Add completions and hover (facebook#79)

Summary:
Pull Request resolved: facebook#79

This is code from facebook#68, with cleanups.

Differential Revision: D47208501

fbshipit-source-id: 7f06543338246494054e739c6fc2066bbe31941f

starlark/src/docs/markdown.rs

@@ -15,6 +15,8 @@
  * limitations under the License.
  */
 
+use std::slice;
+
 use dupe::Dupe;
 use itertools::Itertools;
 use starlark_map::small_map::SmallMap;
@@ -238,15 +240,26 @@ fn render_object(name: &str, object: &DocObject) -> String {
     render_members(name, true, &object.docs, &object.members)
 }
 
-fn render_doc_item(name: &str, item: &DocItem) -> String {
-    match &item {
+pub(crate) fn render_doc_item(name: &str, item: &DocItem) -> String {
+    match item {
         DocItem::Module(m) => render_module(name, m),
         DocItem::Object(o) => render_object(name, o),
         DocItem::Function(f) => render_function(name, f),
         DocItem::Property(p) => render_property(name, p),
     }
 }
 
+pub(crate) fn render_doc_member(name: &str, item: &DocMember) -> String {
+    match item {
+        DocMember::Function(f) => render_function(name, f),
+        DocMember::Property(p) => render_property(name, p),
+    }
+}
+
+pub(crate) fn render_doc_param(item: &DocParam) -> String {
+    render_function_parameters(slice::from_ref(item)).unwrap_or_default()
+}
+
 impl RenderMarkdown for Doc {
     fn render_markdown_opt(&self, flavor: MarkdownFlavor) -> Option<String> {
         match flavor {

starlark/src/docs/mod.rs

@@ -20,7 +20,7 @@
 // TODO(nga): document it
 #![allow(missing_docs)]
 
-mod markdown;
+pub(crate) mod markdown;
 
 use std::collections::HashMap;
 
@@ -349,7 +349,7 @@ pub struct DocModule {
 }
 
 impl DocModule {
-    fn render_as_code(&self) -> String {
+    pub(crate) fn render_as_code(&self) -> String {
         let mut res = self
             .docs
             .as_ref()
@@ -425,7 +425,7 @@ impl DocFunction {
         }
     }
 
-    fn render_as_code(&self, name: &str) -> String {
+    pub(crate) fn render_as_code(&self, name: &str) -> String {
         let params: Vec<_> = self.params.iter().map(DocParam::render_as_code).collect();
         let spacer_len = if params.is_empty() {
             0
@@ -453,6 +453,19 @@ impl DocFunction {
         format!("def {}{}{}:\n{}    pass", name, params, ret, docstring)
     }
 
+    pub(crate) fn find_param_with_name(&self, param_name: &str) -> Option<&DocParam> {
+        self.params.iter().find(|p| match p {
+            DocParam::Arg { name, .. }
+            | DocParam::Args { name, .. }
+            | DocParam::Kwargs { name, .. }
+                if name == param_name =>
+            {
+                true
+            }
+            _ => false,
+        })
+    }
+
     /// Parses function documentation out of a docstring
     ///
     /// # Arguments
@@ -673,7 +686,7 @@ pub struct DocProperty {
 }
 
 impl DocProperty {
-    fn render_as_code(&self, name: &str) -> String {
+    pub(crate) fn render_as_code(&self, name: &str) -> String {
         match (
             &self.typ,
             self.docs.as_ref().map(DocString::render_as_quoted_code),
@@ -734,7 +747,7 @@ pub struct DocObject {
 }
 
 impl DocObject {
-    fn render_as_code(&self, name: &str) -> String {
+    pub(crate) fn render_as_code(&self, name: &str) -> String {
         let summary = self
             .docs
             .as_ref()
@@ -783,6 +796,55 @@ pub enum DocItem {
     Property(DocProperty),
 }
 
+impl DocItem {
+    /// Get the underlying [`DocString`] for this item, if it exists.
+    pub fn get_doc_string(&self) -> Option<&DocString> {
+        match self {
+            DocItem::Module(m) => m.docs.as_ref(),
+            DocItem::Object(o) => o.docs.as_ref(),
+            DocItem::Function(f) => f.docs.as_ref(),
+            DocItem::Property(p) => p.docs.as_ref(),
+        }
+    }
+
+    /// Get the summary of the underlying [`DocString`] for this item, if it exists.
+    pub fn get_doc_summary(&self) -> Option<&str> {
+        self.get_doc_string().map(|ds| ds.summary.as_str())
+    }
+}
+
+impl DocMember {
+    /// Get the underlying [`DocString`] for this item, if it exists.
+    pub fn get_doc_string(&self) -> Option<&DocString> {
+        match self {
+            DocMember::Function(f) => f.docs.as_ref(),
+            DocMember::Property(p) => p.docs.as_ref(),
+        }
+    }
+
+    /// Get the summary of the underlying [`DocString`] for this item, if it exists.
+    pub fn get_doc_summary(&self) -> Option<&str> {
+        self.get_doc_string().map(|ds| ds.summary.as_str())
+    }
+}
+
+impl DocParam {
+    /// Get the underlying [`DocString`] for this item, if it exists.
+    pub fn get_doc_string(&self) -> Option<&DocString> {
+        match self {
+            DocParam::Arg { docs, .. }
+            | DocParam::Args { docs, .. }
+            | DocParam::Kwargs { docs, .. } => docs.as_ref(),
+            _ => None,
+        }
+    }
+
+    /// Get the summary of the underlying [`DocString`] for this item, if it exists.
+    pub fn get_doc_summary(&self) -> Option<&str> {
+        self.get_doc_string().map(|ds| ds.summary.as_str())
+    }
+}
+
 /// The main structure that represents the documentation for a given symbol / module.
 #[derive(Debug, Clone, PartialEq, Serialize)]
 pub struct Doc {