refactor: factor out AstParser from DocParser (#4923)

7 files changed, 204 insertions, 153 deletions

diff --git a/cli/doc/class.rs b/cli/doc/class.rs
index 004be9e74..c4603972b 100644
--- a/cli/doc/class.rs
+++ b/cli/doc/class.rs
@@ -118,7 +118,7 @@ pub fn get_doc_for_class_decl(
       Constructor(ctor) => {
         let ctor_js_doc = doc_parser.js_doc_for_span(ctor.span());
         let constructor_name =
-          prop_name_to_string(&doc_parser.source_map, &ctor.key);
+          prop_name_to_string(&doc_parser.ast_parser.source_map, &ctor.key);
 
         let mut params = vec![];
 
@@ -146,17 +146,16 @@ pub fn get_doc_for_class_decl(
           accessibility: ctor.accessibility,
           name: constructor_name,
           params,
-          location: doc_parser
-            .source_map
-            .lookup_char_pos(ctor.span.lo())
-            .into(),
+          location: doc_parser.ast_parser.get_span_location(ctor.span).into(),
         };
         constructors.push(constructor_def);
       }
       Method(class_method) => {
         let method_js_doc = doc_parser.js_doc_for_span(class_method.span());
-        let method_name =
-          prop_name_to_string(&doc_parser.source_map, &class_method.key);
+        let method_name = prop_name_to_string(
+          &doc_parser.ast_parser.source_map,
+          &class_method.key,
+        );
         let fn_def = function_to_function_def(&class_method.function);
         let method_def = ClassMethodDef {
           js_doc: method_js_doc,
@@ -168,8 +167,8 @@ pub fn get_doc_for_class_decl(
           kind: class_method.kind,
           function_def: fn_def,
           location: doc_parser
-            .source_map
-            .lookup_char_pos(class_method.span.lo())
+            .ast_parser
+            .get_span_location(class_method.span)
             .into(),
         };
         methods.push(method_def);
@@ -198,8 +197,8 @@ pub fn get_doc_for_class_decl(
           accessibility: class_prop.accessibility,
           name: prop_name,
           location: doc_parser
-            .source_map
-            .lookup_char_pos(class_prop.span.lo())
+            .ast_parser
+            .get_span_location(class_prop.span)
             .into(),
         };
         properties.push(prop_def);
diff --git a/cli/doc/interface.rs b/cli/doc/interface.rs
index dd9acc650..fb7a2c853 100644
--- a/cli/doc/interface.rs
+++ b/cli/doc/interface.rs
@@ -114,8 +114,8 @@ pub fn get_doc_for_ts_interface_decl(
           name,
           js_doc: method_js_doc,
           location: doc_parser
-            .source_map
-            .lookup_char_pos(ts_method_sig.span.lo())
+            .ast_parser
+            .get_span_location(ts_method_sig.span)
             .into(),
           optional: ts_method_sig.optional,
           params,
@@ -151,8 +151,8 @@ pub fn get_doc_for_ts_interface_decl(
           name,
           js_doc: prop_js_doc,
           location: doc_parser
-            .source_map
-            .lookup_char_pos(ts_prop_sig.span.lo())
+            .ast_parser
+            .get_span_location(ts_prop_sig.span)
             .into(),
           params,
           ts_type,
@@ -183,8 +183,8 @@ pub fn get_doc_for_ts_interface_decl(
         let call_sig_def = InterfaceCallSignatureDef {
           js_doc: call_sig_js_doc,
           location: doc_parser
-            .source_map
-            .lookup_char_pos(ts_call_sig.span.lo())
+            .ast_parser
+            .get_span_location(ts_call_sig.span)
             .into(),
           params,
           ts_type,
diff --git a/cli/doc/module.rs b/cli/doc/module.rs
index d2284b36c..2de9c7ca8 100644
--- a/cli/doc/module.rs
+++ b/cli/doc/module.rs
@@ -14,10 +14,7 @@ pub fn get_doc_node_for_export_decl(
   use crate::swc_ecma_ast::Decl;
 
   let js_doc = doc_parser.js_doc_for_span(export_span);
-  let location = doc_parser
-    .source_map
-    .lookup_char_pos(export_span.lo())
-    .into();
+  let location = doc_parser.ast_parser.get_span_location(export_span).into();
 
   match &export_decl.decl {
     Decl::Class(class_decl) => {
diff --git a/cli/doc/namespace.rs b/cli/doc/namespace.rs
index 02f22b661..6cbc619e8 100644
--- a/cli/doc/namespace.rs
+++ b/cli/doc/namespace.rs
@@ -17,8 +17,8 @@ pub fn get_doc_for_ts_namespace_decl(
 ) -> DocNode {
   let js_doc = doc_parser.js_doc_for_span(ts_namespace_decl.span);
   let location = doc_parser
-    .source_map
-    .lookup_char_pos(ts_namespace_decl.span.lo())
+    .ast_parser
+    .get_span_location(ts_namespace_decl.span)
     .into();
   let namespace_name = ts_namespace_decl.id.sym.to_string();
 
diff --git a/cli/doc/parser.rs b/cli/doc/parser.rs
index 35694aa9a..2a15daa59 100644
--- a/cli/doc/parser.rs
+++ b/cli/doc/parser.rs
@@ -1,39 +1,20 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 use crate::op_error::OpError;
-use crate::swc_common;
 use crate::swc_common::comments::CommentKind;
-use crate::swc_common::comments::Comments;
-use crate::swc_common::errors::Diagnostic;
-use crate::swc_common::errors::DiagnosticBuilder;
-use crate::swc_common::errors::Emitter;
-use crate::swc_common::errors::Handler;
-use crate::swc_common::errors::HandlerFlags;
-use crate::swc_common::FileName;
-use crate::swc_common::Globals;
-use crate::swc_common::SourceMap;
 use crate::swc_common::Span;
 use crate::swc_ecma_ast;
 use crate::swc_ecma_ast::Decl;
 use crate::swc_ecma_ast::ModuleDecl;
 use crate::swc_ecma_ast::Stmt;
-use crate::swc_ecma_parser::lexer::Lexer;
-use crate::swc_ecma_parser::JscTarget;
-use crate::swc_ecma_parser::Parser;
-use crate::swc_ecma_parser::Session;
-use crate::swc_ecma_parser::SourceFileInput;
-use crate::swc_ecma_parser::Syntax;
-use crate::swc_ecma_parser::TsConfig;
+use crate::swc_util::AstParser;
+use crate::swc_util::SwcDiagnosticBuffer;
 
 use deno_core::ErrBox;
 use deno_core::ModuleSpecifier;
 use futures::Future;
 use regex::Regex;
 use std::collections::HashMap;
-use std::error::Error;
-use std::fmt;
 use std::pin::Pin;
-use std::sync::Arc;
-use std::sync::RwLock;
 
 use super::namespace::NamespaceDef;
 use super::node;
@@ -42,50 +23,6 @@ use super::DocNode;
 use super::DocNodeKind;
 use super::Location;
 
-#[derive(Clone, Debug)]
-pub struct SwcDiagnosticBuffer {
-  pub diagnostics: Vec<Diagnostic>,
-}
-
-impl Error for SwcDiagnosticBuffer {}
-
-impl fmt::Display for SwcDiagnosticBuffer {
-  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-    let msg = self
-      .diagnostics
-      .iter()
-      .map(|d| d.message())
-      .collect::<Vec<String>>()
-      .join(",");
-
-    f.pad(&msg)
-  }
-}
-
-#[derive(Clone)]
-pub struct SwcErrorBuffer(Arc<RwLock<SwcDiagnosticBuffer>>);
-
-impl SwcErrorBuffer {
-  pub fn default() -> Self {
-    Self(Arc::new(RwLock::new(SwcDiagnosticBuffer {
-      diagnostics: vec![],
-    })))
-  }
-}
-
-impl Emitter for SwcErrorBuffer {
-  fn emit(&mut self, db: &DiagnosticBuilder) {
-    self.0.write().unwrap().diagnostics.push((**db).clone());
-  }
-}
-
-impl From<SwcErrorBuffer> for SwcDiagnosticBuffer {
-  fn from(buf: SwcErrorBuffer) -> Self {
-    let s = buf.0.read().unwrap();
-    s.clone()
-  }
-}
-
 pub trait DocFileLoader {
   fn resolve(
     &self,
@@ -102,34 +39,15 @@ pub trait DocFileLoader {
 }
 
 pub struct DocParser {
+  pub ast_parser: AstParser,
   pub loader: Box<dyn DocFileLoader>,
-  pub buffered_error: SwcErrorBuffer,
-  pub source_map: Arc<SourceMap>,
-  pub handler: Handler,
-  pub comments: Comments,
-  pub globals: Globals,
 }
 
 impl DocParser {
   pub fn new(loader: Box<dyn DocFileLoader>) -> Self {
-    let buffered_error = SwcErrorBuffer::default();
-
-    let handler = Handler::with_emitter_and_flags(
-      Box::new(buffered_error.clone()),
-      HandlerFlags {
-        dont_buffer_diagnostics: true,
-        can_emit_warnings: true,
-        ..Default::default()
-      },
-    );
-
     DocParser {
       loader,
-      buffered_error,
-      source_map: Arc::new(SourceMap::default()),
-      handler,
-      comments: Comments::default(),
-      globals: Globals::new(),
+      ast_parser: AstParser::new(),
     }
   }
 
@@ -138,47 +56,19 @@ impl DocParser {
     file_name: &str,
     source_code: &str,
   ) -> Result<ModuleDoc, SwcDiagnosticBuffer> {
-    swc_common::GLOBALS.set(&self.globals, || {
-      let swc_source_file = self.source_map.new_source_file(
-        FileName::Custom(file_name.to_string()),
-        source_code.to_string(),
-      );
-
-      let buffered_err = self.buffered_error.clone();
-      let session = Session {
-        handler: &self.handler,
-      };
-
-      let mut ts_config = TsConfig::default();
-      ts_config.dynamic_import = true;
-      let syntax = Syntax::Typescript(ts_config);
-
-      let lexer = Lexer::new(
-        session,
-        syntax,
-        JscTarget::Es2019,
-        SourceFileInput::from(&*swc_source_file),
-        Some(&self.comments),
-      );
-
-      let mut parser = Parser::new_from(session, lexer);
-
-      let module =
-        parser
-          .parse_module()
-          .map_err(move |mut err: DiagnosticBuilder| {
-            err.cancel();
-            SwcDiagnosticBuffer::from(buffered_err)
-          })?;
-
-      let doc_entries = self.get_doc_nodes_for_module_body(module.body.clone());
-      let reexports = self.get_reexports_for_module_body(module.body);
-      let module_doc = ModuleDoc {
-        exports: doc_entries,
-        reexports,
-      };
-      Ok(module_doc)
-    })
+    self
+      .ast_parser
+      .parse_module(file_name, source_code, |parse_result| {
+        let module = parse_result?;
+        let doc_entries =
+          self.get_doc_nodes_for_module_body(module.body.clone());
+        let reexports = self.get_reexports_for_module_body(module.body);
+        let module_doc = ModuleDoc {
+          exports: doc_entries,
+          reexports,
+        };
+        Ok(module_doc)
+      })
   }
 
   pub async fn parse(&self, file_name: &str) -> Result<Vec<DocNode>, ErrBox> {
@@ -323,7 +213,7 @@ impl DocParser {
 
   fn details_for_span(&self, span: Span) -> (Option<String>, Location) {
     let js_doc = self.js_doc_for_span(span);
-    let location = self.source_map.lookup_char_pos(span.lo()).into();
+    let location = self.ast_parser.get_span_location(span).into();
     (js_doc, location)
   }
 
@@ -567,13 +457,13 @@ impl DocParser {
   }
 
   pub fn js_doc_for_span(&self, span: Span) -> Option<String> {
-    let comments = self.comments.take_leading_comments(span.lo())?;
+    let comments = self.ast_parser.get_span_comments(span);
     let js_doc_comment = comments.iter().find(|comment| {
       comment.kind == CommentKind::Block && comment.text.starts_with('*')
     })?;
 
     let mut margin_pat = String::from("");
-    if let Some(margin) = self.source_map.span_to_margin(span) {
+    if let Some(margin) = self.ast_parser.source_map.span_to_margin(span) {
       for _ in 0..margin {
         margin_pat.push(' ');
       }
diff --git a/cli/lib.rs b/cli/lib.rs
index 2cd077ebb..9d35710ab 100644
--- a/cli/lib.rs
+++ b/cli/lib.rs
@@ -53,6 +53,7 @@ pub mod signal;
 pub mod source_maps;
 mod startup_data;
 pub mod state;
+mod swc_util;
 mod test_runner;
 pub mod test_util;
 mod tokio_util;
diff --git a/cli/swc_util.rs b/cli/swc_util.rs
new file mode 100644
index 000000000..2086a5ded
--- /dev/null
+++ b/cli/swc_util.rs
@@ -0,0 +1,164 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use crate::swc_common;
+use crate::swc_common::comments::Comments;
+use crate::swc_common::errors::Diagnostic;
+use crate::swc_common::errors::DiagnosticBuilder;
+use crate::swc_common::errors::Emitter;
+use crate::swc_common::errors::Handler;
+use crate::swc_common::errors::HandlerFlags;
+use crate::swc_common::FileName;
+use crate::swc_common::Globals;
+use crate::swc_common::SourceMap;
+use crate::swc_common::Span;
+use crate::swc_ecma_ast;
+use crate::swc_ecma_parser::lexer::Lexer;
+use crate::swc_ecma_parser::JscTarget;
+use crate::swc_ecma_parser::Parser;
+use crate::swc_ecma_parser::Session;
+use crate::swc_ecma_parser::SourceFileInput;
+use crate::swc_ecma_parser::Syntax;
+use crate::swc_ecma_parser::TsConfig;
+
+use std::error::Error;
+use std::fmt;
+use std::sync::Arc;
+use std::sync::RwLock;
+
+#[derive(Clone, Debug)]
+pub struct SwcDiagnosticBuffer {
+  pub diagnostics: Vec<Diagnostic>,
+}
+
+impl Error for SwcDiagnosticBuffer {}
+
+impl fmt::Display for SwcDiagnosticBuffer {
+  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    let msg = self
+      .diagnostics
+      .iter()
+      .map(|d| d.message())
+      .collect::<Vec<String>>()
+      .join(",");
+
+    f.pad(&msg)
+  }
+}
+
+#[derive(Clone)]
+pub struct SwcErrorBuffer(Arc<RwLock<SwcDiagnosticBuffer>>);
+
+impl SwcErrorBuffer {
+  pub fn default() -> Self {
+    Self(Arc::new(RwLock::new(SwcDiagnosticBuffer {
+      diagnostics: vec![],
+    })))
+  }
+}
+
+impl Emitter for SwcErrorBuffer {
+  fn emit(&mut self, db: &DiagnosticBuilder) {
+    self.0.write().unwrap().diagnostics.push((**db).clone());
+  }
+}
+
+impl From<SwcErrorBuffer> for SwcDiagnosticBuffer {
+  fn from(buf: SwcErrorBuffer) -> Self {
+    let s = buf.0.read().unwrap();
+    s.clone()
+  }
+}
+
+/// Low-level utility structure with common AST parsing functions.
+///
+/// Allows to build more complicated parser by providing a callback
+/// to `parse_module`.
+pub struct AstParser {
+  pub buffered_error: SwcErrorBuffer,
+  pub source_map: Arc<SourceMap>,
+  pub handler: Handler,
+  pub comments: Comments,
+  pub globals: Globals,
+}
+
+impl AstParser {
+  pub fn new() -> Self {
+    let buffered_error = SwcErrorBuffer::default();
+
+    let handler = Handler::with_emitter_and_flags(
+      Box::new(buffered_error.clone()),
+      HandlerFlags {
+        dont_buffer_diagnostics: true,
+        can_emit_warnings: true,
+        ..Default::default()
+      },
+    );
+
+    AstParser {
+      buffered_error,
+      source_map: Arc::new(SourceMap::default()),
+      handler,
+      comments: Comments::default(),
+      globals: Globals::new(),
+    }
+  }
+
+  pub fn parse_module<F, R>(
+    &self,
+    file_name: &str,
+    source_code: &str,
+    callback: F,
+  ) -> R
+  where
+    F: FnOnce(Result<swc_ecma_ast::Module, SwcDiagnosticBuffer>) -> R,
+  {
+    swc_common::GLOBALS.set(&self.globals, || {
+      let swc_source_file = self.source_map.new_source_file(
+        FileName::Custom(file_name.to_string()),
+        source_code.to_string(),
+      );
+
+      let buffered_err = self.buffered_error.clone();
+      let session = Session {
+        handler: &self.handler,
+      };
+
+      let mut ts_config = TsConfig::default();
+      ts_config.dynamic_import = true;
+      let syntax = Syntax::Typescript(ts_config);
+
+      let lexer = Lexer::new(
+        session,
+        syntax,
+        JscTarget::Es2019,
+        SourceFileInput::from(&*swc_source_file),
+        Some(&self.comments),
+      );
+
+      let mut parser = Parser::new_from(session, lexer);
+
+      let parse_result =
+        parser
+          .parse_module()
+          .map_err(move |mut err: DiagnosticBuilder| {
+            err.cancel();
+            SwcDiagnosticBuffer::from(buffered_err)
+          });
+
+      callback(parse_result)
+    })
+  }
+
+  pub fn get_span_location(&self, span: Span) -> swc_common::Loc {
+    self.source_map.lookup_char_pos(span.lo())
+  }
+
+  pub fn get_span_comments(
+    &self,
+    span: Span,
+  ) -> Vec<swc_common::comments::Comment> {
+    self
+      .comments
+      .take_leading_comments(span.lo())
+      .unwrap_or_else(|| vec![])
+  }
+}