feat(css/parser): Improve parser api (#2847)

swc_css_parser:
 - Allow parsing as more types.

crates/swc_css_parser/src/parser/at_rule.rs

@@ -278,21 +278,13 @@ where
         let span = self.input.cur_span()?;
 
         let src = match cur!(self) {
-            Token::Str { .. } => {
-                let str = self.parse()?;
-
-                Ok(ImportSource::Str(str))
-            }
+            Token::Str { .. } => Ok(ImportSource::Str(self.parse()?)),
             Token::Function { value, .. } if *value.to_ascii_lowercase() == js_word!("url") => {
                 let func = self.parse()?;
 
                 Ok(ImportSource::Fn(func))
             }
-            Token::Url { .. } => {
-                let url = self.parse()?;
-
-                Ok(ImportSource::Url(url))
-            }
+            Token::Url { .. } => Ok(ImportSource::Url(self.parse()?)),
             _ => Err(Error::new(
                 span,
                 ErrorKind::Expected("url('https://example.com') or 'https://example.com'"),
@@ -520,7 +512,7 @@ where
         let span = self.input.cur_span()?;
 
         if is!(self, Ident) {
-            self.parse_id().map(KeyframeSelector::Ident)
+            self.parse().map(KeyframeSelector::Ident)
         } else if is!(self, Percent) {
             self.parse().map(KeyframeSelector::Percent)
         } else {
@@ -706,12 +698,12 @@ where
                 query,
             })
         } else if is!(self, Ident) {
-            let ident = self.parse_id()?;
+            let ident = self.parse()?;
             MediaQuery::Ident(ident)
         } else if eat!(self, "(") {
             if is!(self, Ident) {
                 let span = self.input.cur_span()?;
-                let id = self.parse_id()?;
+                let id = self.parse()?;
 
                 self.input.skip_ws()?;
 
@@ -844,13 +836,13 @@ where
         let start = self.input.cur_span()?.lo;
 
         let ident = if is!(self, Ident) {
-            Some(self.parse_id()?)
+            Some(self.parse()?)
         } else {
             None
         };
 
         let pseudo = if eat!(self, ":") {
-            Some(self.parse_id()?)
+            Some(self.parse()?)
         } else {
             None
         };

crates/swc_css_parser/src/parser/mod.rs

@@ -1,8 +1,5 @@
 use self::input::{Buffer, ParserInput};
-use crate::{
-    error::{Error, ErrorKind},
-    Parse,
-};
+use crate::{error::Error, Parse};
 use std::mem::take;
 use swc_common::Span;
 use swc_css_ast::*;
@@ -85,20 +82,6 @@ where
     pub fn parse_all(&mut self) -> PResult<Stylesheet> {
         self.parse()
     }
-
-    fn parse_id(&mut self) -> PResult<Ident> {
-        let span = self.input.cur_span()?;
-        if !is!(self, Ident) {
-            return Err(Error::new(span, ErrorKind::Expected("Ident")));
-        }
-
-        match bump!(self) {
-            Token::Ident { value, raw } => Ok(Ident { span, value, raw }),
-            _ => {
-                unreachable!()
-            }
-        }
-    }
 }
 
 #[derive(Clone, Copy)]

crates/swc_css_parser/src/parser/style_rule.rs

@@ -157,7 +157,7 @@ where
 
         self.input.skip_ws()?;
 
-        let property = self.parse_id()?;
+        let property = self.parse()?;
 
         self.input.skip_ws()?;
 

crates/swc_css_parser/src/parser/value/mod.rs

@@ -192,16 +192,7 @@ where
 
         let span = self.input.cur_span()?;
         match cur!(self) {
-            Token::Str { .. } => {
-                let token = bump!(self);
-
-                match token {
-                    Token::Str { value, raw } => return Ok(Value::Str(Str { span, value, raw })),
-                    _ => {
-                        unreachable!()
-                    }
-                }
-            }
+            Token::Str { .. } => return Ok(Value::Str(self.parse()?)),
 
             Token::Num { .. } => return self.parse_numeric_value(),
 
@@ -211,7 +202,7 @@ where
 
             Token::Dimension { .. } => return self.parse_numeric_value(),
 
-            Token::Ident { .. } => return self.parse_value_ident_or_fn(),
+            Token::Ident { .. } => return Ok(Value::Ident(self.parse()?)),
 
             tok!("[") => return self.parse_square_brackets_value().map(From::from),
 
@@ -260,20 +251,7 @@ where
                 }));
             }
 
-            Token::Url { .. } => {
-                let url = match bump!(self) {
-                    Token::Url { value, raw } => (value, raw),
-                    _ => {
-                        unreachable!()
-                    }
-                };
-
-                return Ok(Value::Url(UrlValue {
-                    span: span!(self, span.lo),
-                    url: url.0,
-                    raw: url.1,
-                }));
-            }
+            Token::Url { .. } => return Ok(Value::Url(self.parse()?)),
 
             _ => {}
         }
@@ -575,6 +553,26 @@ where
     }
 }
 
+impl<I> Parse<Ident> for Parser<I>
+where
+    I: ParserInput,
+{
+    fn parse(&mut self) -> PResult<Ident> {
+        let span = self.input.cur_span()?;
+
+        if !is!(self, Ident) {
+            return Err(Error::new(span, ErrorKind::Expected("Ident")));
+        }
+
+        match bump!(self) {
+            Token::Ident { value, raw } => Ok(Ident { span, value, raw }),
+            _ => {
+                unreachable!()
+            }
+        }
+    }
+}
+
 impl<I> Parse<PercentValue> for Parser<I>
 where
     I: ParserInput,