Simplify save-analysis JSON dumper interface

src/librustc_save_analysis/dump_visitor.rs

@@ -38,7 +38,7 @@ use syntax_pos::*;
 
 use crate::{escape, generated_code, id_from_def_id, id_from_node_id, lower_attributes,
             PathCollector, SaveContext};
-use crate::json_dumper::{Access, DumpOutput, JsonDumper};
+use crate::json_dumper::{Access, JsonDumper};
 use crate::span_utils::SpanUtils;
 use crate::sig;
 
@@ -75,10 +75,10 @@ macro_rules! access_from_vis {
     };
 }
 
-pub struct DumpVisitor<'l, 'tcx, 'll, O: DumpOutput> {
+pub struct DumpVisitor<'l, 'tcx, 'll> {
     save_ctxt: SaveContext<'l, 'tcx>,
     tcx: TyCtxt<'tcx>,
-    dumper: &'ll mut JsonDumper<O>,
+    dumper: &'ll mut JsonDumper,
 
     span: SpanUtils<'l>,
 
@@ -92,11 +92,11 @@ pub struct DumpVisitor<'l, 'tcx, 'll, O: DumpOutput> {
     // macro_calls: FxHashSet<Span>,
 }
 
-impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
+impl<'l, 'tcx, 'll> DumpVisitor<'l, 'tcx, 'll> {
     pub fn new(
         save_ctxt: SaveContext<'l, 'tcx>,
-        dumper: &'ll mut JsonDumper<O>,
-    ) -> DumpVisitor<'l, 'tcx, 'll, O> {
+        dumper: &'ll mut JsonDumper,
+    ) -> DumpVisitor<'l, 'tcx, 'll> {
         let span_utils = SpanUtils::new(&save_ctxt.tcx.sess);
         DumpVisitor {
             tcx: save_ctxt.tcx,
@@ -111,7 +111,7 @@ impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
 
     fn nest_scope<F>(&mut self, scope_id: NodeId, f: F)
     where
-        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll, O>),
+        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll>),
     {
         let parent_scope = self.cur_scope;
         self.cur_scope = scope_id;
@@ -121,7 +121,7 @@ impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
 
     fn nest_tables<F>(&mut self, item_id: NodeId, f: F)
     where
-        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll, O>),
+        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll>),
     {
         let item_def_id = self.tcx.hir().local_def_id_from_node_id(item_id);
         if self.tcx.has_typeck_tables(item_def_id) {
@@ -1311,7 +1311,7 @@ impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
     }
 }
 
-impl<'l, 'tcx, 'll, O: DumpOutput + 'll> Visitor<'l> for DumpVisitor<'l, 'tcx, 'll, O> {
+impl<'l, 'tcx, 'll> Visitor<'l> for DumpVisitor<'l, 'tcx, 'll> {
     fn visit_mod(&mut self, m: &'l ast::Mod, span: Span, attrs: &[ast::Attribute], id: NodeId) {
         // Since we handle explicit modules ourselves in visit_item, this should
         // only get called for the root module of a crate.

src/librustc_save_analysis/json_dumper.rs

@@ -1,80 +1,33 @@
-use std::io::Write;
-
 use rls_data::config::Config;
 use rls_data::{self, Analysis, CompilationOptions, CratePreludeData, Def, DefKind, Impl, Import,
                MacroRef, Ref, RefKind, Relation};
 use rls_span::{Column, Row};
 
-use log::error;
-
 #[derive(Debug)]
 pub struct Access {
     pub reachable: bool,
     pub public: bool,
 }
 
-pub struct JsonDumper<O: DumpOutput> {
+pub struct JsonDumper {
     result: Analysis,
     config: Config,
-    output: O,
 }
 
-pub trait DumpOutput {
-    fn dump(&mut self, result: &Analysis);
-}
-
-pub struct WriteOutput<'b, W: Write> {
-    output: &'b mut W,
-}
-
-impl<'b, W: Write> DumpOutput for WriteOutput<'b, W> {
-    fn dump(&mut self, result: &Analysis) {
-        if let Err(e) = serde_json::to_writer(self.output.by_ref(), result) {
-            error!("Can't serialize save-analysis: {:?}", e);
-        }
-    }
-}
-
-pub struct CallbackOutput<'b> {
-    callback: &'b mut dyn FnMut(&Analysis),
-}
-
-impl<'b> DumpOutput for CallbackOutput<'b> {
-    fn dump(&mut self, result: &Analysis) {
-        (self.callback)(result)
-    }
-}
-
-impl<'b, W: Write> JsonDumper<WriteOutput<'b, W>> {
-    pub fn new(writer: &'b mut W, config: Config) -> JsonDumper<WriteOutput<'b, W>> {
+impl JsonDumper {
+    pub fn new(config: Config) -> JsonDumper {
         JsonDumper {
-            output: WriteOutput { output: writer },
             config: config.clone(),
             result: Analysis::new(config),
         }
     }
-}
 
-impl<'b> JsonDumper<CallbackOutput<'b>> {
-    pub fn with_callback(
-        callback: &'b mut dyn FnMut(&Analysis),
-        config: Config,
-    ) -> JsonDumper<CallbackOutput<'b>> {
-        JsonDumper {
-            output: CallbackOutput { callback },
-            config: config.clone(),
-            result: Analysis::new(config),
-        }
+    pub fn to_output(self, f: impl FnOnce(&Analysis)) {
+        f(&self.result)
     }
 }
 
-impl<O: DumpOutput> Drop for JsonDumper<O> {
-    fn drop(&mut self) {
-        self.output.dump(&self.result);
-    }
-}
-
-impl<'b, O: DumpOutput + 'b> JsonDumper<O> {
+impl JsonDumper {
     pub fn crate_prelude(&mut self, data: CratePreludeData) {
         self.result.prelude = Some(data)
     }

src/librustc_save_analysis/lib.rs

@@ -1075,17 +1075,19 @@ impl<'a> SaveHandler for DumpHandler<'a> {
         input: &'l Input,
     ) {
         let sess = &save_ctxt.tcx.sess;
-        let file_name = {
-            let (mut output, file_name) = self.output_file(&save_ctxt);
-            let mut dumper = JsonDumper::new(&mut output, save_ctxt.config.clone());
-            let mut visitor = DumpVisitor::new(save_ctxt, &mut dumper);
+        let (output, file_name) = self.output_file(&save_ctxt);
+        let mut dumper = JsonDumper::new(save_ctxt.config.clone());
+        let mut visitor = DumpVisitor::new(save_ctxt, &mut dumper);
 
-            visitor.dump_crate_info(cratename, krate);
-            visitor.dump_compilation_options(input, cratename);
-            visit::walk_crate(&mut visitor, krate);
+        visitor.dump_crate_info(cratename, krate);
+        visitor.dump_compilation_options(input, cratename);
+        visit::walk_crate(&mut visitor, krate);
 
-            file_name
-        };
+        dumper.to_output(|analysis| {
+            if let Err(e) = serde_json::to_writer(output, analysis) {
+                error!("Can't serialize save-analysis: {:?}", e);
+            }
+        });
 
         if sess.opts.debugging_opts.emit_artifact_notifications {
             sess.parse_sess.span_diagnostic
@@ -1112,12 +1114,14 @@ impl<'b> SaveHandler for CallbackHandler<'b> {
         // using the JsonDumper to collect the save-analysis results, but not
         // actually to dump them to a file. This is all a bit convoluted and
         // there is certainly a simpler design here trying to get out (FIXME).
-        let mut dumper = JsonDumper::with_callback(self.callback, save_ctxt.config.clone());
+        let mut dumper = JsonDumper::new(save_ctxt.config.clone());
         let mut visitor = DumpVisitor::new(save_ctxt, &mut dumper);
 
         visitor.dump_crate_info(cratename, krate);
         visitor.dump_compilation_options(input, cratename);
         visit::walk_crate(&mut visitor, krate);
+
+        dumper.to_output(|a| (self.callback)(a))
     }
 }