1 files changed, 151 insertions, 0 deletions

diff --git a/crates/ra_hir/src/function.rs b/crates/ra_hir/src/function.rs
new file mode 100644
index 000000000..5187dc051
--- /dev/null
+++ b/crates/ra_hir/src/function.rs
@@ -0,0 +1,151 @@
+mod scope;
+
+use std::{
+    cmp::{max, min},
+    sync::Arc,
+};
+
+use ra_syntax::{
+    TextRange, TextUnit,
+    ast::{self, AstNode, DocCommentsOwner, NameOwner},
+};
+
+use crate::{ DefId, HirDatabase };
+
+pub use self::scope::FnScopes;
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub struct FnId(pub(crate) DefId);
+
+pub struct Function {
+    fn_id: FnId,
+}
+
+impl Function {
+    pub(crate) fn new(def_id: DefId) -> Function {
+        let fn_id = FnId(def_id);
+        Function { fn_id }
+    }
+
+    pub fn scope(&self, db: &impl HirDatabase) -> Arc<FnScopes> {
+        db.fn_scopes(self.fn_id)
+    }
+
+    pub fn signature_info(&self, db: &impl HirDatabase) -> Option<FnSignatureInfo> {
+        let syntax = db.fn_syntax(self.fn_id);
+        FnSignatureInfo::new(syntax.borrowed())
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct FnSignatureInfo {
+    pub name: String,
+    pub label: String,
+    pub ret_type: Option<String>,
+    pub params: Vec<String>,
+    pub doc: Option<String>,
+}
+
+impl FnSignatureInfo {
+    fn new(node: ast::FnDef) -> Option<Self> {
+        let name = node.name()?.text().to_string();
+
+        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);
+        let ret_type = node.ret_type().map(|r| r.syntax().text().to_string());
+
+        Some(FnSignatureInfo {
+            name,
+            ret_type,
+            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
+    }
+}