Adds function returning only fn signature in function code blocks (F…

…uelLabs#3545)

This PR adds a function `trim_fn_body()` that returns only the function
signature for documentable function code blocks.

Result:
![Screen Shot 2022-12-08 at 1 25 46
PM](https://user-images.githubusercontent.com/57543709/206549104-1b5b1e79-d573-422b-9bb2-eaa1af6bfa37.png)

Closes FuelLabs#3540

Co-authored-by: Mohammad Fawaz <[email protected]>

forc-plugins/forc-doc/src/descriptor.rs

@@ -55,12 +55,12 @@ pub(crate) enum Descriptor {
 
 impl Descriptor {
     pub(crate) fn from_typed_decl(
-        d: &TyDeclaration,
+        ty_decl: &TyDeclaration,
         module_prefix: Vec<String>,
         document_private_items: bool,
     ) -> Result<Self> {
         use TyDeclaration::*;
-        match d {
+        match ty_decl {
             StructDeclaration(ref decl_id) => {
                 let struct_decl = de_get_struct(decl_id.clone(), &decl_id.span())?;
                 if !document_private_items && struct_decl.visibility.is_private() {

forc-plugins/forc-doc/src/render.rs

@@ -480,6 +480,13 @@ fn attrsmap_to_html_string(attributes: &AttributesMap) -> String {
     options.parse.default_info_string = Some("sway".into());
     markdown_to_html(&format_docs(&docs), &options)
 }
+/// Takes a formatted String fn and returns only the function signature.
+fn trim_fn_body(f: String) -> String {
+    match f.find('{') {
+        Some(index) => f.split_at(index).0.to_string(),
+        None => f,
+    }
+}
 
 trait Renderable {
     fn render(&self, module: String, module_depth: usize, decl_ty: String) -> Box<dyn RenderBox>;
@@ -615,7 +622,7 @@ impl Renderable for TyFunctionDeclaration {
             visibility: _,
         } = &self;
         let name = name.as_str().to_string();
-        let code_str = parse::parse_format::<sway_ast::ItemFn>(span.as_str());
+        let code_str = trim_fn_body(parse::parse_format::<sway_ast::ItemFn>(span.as_str()));
         let function_attributes = attrsmap_to_html_string(attributes);
         box_html! {
             : html_head(module_depth, module.clone(), decl_ty.clone(), name.clone());