Pull the parsing bits out

1 files changed, 1048 insertions, 0 deletions

diff --git a/src/parser.rs b/src/parser.rs
new file mode 100644
index 0000000..19f019a
--- /dev/null
+++ b/src/parser.rs
@@ -0,0 +1,1048 @@
+use std::ops::Range;
+
+#[derive(Debug)]
+pub struct Challenge {
+    pub scheme: Range<usize>,
+    pub params: Vec<AuthParam>,
+}
+
+// RFC 7230
+fn parse_token(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+    while str.len() > pos {
+        match str[pos] {
+            // RFC 5234
+            'a'..='z' | 'A'..='Z' => pos += 1,
+            '0'..='9' => pos += 1,
+            // RFC 7230
+            '!' | '#' | '$' | '%' | '&' | '\'' | '*' | '+' | '-' | '.' | '^' | '_' | '`' | '|' | '~'
+                => pos += 1,
+            _ => break,
+        }
+    }
+
+    // Must have matched 1
+    if pos == start {
+        return None;
+    }
+
+    return Some((start..pos, pos));
+}
+
+#[cfg(test)]
+mod test_token {
+    use super::*;
+
+    #[test]
+    fn rejects_nontchar() {
+        let data = vec!['>'];
+
+        let res = parse_token(&data, 0);
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn matches_letter() {
+        let data = vec!['a'];
+
+        let (range, pos) = parse_token(&data, 0).unwrap();
+        assert_eq!(pos, 1);
+        assert_eq!(range.start, 0);
+        assert_eq!(range.end, 1);
+    }
+
+    #[test]
+    fn matches_multiple_letters() {
+        let data = vec!['a', '1', '|'];
+
+        let (range, pos) = parse_token(&data, 0).unwrap();
+        assert_eq!(pos, 3);
+        assert_eq!(range.start, 0);
+        assert_eq!(range.end, 3);
+    }
+}
+
+fn parse_qdtext(str: &Vec<char>, start: usize) -> Option<usize> {
+    match str[start] {
+        '\x00'..='\x1F' | '"' | '\x7F' => return None,
+        _ => return Some(start + 1),
+    }
+}
+
+fn parse_quotedpair(str: &Vec<char>, start: usize) -> Option<usize> {
+    if str[start] != '\\' {
+        return None;
+    }
+
+    return Some(start + 2);
+}
+
+fn parse_quotedstring(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+    if str[pos] != '"' {
+        return None;
+    }
+    pos += 1;
+
+    loop {
+        if let Some(npos) = parse_qdtext(str, pos) {
+            pos = npos;
+        } else if let Some(npos) = parse_quotedpair(str, pos) {
+            pos = npos;
+        } else {
+            break;
+        }
+    }
+
+    if str[pos] != '"' {
+        return None;
+    }
+    pos += 1;
+
+    return Some((start+1..pos-1, pos));
+}
+
+fn parse_sp(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    if str.len() <= start {
+        return None;
+    }
+
+    let mut pos = start;
+    match str[pos] {
+        ' ' => pos += 1,
+        _ => return None,
+    }
+
+    if pos == start {
+        return None;
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_crlf(str: &Vec<char>, start: usize) -> Option<usize> {
+    if str.len() - 2 < start {
+        return None;
+    }
+
+    if str[start] == '\r' && str[start+1] == '\n' {
+        return Some(start + 2);
+    }
+
+    return None;
+}
+
+fn parse_lws(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    match parse_crlf(str, pos) {
+        Some(npos) => pos = npos,
+        None => {},
+    }
+
+    match parse_sp(str, pos) {
+        Some((_, npos)) => pos = npos,
+        None => return None,
+    }
+    loop {
+        match parse_sp(str, pos) {
+            Some((_, npos)) => pos = npos,
+            None => break,
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+#[derive(Debug)]
+pub struct AuthParam {
+    pub key: Range<usize>,
+    pub value: Range<usize>,
+}
+
+fn parse_param(str: &Vec<char>, start: usize) -> Option<(AuthParam, usize)> {
+    let pos = start;
+    let (param_range, pos) = parse_token(str, pos)?;
+
+    let mut pos = pos;
+    if str[pos] == '=' {
+        pos += 1;
+    } else {
+        todo!();
+    }
+
+    let value_range;
+    if let Some((range, npos)) = parse_token(str, pos) {
+        value_range = range;
+        pos = npos;
+    } else if let Some((range, npos)) = parse_quotedstring(str, pos) {
+        value_range = range;
+        pos = npos;
+    } else {
+        todo!("{:?}", &str[pos..]);
+    }
+
+    return Some((AuthParam{key: param_range, value: value_range}, pos));
+}
+
+pub fn parse_challenge(str: &Vec<char>, start: usize) -> Option<(Challenge, usize)> {
+    let pos = start;
+    let (scheme_range, pos) = parse_token(str, pos).unwrap();
+
+    let (_, pos) = parse_sp(str, pos).unwrap();
+    let mut pos = pos;
+    loop {
+        match parse_sp(str, pos) {
+            Some((_, npos)) => pos = npos,
+            None => break,
+        }
+    }
+
+    let mut params = vec!();
+
+    let mut pos = pos;
+    loop {
+        match parse_lws(str, pos) {
+            Some((_, npos)) => pos = npos,
+            None => break,
+        }
+    }
+    let (param, pos) = parse_param(str, pos).unwrap();
+    params.push(param);
+    let mut pos = pos;
+    loop {
+        loop {
+            match parse_lws(str, pos) {
+                Some((_, npos)) => pos = npos,
+                None => break,
+            }
+        }
+
+        if pos >= str.len() || str[pos] != ',' {
+            break;
+        }
+        pos += 1;
+
+        loop {
+            match parse_lws(str, pos) {
+                Some((_, npos)) => pos = npos,
+                None => break,
+            }
+        }
+
+        match parse_param(str, pos) {
+            Some((param, npos)) => {
+                pos = npos;
+                params.push(param);
+            },
+            None => return None,
+        }
+    }
+
+    if pos < str.len() {
+        return None;
+    }
+    return Some((Challenge {scheme: scheme_range, params}, pos));
+}
+
+#[derive(Debug)]
+pub enum LinkParam {
+    Rel{relation: Range<usize>},
+}
+
+impl LinkParam {
+    pub fn value(&self) -> &Range<usize> {
+        match self {
+            LinkParam::Rel{relation} => &relation,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct LinkValue {
+    uri: Range<usize>,
+    pub params: Vec<LinkParam>,
+}
+
+fn parse_alpha(str: &Vec<char>, pos: usize) -> Option<(Range<usize>, usize)> {
+    if pos >= str.len() {
+        return None;
+    }
+
+    return match str[pos] {
+        'a'..='z' | 'A'..='Z' => Some((pos..pos+1, pos+1)),
+        _ => None,
+    }
+}
+
+fn parse_digit(str: &Vec<char>, pos: usize) -> Option<(Range<usize>, usize)> {
+    if pos >= str.len() {
+        return None;
+    }
+
+    return match str[pos] {
+        '0'..='9' => Some((pos..pos+1, pos+1)),
+        _ => None,
+    }
+}
+
+fn parse_scheme(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    let (_, npos) = parse_alpha(str, pos)?;
+    pos = npos;
+
+    loop {
+        if let Some((_, npos)) = parse_alpha(str, pos) {
+            pos = npos;
+        } else {
+            break;
+        }
+    };
+
+    return None;
+}
+
+fn parse_reg_name(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    loop {
+        if let Some((_, npos)) = parse_unreserved(str, pos) {
+            pos = npos;
+        } else if let Some((_, npos)) = parse_pct_encoded(str, pos) {
+            pos = npos;
+        } else if let Some((_, npos)) = parse_sub_delims(str, pos) {
+            pos = npos;
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_ip_literal(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    return None;
+}
+
+fn parse_port(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    return None;
+}
+
+fn parse_host(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if let Some((_, npos)) = parse_ip_literal(str, pos) {
+        pos = npos;
+        return Some((start..pos, pos));
+    }
+
+    if let Some((_, npos)) = parse_reg_name(str, pos) {
+        pos = npos;
+        return Some((start..pos, pos));
+    }
+
+    return None;
+}
+
+fn parse_userinfo(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    loop {
+        if let Some((_, npos)) = parse_unreserved(str, pos) {
+            pos = npos;
+        } else if let Some((_, npos)) = parse_pct_encoded(str, pos) {
+            pos = npos;
+        } else if let Some((_, npos)) = parse_sub_delims(str, pos) {
+            pos = npos;
+        } else if let Some(ch) = str.get(pos) && *ch == ':' {
+            pos += 1;
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_authority(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if let Some((_, npos)) = parse_userinfo(str, pos) {
+        if let Some(ch) = str.get(npos) && *ch == '@' {
+            pos = npos;
+        }
+    }
+    // If the character after the userinfo isn't a @ we roll back that parse and try it as a host.
+
+    if let Some((_, npos)) = parse_host(str, pos) {
+        pos = npos;
+    } else {
+        return None;
+    }
+
+    if let Some(ch) = str.get(pos) && *ch == ':' {
+        if let Some((_, npos)) = parse_port(str, pos) {
+            pos = npos;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_relative_part_1(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if str[pos] != '/' || str[pos+1] != '/' {
+        return None;
+    }
+    pos += 2;
+
+    let (_, npos) = parse_authority(str, pos)?;
+    pos = npos;
+
+    let (_, npos) = parse_path_abempty(str, pos)?;
+    pos = npos;
+
+    return Some((start..pos, pos));
+}
+
+fn parse_unreserved(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    if let Some(x) = parse_alpha(str, start) {
+        return Some(x);
+    }
+
+    if let Some(x) = parse_digit(str, start) {
+        return Some(x);
+    }
+
+    if start >= str.len() {
+        return None;
+    }
+    match str[start] {
+        '-' | '.' | '_' | '~' => Some((start..start+1, start+1)),
+        _ => None
+    }
+}
+
+fn parse_pct_encoded(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    return None;
+}
+
+fn parse_sub_delims(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    if start >= str.len() {
+        return None;
+    }
+
+    match str[start] {
+        '!' | '$' | '&' | '\'' | '(' | ')' | '*' | '+' | ',' | ';' | '=' => Some((start..start+1, start+1)),
+        _ => None
+    }
+
+}
+
+fn parse_pchar(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    if let Some(x) = parse_unreserved(str, start) {
+        return Some(x);
+    }
+
+    if let Some(x) = parse_sub_delims(str, start) {
+        return Some(x);
+    }
+
+    return None;
+}
+
+fn parse_segment_nz(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    let (_, npos) = parse_pchar(str, pos)?;
+    pos = npos;
+
+    loop {
+        if let Some((_, npos)) = parse_pchar(str, pos) {
+            pos = npos;
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_segment(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    loop {
+        if let Some((_, npos)) = parse_pchar(str, pos) {
+            pos = npos;
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_path_absolute(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if str[pos] != '/' {
+        return None;
+    }
+    pos += 1;
+
+    if let Some((_, npos)) = parse_segment_nz(str, pos) {
+        pos = npos;
+
+        loop {
+            if str[pos] != '/' {
+                break;
+            }
+
+            if let Some((_, npos)) = parse_segment(str, pos+1) {
+                pos = npos;
+            } else {
+                break;
+            }
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_path_abempty(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    loop {
+        if let Some(ch) = str.get(pos) && *ch == '/' {
+            if let Some((_, npos)) = parse_segment(str, pos+1) {
+                pos = npos;
+            } else {
+                break;
+            }
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_relative_part(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if let Some((_, npos)) = parse_relative_part_1(str, pos) {
+        pos = npos;
+        return Some((start..pos, pos));
+    }
+
+    if let Some((_, npos)) = parse_path_absolute(str, pos) {
+        pos = npos;
+        return Some((start..pos, pos));
+    }
+
+    return None;
+}
+
+#[cfg(test)]
+mod test_relative_part {
+    use super::*;
+
+    #[test]
+    fn absolute_path() {
+        let data = "/foo?".chars().collect();
+
+        let (range, pos) = parse_relative_part(&data, 0).unwrap();
+        assert_eq!(pos, 4);
+        assert_eq!(range.start, 0);
+        assert_eq!(range.end, 4);
+    }
+}
+
+fn parse_query(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if start >= str.len() {
+        return None;
+    }
+
+    loop {
+        if let Some((_, npos)) = parse_pchar(str, pos) {
+            pos = npos;
+        } else if let Some(ch) = str.get(pos) && *ch == '/' {
+            pos += 1;
+        } else if let Some(ch) = str.get(pos) && *ch == '?' {
+            pos += 1;
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_fragment(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    return None;
+}
+
+// RFC 3986
+fn parse_relative_ref(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    let (_, npos) = parse_relative_part(str, pos)?;
+    pos = npos;
+
+    if let Some(ch) = str.get(pos) && *ch == '?' && let Some((_, npos)) = parse_query(str, pos+1) {
+        pos = npos;
+    }
+
+    if let Some(ch) = str.get(pos) && *ch == '#' && let Some((_, npos)) = parse_fragment(str, pos+1) {
+        pos = npos;
+    }
+
+    return Some((start..pos, pos));
+}
+
+#[cfg(test)]
+mod test_relative_ref {
+    use super::*;
+
+    #[test]
+    fn reject_not_starting_slash() {
+        let data = vec!['?'];
+
+        let res = parse_relative_ref(&data, 0);
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn simple() {
+        let data = vec!['/', '/', 'h', 'e', 'l', 'l', 'o', '/'];
+
+        let (range, pos) = parse_relative_ref(&data, 0).unwrap();
+        assert_eq!(pos, 8);
+        assert_eq!(range.start, 0);
+        assert_eq!(range.end, 8);
+    }
+
+    #[test]
+    fn with_query_parameter() {
+        let data = "/foo?bar=baz".chars().collect();
+
+        let (range, pos) = parse_relative_ref(&data, 0).unwrap();
+        assert_eq!(pos, 12);
+        assert_eq!(range.start, 0);
+        assert_eq!(range.end, 12);
+    }
+}
+
+fn parse_uri(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    let(_, npos) = parse_scheme(str, pos)?;
+    pos = npos;
+
+    return Some((start..pos, pos));
+}
+
+fn parse_exact_string(str: &Vec<char>, start: usize, to_match: &str) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+    let end = pos + to_match.len();
+
+    if end > str.len() {
+        return None;
+    }
+
+    if !to_match.chars().eq(str[start..start+to_match.len()].iter().map(|x| *x)) {
+        return None;
+    }
+    pos += to_match.len();
+
+    return Some((start..pos, pos));
+}
+
+fn parse_loalpha(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    match str.get(start) {
+        Some('a'..='z') => Some((start..start+1, start+1)),
+        _ => None,
+    }
+}
+
+fn parse_relation_type(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    let (_, npos) = parse_loalpha(str, pos)?;
+    pos = npos;
+
+    loop {
+        if let Some((_, npos)) = parse_loalpha(str, pos) {
+            pos = npos;
+            continue;
+        } else if let Some((_, npos)) = parse_digit(str, pos) {
+            pos = npos;
+            continue;
+        } else if let Some((_, npos)) = parse_exact_string(str, pos, ".") {
+            pos = npos;
+            continue;
+        } else if let Some((_, npos)) = parse_exact_string(str, pos, "-") {
+            pos = npos;
+            continue;
+        } else {
+            break;
+        }
+    }
+
+    return Some((start..pos, pos));
+}
+
+fn parse_relation_types(str: &Vec<char>, start: usize) -> Option<(Range<usize>, usize)> {
+    let mut pos = start;
+
+    if let Some((_, npos)) = parse_relation_type(str, pos) {
+        pos = npos;
+
+        return Some((start..pos, pos));
+    } else if let Some((_, npos)) = parse_exact_string(str, pos, "\"") {
+        pos = npos;
+
+        if let Some((_, npos)) = parse_relation_type(str, pos) {
+            pos = npos;
+
+            loop {
+                if let Some((_, npos)) = parse_sp(str, pos) {
+
+                    loop {
+                        if let Some((_, npos)) = parse_sp(str, pos) {
+                            pos = npos;
+                        } else {
+                            break;
+                        }
+                    }
+
+                    pos = npos;
+                    if let Some((_, npos)) = parse_relation_type(str, pos) {
+                        pos = npos;
+                        continue;
+                    }
+                }
+                break;
+            }
+
+            if let Some((_, npos)) = parse_exact_string(str, pos, "\"") {
+                pos = npos;
+                return Some((start+1..pos-1, pos));
+            }
+        }
+    }
+
+    return None;
+}
+
+fn parse_link_param(str: &Vec<char>, start: usize) -> Option<(LinkParam, usize)> {
+    let mut pos = start;
+
+    // Non-standard but seen in the wild
+    if let Some((_, npos)) = parse_sp(str, pos) {
+        pos = npos;
+    }
+
+    if let Some((_, npos)) = parse_exact_string(str, pos, "rel=") {
+        if let Some((relation, npos)) = parse_relation_types(str, npos) {
+            pos = npos;
+            return Some((LinkParam::Rel{relation}, pos));
+        }
+    }
+
+    return None;
+}
+
+fn parse_link_value(str: &Vec<char>, start: usize) -> Option<(LinkValue, usize)> {
+    let mut pos = start;
+
+    if let Some((_, npos)) = parse_exact_string(str, pos, "<") {
+        pos = npos;
+    } else {
+        return None;
+    }
+
+    let uri_range;
+    let mut params = vec!();
+
+    if let Some((range, npos)) = parse_uri(str, pos) {
+        uri_range = range;
+        pos = npos;
+    } else if let Some((range, npos)) = parse_relative_ref(str, pos) {
+        uri_range = range;
+        pos = npos;
+    } else {
+        return None;
+    }
+
+    if let Some((_, npos)) = parse_exact_string(str, pos, ">") {
+        pos = npos;
+    } else {
+        return None;
+    }
+
+    loop {
+        if let Some((_, npos)) = parse_exact_string(str, pos, ";") {
+            pos = npos;
+        } else {
+            break;
+        }
+
+        if let Some((param, npos)) = parse_link_param(str, pos) {
+            pos = npos;
+            params.push(param);
+        } else {
+            break;
+        }
+    }
+
+    return Some((LinkValue{ uri: uri_range, params: params }, pos));
+}
+
+pub fn parse_link(str: &Vec<char>, start: usize) -> Option<(Vec<LinkValue>, usize)> {
+    let mut pos = start;
+
+    let mut values = vec!();
+
+    loop {
+        match parse_lws(str, pos) {
+            Some((_, npos)) => pos = npos,
+            None => break,
+        }
+    }
+
+    let (param, npos) = parse_link_value(str, pos)?;
+    values.push(param);
+    pos = npos;
+
+    loop {
+        let mut ipos = pos;
+        loop {
+            match parse_lws(str, ipos) {
+                Some((_, npos)) => ipos = npos,
+                None => break,
+            }
+        }
+
+        if ipos >= str.len() || str[ipos] != ',' {
+            break;
+        }
+        ipos += 1;
+
+        loop {
+            match parse_lws(str, ipos) {
+                Some((_, npos)) => ipos = npos,
+                None => break,
+            }
+        }
+
+        match parse_link_value(str, ipos) {
+            Some((param, npos)) => {
+                ipos = npos;
+                values.push(param);
+            },
+            None => {
+                break;
+            },
+        }
+
+        pos = ipos;
+    }
+
+
+    return Some((values, pos));
+}
+
+#[cfg(test)]
+mod test_link {
+    use super::*;
+
+    #[test]
+    fn parses_relative_authority_only() {
+        let data: Vec<char> = "<//example.com>".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 15);
+        assert_eq!(links.len(), 1);
+        assert_eq!(links[0].uri, 1..14);
+        assert_eq!(links[0].params.len(), 0);
+    }
+
+    #[test]
+    fn parses_relative_absolute_path() {
+        let data: Vec<char> = "</path/to/resource>".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 19);
+        assert_eq!(links.len(), 1);
+        assert_eq!(links[0].uri, 1..18);
+    }
+
+    #[test]
+    fn parses_relative_with_query() {
+        let data: Vec<char> = "</foo?bar=baz>".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 14);
+        assert_eq!(links.len(), 1);
+        assert_eq!(links[0].uri, 1..13);
+    }
+
+    #[test]
+    fn parses_rel_param_unquoted() {
+        let data: Vec<char> = "<//example.com>; rel=preconnect".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 31);
+
+        match &links[0].params[0] {
+            LinkParam::Rel { relation } => {
+                assert_eq!(relation.clone(), 21..31);
+            }
+            _ => assert!(false),
+        }
+    }
+
+    #[test]
+    fn parses_multiple_links_with_lws() {
+        let data: Vec<char> = "<//a>; rel=preconnect, <//b>".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 28);
+        assert_eq!(links.len(), 2);
+
+        match &links[0].params[0] {
+            LinkParam::Rel { relation } => {
+                assert_eq!(relation.clone(), 11..21);
+            }
+        }
+
+        assert_eq!(links[1].params.len(), 0);
+        assert_eq!(links[0].uri, 1..4);
+        assert_eq!(links[1].uri, 24..27);
+    }
+
+    #[test]
+    fn parses_lws_between_link_values() {
+        let data: Vec<char> = "<//a>,\r\n <//b>".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 14);
+        assert_eq!(links.len(), 2);
+        assert_eq!(links[0].uri, 1..4);
+        assert_eq!(links[1].uri, 10..13);
+    }
+
+    #[test]
+    // Is this correct?
+    fn rejects_absolute_uri() {
+        let data: Vec<char> = "<http://example.com>".chars().collect();
+
+        let res = parse_link(&data, 0);
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn rejects_missing_closing_delimiter() {
+        let data: Vec<char> = "<//example.com".chars().collect();
+
+        let res = parse_link(&data, 0);
+        assert!(res.is_none());
+    }
+
+    #[test]
+    fn parses_quoted_rel_multiple_values() {
+        let data: Vec<char> = "<//example.com>; rel=\"preconnect dns-prefetch\"".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, data.len());
+        assert_eq!(links.len(), 1);
+        assert_eq!(links[0].params.len(), 1);
+
+        match &links[0].params[0] {
+            LinkParam::Rel { relation } => {
+                assert_eq!(relation.clone(), 22..45);
+            }
+        }
+    }
+
+    #[test]
+    #[ignore = "absolute URI targets are not parsed yet"]
+    fn parses_absolute_uri_with_rel() {
+        let data: Vec<char> = "<http://example.com>; rel=preconnect".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 35);
+        assert_eq!(links.len(), 1);
+        assert_eq!(links[0].uri, 1..19);
+        match &links[0].params[0] {
+            LinkParam::Rel { relation } => assert_eq!(relation.clone(), 22..32),
+        }
+    }
+
+    #[test]
+    #[ignore = "additional parameters beyond rel= are not parsed"]
+    fn parses_title_parameter() {
+        let data: Vec<char> = "<//example.com>; rel=preconnect; title=\"Example\"".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 57);
+        assert_eq!(links.len(), 1);
+        assert_eq!(links[0].params.len(), 2);
+    }
+
+    #[test]
+    #[ignore = "extended title* parameter not supported"]
+    fn parses_title_star_parameter() {
+        let data: Vec<char> = "<//example.com>; rel=preconnect; title*=UTF-8''Ex%C3%A4mple".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 65);
+        assert_eq!(links.len(), 1);
+    }
+
+    #[test]
+    #[ignore = "anchor parameter not parsed"]
+    fn parses_anchor_parameter() {
+        let data: Vec<char> = "<//example.com>; rel=preconnect; anchor=\"/base\"".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 56);
+        assert_eq!(links.len(), 1);
+    }
+
+    #[test]
+    #[ignore = "hreflang parameter not parsed"]
+    fn parses_hreflang_parameter() {
+        let data: Vec<char> = "<//example.com>; rel=preconnect; hreflang=en".chars().collect();
+
+        let (links, pos) = parse_link(&data, 0).unwrap();
+
+        assert_eq!(pos, 53);
+        assert_eq!(links.len(), 1);
+    }
+
+    #[test]
+    #[ignore = "percent-encoded paths are not supported"]
+    fn rejects_percent_encoded_path() {
+        let data: Vec<char> = "</pa%20th>".chars().collect();
+
+        let res = parse_link(&data, 0);
+        assert!(res.is_some());
+    }
+}