2 files changed, 112 insertions, 11 deletions

diff --git a/crates/ra_analysis/src/call_info.rs b/crates/ra_analysis/src/call_info.rs
index 2fcd03c9b..911ac3955 100644
--- a/crates/ra_analysis/src/call_info.rs
+++ b/crates/ra_analysis/src/call_info.rs
@@ -1,16 +1,17 @@
+use std::cmp::{max, min};
+
 use ra_db::{SyntaxDatabase, Cancelable};
 use ra_syntax::{
     AstNode, SyntaxNode, TextUnit, TextRange,
     SyntaxKind::FN_DEF,
-    ast::{self, ArgListOwner},
+    ast::{self, ArgListOwner, DocCommentsOwner},
 };
 use ra_editor::find_node_at_offset;
-use hir::FnSignatureInfo;
 
 use crate::{FilePosition, CallInfo, db::RootDatabase};
 
 pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Cancelable<Option<CallInfo>> {
-    let (sig_info, active_parameter) = ctry!(call_info_(db, position)?);
+    let (sig_info, active_parameter) = ctry!(signature_and_active_param(db, position)?);
     let res = CallInfo {
         label: sig_info.label,
         doc: sig_info.doc,
@@ -21,7 +22,7 @@ pub(crate) fn call_info(db: &RootDatabase, position: FilePosition) -> Cancelable
 }
 
 /// Computes parameter information for the given call expression.
-fn call_info_(
+fn signature_and_active_param(
     db: &RootDatabase,
     position: FilePosition,
 ) -> Cancelable<Option<(FnSignatureInfo, Option<usize>)>> {
@@ -39,12 +40,7 @@ fn call_info_(
             let fn_file = db.source_file(symbol.file_id);
             let fn_def = symbol.ptr.resolve(&fn_file);
             let fn_def = ast::FnDef::cast(&fn_def).unwrap();
-            let descr = ctry!(hir::source_binder::function_from_source(
-                db,
-                symbol.file_id,
-                fn_def
-            )?);
-            if let Some(descriptor) = descr.signature_info(db) {
+            if let Some(descriptor) = FnSignatureInfo::new(fn_def) {
                 // If we have a calling expression let's find which argument we are on
                 let mut current_parameter = None;
 
@@ -129,6 +125,112 @@ impl<'a> FnCallNode<'a> {
     }
 }
 
+#[derive(Debug, Clone)]
+struct FnSignatureInfo {
+    label: String,
+    params: Vec<String>,
+    doc: Option<String>,
+}
+
+impl FnSignatureInfo {
+    fn new(node: &ast::FnDef) -> Option<Self> {
+        let mut doc = None;
+
+        // Strip the body out for the label.
+        let mut label: String = if let Some(body) = node.body() {
+            let body_range = body.syntax().range();
+            let label: String = node
+                .syntax()
+                .children()
+                .filter(|child| !child.range().is_subrange(&body_range))
+                .map(|node| node.text().to_string())
+                .collect();
+            label
+        } else {
+            node.syntax().text().to_string()
+        };
+
+        if let Some((comment_range, docs)) = FnSignatureInfo::extract_doc_comments(node) {
+            let comment_range = comment_range
+                .checked_sub(node.syntax().range().start())
+                .unwrap();
+            let start = comment_range.start().to_usize();
+            let end = comment_range.end().to_usize();
+
+            // Remove the comment from the label
+            label.replace_range(start..end, "");
+
+            // Massage markdown
+            let mut processed_lines = Vec::new();
+            let mut in_code_block = false;
+            for line in docs.lines() {
+                if line.starts_with("```") {
+                    in_code_block = !in_code_block;
+                }
+
+                let line = if in_code_block && line.starts_with("```") && !line.contains("rust") {
+                    "```rust".into()
+                } else {
+                    line.to_string()
+                };
+
+                processed_lines.push(line);
+            }
+
+            if !processed_lines.is_empty() {
+                doc = Some(processed_lines.join("\n"));
+            }
+        }
+
+        let params = FnSignatureInfo::param_list(node);
+
+        Some(FnSignatureInfo {
+            params,
+            label: label.trim().to_owned(),
+            doc,
+        })
+    }
+
+    fn extract_doc_comments(node: &ast::FnDef) -> Option<(TextRange, String)> {
+        if node.doc_comments().count() == 0 {
+            return None;
+        }
+
+        let comment_text = node.doc_comment_text();
+
+        let (begin, end) = node
+            .doc_comments()
+            .map(|comment| comment.syntax().range())
+            .map(|range| (range.start().to_usize(), range.end().to_usize()))
+            .fold((std::usize::MAX, std::usize::MIN), |acc, range| {
+                (min(acc.0, range.0), max(acc.1, range.1))
+            });
+
+        let range = TextRange::from_to(TextUnit::from_usize(begin), TextUnit::from_usize(end));
+
+        Some((range, comment_text))
+    }
+
+    fn param_list(node: &ast::FnDef) -> Vec<String> {
+        let mut res = vec![];
+        if let Some(param_list) = node.param_list() {
+            if let Some(self_param) = param_list.self_param() {
+                res.push(self_param.syntax().text().to_string())
+            }
+
+            // Maybe use param.pat here? See if we can just extract the name?
+            //res.extend(param_list.params().map(|p| p.syntax().text().to_string()));
+            res.extend(
+                param_list
+                    .params()
+                    .filter_map(|p| p.pat())
+                    .map(|pat| pat.syntax().text().to_string()),
+            );
+        }
+        res
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/crates/ra_analysis/src/lib.rs b/crates/ra_analysis/src/lib.rs
index 4fa6750aa..771a349c8 100644
--- a/crates/ra_analysis/src/lib.rs
+++ b/crates/ra_analysis/src/lib.rs
@@ -40,7 +40,6 @@ pub use crate::{
     completion::{CompletionItem, CompletionItemKind, InsertText},
     runnables::{Runnable, RunnableKind},
 };
-pub use hir::FnSignatureInfo;
 pub use ra_editor::{Fold, FoldKind, HighlightedRange, LineIndex, Severity, StructureNode};
 
 pub use ra_db::{