Auto merge of #155 - jdm:err2, r=SimonSapin

Return meaningful error values when parsing

This is #143 with an extra commit added to accommodate changes requested in servo/servo#16752.

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Author: bors-servo

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 
 name = "cssparser"
-version = "0.13.7"
+version = "0.14.0"
 authors = [ "Simon Sapin <simon.sapin@exyr.org>" ]
 
 description = "Rust implementation of CSS Syntax Level 3"

src/color.rs

@@ -5,7 +5,7 @@
 use std::fmt;
 use std::f32::consts::PI;
 
-use super::{Token, Parser, ToCss};
+use super::{Token, Parser, ToCss, ParseError, BasicParseError};
 use tokenizer::NumericValue;
 
 #[cfg(feature = "serde")]
@@ -141,46 +141,48 @@ impl Color {
     /// Parse a <color> value, per CSS Color Module Level 3.
     ///
     /// FIXME(#2) Deprecated CSS2 System Colors are not supported yet.
-    pub fn parse(input: &mut Parser) -> Result<Color, ()> {
-        match try!(input.next()) {
-            Token::Hash(value) | Token::IDHash(value) => {
+    pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Color, BasicParseError<'i>> {
+        let token = try!(input.next());
+        match token {
+            Token::Hash(ref value) | Token::IDHash(ref value) => {
                 Color::parse_hash(value.as_bytes())
             },
-            Token::Ident(value) => parse_color_keyword(&*value),
-            Token::Function(name) => {
-                input.parse_nested_block(|arguments| {
+            Token::Ident(ref value) => parse_color_keyword(&*value),
+            Token::Function(ref name) => {
+                return input.parse_nested_block(|arguments| {
                     parse_color_function(&*name, arguments)
-                })
+                        .map_err(|e| ParseError::Basic(e))
+                }).map_err(ParseError::<()>::basic);
             }
             _ => Err(())
-        }
+        }.map_err(|()| BasicParseError::UnexpectedToken(token))
     }
 
     /// Parse a color hash, without the leading '#' character.
     #[inline]
     pub fn parse_hash(value: &[u8]) -> Result<Self, ()> {
         match value.len() {
-            8 => rgba(
+            8 => Ok(rgba(
                 try!(from_hex(value[0])) * 16 + try!(from_hex(value[1])),
                 try!(from_hex(value[2])) * 16 + try!(from_hex(value[3])),
                 try!(from_hex(value[4])) * 16 + try!(from_hex(value[5])),
-                try!(from_hex(value[6])) * 16 + try!(from_hex(value[7])),
+                try!(from_hex(value[6])) * 16 + try!(from_hex(value[7]))),
             ),
-            6 => rgb(
+            6 => Ok(rgb(
                 try!(from_hex(value[0])) * 16 + try!(from_hex(value[1])),
                 try!(from_hex(value[2])) * 16 + try!(from_hex(value[3])),
-                try!(from_hex(value[4])) * 16 + try!(from_hex(value[5])),
+                try!(from_hex(value[4])) * 16 + try!(from_hex(value[5]))),
             ),
-            4 => rgba(
+            4 => Ok(rgba(
                 try!(from_hex(value[0])) * 17,
                 try!(from_hex(value[1])) * 17,
                 try!(from_hex(value[2])) * 17,
-                try!(from_hex(value[3])) * 17,
+                try!(from_hex(value[3])) * 17),
             ),
-            3 => rgb(
+            3 => Ok(rgb(
                 try!(from_hex(value[0])) * 17,
                 try!(from_hex(value[1])) * 17,
-                try!(from_hex(value[2])) * 17,
+                try!(from_hex(value[2])) * 17),
             ),
             _ => Err(())
         }
@@ -190,13 +192,13 @@ impl Color {
 
 
 #[inline]
-fn rgb(red: u8, green: u8, blue: u8) -> Result<Color, ()> {
+fn rgb(red: u8, green: u8, blue: u8) -> Color {
     rgba(red, green, blue, 255)
 }
 
 #[inline]
-fn rgba(red: u8, green: u8, blue: u8, alpha: u8) -> Result<Color, ()> {
-    Ok(Color::RGBA(RGBA::new(red, green, blue, alpha)))
+fn rgba(red: u8, green: u8, blue: u8, alpha: u8) -> Color {
+    Color::RGBA(RGBA::new(red, green, blue, alpha))
 }
 
 
@@ -410,11 +412,11 @@ fn clamp_floor_256_f32(val: f32) -> u8 {
 }
 
 #[inline]
-fn parse_color_function(name: &str, arguments: &mut Parser) -> Result<Color, ()> {
+fn parse_color_function<'i, 't>(name: &str, arguments: &mut Parser<'i, 't>) -> Result<Color, BasicParseError<'i>> {
     let (red, green, blue, uses_commas) = match_ignore_ascii_case! { name,
         "rgb" | "rgba" => parse_rgb_components_rgb(arguments)?,
         "hsl" | "hsla" => parse_rgb_components_hsl(arguments)?,
-        _ => return Err(())
+        _ => return Err(BasicParseError::UnexpectedToken(Token::Ident(name.to_owned().into()))),
     };
 
     let alpha = if !arguments.is_exhausted() {
@@ -423,7 +425,7 @@ fn parse_color_function(name: &str, arguments: &mut Parser) -> Result<Color, ()>
         } else {
             match try!(arguments.next()) {
                 Token::Delim('/') => {},
-                _ => return Err(())
+                t => return Err(BasicParseError::UnexpectedToken(t)),
             };
         };
         let token = try!(arguments.next());
@@ -434,21 +436,21 @@ fn parse_color_function(name: &str, arguments: &mut Parser) -> Result<Color, ()>
             Token::Percentage(ref v) => {
                 clamp_unit_f32(v.unit_value)
             }
-            _ => {
-                return Err(())
+            t => {
+                return Err(BasicParseError::UnexpectedToken(t))
             }
         }
     } else {
         255
     };
 
     try!(arguments.expect_exhausted());
-    rgba(red, green, blue, alpha)
+    Ok(rgba(red, green, blue, alpha))
 }
 
 
 #[inline]
-fn parse_rgb_components_rgb(arguments: &mut Parser) -> Result<(u8, u8, u8, bool), ()> {
+fn parse_rgb_components_rgb<'i, 't>(arguments: &mut Parser<'i, 't>) -> Result<(u8, u8, u8, bool), BasicParseError<'i>> {
     let red: u8;
     let green: u8;
     let blue: u8;
@@ -465,7 +467,7 @@ fn parse_rgb_components_rgb(arguments: &mut Parser) -> Result<(u8, u8, u8, bool)
                     uses_commas = true;
                     try!(arguments.expect_number())
                 }
-                _ => return Err(())
+                t => return Err(BasicParseError::UnexpectedToken(t))
             });
             if uses_commas {
                 try!(arguments.expect_comma());
@@ -480,36 +482,38 @@ fn parse_rgb_components_rgb(arguments: &mut Parser) -> Result<(u8, u8, u8, bool)
                     uses_commas = true;
                     try!(arguments.expect_percentage())
                 }
-                _ => return Err(())
+                t => return Err(BasicParseError::UnexpectedToken(t))
             });
             if uses_commas {
                 try!(arguments.expect_comma());
             }
             blue = clamp_unit_f32(try!(arguments.expect_percentage()));
         }
-        _ => return Err(())
+        t => return Err(BasicParseError::UnexpectedToken(t))
     };
     return Ok((red, green, blue, uses_commas));
 }
 
 #[inline]
-fn parse_rgb_components_hsl(arguments: &mut Parser) -> Result<(u8, u8, u8, bool), ()> {
+fn parse_rgb_components_hsl<'i, 't>(arguments: &mut Parser<'i, 't>) -> Result<(u8, u8, u8, bool), BasicParseError<'i>> {
     let mut uses_commas = false;
     // Hue given as an angle
     // https://drafts.csswg.org/css-values/#angles
-    let hue_degrees = match try!(arguments.next()) {
-        Token::Number(NumericValue { value: v, .. }) => v,
-        Token::Dimension(NumericValue { value: v, .. }, unit) => {
+    let token = try!(arguments.next());
+    let hue_degrees = match token {
+        Token::Number(NumericValue { value: v, .. }) => Ok(v),
+        Token::Dimension(NumericValue { value: v, .. }, ref unit) => {
             match_ignore_ascii_case! { &*unit,
-                "deg" => v,
-                "grad" => v * 360. / 400.,
-                "rad" => v * 360. / (2. * PI),
-                "turn" => v * 360.,
-                _ => return Err(())
+                "deg" => Ok(v),
+                "grad" => Ok(v * 360. / 400.),
+                "rad" => Ok(v * 360. / (2. * PI)),
+                "turn" => Ok(v * 360.),
+                _ => Err(()),
             }
         }
-        _ => return Err(())
+        t => return Err(BasicParseError::UnexpectedToken(t))
     };
+    let hue_degrees = try!(hue_degrees.map_err(|()| BasicParseError::UnexpectedToken(token)));
     // Subtract an integer before rounding, to avoid some rounding errors:
     let hue_normalized_degrees = hue_degrees - 360. * (hue_degrees / 360.).floor();
     let hue = hue_normalized_degrees / 360.;
@@ -522,7 +526,7 @@ fn parse_rgb_components_hsl(arguments: &mut Parser) -> Result<(u8, u8, u8, bool)
             uses_commas = true;
             try!(arguments.expect_percentage())
         }
-        _ => return Err(())
+        t => return Err(BasicParseError::UnexpectedToken(t))
     };
     let saturation = saturation.max(0.).min(1.);
 

src/lib.rs

@@ -89,7 +89,7 @@ pub use from_bytes::{stylesheet_encoding, EncodingSupport};
 pub use color::{RGBA, Color, parse_color_keyword};
 pub use nth::parse_nth;
 pub use serializer::{ToCss, CssStringWriter, serialize_identifier, serialize_string, TokenSerializationType};
-pub use parser::{Parser, Delimiter, Delimiters, SourcePosition};
+pub use parser::{Parser, Delimiter, Delimiters, SourcePosition, ParseError, BasicParseError, ParserInput};
 pub use unicode_range::UnicodeRange;
 
 // For macros

src/nth.rs

@@ -4,76 +4,98 @@
 
 use std::ascii::AsciiExt;
 
-use super::{Token, Parser};
+use super::{Token, Parser, BasicParseError};
 
 
 /// Parse the *An+B* notation, as found in the `:nth-child()` selector.
 /// The input is typically the arguments of a function,
 /// in which case the caller needs to check if the arguments’ parser is exhausted.
 /// Return `Ok((A, B))`, or `Err(())` for a syntax error.
-pub fn parse_nth(input: &mut Parser) -> Result<(i32, i32), ()> {
-    match try!(input.next()) {
-        Token::Number(value) => Ok((0, try!(value.int_value.ok_or(())) as i32)),
-        Token::Dimension(value, unit) => {
-            let a = try!(value.int_value.ok_or(())) as i32;
-            match_ignore_ascii_case! { &unit,
-                "n" => parse_b(input, a),
-                "n-" => parse_signless_b(input, a, -1),
-                _ => Ok((a, try!(parse_n_dash_digits(&*unit))))
+pub fn parse_nth<'i, 't>(input: &mut Parser<'i, 't>) -> Result<(i32, i32), BasicParseError<'i>> {
+    let token = try!(input.next());
+    match token {
+        Token::Number(ref value) => {
+            match value.int_value {
+                Some(v) => Ok((0, v as i32)),
+                None => Err(()),
             }
         }
-        Token::Ident(value) => {
+        Token::Dimension(value, ref unit) => {
+            match value.int_value {
+                Some(v) => {
+                    let a = v as i32;
+                    match_ignore_ascii_case! {
+                        &unit,
+                        "n" => Ok(try!(parse_b(input, a))),
+                        "n-" => Ok(try!(parse_signless_b(input, a, -1))),
+                        _ => {
+                            parse_n_dash_digits(&*unit).map(|val| (a, val))
+                        }
+                    }
+                }
+                None => Err(()),
+            }
+        }
+        Token::Ident(ref value) => {
             match_ignore_ascii_case! { &value,
                 "even" => Ok((2, 0)),
                 "odd" => Ok((2, 1)),
-                "n" => parse_b(input, 1),
-                "-n" => parse_b(input, -1),
-                "n-" => parse_signless_b(input, 1, -1),
-                "-n-" => parse_signless_b(input, -1, -1),
+                "n" => Ok(try!(parse_b(input, 1))),
+                "-n" => Ok(try!(parse_b(input, -1))),
+                "n-" => Ok(try!(parse_signless_b(input, 1, -1))),
+                "-n-" => Ok(try!(parse_signless_b(input, -1, -1))),
                 _ => if value.starts_with("-") {
-                    Ok((-1, try!(parse_n_dash_digits(&value[1..]))))
+                    parse_n_dash_digits(&value[1..]).map(|v| (-1, v))
                 } else {
-                    Ok((1, try!(parse_n_dash_digits(&*value))))
+                    parse_n_dash_digits(&*value).map(|v| (1, v))
                 }
             }
         }
         Token::Delim('+') => match try!(input.next_including_whitespace()) {
             Token::Ident(value) => {
                 match_ignore_ascii_case! { &value,
-                    "n" => parse_b(input, 1),
-                    "n-" => parse_signless_b(input, 1, -1),
-                    _ => Ok((1, try!(parse_n_dash_digits(&*value))))
+                    "n" => Ok(try!(parse_b(input, 1))),
+                    "n-" => Ok(try!(parse_signless_b(input, 1, -1))),
+                    _ => parse_n_dash_digits(&*value).map(|v| (1, v))
                 }
             }
-            _ => Err(())
+            t => return Err(BasicParseError::UnexpectedToken(t)),
         },
-        _ => Err(())
-    }
+        _ => Err(()),
+    }.map_err(|()| BasicParseError::UnexpectedToken(token))
 }
 
 
-fn parse_b(input: &mut Parser, a: i32) -> Result<(i32, i32), ()> {
+fn parse_b<'i, 't>(input: &mut Parser<'i, 't>, a: i32) -> Result<(i32, i32), BasicParseError<'i>> {
     let start_position = input.position();
-    match input.next() {
-        Ok(Token::Delim('+')) => parse_signless_b(input, a, 1),
-        Ok(Token::Delim('-')) => parse_signless_b(input, a, -1),
+    let token = input.next();
+    match token {
+        Ok(Token::Delim('+')) => Ok(try!(parse_signless_b(input, a, 1))),
+        Ok(Token::Delim('-')) => Ok(try!(parse_signless_b(input, a, -1))),
         Ok(Token::Number(ref value)) if value.has_sign => {
-            Ok((a, try!(value.int_value.ok_or(())) as i32))
+            match value.int_value {
+                Some(v) => Ok((a, v as i32)),
+                None => Err(()),
+            }
         }
         _ => {
             input.reset(start_position);
             Ok((a, 0))
         }
-    }
+    }.map_err(|()| BasicParseError::UnexpectedToken(token.unwrap()))
 }
 
-fn parse_signless_b(input: &mut Parser, a: i32, b_sign: i32) -> Result<(i32, i32), ()> {
-    match try!(input.next()) {
+fn parse_signless_b<'i, 't>(input: &mut Parser<'i, 't>, a: i32, b_sign: i32) -> Result<(i32, i32), BasicParseError<'i>> {
+    let token = try!(input.next());
+    match token {
         Token::Number(ref value) if !value.has_sign => {
-            Ok((a, b_sign * (try!(value.int_value.ok_or(())) as i32)))
+            match value.int_value {
+                Some(v) => Ok((a, b_sign * v as i32)),
+                None => Err(()),
+            }
         }
         _ => Err(())
-    }
+    }.map_err(|()| BasicParseError::UnexpectedToken(token))
 }
 
 fn parse_n_dash_digits(string: &str) -> Result<i32, ()> {