From 34639b0ae3926fe40ab649d509fb0bb084b7cc35 Mon Sep 17 00:00:00 2001
From: Dmitry Vasilev <dmitry.vasil@gmail.com>
Date: Mon, 5 Jun 2023 12:08:20 +0300
Subject: [PATCH] default import and export

---
 src/ast_utils.js        | 26 ++-------------
 src/cmd.js              | 17 +++++++---
 src/eval.js             | 41 +++++++++++++++--------
 src/find_definitions.js | 33 +++++++++---------
 src/parse_js.js         | 74 +++++++++++++++++++++++++++++------------
 test/test.js            | 31 +++++++++++++++++
 6 files changed, 142 insertions(+), 80 deletions(-)

diff --git a/src/ast_utils.js b/src/ast_utils.js
index 375603b..918c503 100644
--- a/src/ast_utils.js
+++ b/src/ast_utils.js
@@ -41,34 +41,12 @@ export const map_destructuring_identifiers = (node, mapper) => {
 }
 
 export const collect_imports = module => {
-  const import_statements =
+  return uniq(
     module.stmts
       .filter(n => n.type == 'import')
       .filter(n => !n.is_external)
-
-  const imported_modules = uniq(
-    import_statements.map(n => n.full_import_path)
+      .map(n => n.full_import_path)
   )
-
-  const imports = 
-    import_statements
-    .map(n => 
-      n.imports.map(i => 
-        ({name: i.value, module: n.full_import_path})
-      )
-    )
-    .flat()
-
-  const by_module = Object.fromEntries(imported_modules.map(m => 
-    [
-      m,
-      imports
-        .filter(i => i.module == m)
-        .map(i => i.name)
-    ]
-  ))
-
-  return by_module
 }
 
 export const collect_external_imports = modules =>
diff --git a/src/cmd.js b/src/cmd.js
index bb18aea..9ced303 100644
--- a/src/cmd.js
+++ b/src/cmd.js
@@ -1,12 +1,11 @@
-import {map_object, filter_object, collect_nodes_with_parents, uniq} 
+import {map_object, map_find, filter_object, collect_nodes_with_parents, uniq} 
   from './utils.js'
 import {
   is_eq, is_child, ancestry, ancestry_inc, map_tree,
   find_leaf, find_fn_by_location, find_node, find_error_origin_node,
-  collect_external_imports
+  collect_external_imports, collect_destructuring_identifiers
 } from './ast_utils.js'
 import {load_modules} from './parse_js.js'
-import {find_export} from './find_definitions.js'
 import {eval_modules} from './eval.js'
 import {
   root_calltree_node, root_calltree_module, make_calltree, 
@@ -555,7 +554,17 @@ const goto_definition = (state, index) => {
       } else {
         let loc
         if(d.module != null) {
-          const exp = find_export(node.value, state.parse_result.modules[d.module])
+          const exp = map_find(state.parse_result.modules[d.module].stmts, n => {
+            if(n.type != 'export') {
+              return null
+            }
+            if(n.is_default && d.is_default) {
+              return n.children[0]
+            } else if(!n.is_default && !d.is_default) {
+              const ids = collect_destructuring_identifiers(n.binding.name_node)
+              return ids.find(i => i.value == node.value)
+            }
+          })
           loc = {module: d.module, index: exp.index}
         } else {
           loc = {module: state.current_module, index: d.index}
diff --git a/src/eval.js b/src/eval.js
index 56c91ad..4283531 100644
--- a/src/eval.js
+++ b/src/eval.js
@@ -261,18 +261,25 @@ ${JSON.stringify(errormessage)}, true)`
   } else if(node.type == 'destructuring_pair') {
     return do_codegen(node.key) + ' : ' + do_codegen(node.value);
   } else if(node.type == 'import') {
-    const names = node.imports.map(n => n.value)
-    if(names.length == 0) {
-      return ''
+    let names, def
+    if(node.default_import != null) {
+      def = `default: ${node.default_import},`
+      names = node.children.slice(1).map(n => n.value)
     } else {
-      return `const {${names.join(',')}} = __cxt.modules['${node.full_import_path}'];`;
+      def = ''
+      names = node.children.map(n => n.value)
     }
+    return `const {${def} ${names.join(',')}} = __cxt.modules['${node.full_import_path}'];`;
   } else if(node.type == 'export') {
-    const identifiers = collect_destructuring_identifiers(node.binding.name_node)
-      .map(i => i.value)
-    return do_codegen(node.binding)
-      +
-      `Object.assign(__cxt.modules['${node_cxt.module}'], {${identifiers.join(',')}});`
+    if(node.is_default) {
+      return `__cxt.modules['${node_cxt.module}'].default = ${do_codegen(node.children[0])};`
+    } else {
+      const identifiers = collect_destructuring_identifiers(node.binding.name_node)
+        .map(i => i.value)
+      return do_codegen(node.binding)
+        +
+        `Object.assign(__cxt.modules['${node_cxt.module}'], {${identifiers.join(',')}});`
+    }
   } else if(node.type == 'function_decl') {
     const expr = node.children[0]
     return `const ${expr.name} = ${codegen_function_expr(expr, node_cxt)};`
@@ -991,12 +998,20 @@ const eval_statement = (s, scope, calls, context) => {
       node: {...s, children: [node], result: {ok: node.result.ok}}
     }
   } else if(s.type == 'import') {
-    const children = s.imports.map(i => (
-      {...i, 
-        result: {ok: true, value: context.modules[s.full_import_path][i.value]}
+    const module = context.modules[s.full_import_path]
+    const children = s.children.map((imp, i) => (
+      {...imp, 
+        result: {
+          ok: true, 
+          value: imp.definition.is_default
+            ? module['default']
+            : module[imp.value]
+        }
       }
     ))
-    const imported_scope = Object.fromEntries(children.map(i => [i.value, i.result.value]))
+    const imported_scope = Object.fromEntries(
+      children.map(imp => [imp.value, imp.result.value])
+    )
     return {
       ok: true,
       scope: {...scope, ...imported_scope},
diff --git a/src/find_definitions.js b/src/find_definitions.js
index 0e3f924..88564b5 100644
--- a/src/find_definitions.js
+++ b/src/find_definitions.js
@@ -22,7 +22,7 @@ const map_find_definitions = (nodes, mapper) => {
 const scope_from_node = n => {
   if(n.type == 'import') {
     return Object.fromEntries(
-      n.imports.map(i => [i.value, i])
+      n.children.map(i => [i.value, i])
     )
   } else if(n.type == 'export'){
     return scope_from_node(n.binding)
@@ -137,7 +137,13 @@ export const find_definitions = (ast, scope = {}, closure_scope = {}, module_nam
     let children, full_import_path
     if(ast.type == 'import') {
       full_import_path = concat_path(module_name, ast.module)
-      children = ast.children.map(c => ({...c, definition: {module: full_import_path}}))
+      children = ast.children.map((c, i) => ({
+        ...c, 
+        definition: {
+          module: full_import_path, 
+          is_default: i == 0 && ast.default_import != null,
+        }
+      }))
     } else if(ast.type == 'const') {
       children = [add_trivial_definition(ast.name_node), ...ast.children.slice(1)]
     } else if(ast.type == 'let') {
@@ -162,16 +168,6 @@ export const find_definitions = (ast, scope = {}, closure_scope = {}, module_nam
   }
 }
 
-export const find_export = (name, module) => {
-  return map_find(module.stmts, n => {
-    if(n.type != 'export') {
-      return null
-    }
-    const ids = collect_destructuring_identifiers(n.binding.name_node)
-    return ids.find(i => i.value == name)
-  })
-}
-
 const BASE = 'dummy://dummy/'
 const concat_path = (base, i) => {
   const result = new URL(i, BASE + base).toString()
@@ -184,11 +180,9 @@ const concat_path = (base, i) => {
 
 export const topsort_modules = (modules) => {
   const sort_module_deps = (module) => {
-    return Object.keys(collect_imports(modules[module]))
-      .reduce(
-        (result, m) => result.concat(sort_module_deps(m)),
-        []
-      )
+    return collect_imports(modules[module])
+      .map(m => sort_module_deps(m))
+      .flat()
       .concat(module)
   }
 
@@ -235,6 +229,8 @@ export const check_imports = modules => {
       .reduce(
         (imports, n) => [
           ...imports,
+          // TODO imports
+          // TODO use flatmap
           ...(n.imports.map(i => ({name: i.value, from: n.module})))
         ],
         []
@@ -245,7 +241,8 @@ export const check_imports = modules => {
       .reduce((all, current) => [...all, ...current], [])
 
     return {imports, exports}
-    //TODO check for each import, there is export
+    // TODO check for each import, there is export. For default import there is
+    // default export
   })
   // Topological sort
   // For each module
diff --git a/src/parse_js.js b/src/parse_js.js
index 265d50a..a541abd 100644
--- a/src/parse_js.js
+++ b/src/parse_js.js
@@ -1226,20 +1226,34 @@ const import_statement =
       optional(by_type('pragma_external')),
       seq([
         literal('import'),
+        // TODO import can have both named import and default import,
+        // like 'import foo, {bar} from "module"'
         optional(
-          seq([
-            list(
-              ['{', '}'],
+          seq_select(0, [
+            either(
+              list(
+                ['{', '}'],
+                identifier,
+              ),
               identifier,
             ),
             literal('from'),
-          ])
+          ]),
         ),
         string_literal
       ])
     ]),
     ({value: [pragma_external, imp]}) => {
-      const {value: [_import, identifiers, module], ...node} = imp
+      const {value: [_import, imports, module], ...node} = imp
+      let default_import, children
+      if(imports == null) {
+        children = []
+      } else if(imports.value.type == 'identifier') {
+        default_import = imports.value.value
+        children = [imports.value]
+      } else {
+        children = imports.value.value
+      }
       // remove quotes
       const module_string = module.value.slice(1, module.value.length - 1)
       // if url starts with protocol, then it is always external
@@ -1252,25 +1266,44 @@ const import_statement =
         // TODO refactor hanlding of string literals. Drop quotes from value and
         // fix codegen for string_literal
         module: module_string,
-        children: identifiers == null ? [] : identifiers.value[0].value,
+        default_import,
+        children,
       }
     }
   )
 
 const export_statement =
-  if_ok(
-    seq_select(1, [
-      literal('export'),
-      // TODO export let statement, export default, etc. Or not allow
-      // let statement because export let cannot be compiled properly?
-      const_statement,
-    ]),
-    ({value, ...node}) => ({
-      ...node,
-      not_evaluatable: true,
-      type: 'export',
-      children: [value],
-    })
+  either(
+    if_ok(
+      seq_select(1, [
+        literal('export'),
+        // TODO export let statement, export default, etc. Or not allow
+        // let statement because export let cannot be compiled properly?
+        const_statement,
+      ]),
+      ({value, ...node}) => ({
+        ...node,
+        not_evaluatable: true,
+        type: 'export',
+        is_default: false,
+        children: [value],
+      })
+    ),
+    if_ok(
+      seq_select(2, [
+        literal('export'),
+        literal('default'),
+        expr,
+      ]),
+      ({value, ...node}) => ({
+        ...node,
+        not_evaluatable: true,
+        type: 'export',
+        is_default: true,
+        children: [value],
+      })
+    ),
+
   )
 
 
@@ -1479,7 +1512,6 @@ const update_children_not_rec = (node, children = node.children) => {
     }
   } else if(node.type == 'import') {
     return {...node,
-      imports: children,
       is_statement: true,
     }
   } else if(node.type == 'export') {
@@ -1685,7 +1717,7 @@ const do_load_modules = (module_names, loader, already_loaded) => {
 
   const deps = uniq(
     Object.values(modules)
-      .map(m => Object.keys(collect_imports(m)))
+      .map(m => collect_imports(m))
       .flat()
   )
 
diff --git a/test/test.js b/test/test.js
index 37141d9..290919b 100644
--- a/test/test.js
+++ b/test/test.js
@@ -1145,6 +1145,37 @@ export const tests = [
     assert_equal(state.parse_result.ok, true)
   }),
 
+  test('modules default export', () => {
+    const modules = {
+      '' : "import foo from 'foo'; foo",
+      'foo': `export default 1`
+    }
+    assert_code_evals_to(modules , 1)
+
+    const i = test_initial_state(modules)
+    const s = COMMANDS.goto_definition(i, modules[''].indexOf('foo')).state
+    assert_equal(current_cursor_position(s), modules['foo'].indexOf('1'))
+    assert_equal(s.current_module, 'foo')
+  }),
+
+  test('modules default import', () => {
+    const code = `
+      // external
+      import foo from 'foo.js'
+      foo
+    `
+    const initial = test_initial_state(code)
+
+    const next = COMMANDS.external_imports_loaded(initial, initial, {
+      'foo.js': {
+        ok: true,
+        module: {
+          'default': 'foo_value'
+        },
+      }
+    })
+    assert_equal(active_frame(next).children.at(-1).result.value, 'foo_value')
+  }),
 
   // Static analysis