i>, | 
 | } | 
 |  | 
 | impl<'i> Input<'i> { | 
 |     pub fn new_no_trim(input: &'i str) -> Self { | 
 |         Input { | 
 |             chars: input.chars(), | 
 |         } | 
 |     } | 
 |  | 
 |     pub fn new_trim_tab_and_newlines( | 
 |         original_input: &'i str, | 
 |         vfn: Option<&dyn Fn(SyntaxViolation)>, | 
 |     ) -> Self { | 
 |         let input = original_input.trim_matches(ascii_tab_or_new_line); | 
 |         if let Some(vfn) = vfn { | 
 |             if input.len() < original_input.len() { | 
 |                 vfn(SyntaxViolation::C0SpaceIgnored) | 
 |             } | 
 |             if input.chars().any(|c| matches!(c, '\t' | '\n' | '\r')) { | 
 |                 vfn(SyntaxViolation::TabOrNewlineIgnored) | 
 |             } | 
 |         } | 
 |         Input { | 
 |             chars: input.chars(), | 
 |         } | 
 |     } | 
 |  | 
 |     pub fn new_trim_c0_control_and_space( | 
 |         original_input: &'i str, | 
 |         vfn: Option<&dyn Fn(SyntaxViolation)>, | 
 |     ) -> Self { | 
 |         let input = original_input.trim_matches(c0_control_or_space); | 
 |         if let Some(vfn) = vfn { | 
 |             if input.len() < original_input.len() { | 
 |                 vfn(SyntaxViolation::C0SpaceIgnored) | 
 |             } | 
 |             if input.chars().any(|c| matches!(c, '\t' | '\n' | '\r')) { | 
 |                 vfn(SyntaxViolation::TabOrNewlineIgnored) | 
 |             } | 
 |         } | 
 |         Input { | 
 |             chars: input.chars(), | 
 |         } | 
 |     } | 
 |  | 
 |     #[inline] | 
 |     pub fn is_empty(&self) -> bool { | 
 |         self.clone().next().is_none() | 
 |     } | 
 |  | 
 |     #[inline] | 
 |     fn starts_with<P: Pattern>(&self, p: P) -> bool { | 
 |         p.split_prefix(&mut self.clone()) | 
 |     } | 
 |  | 
 |     #[inline] | 
 |     pub fn split_prefix<P: Pattern>(&self, p: P) -> Option<Self> { | 
 |         let mut remaining = self.clone(); | 
 |         if p.split_prefix(&mut remaining) { | 
 |             Some(remaining) | 
 |         } else { | 
 |             None | 
 |         } | 
 |     } | 
 |  | 
 |     #[inline] | 
 |     fn split_first(&self) -> (Option<char>, Self) { | 
 |         let mut remaining = self.clone(); | 
 |         (remaining.next(), remaining) | 
 |     } | 
 |  | 
 |     #[inline] | 
 |     fn count_matching<F: Fn(char) -> bool>(&self, f: F) -> (u32, Self) { | 
 |         let mut count = 0; | 
 |         let mut remaining = self.clone(); | 
 |         loop { | 
 |             let mut input = remaining.clone(); | 
 |             if matches!(input.next(), Some(c) if f(c)) { | 
 |                 remaining = input; | 
 |                 count += 1; | 
 |             } else { | 
 |                 return (count, remaining); | 
 |             } | 
 |         } | 
 |     } | 
 |  | 
 |     #[inline] | 
 |     fn next_utf8(&mut self) -> Option<(char, &'i str)> { | 
 |         loop { | 
 |             let utf8 = self.chars.as_str(); | 
 |             match self.chars.next() { | 
 |                 Some(c) => { | 
 |                     if !matches!(c, '\t' | '\n' | '\r') { | 
 |                         return Some((c, &utf8[..c.len_utf8()])); | 
 |                     } | 
 |                 } | 
 |                 None => return None, | 
 |             } | 
 |         } | 
 |     } | 
 | } | 
 |  | 
 | pub trait Pattern { | 
 |     fn split_prefix(self, input: &mut Input) -> bool; | 
 | } | 
 |  | 
 | impl Pattern for char { | 
 |     fn split_prefix(self, input: &mut Input) -> bool { | 
 |         input.next() == Some(self) | 
 |     } | 
 | } | 
 |  | 
 | impl<'a> Pattern for &'a str { | 
 |     fn split_prefix(self, input: &mut Input) -> bool { | 
 |         for c in self.chars() { | 
 |             if input.next() != Some(c) { | 
 |                 return false; | 
 |             } | 
 |         } | 
 |         true | 
 |     } | 
 | } | 
 |  | 
 | impl<F: FnMut(char) -> bool> Pattern for F { | 
 |     fn split_prefix(self, input: &mut Input) -> bool { | 
 |         input.next().map_or(false, self) | 
 |     } | 
 | } | 
 |  | 
 | impl<'i> Iterator for Input<'i> { | 
 |     type Item = char; | 
 |     fn next(&mut self) -> Option<char> { | 
 |         self.chars | 
 |             .by_ref() | 
 |             .find(|&c| !matches!(c, '\t' | '\n' | '\r')) | 
 |     } | 
 | } | 
 |  | 
 | pub struct Parser<'a> { | 
 |     pub serialization: String, | 
 |     pub base_url: Option<&'a Url>, | 
 |     pub query_encoding_override: EncodingOverride<'a>, | 
 |     pub violation_fn: Option<&'a dyn Fn(SyntaxViolation)>, | 
 |     pub context: Context, | 
 | } | 
 |  | 
 | #[derive(PartialEq, Eq, Copy, Clone)] | 
 | pub enum Context { | 
 |     UrlParser, | 
 |     Setter, | 
 |     PathSegmentSetter, | 
 | } | 
 |  | 
 | impl<'a> Parser<'a> { | 
 |     fn log_violation(&self, v: SyntaxViolation) { | 
 |         if let Some(f) = self.violation_fn { | 
 |             f(v) | 
 |         } | 
 |     } | 
 |  | 
 |     fn log_violation_if(&self, v: SyntaxViolation, test: impl FnOnce() -> bool) { | 
 |         if let Some(f) = self.violation_fn { | 
 |             if test() { | 
 |                 f(v) | 
 |             } | 
 |         } | 
 |     } | 
 |  | 
 |     pub fn for_setter(serialization: String) -> Parser<'a> { | 
 |         Parser { | 
 |             serialization, | 
 |             base_url: None, | 
 |             query_encoding_override: None, | 
 |             violation_fn: None, | 
 |             context: Context::Setter, | 
 |         } | 
 |     } | 
 |  | 
 |     /// https://url.spec.whatwg.org/#concept-basic-url-parser | 
 |     pub fn parse_url(mut self, input: &str) -> ParseResult<Url> { | 
 |         let input = Input::new_trim_c0_control_and_space(input, self.violation_fn); | 
 |         if let Ok(remaining) = self.parse_scheme(input.clone()) { | 
 |             return self.parse_with_scheme(remaining); | 
 |         } | 
 |  | 
 |         // No-scheme state | 
 |         if let Some(base_url) = self.base_url { | 
 |             if input.starts_with('#') { | 
 |                 self.fragment_only(base_url, input) | 
 |             } else if base_url.cannot_be_a_base() { | 
 |                 Err(ParseError::RelativeUrlWithCannotBeABaseBase) | 
 |             } else { | 
 |                 let scheme_type = SchemeType::from(base_url.scheme()); | 
 |                 if scheme_type.is_file() { | 
 |                     self.parse_file(input, scheme_type, Some(base_url)) | 
 |                 } else { | 
 |                     self.parse_relative(input, scheme_type, base_url) | 
 |                 } | 
 |             } | 
 |         } else { | 
 |             Err(ParseError::RelativeUrlWithoutBase) | 
 |         } | 
 |     } | 
 |  | 
 |     pub fn parse_scheme<'i>(&mut self, mut input: Input<'i>) -> Result<Input<'i>, ()> { | 
 |         if input.is_empty() || !input.starts_with(ascii_alpha) { | 
 |             return Err(()); | 
 |         } | 
 |         debug_assert!(self.serialization.is_empty()); | 
 |         while let Some(c) = input.next() { | 
 |             match c { | 
 |                 'a'..='z' | 'A'..='Z' | '0'..='9' | '+' | '-' | '.' => { | 
 |                     self.serialization.push(c.to_ascii_lowercase()) | 
 |                 } | 
 |                 ':' => return Ok(input), | 
 |                 _ => { | 
 |                     self.serialization.clear(); | 
 |                     return Err(()); | 
 |                 } | 
 |             } | 
 |         } | 
 |         // EOF before ':' | 
 |         if self.context == Context::Setter { | 
 |             Ok(input) | 
 |         } else { | 
 |             self.serialization.clear(); | 
 |             Err(()) | 
 |         } | 
 |     } | 
 |  | 
 |     fn parse_with_scheme(mut self, input: Input<'_>) -> ParseResult<Url> { | 
 |         use crate::SyntaxViolation::{ExpectedDoubleSlash, ExpectedFileDoubleSlash}; | 
 |         let scheme_end = to_u32(self.serialization.len())?; | 
 |         let scheme_type = SchemeType::from(&self.serialization); | 
 |         self.serialization.push(':'); | 
 |         match scheme_type { | 
 |             SchemeType::File => { | 
 |                 self.log_violation_if(ExpectedFileDoubleSlash, || !input.starts_with("//")); | 
 |                 let base_file_url = self.base_url.and_then(|base| { | 
 |                     if base.scheme() == "file" { | 
 |                         Some(base) | 
 |                     } else { | 
 |                         None | 
 |                     } | 
 |                 }); | 
 |                 self.serialization.clear(); | 
 |                 self.parse_file(input, scheme_type, base_file_url) | 
 |             } | 
 |             SchemeType::SpecialNotFile => { | 
 |                 // special relative or authority state | 
 |                 let (slashes_count, remaining) = input.count_matching(|c| matches!(c, '/' | '\\')); | 
 |                 if let Some(base_url) = self.base_url { | 
 |                     if slashes_count < 2 | 
 |                         && base_url.scheme() == &self.serialization[..scheme_end as usize] | 
 |                     { | 
 |                         // "Cannot-be-a-base" URLs only happen with "not special" schemes. | 
 |                         debug_assert!(!base_url.cannot_be_a_base()); | 
 |                         self.serialization.clear(); | 
 |                         return self.parse_relative(input, scheme_type, base_url); | 
 |                     } | 
 |                 } | 
 |                 // special authority slashes state | 
 |                 self.log_violation_if(ExpectedDoubleSlash, || { | 
 |                     input | 
 |                         .clone() | 
 |                         .take_while(|&c| matches!(c, '/' | '\\')) | 
 |                         .collect::<String>() | 
 |                         != "//" | 
 |                 }); | 
 |                 self.after_double_slash(remaining, scheme_type, scheme_end) | 
 |             } | 
 |             SchemeType::NotSpecial => self.parse_non_special(input, scheme_type, scheme_end), | 
 |         } | 
 |     } | 
 |  | 
 |     /// Scheme other than file, http, https, ws, ws, ftp. | 
 |     fn parse_non_special( | 
 |         mut self, | 
 |         input: Input<'_>, | 
 |         scheme_type: SchemeType, | 
 |         scheme_end: u32, | 
 |     ) -> ParseResult<Url> { | 
 |         // path or authority state ( | 
 |         if let Some(input) = input.split_prefix("//") { | 
 |             return self.after_double_slash(input, scheme_type, scheme_end); | 
 |         } | 
 |         // Anarchist URL (no authority) | 
 |         let path_start = to_u32(self.serialization.len())?; | 
 |         let username_end = path_start; | 
 |         let host_start = path_start; | 
 |         let host_end = path_start; | 
 |         let host = HostInternal::None; | 
 |         let port = None; | 
 |         let remaining = if let Some(input) = input.split_prefix('/') { | 
 |             self.serialization.push('/'); | 
 |             self.parse_path(scheme_type, &mut false, path_start as usize, input) | 
 |         } else { | 
 |             self.parse_cannot_be_a_base_path(input) | 
 |         }; | 
 |         self.with_query_and_fragment( | 
 |             scheme_type, | 
 |             scheme_end, | 
 |             username_end, | 
 |             host_start, | 
 |             host_end, | 
 |             host, | 
 |             port, | 
 |             path_start, | 
 |             remaining, | 
 |         ) | 
 |     } | 
 |  | 
 |     fn parse_file( | 
 |         mut self, | 
 |         input: Input<'_>, | 
 |         scheme_type: SchemeType, | 
 |         base_file_url: Option<&Url>, | 
 |     ) -> ParseResult<Url> { | 
 |         use crate::SyntaxViolation::Backslash; | 
 |         // file state | 
 |         debug_assert!(self.serialization.is_empty()); | 
 |         let (first_char, input_after_first_char) = input.split_first(); | 
 |         if matches!(first_char, Some('/') | Some('\\')) { | 
 |             self.log_violation_if(SyntaxViolation::Backslash, || first_char == Some('\\')); | 
 |             // file slash state | 
 |             let (next_char, input_after_next_char) = input_after_first_char.split_first(); | 
 |             if matches!(next_char, Some('/') | Some('\\')) { | 
 |                 self.log_violation_if(Backslash, || next_char == Some('\\')); | 
 |                 // file host state | 
 |                 self.serialization.push_str("file://"); | 
 |                 let scheme_end = "file".len() as u32; | 
 |                 let host_start = "file://".len() as u32; | 
 |                 let (path_start, mut host, remaining) = | 
 |                     self.parse_file_host(input_after_next_char)?; | 
 |                 let mut host_end = to_u32(self.serialization.len())?; | 
 |                 let mut has_host = !matches!(host, HostInternal::None); | 
 |                 let remaining = if path_start { | 
 |                     self.parse_path_start(SchemeType::File, &mut has_host, remaining) | 
 |                 } else { | 
 |                     let path_start = self.serialization.len(); | 
 |                     self.serialization.push('/'); | 
 |                     self.parse_path(SchemeType::File, &mut has_host, path_start, remaining) | 
 |                 }; | 
 |  | 
 |                 // For file URLs that have a host and whose path starts | 
 |                 // with the windows drive letter we just remove the host. | 
 |                 if !has_host { | 
 |                     self.serialization | 
 |                         .drain(host_start as usize..host_end as usize); | 
 |                     host_end = host_start; | 
 |                     host = HostInternal::None; | 
 |                 } | 
 |                 let (query_start, fragment_start) = | 
 |                     self.parse_query_and_fragment(scheme_type, scheme_end, remaining)?; | 
 |                 return Ok(Url { | 
 |                     serialization: self.serialization, | 
 |                     scheme_end, | 
 |                     username_end: host_start, | 
 |                     host_start, | 
 |                     host_end, | 
 |                     host, | 
 |                     port: None, | 
 |                     path_start: host_end, | 
 |                     query_start, | 
 |                     fragment_start, | 
 |                 }); | 
 |             } else { | 
 |                 self.serialization.push_str("file://"); | 
 |                 let scheme_end = "file".len() as u32; | 
 |                 let host_start = "file://".len(); | 
 |                 let mut host_end = host_start; | 
 |                 let mut host = HostInternal::None; | 
 |                 if !starts_with_windows_drive_letter_segment(&input_after_first_char) { | 
 |                     if let Some(base_url) = base_file_url { | 
 |                         let first_segment = base_url.path_segments().unwrap().next().unwrap(); | 
 |                         if is_normalized_windows_drive_letter(first_segment) { | 
 |                             self.serialization.push('/'); | 
 |                             self.serialization.push_str(first_segment); | 
 |                         } else if let Some(host_str) = base_url.host_str() { | 
 |                             self.serialization.push_str(host_str); | 
 |                             host_end = self.serialization.len(); | 
 |                             host = base_url.host; | 
 |                         } | 
 |                     } | 
 |                 } | 
 |                 // If c is the EOF code point, U+002F (/), U+005C (\), U+003F (?), or U+0023 (#), then decrease pointer by one | 
 |                 let parse_path_input = if let Some(c) = first_char { | 
 |                     if c == '/' || c == '\\' || c == '?' || c == '#' { | 
 |                         input | 
 |                     } else { | 
 |                         input_after_first_char | 
 |                     } | 
 |                 } else { | 
 |                     input_after_first_char | 
 |                 }; | 
 |  | 
 |                 let remaining = | 
 |                     self.parse_path(SchemeType::File, &mut false, host_end, parse_path_input); | 
 |  | 
 |                 let host_start = host_start as u32; | 
 |  | 
 |                 let (query_start, fragment_start) = | 
 |                     self.parse_query_and_fragment(scheme_type, scheme_end, remaining)?; | 
 |  | 
 |                 let host_end = host_end as u32; | 
 |                 return Ok(Url { | 
 |                     serialization: self.serialization, | 
 |                     scheme_end, | 
 |                     username_end: host_start, | 
 |                     host_start, | 
 |                     host_end, | 
 |                     host, | 
 |                     port: None, | 
 |                     path_start: host_end, | 
 |                     query_start, | 
 |                     fragment_start, | 
 |                 }); | 
 |             } | 
 |         } | 
 |         if let Some(base_url) = base_file_url { | 
 |             match first_char { | 
 |                 None => { | 
 |                     // Copy everything except the fragment | 
 |                     let before_fragment = match base_url.fragment_start { | 
 |                         Some(i) => &base_url.serialization[..i as usize], | 
 |                         None => &*base_url.serialization, | 
 |                     }; | 
 |                     self.serialization.push_str(before_fragment); | 
 |                     Ok(Url { | 
 |                         serialization: self.serialization, | 
 |                         fragment_start: None, | 
 |                         ..*base_url | 
 |                     }) | 
 |                 } | 
 |                 Some('?') => { | 
 |                     // Copy everything up to the query string | 
 |                     let before_query = match (base_url.query_start, base_url.fragment_start) { | 
 |                         (None, None) => &*base_url.serialization, | 
 |                         (Some(i), _) | (None, Some(i)) => base_url.slice(..i), | 
 |                     }; | 
 |                     self.serialization.push_str(before_query); | 
 |                     let (query_start, fragment_start) = | 
 |                         self.parse_query_and_fragment(scheme_type, base_url.scheme_end, input)?; | 
 |                     Ok(Url { | 
 |                         serialization: self.serialization, | 
 |                         query_start, | 
 |                         fragment_start, | 
 |                         ..*base_url | 
 |                     }) | 
 |                 } | 
 |                 Some('#') => self.fragment_only(base_url, input), | 
 |                 _ => { | 
 |                     if !starts_with_windows_drive_letter_segment(&input) { | 
 |                         let before_query = match (base_url.query_start, base_url.fragment_start) { | 
 |                             (None, None) => &*base_url.serialization, | 
 |                             (Some(i), _) | (None, Some(i)) => base_url.slice(..i), | 
 |                         }; | 
 |                         self.serialization.push_str(before_query); | 
 |                         self.shorten_path(SchemeType::File, base_url.path_start as usize); | 
 |                         let remaining = self.parse_path( | 
 |                             SchemeType::File, | 
 |                             &mut true, | 
 |                             base_url.path_start as usize, | 
 |                             input, | 
 |                         ); | 
 |                         self.with_query_and_fragment( | 
 |                             SchemeType::File, | 
 |                             base_url.scheme_end, | 
 |                             base_url.username_end, | 
 |                             base_url.host_start, | 
 |                             base_url.host_end, | 
 |                             base_url.host, | 
 |                             base_url.port, | 
 |                             base_url.path_start, | 
 |                             remaining, | 
 |                         ) | 
 |                     } else { | 
 |                         self.serialization.push_str("file:///"); | 
 |                         let scheme_end = "file".len() as u32; | 
 |                         let path_start = "file://".len(); | 
 |                         let remaining = | 
 |                             self.parse_path(SchemeType::File, &mut false, path_start, input); | 
 |                         let (query_start, fragment_start) = | 
 |                             self.parse_query_and_fragment(SchemeType::File, scheme_end, remaining)?; | 
 |                         let path_start = path_start as u32; | 
 |                         Ok(Url { | 
 |                             serialization: self.serialization, | 
 |                             scheme_end, | 
 |                             username_end: path_start, | 
 |                             host_start: path_start, | 
 |                             host_end: path_start, | 
 |                             host: HostInternal::None, | 
 |                             port: None, | 
 |                             path_start, | 
 |                             query_start, | 
 |                             fragment_start, | 
 |                         }) | 
 |                     } | 
 |                 } | 
 |             } | 
 |         } else { | 
 |             self.serialization.push_str("file:///"); | 
 |             let scheme_end = "file".len() as u32; | 
 |             let path_start = "file://".len(); | 
 |             let remaining = self.parse_path(SchemeType::File, &mut false, path_start, input); | 
 |             let (query_start, fragment_start) = | 
 |                 self.parse_query_and_fragment(SchemeType::File, scheme_end, remaining)?; | 
 |             let path_start = path_start as u32; | 
 |             Ok(Url { | 
 |                 serialization: self.serialization, | 
 |                 scheme_end, | 
 |                 username_end: path_start, | 
 |                 host_start: path_start, | 
 |                 host_end: path_start, | 
 |                 host: HostInternal::None, | 
 |                 port: None, | 
 |                 path_start, | 
 |                 query_start, | 
 |                 fragment_start, | 
 |             }) | 
 |         } | 
 |     } | 
 |  | 
 |     fn parse_relative( | 
 |         mut self, | 
 |         input: Input<'_>, | 
 |         scheme_type: SchemeType, | 
 |         base_url: &Url, | 
 |     ) -> ParseResult<Url> { | 
 |         // relative state | 
 |         debug_assert!(self.serialization.is_empty()); | 
 |         let (first_char, input_after_first_char) = input.split_first(); | 
 |         match first_char { | 
 |             None => { | 
 |                 // Copy everything except the fragment | 
 |                 let before_fragment = match base_url.fragment_start { | 
 |                     Some(i) => &base_url.serialization[..i as usize], | 
 |                     None => &*base_url.serialization, | 
 |                 }; | 
 |                 self.serialization.push_str(before_fragment); | 
 |                 Ok(Url { | 
 |                     serialization: self.serialization, | 
 |                     fragment_start: None, | 
 |                     ..*base_url | 
 |                 }) | 
 |             } | 
 |             Some('?') => { | 
 |                 // Copy everything up to the query string | 
 |                 let before_query = match (base_url.query_start, base_url.fragment_start) { | 
 |                     (None, None) => &*base_url.serialization, | 
 |                     (Some(i), _) | (None, Some(i)) => base_url.slice(..i), | 
 |                 }; | 
 |                 self.serialization.push_str(before_query); | 
 |                 let (query_start, fragment_start) = | 
 |                     self.parse_query_and_fragment(scheme_type, base_url.scheme_end, input)?; | 
 |                 Ok(Url { | 
 |                     serialization: self.serialization, | 
 |                     query_start, | 
 |                     fragment_start, | 
 |                     ..*base_url | 
 |                 }) | 
 |             } | 
 |             Some('#') => self.fragment_only(base_url, input), | 
 |             Some('/') | Some('\\') => { | 
 |                 let (slashes_count, remaining) = input.count_matching(|c| matches!(c, '/' | '\\')); | 
 |                 if slashes_count >= 2 { | 
 |                     self.log_violation_if(SyntaxViolation::ExpectedDoubleSlash, || { | 
 |                         input | 
 |                             .clone() | 
 |                             .take_while(|&c| matches!(c, '/' | '\\')) | 
 |                             .collect::<String>() | 
 |                             != "//" | 
 |                     }); | 
 |                     let scheme_end = base_url.scheme_end; | 
 |                     debug_assert!(base_url.byte_at(scheme_end) == b':'); | 
 |                     self.serialization | 
 |                         .push_str(base_url.slice(..scheme_end + 1)); | 
 |                     if let Some(after_prefix) = input.split_prefix("//") { | 
 |                         return self.after_double_slash(after_prefix, scheme_type, scheme_end); | 
 |                     } | 
 |                     return self.after_double_slash(remaining, scheme_type, scheme_end); | 
 |                 } | 
 |                 let path_start = base_url.path_start; | 
 |                 self.serialization.push_str(base_url.slice(..path_start)); | 
 |                 self.serialization.push('/'); | 
 |                 let remaining = self.parse_path( | 
 |                     scheme_type, | 
 |                     &mut true, | 
 |                     path_start as usize, | 
 |                     input_after_first_char, | 
 |                 ); | 
 |                 self.with_query_and_fragment( | 
 |                     scheme_type, | 
 |                     base_url.scheme_end, | 
 |                     base_url.username_end, | 
 |                     base_url.host_start, | 
 |                     base_url.host_end, | 
 |                     base_url.host, | 
 |                     base_url.port, | 
 |                     base_url.path_start, | 
 |                     remaining, | 
 |                 ) | 
 |             } | 
 |             _ => { | 
 |                 let before_query = match (base_url.query_start, base_url.fragment_start) { | 
 |                     (None, None) => &*base_url.serialization, | 
 |                     (Some(i), _) | (None, Some(i)) => base_url.slice(..i), | 
 |                 }; | 
 |                 self.serialization.push_str(before_query); | 
 |                 // FIXME spec says just "remove last entry", not the "pop" algorithm | 
 |                 self.pop_path(scheme_type, base_url.path_start as usize); | 
 |                 // A special url always has a path. | 
 |                 // A path always starts with '/' | 
 |                 if self.serialization.len() == base_url.path_start as usize | 
 |                     && (SchemeType::from(base_url.scheme()).is_special() || !input.is_empty()) | 
 |                 { | 
 |                     self.serialization.push('/'); | 
 |                 } | 
 |                 let remaining = match input.split_first() { | 
 |                     (Some('/'), remaining) => self.parse_path( | 
 |                         scheme_type, | 
 |                         &mut true, | 
 |                         base_url.path_start as usize, | 
 |                         remaining, | 
 |                     ), | 
 |                     _ => { | 
 |                         self.parse_path(scheme_type, &mut true, base_url.path_start as usize, input) | 
 |                     } | 
 |                 }; | 
 |                 self.with_query_and_fragment( | 
 |                     scheme_type, | 
 |                     base_url.scheme_end, | 
 |                     base_url.username_end, | 
 |                     base_url.host_start, | 
 |                     base_url.host_end, | 
 |                     base_url.host, | 
 |                     base_url.port, | 
 |                     base_url.path_start, | 
 |                     remaining, | 
 |                 ) | 
 |             } | 
 |         } | 
 |     } | 
 |  | 
 |     fn after_double_slash( | 
 |         mut self, | 
 |         input: Input<'_>, | 
 |         scheme_type: SchemeType, | 
 |         scheme_end: u32, | 
 |     ) -> ParseResult<Url> { | 
 |         self.serialization.push('/'); | 
 |         self.serialization.push('/'); | 
 |         // authority state | 
 |         let before_authority = self.serialization.len(); | 
 |         let (username_end, remaining) = self.parse_userinfo(input, scheme_type)?; | 
 |         let has_authority = before_authority != self.serialization.len(); | 
 |         // host state | 
 |         let host_start = to_u32(self.serialization.len())?; | 
 |         let (host_end, host, port, remaining) = | 
 |             self.parse_host_and_port(remaining, scheme_end, scheme_type)?; | 
 |         if host == HostInternal::None && has_authority { | 
 |             return Err(ParseError::EmptyHost); | 
 |         } | 
 |         // path state | 
 |         let path_start = to_u32(self.serialization.len())?; | 
 |         let remaining = self.parse_path_start(scheme_type, &mut true, remaining); | 
 |         self.with_query_and_fragment( | 
 |             scheme_type, | 
 |             scheme_end, | 
 |             username_end, | 
 |             host_start, | 
 |             host_end, | 
 |             host, | 
 |             port, | 
 |             path_start, | 
 |             remaining, | 
 |         ) | 
 |     } | 
 |  | 
 |     /// Return (username_end, remaining) | 
 |     fn parse_userinfo<'i>( | 
 |         &mut self, | 
 |         mut input: Input<'i>, | 
 |         scheme_type: SchemeType, | 
 |     ) -> ParseResult<(u32, Input<'i>)> { | 
 |         let mut last_at = None; | 
 |         let mut remaining = input.clone(); | 
 |         let mut char_count = 0; | 
 |         while let Some(c) = remaining.next() { | 
 |             match c { | 
 |                 '@' => { | 
 |                     if last_at.is_some() { | 
 |                         self.log_violation(SyntaxViolation::UnencodedAtSign) | 
 |                     } else { | 
 |                         self.log_violation(SyntaxViolation::EmbeddedCredentials) | 
 |                     } | 
 |                     last_at = Some((char_count, remaining.clone())) | 
 |                 } | 
 |                 '/' | '?' | '#' => break, | 
 |                 '\\' if scheme_type.is_special() => break, | 
 |                 _ => (), | 
 |             } | 
 |             char_count += 1; | 
 |         } | 
 |         let (mut userinfo_char_count, remaining) = match last_at { | 
 |             None => return Ok((to_u32(self.serialization.len())?, input)), | 
 |             Some((0, remaining)) => { | 
 |                 // Otherwise, if one of the following is true | 
 |                 // c is the EOF code point, U+002F (/), U+003F (?), or U+0023 (#) | 
 |                 // url is special and c is U+005C (\) | 
 |                 // If @ flag is set and buffer is the empty string, validation error, return failure. | 
 |                 if let (Some(c), _) = remaining.split_first() { | 
 |                     if c == '/' || c == '?' || c == '#' || (scheme_type.is_special() && c == '\\') { | 
 |                         return Err(ParseError::EmptyHost); | 
 |                     } | 
 |                 } | 
 |                 return Ok((to_u32(self.serialization.len())?, remaining)); | 
 |             } | 
 |             Some(x) => x, | 
 |         }; | 
 |  | 
 |         let mut username_end = None; | 
 |         let mut has_password = false; | 
 |         let mut has_username = false; | 
 |         while userinfo_char_count > 0 { | 
 |             let (c, utf8_c) = input.next_utf8().unwrap(); | 
 |             userinfo_char_count -= 1; | 
 |             if c == ':' && username_end.is_none() { | 
 |                 // Start parsing password | 
 |                 username_end = Some(to_u32(self.serialization.len())?); | 
 |                 // We don't add a colon if the password is empty | 
 |                 if userinfo_char_count > 0 { | 
 |                     self.serialization.push(':'); | 
 |                     has_password = true; | 
 |                 } | 
 |             } else { | 
 |                 if !has_password { | 
 |                     has_username = true; | 
 |                 } | 
 |                 self.check_url_code_point(c, &input); | 
 |                 self.serialization | 
 |                     .extend(utf8_percent_encode(utf8_c, USERINFO)); | 
 |             } | 
 |         } | 
 |         let username_end = match username_end { | 
 |             Some(i) => i, | 
 |             None => to_u32(self.serialization.len())?, | 
 |         }; | 
 |         if has_username || has_password { | 
 |             self.serialization.push('@'); | 
 |         } | 
 |         Ok((username_end, remaining)) | 
 |     } | 
 |  | 
 |     fn parse_host_and_port<'i>( | 
 |         &mut self, | 
 |         input: Input<'i>, | 
 |         scheme_end: u32, | 
 |         scheme_type: SchemeType, | 
 |     ) -> ParseResult<(u32, HostInternal, Option<u16>, Input<'i>)> { | 
 |         let (host, remaining) = Parser::parse_host(input, scheme_type)?; | 
 |         write!(&mut self.serialization, "{}", host).unwrap(); | 
 |         let host_end = to_u32(self.serialization.len())?; | 
 |         if let Host::Domain(h) = &host { | 
 |             if h.is_empty() { | 
 |                 // Port with an empty host | 
 |                 if remaining.starts_with(":") { | 
 |                     return Err(ParseError::EmptyHost); | 
 |                 } | 
 |                 if scheme_type.is_special() { | 
 |                     return Err(ParseError::EmptyHost); | 
 |                 } | 
 |             } | 
 |         }; | 
 |  | 
 |         let (port, remaining) = if let Some(remaining) = remaining.split_prefix(':') { | 
 |             let scheme = || default_port(&self.serialization[..scheme_end as usize]); | 
 |             Parser::parse_port(remaining, scheme, self.context)? | 
 |         } else { | 
 |             (None, remaining) | 
 |         }; | 
 |         if let Some(port) = port { | 
 |             write!(&mut self.serialization, ":{}", port).unwrap() | 
 |         } | 
 |         Ok((host_end, host.into(), port, remaining)) | 
 |     } | 
 |  | 
 |     pub fn parse_host( | 
 |         mut input: Input<'_>, | 
 |         scheme_type: SchemeType, | 
 |     ) -> ParseResult<(Host<String>, Input<'_>)> { | 
 |         if scheme_type.is_file() { | 
 |             return Parser::get_file_host(input); | 
 |         } | 
 |         // Undo the Input abstraction here to avoid allocating in the common case | 
 |         // where the host part of the input does not contain any tab or newline | 
 |         let input_str = input.chars.as_str(); | 
 |         let mut inside_square_brackets = false; | 
 |         let mut has_ignored_chars = false; | 
 |         let mut non_ignored_chars = 0; | 
 |         let mut bytes = 0; | 
 |         for c in input_str.chars() { | 
 |             match c { | 
 |                 ':' if !inside_square_brackets => break, | 
 |                 '\\' if scheme_type.is_special() => break, | 
 |                 '/' | '?' | '#' => break, | 
 |                 '\t' | '\n' | '\r' => { | 
 |                     has_ignored_chars = true; | 
 |                 } | 
 |                 '[' => { | 
 |                     inside_square_brackets = true; | 
 |                     non_ignored_chars += 1 | 
 |                 } | 
 |                 ']' => { | 
 |                     inside_square_brackets = false; | 
 |                     non_ignored_chars += 1 | 
 |                 } | 
 |                 _ => non_ignored_chars += 1, | 
 |             } | 
 |             bytes += c.len_utf8(); | 
 |         } | 
 |         let replaced: String; | 
 |         let host_str; | 
 |         { | 
 |             let host_input = input.by_ref().take(non_ignored_chars); | 
 |             if has_ignored_chars { | 
 |                 replaced = host_input.collect(); | 
 |                 host_str = &*replaced | 
 |             } else { | 
 |                 for _ in host_input {} | 
 |                 host_str = &input_str[..bytes] | 
 |             } | 
 |         } | 
 |         if scheme_type == SchemeType::SpecialNotFile && host_str.is_empty() { | 
 |             return Err(ParseError::EmptyHost); | 
 |         } | 
 |         if !scheme_type.is_special() { | 
 |             let host = Host::parse_opaque(host_str)?; | 
 |             return Ok((host, input)); | 
 |         } | 
 |         let host = Host::parse(host_str)?; | 
 |         Ok((host, input)) | 
 |     } | 
 |  | 
 |     fn get_file_host(input: Input<'_>) -> ParseResult<(Host<String>, Input<'_>)> { | 
 |         let (_, host_str, remaining) = Parser::file_host(input)?; | 
 |         let host = match Host::parse(&host_str)? { | 
 |             Host::Domain(ref d) if d == "localhost" => Host::Domain("".to_string()), | 
 |             host => host, | 
 |         }; | 
 |         Ok((host, remaining)) | 
 |     } | 
 |  | 
 |     fn parse_file_host<'i>( | 
 |         &mut self, | 
 |         input: Input<'i>, | 
 |     ) -> ParseResult<(bool, HostInternal, Input<'i>)> { | 
 |         let has_host; | 
 |         let (_, host_str, remaining) = Parser::file_host(input)?; | 
 |         let host = if host_str.is_empty() { | 
 |             has_host = false; | 
 |             HostInternal::None | 
 |         } else { | 
 |             match Host::parse(&host_str)? { | 
 |                 Host::Domain(ref d) if d == "localhost" => { | 
 |                     has_host = false; | 
 |                     HostInternal::None | 
 |                 } | 
 |                 host => { | 
 |                     write!(&mut self.serialization, "{}", host).unwrap(); | 
 |                     has_host = true; | 
 |                     host.into() | 
 |                 } | 
 |             } | 
 |         }; | 
 |         Ok((has_host, host, remaining)) | 
 |     } | 
 |  | 
 |     pub fn file_host(input: Input) -> ParseResult<(bool, String, Input)> { | 
 |         // Undo the Input abstraction here to avoid allocating in the common case | 
 |         // where the host part of the input does not contain any tab or newline | 
 |         let input_str = input.chars.as_str(); | 
 |         let mut has_ignored_chars = false; | 
 |         let mut non_ignored_chars = 0; | 
 |         let mut bytes = 0; | 
 |         for c in input_str.chars() { | 
 |             match c { | 
 |                 '/' | '\\' | '?' | '#' => break, | 
 |                 '\t' | '\n' | '\r' => has_ignored_chars = true, | 
 |                 _ => non_ignored_chars += 1, | 
 |             } | 
 |             bytes += c.len_utf8(); | 
 |         } | 
 |         let replaced: String; | 
 |         let host_str; | 
 |         let mut remaining = input.clone(); | 
 |         { | 
 |             let host_input = remaining.by_ref().take(non_ignored_chars); | 
 |             if has_ignored_chars { | 
 |                 replaced = host_input.collect(); | 
 |                 host_str = &*replaced | 
 |             } else { | 
 |                 for _ in host_input {} | 
 |                 host_str = &input_str[..bytes] | 
 |             } | 
 |         } | 
 |         if is_windows_drive_letter(host_str) { | 
 |             return Ok((false, "".to_string(), input)); | 
 |         } | 
 |         Ok((true, host_str.to_string(), remaining)) | 
 |     } | 
 |  | 
 |     pub fn parse_port<P>( | 
 |         mut input: Input<'_>, | 
 |         default_port: P, | 
 |         context: Context, | 
 |     ) -> ParseResult<(Option<u16>, Input<'_>)> | 
 |     where | 
 |         P: Fn() -> Option<u16>, | 
 |     { | 
 |         let mut port: u32 = 0; | 
 |         let mut has_any_digit = false; | 
 |         while let (Some(c), remaining) = input.split_first() { | 
 |             if let Some(digit) = c.to_digit(10) { | 
 |                 port = port * 10 + digit; | 
 |                 if port > ::std::u16::MAX as u32 { | 
 |                     return Err(ParseError::InvalidPort); | 
 |                 } | 
 |                 has_any_digit = true; | 
 |             } else if context == Context::UrlParser && !matches!(c, '/' | '\\' | '?' | '#') { | 
 |                 return Err(ParseError::InvalidPort); | 
 |             } else { | 
 |                 break; | 
 |             } | 
 |             input = remaining; | 
 |         } | 
 |         let mut opt_port = Some(port as u16); | 
 |         if !has_any_digit || opt_port == default_port() { | 
 |             opt_port = None; | 
 |         } | 
 |         Ok((opt_port, input)) | 
 |     } | 
 |  | 
 |     pub fn parse_path_start<'i>( | 
 |         &mut self, | 
 |         scheme_type: SchemeType, | 
 |         has_host: &mut bool, | 
 |         input: Input<'i>, | 
 |     ) -> Input<'i> { | 
 |         let path_start = self.serialization.len(); | 
 |         let (maybe_c, remaining) = input.split_first(); | 
 |         // If url is special, then: | 
 |         if scheme_type.is_special() { | 
 |             if maybe_c == Some('\\') { | 
 |                 // If c is U+005C (\), validation error. | 
 |                 self.log_violation(SyntaxViolation::Backslash); | 
 |             } | 
 |             // A special URL always has a non-empty path. | 
 |             if !self.serialization.ends_with('/') { | 
 |                 self.serialization.push('/'); | 
 |                 // We have already made sure the forward slash is present. | 
 |                 if maybe_c == Some('/') || maybe_c == Some('\\') { | 
 |                     return self.parse_path(scheme_type, has_host, path_start, remaining); | 
 |                 } | 
 |             } | 
 |             return self.parse_path(scheme_type, has_host, path_start, input); | 
 |         } else if maybe_c == Some('?') || maybe_c == Some('#') { | 
 |             // Otherwise, if state override is not given and c is U+003F (?), | 
 |             // set url’s query to the empty string and state to query state. | 
 |             // Otherwise, if state override is not given and c is U+0023 (#), | 
 |             // set url’s fragment to the empty string and state to fragment state. | 
 |             // The query and path states will be handled by the caller. | 
 |             return input; | 
 |         } | 
 |  | 
 |         if maybe_c.is_some() && maybe_c != Some('/') { | 
 |             self.serialization.push('/'); | 
 |         } | 
 |         // Otherwise, if c is not the EOF code point: | 
 |         self.parse_path(scheme_type, has_host, path_start, input) | 
 |     } | 
 |  | 
 |     pub fn parse_path<'i>( | 
 |         &mut self, | 
 |         scheme_type: SchemeType, | 
 |         has_host: &mut bool, | 
 |         path_start: usize, | 
 |         mut input: Input<'i>, | 
 |     ) -> Input<'i> { | 
 |         // Relative path state | 
 |         loop { | 
 |             let mut segment_start = self.serialization.len(); | 
 |             let mut ends_with_slash = false; | 
 |             loop { | 
 |                 let input_before_c = input.clone(); | 
 |                 let (c, utf8_c) = if let Some(x) = input.next_utf8() { | 
 |                     x | 
 |                 } else { | 
 |                     break; | 
 |                 }; | 
 |                 match c { | 
 |                     '/' if self.context != Context::PathSegmentSetter => { | 
 |                         self.serialization.push(c); | 
 |                         ends_with_slash = true; | 
 |                         break; | 
 |                     } | 
 |                     '\\' if self.context != Context::PathSegmentSetter | 
 |                         && scheme_type.is_special() => | 
 |                     { | 
 |                         self.log_violation(SyntaxViolation::Backslash); | 
 |                         self.serialization.push('/'); | 
 |                         ends_with_slash = true; | 
 |                         break; | 
 |                     } | 
 |                     '?' | '#' if self.context == Context::UrlParser => { | 
 |                         input = input_before_c; | 
 |                         break; | 
 |                     } | 
 |                     _ => { | 
 |                         self.check_url_code_point(c, &input); | 
 |                         if scheme_type.is_file() | 
 |                             && self.serialization.len() > path_start | 
 |                             && is_normalized_windows_drive_letter( | 
 |                                 &self.serialization[path_start + 1..], | 
 |                             ) | 
 |                         { | 
 |                             self.serialization.push('/'); | 
 |                             segment_start += 1; | 
 |                         } | 
 |                         if self.context == Context::PathSegmentSetter { | 
 |                             if scheme_type.is_special() { | 
 |                                 self.serialization | 
 |                                     .extend(utf8_percent_encode(utf8_c, SPECIAL_PATH_SEGMENT)); | 
 |                             } else { | 
 |                                 self.serialization | 
 |                                     .extend(utf8_percent_encode(utf8_c, PATH_SEGMENT)); | 
 |                             } | 
 |                         } else { | 
 |                             self.serialization.extend(utf8_percent_encode(utf8_c, PATH)); | 
 |                         } | 
 |                     } | 
 |                 } | 
 |             } | 
 |             let segment_before_slash = if ends_with_slash { | 
 |                 &self.serialization[segment_start..self.serialization.len() - 1] | 
 |             } else { | 
 |                 &self.serialization[segment_start..self.serialization.len()] | 
 |             }; | 
 |             match segment_before_slash { | 
 |                 // If buffer is a double-dot path segment, shorten url’s path, | 
 |                 ".." | "%2e%2e" | "%2e%2E" | "%2E%2e" | "%2E%2E" | "%2e." | "%2E." | ".%2e" | 
 |                 | ".%2E" => { | 
 |                     debug_assert!(self.serialization.as_bytes()[segment_start - 1] == b'/'); | 
 |                     self.serialization.truncate(segment_start); | 
 |                     if self.serialization.ends_with('/') | 
 |                         && Parser::last_slash_can_be_removed(&self.serialization, path_start) | 
 |                     { | 
 |                         self.serialization.pop(); | 
 |                     } | 
 |                     self.shorten_path(scheme_type, path_start); | 
 |  | 
 |                     // and then if neither c is U+002F (/), nor url is special and c is U+005C (\), append the empty string to url’s path. | 
 |                     if ends_with_slash && !self.serialization.ends_with('/') { | 
 |                         self.serialization.push('/'); | 
 |                     } | 
 |                 } | 
 |                 // Otherwise, if buffer is a single-dot path segment and if neither c is U+002F (/), | 
 |                 // nor url is special and c is U+005C (\), append the empty string to url’s path. | 
 |                 "." | "%2e" | "%2E" => { | 
 |                     self.serialization.truncate(segment_start); | 
 |                     if !self.serialization.ends_with('/') { | 
 |                         self.serialization.push('/'); | 
 |                     } | 
 |                 } | 
 |                 _ => { | 
 |                     // If url’s scheme is "file", url’s path is empty, and buffer is a Windows drive letter, then | 
 |                     if scheme_type.is_file() | 
 |                         && segment_start == path_start + 1 | 
 |                         && is_windows_drive_letter(segment_before_slash) | 
 |                     { | 
 |                         // Replace the second code point in buffer with U+003A (:). | 
 |                         if let Some(c) = segment_before_slash.chars().next() { | 
 |                             self.serialization.truncate(segment_start); | 
 |                             self.serialization.push(c); | 
 |                             self.serialization.push(':'); | 
 |                             if ends_with_slash { | 
 |                                 self.serialization.push('/'); | 
 |                             } | 
 |                         } | 
 |                         // If url’s host is neither the empty string nor null, | 
 |                         // validation error, set url’s host to the empty string. | 
 |                         if *has_host { | 
 |                             self.log_violation(SyntaxViolation::FileWithHostAndWindowsDrive); | 
 |                             *has_host = false; // FIXME account for this in callers | 
 |                         } | 
 |                     } | 
 |                 } | 
 |             } | 
 |             if !ends_with_slash { | 
 |                 break; | 
 |             } | 
 |         } | 
 |         if scheme_type.is_file() { | 
 |             // while url’s path’s size is greater than 1 | 
 |             // and url’s path[0] is the empty string, | 
 |             // validation error, remove the first item from url’s path. | 
 |             //FIXME: log violation | 
 |             let path = self.serialization.split_off(path_start); | 
 |             self.serialization.push('/'); | 
 |             self.serialization.push_str(path.trim_start_matches('/')); | 
 |         } | 
 |  | 
 |         input | 
 |     } | 
 |  | 
 |     fn last_slash_can_be_removed(serialization: &str, path_start: usize) -> bool { | 
 |         let url_before_segment = &serialization[..serialization.len() - 1]; | 
 |         if let Some(segment_before_start) = url_before_segment.rfind('/') { | 
 |             // Do not remove the root slash | 
 |             segment_before_start >= path_start | 
 |                 // Or a windows drive letter slash | 
 |                 && !path_starts_with_windows_drive_letter(&serialization[segment_before_start..]) | 
 |         } else { | 
 |             false | 
 |         } | 
 |     } | 
 |  | 
 |     /// https://url.spec.whatwg.org/#shorten-a-urls-path | 
 |     fn shorten_path(&mut self, scheme_type: SchemeType, path_start: usize) { | 
 |         // If path is empty, then return. | 
 |         if self.serialization.len() == path_start { | 
 |             return; | 
 |         } | 
 |         // If url’s scheme is "file", path’s size is 1, and path[0] is a normalized Windows drive letter, then return. | 
 |         if scheme_type.is_file() | 
 |             && is_normalized_windows_drive_letter(&self.serialization[path_start..]) | 
 |         { | 
 |             return; | 
 |         } | 
 |         // Remove path’s last item. | 
 |         self.pop_path(scheme_type, path_start); | 
 |     } | 
 |  | 
 |     /// https://url.spec.whatwg.org/#pop-a-urls-path | 
 |     fn pop_path(&mut self, scheme_type: SchemeType, path_start: usize) { | 
 |         if self.serialization.len() > path_start { | 
 |             let slash_position = self.serialization[path_start..].rfind('/').unwrap(); | 
 |             // + 1 since rfind returns the position before the slash. | 
 |             let segment_start = path_start + slash_position + 1; | 
 |             // Don’t pop a Windows drive letter | 
 |             if !(scheme_type.is_file() | 
 |                 && is_normalized_windows_drive_letter(&self.serialization[segment_start..])) | 
 |             { | 
 |                 self.serialization.truncate(segment_start); | 
 |             } | 
 |         } | 
 |     } | 
 |  | 
 |     pub fn parse_cannot_be_a_base_path<'i>(&mut self, mut input: Input<'i>) -> Input<'i> { | 
 |         loop { | 
 |             let input_before_c = input.clone(); | 
 |             match input.next_utf8() { | 
 |                 Some(('?', _)) | Some(('#', _)) if self.context == Context::UrlParser => { | 
 |                     return input_before_c | 
 |                 } | 
 |                 Some((c, utf8_c)) => { | 
 |                     self.check_url_code_point(c, &input); | 
 |                     self.serialization | 
 |                         .extend(utf8_percent_encode(utf8_c, CONTROLS)); | 
 |                 } | 
 |                 None => return input, | 
 |             } | 
 |         } | 
 |     } | 
 |  | 
 |     #[allow(clippy::too_many_arguments)] | 
 |     fn with_query_and_fragment( | 
 |         mut self, | 
 |         scheme_type: SchemeType, | 
 |         scheme_end: u32, | 
 |         username_end: u32, | 
 |         host_start: u32, | 
 |         host_end: u32, | 
 |         host: HostInternal, | 
 |         port: Option<u16>, | 
 |         mut path_start: u32, | 
 |         remaining: Input<'_>, | 
 |     ) -> ParseResult<Url> { | 
 |         // Special case for anarchist URL's with a leading empty path segment | 
 |         // This prevents web+demo:/.//not-a-host/ or web+demo:/path/..//not-a-host/, | 
 |         // when parsed and then serialized, from ending up as web+demo://not-a-host/ | 
 |         // (they end up as web+demo:/.//not-a-host/). | 
 |         // | 
 |         // If url’s host is null, url does not have an opaque path, | 
 |         // url’s path’s size is greater than 1, and url’s path[0] is the empty string, | 
 |         // then append U+002F (/) followed by U+002E (.) to output. | 
 |         let scheme_end_as_usize = scheme_end as usize; | 
 |         let path_start_as_usize = path_start as usize; | 
 |         if path_start_as_usize == scheme_end_as_usize + 1 { | 
 |             // Anarchist URL | 
 |             if self.serialization[path_start_as_usize..].starts_with("//") { | 
 |                 // Case 1: The base URL did not have an empty path segment, but the resulting one does | 
 |                 // Insert the "/." prefix | 
 |                 self.serialization.insert_str(path_start_as_usize, "/."); | 
 |                 path_start += 2; | 
 |             } | 
 |             assert!(!self.serialization[scheme_end_as_usize..].starts_with("://")); | 
 |         } else if path_start_as_usize == scheme_end_as_usize + 3 | 
 |             && &self.serialization[scheme_end_as_usize..path_start_as_usize] == ":/." | 
 |         { | 
 |             // Anarchist URL with leading empty path segment | 
 |             // The base URL has a "/." between the host and the path | 
 |             assert_eq!(self.serialization.as_bytes()[path_start_as_usize], b'/'); | 
 |             if self | 
 |                 .serialization | 
 |                 .as_bytes() | 
 |                 .get(path_start_as_usize + 1) | 
 |                 .copied() | 
 |                 != Some(b'/') | 
 |             { | 
 |                 // Case 2: The base URL had an empty path segment, but the resulting one does not | 
 |                 // Remove the "/." prefix | 
 |                 self.serialization | 
 |                     .replace_range(scheme_end_as_usize..path_start_as_usize, ":"); | 
 |                 path_start -= 2; | 
 |             } | 
 |             assert!(!self.serialization[scheme_end_as_usize..].starts_with("://")); | 
 |         } | 
 |  | 
 |         let (query_start, fragment_start) = | 
 |             self.parse_query_and_fragment(scheme_type, scheme_end, remaining)?; | 
 |         Ok(Url { | 
 |             serialization: self.serialization, | 
 |             scheme_end, | 
 |             username_end, | 
 |             host_start, | 
 |             host_end, | 
 |             host, | 
 |             port, | 
 |             path_start, | 
 |             query_start, | 
 |             fragment_start, | 
 |         }) | 
 |     } | 
 |  | 
 |     /// Return (query_start, fragment_start) | 
 |     fn parse_query_and_fragment( | 
 |         &mut self, | 
 |         scheme_type: SchemeType, | 
 |         scheme_end: u32, | 
 |         mut input: Input<'_>, | 
 |     ) -> ParseResult<(Option<u32>, Option<u32>)> { | 
 |         let mut query_start = None; | 
 |         match input.next() { | 
 |             Some('#') => {} | 
 |             Some('?') => { | 
 |                 query_start = Some(to_u32(self.serialization.len())?); | 
 |                 self.serialization.push('?'); | 
 |                 let remaining = self.parse_query(scheme_type, scheme_end, input); | 
 |                 if let Some(remaining) = remaining { | 
 |                     input = remaining | 
 |                 } else { | 
 |                     return Ok((query_start, None)); | 
 |                 } | 
 |             } | 
 |             None => return Ok((None, None)), | 
 |             _ => panic!("Programming error. parse_query_and_fragment() called without ? or #"), | 
 |         } | 
 |  | 
 |         let fragment_start = to_u32(self.serialization.len())?; | 
 |         self.serialization.push('#'); | 
 |         self.parse_fragment(input); | 
 |         Ok((query_start, Some(fragment_start))) | 
 |     } | 
 |  | 
 |     pub fn parse_query<'i>( | 
 |         &mut self, | 
 |         scheme_type: SchemeType, | 
 |         scheme_end: u32, | 
 |         mut input: Input<'i>, | 
 |     ) -> Option<Input<'i>> { | 
 |         let len = input.chars.as_str().len(); | 
 |         let mut query = String::with_capacity(len); // FIXME: use a streaming decoder instead | 
 |         let mut remaining = None; | 
 |         while let Some(c) = input.next() { | 
 |             if c == '#' && self.context == Context::UrlParser { | 
 |                 remaining = Some(input); | 
 |                 break; | 
 |             } else { | 
 |                 self.check_url_code_point(c, &input); | 
 |                 query.push(c); | 
 |             } | 
 |         } | 
 |  | 
 |         let encoding = match &self.serialization[..scheme_end as usize] { | 
 |             "http" | "https" | "file" | "ftp" => self.query_encoding_override, | 
 |             _ => None, | 
 |         }; | 
 |         let query_bytes = if let Some(o) = encoding { | 
 |             o(&query) | 
 |         } else { | 
 |             query.as_bytes().into() | 
 |         }; | 
 |         let set = if scheme_type.is_special() { | 
 |             SPECIAL_QUERY | 
 |         } else { | 
 |             QUERY | 
 |         }; | 
 |         self.serialization.extend(percent_encode(&query_bytes, set)); | 
 |         remaining | 
 |     } | 
 |  | 
 |     fn fragment_only(mut self, base_url: &Url, mut input: Input<'_>) -> ParseResult<Url> { | 
 |         let before_fragment = match base_url.fragment_start { | 
 |             Some(i) => base_url.slice(..i), | 
 |             None => &*base_url.serialization, | 
 |         }; | 
 |         debug_assert!(self.serialization.is_empty()); | 
 |         self.serialization | 
 |             .reserve(before_fragment.len() + input.chars.as_str().len()); | 
 |         self.serialization.push_str(before_fragment); | 
 |         self.serialization.push('#'); | 
 |         let next = input.next(); | 
 |         debug_assert!(next == Some('#')); | 
 |         self.parse_fragment(input); | 
 |         Ok(Url { | 
 |             serialization: self.serialization, | 
 |             fragment_start: Some(to_u32(before_fragment.len())?), | 
 |             ..*base_url | 
 |         }) | 
 |     } | 
 |  | 
 |     pub fn parse_fragment(&mut self, mut input: Input<'_>) { | 
 |         while let Some((c, utf8_c)) = input.next_utf8() { | 
 |             if c == '\0' { | 
 |                 self.log_violation(SyntaxViolation::NullInFragment) | 
 |             } else { | 
 |                 self.check_url_code_point(c, &input); | 
 |             } | 
 |             self.serialization | 
 |                 .extend(utf8_percent_encode(utf8_c, FRAGMENT)); | 
 |         } | 
 |     } | 
 |  | 
 |     fn check_url_code_point(&self, c: char, input: &Input<'_>) { | 
 |         if let Some(vfn) = self.violation_fn { | 
 |             if c == '%' { | 
 |                 let mut input = input.clone(); | 
 |                 if !matches!((input.next(), input.next()), (Some(a), Some(b)) | 
 |                              if a.is_ascii_hexdigit() && b.is_ascii_hexdigit()) | 
 |                 { | 
 |                     vfn(SyntaxViolation::PercentDecode) | 
 |                 } | 
 |             } else if !is_url_code_point(c) { | 
 |                 vfn(SyntaxViolation::NonUrlCodePoint) | 
 |             } | 
 |         } | 
 |     } | 
 | } | 
 |  | 
 | // Non URL code points: | 
 | // U+0000 to U+0020 (space) | 
 | // " # % < > [ \ ] ^ ` { | } | 
 | // U+007F to U+009F | 
 | // surrogates | 
 | // U+FDD0 to U+FDEF | 
 | // Last two of each plane: U+__FFFE to U+__FFFF for __ in 00 to 10 hex | 
 | #[inline] | 
 | fn is_url_code_point(c: char) -> bool { | 
 |     matches!(c, | 
 |         'a'..='z' | | 
 |         'A'..='Z' | | 
 |         '0'..='9' | | 
 |         '!' | '$' | '&' | '\'' | '(' | ')' | '*' | '+' | ',' | '-' | | 
 |         '.' | '/' | ':' | ';' | '=' | '?' | '@' | '_' | '~' | | 
 |         '\u{A0}'..='\u{D7FF}' | '\u{E000}'..='\u{FDCF}' | '\u{FDF0}'..='\u{FFFD}' | | 
 |         '\u{10000}'..='\u{1FFFD}' | '\u{20000}'..='\u{2FFFD}' | | 
 |         '\u{30000}'..='\u{3FFFD}' | '\u{40000}'..='\u{4FFFD}' | | 
 |         '\u{50000}'..='\u{5FFFD}' | '\u{60000}'..='\u{6FFFD}' | | 
 |         '\u{70000}'..='\u{7FFFD}' | '\u{80000}'..='\u{8FFFD}' | | 
 |         '\u{90000}'..='\u{9FFFD}' | '\u{A0000}'..='\u{AFFFD}' | | 
 |         '\u{B0000}'..='\u{BFFFD}' | '\u{C0000}'..='\u{CFFFD}' | | 
 |         '\u{D0000}'..='\u{DFFFD}' | '\u{E1000}'..='\u{EFFFD}' | | 
 |         '\u{F0000}'..='\u{FFFFD}' | '\u{100000}'..='\u{10FFFD}') | 
 | } | 
 |  | 
 | /// https://url.spec.whatwg.org/#c0-controls-and-space | 
 | #[inline] | 
 | fn c0_control_or_space(ch: char) -> bool { | 
 |     ch <= ' ' // U+0000 to U+0020 | 
 | } | 
 |  | 
 | /// https://infra.spec.whatwg.org/#ascii-tab-or-newline | 
 | #[inline] | 
 | fn ascii_tab_or_new_line(ch: char) -> bool { | 
 |     matches!(ch, '\t' | '\r' | '\n') | 
 | } | 
 |  | 
 | /// https://url.spec.whatwg.org/#ascii-alpha | 
 | #[inline] | 
 | pub fn ascii_alpha(ch: char) -> bool { | 
 |     ch.is_ascii_alphabetic() | 
 | } | 
 |  | 
 | #[inline] | 
 | pub fn to_u32(i: usize) -> ParseResult<u32> { | 
 |     if i <= ::std::u32::MAX as usize { | 
 |         Ok(i as u32) | 
 |     } else { | 
 |         Err(ParseError::Overflow) | 
 |     } | 
 | } | 
 |  | 
 | fn is_normalized_windows_drive_letter(segment: &str) -> bool { | 
 |     is_windows_drive_letter(segment) && segment.as_bytes()[1] == b':' | 
 | } | 
 |  | 
 | /// Whether the scheme is file:, the path has a single segment, and that segment | 
 | /// is a Windows drive letter | 
 | #[inline] | 
 | pub fn is_windows_drive_letter(segment: &str) -> bool { | 
 |     segment.len() == 2 && starts_with_windows_drive_letter(segment) | 
 | } | 
 |  | 
 | /// Whether path starts with a root slash | 
 | /// and a windows drive letter eg: "/c:" or "/a:/" | 
 | fn path_starts_with_windows_drive_letter(s: &str) -> bool { | 
 |     if let Some(c) = s.as_bytes().first() { | 
 |         matches!(c, b'/' | b'\\' | b'?' | b'#') && starts_with_windows_drive_letter(&s[1..]) | 
 |     } else { | 
 |         false | 
 |     } | 
 | } | 
 |  | 
 | fn starts_with_windows_drive_letter(s: &str) -> bool { | 
 |     s.len() >= 2 | 
 |         && ascii_alpha(s.as_bytes()[0] as char) | 
 |         && matches!(s.as_bytes()[1], b':' | b'|') | 
 |         && (s.len() == 2 || matches!(s.as_bytes()[2], b'/' | b'\\' | b'?' | b'#')) | 
 | } | 
 |  | 
 | /// https://url.spec.whatwg.org/#start-with-a-windows-drive-letter | 
 | fn starts_with_windows_drive_letter_segment(input: &Input<'_>) -> bool { | 
 |     let mut input = input.clone(); | 
 |     match (input.next(), input.next(), input.next()) { | 
 |         // its first two code points are a Windows drive letter | 
 |         // its third code point is U+002F (/), U+005C (\), U+003F (?), or U+0023 (#). | 
 |         (Some(a), Some(b), Some(c)) | 
 |             if ascii_alpha(a) && matches!(b, ':' | '|') && matches!(c, '/' | '\\' | '?' | '#') => | 
 |         { | 
 |             true | 
 |         } | 
 |         // its first two code points are a Windows drive letter | 
 |         // its length is 2 | 
 |         (Some(a), Some(b), None) if ascii_alpha(a) && matches!(b, ':' | '|') => true, | 
 |         _ => false, | 
 |     } | 
 | } |