From 5287a2506c19b7f886556f8a73510f57dd234857 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Tue, 2 Apr 2019 12:18:52 +0300
Subject: [PATCH] More future-proof comment kind

---
 crates/ra_ide_api/src/folding_ranges.rs |  7 +-
 crates/ra_ide_api/src/typing.rs         |  2 +-
 crates/ra_syntax/src/ast/tokens.rs      | 85 +++++++++++++++----------
 crates/ra_syntax/src/ast/traits.rs      |  2 +-
 4 files changed, 59 insertions(+), 37 deletions(-)

diff --git a/crates/ra_ide_api/src/folding_ranges.rs b/crates/ra_ide_api/src/folding_ranges.rs
index eada0b7ded..6987fcc9ec 100644
--- a/crates/ra_ide_api/src/folding_ranges.rs
+++ b/crates/ra_ide_api/src/folding_ranges.rs
@@ -145,7 +145,10 @@ fn contiguous_range_for_comment<'a>(
     visited.insert(first);
 
     // Only fold comments of the same flavor
-    let group_flavor = first.flavor();
+    let group_kind = first.kind();
+    if !group_kind.shape.is_line() {
+        return None;
+    }
 
     let mut last = first;
     for element in first.syntax().siblings_with_tokens(Direction::Next) {
@@ -158,7 +161,7 @@ fn contiguous_range_for_comment<'a>(
                     }
                 }
                 if let Some(c) = ast::Comment::cast(token) {
-                    if c.flavor() == group_flavor {
+                    if c.kind() == group_kind {
                         visited.insert(c);
                         last = c;
                         continue;
diff --git a/crates/ra_ide_api/src/typing.rs b/crates/ra_ide_api/src/typing.rs
index aeeeea0821..ae53bca776 100644
--- a/crates/ra_ide_api/src/typing.rs
+++ b/crates/ra_ide_api/src/typing.rs
@@ -15,7 +15,7 @@ pub(crate) fn on_enter(db: &RootDatabase, position: FilePosition) -> Option<Sour
         .left_biased()
         .and_then(ast::Comment::cast)?;
 
-    if comment.flavor() == ast::CommentFlavor::Multiline {
+    if comment.kind().shape.is_block() {
         return None;
     }
 
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
index 76a12cd645..7c30ff15cb 100644
--- a/crates/ra_syntax/src/ast/tokens.rs
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -21,52 +21,71 @@ impl<'a> AstToken<'a> for Comment<'a> {
 }
 
 impl<'a> Comment<'a> {
-    pub fn flavor(&self) -> CommentFlavor {
-        let text = self.text();
-        if text.starts_with("///") {
-            CommentFlavor::OuterDoc
-        } else if text.starts_with("//!") {
-            CommentFlavor::InnerDoc
-        } else if text.starts_with("//") {
-            CommentFlavor::Line
-        } else {
-            CommentFlavor::Multiline
-        }
-    }
-
-    pub fn is_doc_comment(&self) -> bool {
-        self.flavor().is_doc_comment()
+    pub fn kind(&self) -> CommentKind {
+        kind_by_prefix(self.text())
     }
 
     pub fn prefix(&self) -> &'static str {
-        self.flavor().prefix()
+        prefix_by_kind(self.kind())
     }
 }
 
-#[derive(Debug, PartialEq, Eq)]
-pub enum CommentFlavor {
+#[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,
-    OuterDoc,
-    InnerDoc,
-    Multiline,
+    Block,
 }
 
-impl CommentFlavor {
-    pub fn prefix(&self) -> &'static str {
-        match *self {
-            CommentFlavor::Line => "//",
-            CommentFlavor::OuterDoc => "///",
-            CommentFlavor::InnerDoc => "//!",
-            CommentFlavor::Multiline => "/*",
-        }
+impl CommentShape {
+    pub fn is_line(self) -> bool {
+        self == CommentShape::Line
     }
 
-    pub fn is_doc_comment(&self) -> bool {
-        match self {
-            CommentFlavor::OuterDoc | CommentFlavor::InnerDoc => true,
-            _ => false,
+    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>);
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index 43d1509fab..98aa22085a 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -111,7 +111,7 @@ pub trait DocCommentsOwner: AstNode {
         let mut has_comments = false;
         let docs = self
             .doc_comments()
-            .filter(|comment| comment.is_doc_comment())
+            .filter(|comment| comment.kind().doc.is_some())
             .map(|comment| {
                 has_comments = true;
                 let prefix_len = comment.prefix().len();