1 files changed, 113 insertions, 0 deletions

diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
new file mode 100644
index 000000000..08882ea69
--- /dev/null
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -0,0 +1,113 @@
+//! There are many AstNodes, but only a few tokens, so we hand-write them here.
+
+use crate::{
+    SyntaxToken,
+    SyntaxKind::{COMMENT, WHITESPACE},
+    ast::AstToken,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Comment<'a>(SyntaxToken<'a>);
+
+impl<'a> AstToken<'a> for Comment<'a> {
+    fn cast(token: SyntaxToken<'a>) -> Option<Self> {
+        if token.kind() == COMMENT {
+            Some(Comment(token))
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> SyntaxToken<'a> {
+        self.0
+    }
+}
+
+impl<'a> Comment<'a> {
+    pub fn kind(&self) -> CommentKind {
+        kind_by_prefix(self.text())
+    }
+
+    pub fn prefix(&self) -> &'static str {
+        prefix_by_kind(self.kind())
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub struct CommentKind {
+    pub shape: CommentShape,
+    pub doc: Option<CommentPlacement>,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum CommentShape {
+    Line,
+    Block,
+}
+
+impl CommentShape {
+    pub fn is_line(self) -> bool {
+        self == CommentShape::Line
+    }
+
+    pub fn is_block(self) -> bool {
+        self == CommentShape::Block
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum CommentPlacement {
+    Inner,
+    Outer,
+}
+
+const COMMENT_PREFIX_TO_KIND: &[(&str, CommentKind)] = {
+    use {CommentShape::*, CommentPlacement::*};
+    &[
+        ("///", CommentKind { shape: Line, doc: Some(Outer) }),
+        ("//!", CommentKind { shape: Line, doc: Some(Inner) }),
+        ("/**", CommentKind { shape: Block, doc: Some(Outer) }),
+        ("/*!", CommentKind { shape: Block, doc: Some(Inner) }),
+        ("//", CommentKind { shape: Line, doc: None }),
+        ("/*", CommentKind { shape: Block, doc: None }),
+    ]
+};
+
+fn kind_by_prefix(text: &str) -> CommentKind {
+    for (prefix, kind) in COMMENT_PREFIX_TO_KIND.iter() {
+        if text.starts_with(prefix) {
+            return *kind;
+        }
+    }
+    panic!("bad comment text: {:?}", text)
+}
+
+fn prefix_by_kind(kind: CommentKind) -> &'static str {
+    for (prefix, k) in COMMENT_PREFIX_TO_KIND.iter() {
+        if *k == kind {
+            return prefix;
+        }
+    }
+    unreachable!()
+}
+
+pub struct Whitespace<'a>(SyntaxToken<'a>);
+
+impl<'a> AstToken<'a> for Whitespace<'a> {
+    fn cast(token: SyntaxToken<'a>) -> Option<Self> {
+        if token.kind() == WHITESPACE {
+            Some(Whitespace(token))
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> SyntaxToken<'a> {
+        self.0
+    }
+}
+
+impl<'a> Whitespace<'a> {
+    pub fn spans_multiple_lines(&self) -> bool {
+        let text = self.text();
+        text.find('\n').map_or(false, |idx| text[idx + 1..].contains('\n'))
+    }
+}