Add ast for plain and raw string literals

crates/ra_syntax/src/ast/tokens.rs

@@ -2,8 +2,8 @@
 
 use crate::{
     ast::AstToken,
-    SyntaxKind::{COMMENT, WHITESPACE},
-    SyntaxToken,
+    SyntaxKind::{COMMENT, RAW_STRING, STRING, WHITESPACE},
+    SyntaxToken, TextRange, TextUnit,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -11,10 +11,9 @@ pub struct Comment(SyntaxToken);
 
 impl AstToken for Comment {
     fn cast(token: SyntaxToken) -> Option<Self> {
-        if token.kind() == COMMENT {
-            Some(Comment(token))
-        } else {
-            None
+        match token.kind() {
+            COMMENT => Some(Comment(token)),
+            _ => None,
         }
     }
     fn syntax(&self) -> &SyntaxToken {
@@ -94,10 +93,9 @@ pub struct Whitespace(SyntaxToken);
 
 impl AstToken for Whitespace {
     fn cast(token: SyntaxToken) -> Option<Self> {
-        if token.kind() == WHITESPACE {
-            Some(Whitespace(token))
-        } else {
-            None
+        match token.kind() {
+            WHITESPACE => Some(Whitespace(token)),
+            _ => None,
         }
     }
     fn syntax(&self) -> &SyntaxToken {
@@ -111,3 +109,80 @@ impl Whitespace {
         text.find('\n').map_or(false, |idx| text[idx + 1..].contains('\n'))
     }
 }
+
+pub struct String(SyntaxToken);
+
+impl AstToken for String {
+    fn cast(token: SyntaxToken) -> Option<Self> {
+        match token.kind() {
+            STRING => Some(String(token)),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxToken {
+        &self.0
+    }
+}
+
+impl String {
+    pub fn value(&self) -> Option<std::string::String> {
+        let text = self.text().as_str();
+        let usual_string_range = find_usual_string_range(text)?;
+        let start_of_inside = usual_string_range.start().to_usize() + 1;
+        let end_of_inside = usual_string_range.end().to_usize();
+        let inside_str = &text[start_of_inside..end_of_inside];
+
+        let mut buf = std::string::String::with_capacity(inside_str.len());
+        let mut has_error = false;
+        rustc_lexer::unescape::unescape_str(inside_str, &mut |_, unescaped_char| {
+            match unescaped_char {
+                Ok(c) => buf.push(c),
+                Err(_) => has_error = true,
+            }
+        });
+
+        if has_error {
+            return None;
+        }
+        Some(buf)
+    }
+}
+
+pub struct RawString(SyntaxToken);
+
+impl AstToken for RawString {
+    fn cast(token: SyntaxToken) -> Option<Self> {
+        match token.kind() {
+            RAW_STRING => Some(RawString(token)),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxToken {
+        &self.0
+    }
+}
+
+impl RawString {
+    pub fn value(&self) -> Option<std::string::String> {
+        let text = self.text().as_str();
+        let usual_string_range = find_usual_string_range(text)?;
+        let start_of_inside = usual_string_range.start().to_usize() + 1;
+        let end_of_inside = usual_string_range.end().to_usize();
+        let inside_str = &text[start_of_inside..end_of_inside];
+        Some(inside_str.to_string())
+    }
+}
+
+fn find_usual_string_range(s: &str) -> Option<TextRange> {
+    let left_quote = s.find('"')?;
+    let right_quote = s.rfind('"')?;
+    if left_quote == right_quote {
+        // `s` only contains one quote
+        None
+    } else {
+        Some(TextRange::from_to(
+            TextUnit::from(left_quote as u32),
+            TextUnit::from(right_quote as u32),
+        ))
+    }
+}