1 files changed, 139 insertions, 30 deletions

diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index 47bc0032b..5efcaeca0 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -1,8 +1,8 @@
 use std::{
     sync::{
         Arc,
-        atomic::{AtomicBool, Ordering::SeqCst},
     },
+    hash::{Hash, Hasher},
     fmt,
     collections::VecDeque,
     iter,
@@ -12,24 +12,38 @@ use relative_path::RelativePath;
 use rustc_hash::FxHashSet;
 use ra_editor::{self, FileSymbol, LineIndex, find_node_at_offset, LocalEdit, resolve_local_name};
 use ra_syntax::{
-    TextUnit, TextRange, SmolStr, File, AstNode,
+    TextUnit, TextRange, SmolStr, File, AstNode, SyntaxNodeRef,
     SyntaxKind::*,
-    ast::{self, NameOwner},
+    ast::{self, NameOwner, ArgListOwner, Expr},
 };
 
-use {
+use crate::{
     FileId, FileResolver, Query, Diagnostic, SourceChange, SourceFileEdit, Position, FileSystemEdit,
     JobToken, CrateGraph, CrateId,
     roots::{SourceRoot, ReadonlySourceRoot, WritableSourceRoot},
-    descriptors::{ModuleTreeDescriptor, Problem},
+    descriptors::{FnDescriptor, ModuleTreeDescriptor, Problem},
 };
 
-
 #[derive(Clone, Debug)]
 pub(crate) struct FileResolverImp {
     inner: Arc<FileResolver>
 }
 
+impl PartialEq for FileResolverImp {
+    fn eq(&self, other: &FileResolverImp) -> bool {
+        self.inner() == other.inner()
+    }
+}
+
+impl Eq for FileResolverImp {
+}
+
+impl Hash for FileResolverImp {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.inner().hash(hasher);
+    }
+}
+
 impl FileResolverImp {
     pub(crate) fn new(inner: Arc<FileResolver>) -> FileResolverImp {
         FileResolverImp { inner }
@@ -40,6 +54,9 @@ impl FileResolverImp {
     pub(crate) fn resolve(&self, file_id: FileId, path: &RelativePath) -> Option<FileId> {
         self.inner.resolve(file_id, path)
     }
+    fn inner(&self) -> *const FileResolver {
+        &*self.inner
+    }
 }
 
 impl Default for FileResolverImp {
@@ -60,29 +77,27 @@ impl Default for FileResolverImp {
 
 #[derive(Debug)]
 pub(crate) struct AnalysisHostImpl {
-    data: Arc<WorldData>
+    data: WorldData
 }
 
 impl AnalysisHostImpl {
     pub fn new() -> AnalysisHostImpl {
         AnalysisHostImpl {
-            data: Arc::new(WorldData::default()),
+            data: WorldData::default(),
         }
     }
     pub fn analysis(&self) -> AnalysisImpl {
         AnalysisImpl {
-            needs_reindex: AtomicBool::new(false),
             data: self.data.clone(),
         }
     }
     pub fn change_files(&mut self, changes: &mut dyn Iterator<Item=(FileId, Option<String>)>) {
-        let data = self.data_mut();
-        data.root = Arc::new(data.root.apply_changes(changes, None));
+        self.data_mut()
+            .root.apply_changes(changes, None);
     }
     pub fn set_file_resolver(&mut self, resolver: FileResolverImp) {
-        let data = self.data_mut();
-        data.file_resolver = resolver.clone();
-        data.root = Arc::new(data.root.apply_changes(&mut iter::empty(), Some(resolver)));
+        self.data_mut()
+            .root.apply_changes(&mut iter::empty(), Some(resolver));
     }
     pub fn set_crate_graph(&mut self, graph: CrateGraph) {
         let mut visited = FxHashSet::default();
@@ -97,34 +112,24 @@ impl AnalysisHostImpl {
         self.data_mut().libs.push(Arc::new(root));
     }
     fn data_mut(&mut self) -> &mut WorldData {
-        Arc::make_mut(&mut self.data)
+        &mut self.data
     }
 }
 
 pub(crate) struct AnalysisImpl {
-    needs_reindex: AtomicBool,
-    data: Arc<WorldData>,
+    data: WorldData,
 }
 
 impl fmt::Debug for AnalysisImpl {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        (&*self.data).fmt(f)
-    }
-}
-
-impl Clone for AnalysisImpl {
-    fn clone(&self) -> AnalysisImpl {
-        AnalysisImpl {
-            needs_reindex: AtomicBool::new(self.needs_reindex.load(SeqCst)),
-            data: Arc::clone(&self.data),
-        }
+        self.data.fmt(f)
     }
 }
 
 impl AnalysisImpl {
     fn root(&self, file_id: FileId) -> &SourceRoot {
         if self.data.root.contains(file_id) {
-            return &*self.data.root;
+            return &self.data.root;
         }
         &**self.data.libs.iter().find(|it| it.contains(file_id)).unwrap()
     }
@@ -306,6 +311,68 @@ impl AnalysisImpl {
             .collect()
     }
 
+    pub fn resolve_callable(&self, file_id: FileId, offset: TextUnit, token: &JobToken)
+        -> Option<(FnDescriptor, Option<usize>)> {
+
+        let root = self.root(file_id);
+        let file = root.syntax(file_id);
+        let syntax = file.syntax();
+
+        // Find the calling expression and it's NameRef
+        let calling_node = FnCallNode::with_node(syntax, offset)?;
+        let name_ref = calling_node.name_ref()?;
+
+        // Resolve the function's NameRef (NOTE: this isn't entirely accurate).
+        let file_symbols = self.index_resolve(name_ref, token);
+        for (_, fs) in file_symbols {
+            if fs.kind == FN_DEF {
+                if let Some(fn_def) = find_node_at_offset(syntax, fs.node_range.start()) {
+                    if let Some(descriptor) = FnDescriptor::new(fn_def) {
+                        // If we have a calling expression let's find which argument we are on
+                        let mut current_parameter = None;
+
+                        let num_params = descriptor.params.len();
+                        let has_self = fn_def.param_list()
+                            .and_then(|l| l.self_param())
+                            .is_some();
+
+                        if num_params == 1 {
+                            if !has_self {
+                                current_parameter = Some(1);
+                            }
+                        } else if num_params > 1 {
+                            // Count how many parameters into the call we are.
+                            // TODO: This is best effort for now and should be fixed at some point.
+                            // It may be better to see where we are in the arg_list and then check
+                            // where offset is in that list (or beyond).
+                            // Revisit this after we get documentation comments in.
+                            if let Some(ref arg_list) = calling_node.arg_list() {
+                                let start = arg_list.syntax().range().start();
+
+                                let range_search = TextRange::from_to(start, offset);
+                                let mut commas: usize = arg_list.syntax().text()
+                                    .slice(range_search).to_string()
+                                    .matches(",")
+                                    .count();
+
+                                // If we have a method call eat the first param since it's just self.
+                                if has_self {
+                                    commas = commas + 1;
+                                }
+
+                                current_parameter = Some(commas);
+                            }
+                        }
+
+                        return Some((descriptor, current_parameter));
+                    }
+                }
+            }
+        }
+
+        None
+    }
+
     fn index_resolve(&self, name_ref: ast::NameRef, token: &JobToken) -> Vec<(FileId, FileSymbol)> {
         let name = name_ref.text();
         let mut query = Query::new(name.to_string());
@@ -325,9 +392,8 @@ impl AnalysisImpl {
 
 #[derive(Default, Clone, Debug)]
 struct WorldData {
-    file_resolver: FileResolverImp,
     crate_graph: CrateGraph,
-    root: Arc<WritableSourceRoot>,
+    root: WritableSourceRoot,
     libs: Vec<Arc<ReadonlySourceRoot>>,
 }
 
@@ -355,3 +421,46 @@ impl CrateGraph {
         Some(crate_id)
     }
 }
+
+enum FnCallNode<'a> {
+    CallExpr(ast::CallExpr<'a>),
+    MethodCallExpr(ast::MethodCallExpr<'a>)
+}
+
+impl<'a> FnCallNode<'a> {
+    pub fn with_node(syntax: SyntaxNodeRef, offset: TextUnit) -> Option<FnCallNode> {
+        if let Some(expr) = find_node_at_offset::<ast::CallExpr>(syntax, offset) {
+            return Some(FnCallNode::CallExpr(expr));
+        }
+        if let Some(expr) = find_node_at_offset::<ast::MethodCallExpr>(syntax, offset) {
+            return Some(FnCallNode::MethodCallExpr(expr));
+        }
+        None
+    }
+
+    pub fn name_ref(&self) -> Option<ast::NameRef> {
+        match *self {
+            FnCallNode::CallExpr(call_expr) => {
+                Some(match call_expr.expr()? {
+                    Expr::PathExpr(path_expr) => {
+                        path_expr.path()?.segment()?.name_ref()?
+                    },
+                    _ => return None
+                })
+            },
+
+            FnCallNode::MethodCallExpr(call_expr) => {
+                call_expr.syntax().children()
+                    .filter_map(ast::NameRef::cast)
+                    .nth(0)
+            }
+        }
+    }
+
+    pub fn arg_list(&self) -> Option<ast::ArgList> {
+        match *self {
+            FnCallNode::CallExpr(expr) => expr.arg_list(),
+            FnCallNode::MethodCallExpr(expr) => expr.arg_list()
+        }
+    }
+}