Add Parser::expect_no_error_token

Author: SimonSapin

src/parser.rs

@@ -620,6 +620,27 @@ impl<'i, 't> Parser<'i, 't> {
             _ => Err(())
         }
     }
+
+    /// Parse the input until exhaustion and check that it contains no “error” token.
+    ///
+    /// See `Token::is_parse_error`. This also checks nested blocks and functions recursively.
+    #[inline]
+    pub fn expect_no_error_token(&mut self) -> Result<(), ()> {
+        loop {
+            match self.next_including_whitespace_and_comments() {
+                Ok(Token::Function(_)) | Ok(Token::ParenthesisBlock) |
+                Ok(Token::SquareBracketBlock) | Ok(Token::CurlyBracketBlock) => {
+                    try!(self.parse_nested_block(|input| input.expect_no_error_token()))
+                }
+                Ok(token) => {
+                    if token.is_parse_error() {
+                        return Err(())
+                    }
+                }
+                Err(()) => return Ok(())
+            }
+        }
+    }
 }
 
 

src/tests.rs

@@ -267,6 +267,19 @@ fn stylesheet_from_bytes() {
 }
 
 
+#[test]
+fn expect_no_error_token() {
+    assert!(Parser::new("foo 4px ( / { !bar }").expect_no_error_token().is_ok());
+    assert!(Parser::new(")").expect_no_error_token().is_err());
+    assert!(Parser::new("}").expect_no_error_token().is_err());
+    assert!(Parser::new("(a){]").expect_no_error_token().is_err());
+    assert!(Parser::new("'\n'").expect_no_error_token().is_err());
+    assert!(Parser::new("url('\n'").expect_no_error_token().is_err());
+    assert!(Parser::new("url(a b)").expect_no_error_token().is_err());
+    assert!(Parser::new("url(\u{7F})").expect_no_error_token().is_err());
+}
+
+
 fn run_color_tests<F: Fn(Result<Color, ()>) -> Json>(json_data: &str, to_json: F) {
     run_json_tests(json_data, |input| {
         to_json(input.parse_entirely(Color::parse))

src/tokenizer.rs

@@ -158,6 +158,22 @@ pub enum Token<'a> {
 }
 
 
+impl<'a> Token<'a> {
+    /// Return whether this token represents a parse error.
+    ///
+    /// `BadUrl` and `BadString` are tokenizer-level parse errors.
+    ///
+    /// `CloseParenthesis`, `CloseSquareBracket`, and `CloseCurlyBracket` are *unmatched*
+    /// and therefore parse errors when returned by one of the `Parser::next*` methods.
+    pub fn is_parse_error(&self) -> bool {
+        matches!(
+            *self,
+            BadUrl | BadString | CloseParenthesis | CloseSquareBracket | CloseCurlyBracket
+        )
+    }
+}
+
+
 /// The numeric value of `Number` and `Dimension` tokens.
 #[derive(PartialEq, Debug, Copy, Clone)]
 pub struct NumericValue {