Split up the URLPattern implementation (#36391)

The current implementation is already rather large at ~2.5k lines (~2k
LoC). There is still quite a lot of functionality left to implement, so
let's split it up while it's still manageable.

Testing: Covered by existing web platform tests

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/script/dom/urlpattern/tokenizer.rs

@@ -0,0 +1,524 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use script_bindings::error::{Error, Fallible};
+
+/// <https://urlpattern.spec.whatwg.org/#tokenize>
+pub(super) fn tokenize(input: &str, policy: TokenizePolicy) -> Fallible<Vec<Token>> {
+    // Step 1. Let tokenizer be a new tokenizer.
+    // Step 2. Set tokenizer’s input to input.
+    // Step 3. Set tokenizer’s policy to policy.
+    let mut tokenizer = Tokenizer {
+        input,
+        policy,
+        index: 0,
+        next_index: 0,
+        token_list: vec![],
+        code_point: char::MIN,
+    };
+
+    // Step 4. While tokenizer’s index is less than tokenizer’s input’s code point length:
+    while tokenizer.index < tokenizer.input.len() {
+        // Step 4.1 Run seek and get the next code point given tokenizer and tokenizer’s index.
+        tokenizer.seek_and_get_the_next_code_point(tokenizer.index);
+
+        match tokenizer.code_point {
+            // Step 4.2 If tokenizer’s code point is U+002A (*):
+            '*' => {
+                // Step 4.2.1 Run add a token with default position and length given tokenizer and "asterisk".
+                tokenizer.add_a_token_with_default_position_and_length(TokenType::Asterisk);
+
+                // Step 4.2.2 Continue.
+                continue;
+            },
+            // Step 4.3 If tokenizer’s code point is U+002B (+) or U+003F (?):
+            '+' | '?' => {
+                // Step 4.3.1 Run add a token with default position and length given tokenizer and "other-modifier".
+                tokenizer.add_a_token_with_default_position_and_length(TokenType::OtherModifier);
+
+                // Step 4.3.2 Continue.
+                continue;
+            },
+            // Step 4.4 If tokenizer’s code point is U+005C (\):
+            '\\' => {
+                // Step 4.4.1 If tokenizer’s index is equal to tokenizer’s input’s code point length − 1:
+                if tokenizer.is_done() {
+                    // Step 4.4.1.1 Run process a tokenizing error given tokenizer, tokenizer’s next index,
+                    // and tokenizer’s index.
+                    tokenizer.process_a_tokenizing_error(tokenizer.next_index, tokenizer.index)?;
+
+                    // Step 4.4.1.2 Continue.
+                    continue;
+                }
+
+                // Step 4.4.2 Let escaped index be tokenizer’s next index.
+                let escaped_index = tokenizer.index;
+
+                // Step 4.4.3 Run get the next code point given tokenizer.
+                tokenizer.get_the_next_code_point();
+
+                // Step 4.4.4 Run add a token with default length given tokenizer, "escaped-char",
+                // tokenizer’s next index, and escaped index.
+                tokenizer.add_a_token_with_default_length(
+                    TokenType::EscapedChar,
+                    tokenizer.next_index,
+                    escaped_index,
+                );
+
+                // Step 4.4.5 Continue.
+                continue;
+            },
+            // Step 4.5 If tokenizer’s code point is U+007B ({):
+            '{' => {
+                // Step 4.5.1 Run add a token with default position and length given tokenizer and "open".
+                tokenizer.add_a_token_with_default_position_and_length(TokenType::Open);
+
+                // Step 4.5.2 Continue.
+                continue;
+            },
+            // Step 4.6 If tokenizer’s code point is U+007D (}):
+            '}' => {
+                // Step 4.6.1 Run add a token with default position and length given tokenizer and "close".
+                tokenizer.add_a_token_with_default_position_and_length(TokenType::Close);
+
+                // Step 4.6.2 Continue.
+                continue;
+            },
+            // Step 4.7 If tokenizer’s code point is U+003A (:):
+            ':' => {
+                // Step 4.7.1 Let name position be tokenizer’s next index.
+                let mut name_position = tokenizer.next_index;
+
+                // Step 4.7.2 Let name start be name position.
+                let name_start = name_position;
+
+                // Step 4.7.3 While name position is less than tokenizer’s input’s code point length:
+                while name_position < tokenizer.input.len() {
+                    // Step 4.7.3.1 Run seek and get the next code point given tokenizer and name position.
+                    tokenizer.seek_and_get_the_next_code_point(name_position);
+
+                    // Step 4.7.3.2 Let first code point be true if name position equals name start
+                    // and false otherwise.
+                    let first_code_point = name_position == name_start;
+
+                    // Step 4.7.3.3 Let valid code point be the result of running is a valid name
+                    // code point given tokenizer’s code point and first code point.
+                    let valid_code_point =
+                        is_a_valid_name_code_point(tokenizer.code_point, first_code_point);
+
+                    // Step 4.7.3.4 If valid code point is false break.
+                    if !valid_code_point {
+                        break;
+                    }
+
+                    // Step 4.6.3.5 Set name position to tokenizer’s next index.
+                    name_position = tokenizer.next_index;
+                }
+
+                // Step 4.7.4 If name position is less than or equal to name start:
+                if name_position <= name_start {
+                    // Step 4.7.4.1 Run process a tokenizing error given tokenizer, name start, and tokenizer’s index.
+                    tokenizer.process_a_tokenizing_error(name_start, tokenizer.index)?;
+
+                    // Step 4.7.4.2 Continue.
+                    continue;
+                }
+
+                // Step 4.7.5 Run add a token with default length given tokenizer, "name", name position,
+                // and name start.
+                tokenizer.add_a_token_with_default_length(
+                    TokenType::Name,
+                    name_position,
+                    name_start,
+                );
+
+                // Step 4.7.6 Continue.
+                continue;
+            },
+            // Step 4.8 If tokenizer’s code point is U+0028 (():
+            '(' => {
+                // Step 4.8.1 Let depth be 1.
+                let mut depth = 1;
+
+                // Step 4.8.2 Let regexp position be tokenizer’s next index.
+                let mut regexp_position = tokenizer.next_index;
+
+                // Step 4.8.3 Let regexp start be regexp position.
+                let regexp_start = regexp_position;
+
+                // Step 4.8.4 Let error be false.
+                let mut error = false;
+
+                // Step 4.8.5 While regexp position is less than tokenizer’s input’s code point length:
+                while regexp_position < tokenizer.input.len() {
+                    // Step 4.8.5.1 Run seek and get the next code point given tokenizer and regexp position.
+                    tokenizer.seek_and_get_the_next_code_point(regexp_position);
+
+                    // Step 4.8.5.2 If tokenizer’s code point is not an ASCII code point:
+                    if !tokenizer.code_point.is_ascii() {
+                        // Step 4.8.5.1.1 Run process a tokenizing error given tokenizer, regexp start,
+                        // and tokenizer’s index.
+                        tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                        // Step 4.8.5.1.2 Set error to true.
+                        error = true;
+
+                        // Step 4.8.5.1.2 Break.
+                        break;
+                    }
+
+                    // Step 4.8.5.3 If regexp position equals regexp start and tokenizer’s code point is U+003F (?):
+                    if regexp_position == regexp_start && tokenizer.code_point == '?' {
+                        // Step 4.8.5.3.1 Run process a tokenizing error given tokenizer, regexp start,
+                        // and tokenizer’s index.
+                        tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                        // Step 4.8.5.3.2 Set error to true.
+                        error = true;
+
+                        // Step 4.8.5.3.3 Break.
+                        break;
+                    }
+
+                    // Step 4.8.5.4 If tokenizer’s code point is U+005C (\):
+                    if tokenizer.code_point == '\\' {
+                        // Step 4.8.5.4.1 If regexp position equals tokenizer’s input’s code point length − 1:
+                        if tokenizer.is_last_character(regexp_position) {
+                            // Step 4.8.5.4.1.1 Run process a tokenizing error given tokenizer, regexp start,
+                            // and tokenizer’s index.
+                            tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                            // Step 4.8.5.4.1.2 Set error to true.
+                            error = true;
+
+                            // Step 4.8.5.4.1.3 Break
+                            break;
+                        }
+
+                        // Step 4.8.5.4.2 Run get the next code point given tokenizer.
+                        tokenizer.get_the_next_code_point();
+
+                        // Step 4.8.5.4.3 If tokenizer’s code point is not an ASCII code point:
+                        if !tokenizer.code_point.is_ascii() {
+                            // Step 4.8.5.4.3.1 Run process a tokenizing error given tokenizer, regexp start,
+                            // and tokenizer’s index.
+                            tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                            // Step 4.8.5.4.3.2 Set error to true.
+                            error = true;
+
+                            // Step 4.8.5.4.3.3 Break
+                            break;
+                        }
+
+                        // Step 4.8.5.4.4 Set regexp position to tokenizer’s next index.
+                        regexp_position = tokenizer.next_index;
+
+                        // Step 4.8.5.4.5 Continue.
+                        continue;
+                    }
+
+                    // Step 4.8.5.5 If tokenizer’s code point is U+0029 ()):
+                    if tokenizer.code_point == ')' {
+                        // Step 4.8.5.5.1 Decrement depth by 1.
+                        depth -= 1;
+
+                        // Step 4.8.5.5.2 If depth is 0:
+                        if depth == 0 {
+                            // Step 4.8.5.5.2.1 Set regexp position to tokenizer’s next index.
+                            regexp_position = tokenizer.next_index;
+
+                            // Step 4.8.5.5.2.2 Break.
+                            break;
+                        }
+                    }
+                    // Step 4.8.5.6 Otherwise if tokenizer’s code point is U+0028 (():
+                    else if tokenizer.code_point == '(' {
+                        // Step 4.8.5.6.1 Increment depth by 1.
+                        depth += 1;
+
+                        // Step 4.8.5.6.2 If regexp position equals tokenizer’s input’s code point length − 1:
+                        if tokenizer.is_last_character(regexp_position) {
+                            // Step 4.8.5.6.2.1 Run process a tokenizing error given tokenizer, regexp start,
+                            // and tokenizer’s index.
+                            tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                            // Step 4.8.5.6.2.2 Set error to true.
+                            error = true;
+
+                            // Step 4.8.5.6.2.3 Break
+                            break;
+                        }
+
+                        // Step 4.8.5.6.3 Let temporary position be tokenizer’s next index.
+                        let temporary_position = tokenizer.next_index;
+
+                        // Step 4.8.5.6.4 Run get the next code point given tokenizer.
+                        tokenizer.get_the_next_code_point();
+
+                        // Step 4.8.5.6.5 If tokenizer’s code point is not U+003F (?):
+                        if tokenizer.code_point != '?' {
+                            // Step 4.8.5.6.5.1 Run process a tokenizing error given tokenizer, regexp start,
+                            // and tokenizer’s index.
+                            tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                            // Step 4.8.5.6.5.2 Set error to true.
+                            error = true;
+
+                            // Step 4.8.5.6.5.3 Break.
+                            break;
+                        }
+
+                        // Step 4.8.5.6.6 Set tokenizer’s next index to temporary position.
+                        tokenizer.next_index = temporary_position;
+                    }
+
+                    // Step 4.8.5.7 Set regexp position to tokenizer’s next index.
+                    regexp_position = tokenizer.next_index;
+                }
+
+                // Step 4.8.6 If error is true continue.
+                if error {
+                    continue;
+                }
+
+                // Step 4.8.7 If depth is not zero:
+                if depth != 0 {
+                    // Step 4.8.7.1 Run process a tokenizing error given tokenizer, regexp start,
+                    // and tokenizer’s index
+                    tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                    // Step 4.8.7.2 Continue.
+                    continue;
+                }
+
+                // Step 4.8.8 Let regexp length be regexp position − regexp start − 1.
+                let regexp_length = regexp_position - regexp_start - 1;
+
+                // Step 4.8.9 If regexp length is zero:
+                if regexp_length == 0 {
+                    // Step 4.8.9.1 Run process a tokenizing error given tokenizer, regexp start,
+                    // and tokenizer’s index.
+                    tokenizer.process_a_tokenizing_error(regexp_start, tokenizer.index)?;
+
+                    // Step 4.8.9.2 Continue.
+                    continue;
+                }
+
+                // Step 4.8.10 Run add a token given tokenizer, "regexp", regexp position,
+                // regexp start, and regexp length.
+                tokenizer.add_a_token(
+                    TokenType::Regexp,
+                    regexp_position,
+                    regexp_start,
+                    regexp_length,
+                );
+
+                // Step 4.8.11 Continue.
+                continue;
+            },
+            _ => {
+                // Step 4.9 Run add a token with default position and length given tokenizer and "char".
+                tokenizer.add_a_token_with_default_position_and_length(TokenType::Char);
+            },
+        }
+    }
+
+    // Step 5. Run add a token with default length given tokenizer, "end", tokenizer’s index, and tokenizer’s index.
+    tokenizer.add_a_token_with_default_length(TokenType::End, tokenizer.index, tokenizer.index);
+
+    // Step 6.Return tokenizer’s token list.
+    Ok(tokenizer.token_list)
+}
+
+/// <https://urlpattern.spec.whatwg.org/#tokenizer>
+struct Tokenizer<'a> {
+    /// <https://urlpattern.spec.whatwg.org/#tokenizer-input>
+    input: &'a str,
+
+    /// <https://urlpattern.spec.whatwg.org/#tokenizer-policy>
+    policy: TokenizePolicy,
+
+    /// <https://urlpattern.spec.whatwg.org/#tokenizer-index>
+    ///
+    /// Note that we deviate the from the spec and index bytes, not code points.
+    index: usize,
+
+    /// <https://urlpattern.spec.whatwg.org/#tokenizer-next-index>
+    ///
+    /// Note that we deviate the from the spec and index bytes, not code points.
+    next_index: usize,
+
+    /// <https://urlpattern.spec.whatwg.org/#tokenizer-token-list>
+    token_list: Vec<Token<'a>>,
+
+    /// <https://urlpattern.spec.whatwg.org/#tokenizer-code-point>
+    code_point: char,
+}
+
+/// <https://urlpattern.spec.whatwg.org/#token>
+#[derive(Clone, Copy, Debug)]
+#[allow(dead_code)] // index isn't used yet, because constructor strings aren't parsed
+pub(super) struct Token<'a> {
+    /// <https://urlpattern.spec.whatwg.org/#token-index>
+    pub(super) index: usize,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-value>
+    pub(super) value: &'a str,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type>
+    pub(super) token_type: TokenType,
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(super) enum TokenType {
+    /// <https://urlpattern.spec.whatwg.org/#token-type-open>
+    Open,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-close>
+    Close,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-regexp>
+    Regexp,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-name>
+    Name,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-char>
+    Char,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-escaped-char>
+    EscapedChar,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-other-modifier>
+    OtherModifier,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-asterisk>
+    Asterisk,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-end>
+    End,
+
+    /// <https://urlpattern.spec.whatwg.org/#token-type-invalid-char>
+    InvalidChar,
+}
+
+/// <https://urlpattern.spec.whatwg.org/#tokenize-policy>
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub(super) enum TokenizePolicy {
+    /// <https://urlpattern.spec.whatwg.org/#tokenize-policy-strict>
+    Strict,
+
+    /// <https://urlpattern.spec.whatwg.org/#tokenize-policy-lenient>
+    Lenient,
+}
+
+impl Tokenizer<'_> {
+    fn is_last_character(&self, position: usize) -> bool {
+        self.input[position..].chars().count() == 1
+    }
+
+    fn is_done(&self) -> bool {
+        self.input[self.next_index..].is_empty()
+    }
+
+    /// <https://urlpattern.spec.whatwg.org/#get-the-next-code-point>
+    fn get_the_next_code_point(&mut self) {
+        // Step 1. Set tokenizer’s code point to the Unicode code point in tokenizer’s
+        // input at the position indicated by tokenizer’s next index.
+        self.code_point = self.input[self.next_index..]
+            .chars()
+            .next()
+            .expect("URLPattern tokenizer is trying to read out of bounds");
+
+        // Step 2. Increment tokenizer’s next index by 1.
+        // NOTE: Because our next_index is indexing bytes (not code points) we use
+        // the utf8 length of the code point instead.
+        self.next_index = self.next_index.wrapping_add(self.code_point.len_utf8());
+    }
+
+    /// <https://urlpattern.spec.whatwg.org/#seek-and-get-the-next-code-point>
+    fn seek_and_get_the_next_code_point(&mut self, index: usize) {
+        // Step 1. Set tokenizer’s next index to index.
+        self.next_index = index;
+
+        // Step 2. Run get the next code point given tokenizer.
+        self.get_the_next_code_point();
+    }
+
+    /// <https://urlpattern.spec.whatwg.org/#add-a-token>
+    fn add_a_token(
+        &mut self,
+        token_type: TokenType,
+        next_position: usize,
+        value_position: usize,
+        value_length: usize,
+    ) {
+        // Step 1. Let token be a new token.
+        // Step 2. Set token’s type to type.
+        // Step 3. Set token’s index to tokenizer’s index.
+        // Step 4. Set token’s value to the code point substring from value position
+        // with length value length within tokenizer’s input.
+        let token = Token {
+            token_type,
+            index: self.index,
+            value: &self.input[value_position..][..value_length],
+        };
+
+        // Step 5. Append token to the back of tokenizer’s token list.
+        self.token_list.push(token);
+
+        // Step 6. Set tokenizer’s index to next position.
+        self.index = next_position;
+    }
+
+    /// <https://urlpattern.spec.whatwg.org/#add-a-token-with-default-position-and-length>
+    fn add_a_token_with_default_position_and_length(&mut self, token_type: TokenType) {
+        // Step 1. Run add a token with default length given tokenizer, type,
+        // tokenizer’s next index, and tokenizer’s index.
+        self.add_a_token_with_default_length(token_type, self.next_index, self.index);
+    }
+
+    /// <https://urlpattern.spec.whatwg.org/#add-a-token-with-default-length>
+    fn add_a_token_with_default_length(
+        &mut self,
+        token_type: TokenType,
+        next_position: usize,
+        value_position: usize,
+    ) {
+        // Step 1. Let computed length be next position − value position.
+        let computed_length = next_position - value_position;
+
+        // Step 2. Run add a token given tokenizer, type, next position, value position, and computed length.
+        self.add_a_token(token_type, next_position, value_position, computed_length);
+    }
+
+    /// <https://urlpattern.spec.whatwg.org/#process-a-tokenizing-error>
+    fn process_a_tokenizing_error(
+        &mut self,
+        next_position: usize,
+        value_position: usize,
+    ) -> Fallible<()> {
+        // Step 1. If tokenizer’s policy is "strict", then throw a TypeError.
+        if self.policy == TokenizePolicy::Strict {
+            return Err(Error::Type("Failed to tokenize URL pattern".into()));
+        }
+
+        // Step 2. Assert: tokenizer’s policy is "lenient".
+        debug_assert_eq!(self.policy, TokenizePolicy::Lenient);
+
+        // Step 3. Run add a token with default length given tokenizer, "invalid-char",
+        // next position, and value position.
+        self.add_a_token_with_default_length(TokenType::InvalidChar, next_position, value_position);
+
+        Ok(())
+    }
+}
+
+/// <https://urlpattern.spec.whatwg.org/#is-a-valid-name-code-point>
+fn is_a_valid_name_code_point(code_point: char, first: bool) -> bool {
+    // FIXME: implement this check
+    _ = first;
+    code_point.is_alphabetic()
+}