from ... import/export (reversed import/export)

civet.dev/reference.md

@@ -2219,6 +2219,8 @@ class Civet <: Animal, Named
 
 ### Decorators
 
+Civet uses [`@` for `this](#this), so decorators need to use `@@`:
+
 <Playground>
 @@Object.seal
 class Civet
@@ -2503,12 +2505,12 @@ If you have `from` in your `import`, you can omit `import`.
 You can also omit quotes around most filenames.
 
 <Playground>
-fs from fs
+fs from fs/promises
 {basename, dirname} from path
 metadata from ./package.json with type: 'json'
 </Playground>
 
-### Import Like Object Destructuring
+### Import-Like Object Destructuring
 
 <Playground>
 import {X: LocalX, Y: LocalY} from "./util"
@@ -2566,6 +2568,18 @@ Most declarations can also be `export default`:
 export default x := 5
 </Playground>
 
+### Backward Import/Export
+
+Similar to Python, you can put `from` before `import`/`export`.
+Furthermore, `from` is optional.
+This can improve autocompletion behavior.
+
+<Playground>
+from fs/promises import { readFile, writeFile }
+./util import * as util
+./package.json with {type: 'json'} export { version }
+</Playground>
+
 ## Comments
 
 ### JavaScript Comments

source/parser.hera

@@ -1351,6 +1351,8 @@ CallExpression
   # Import declaration as an expression
   Import _ NamedImports __ FromClause ->
     return dynamizeImportDeclarationExpression($0)
+  FromClause:from __:fws Import:i _:iws NamedImports:imports ->
+    return dynamizeImportDeclarationExpression([i, iws, imports, fws, from])
   # Dynamic import(), with optional parentheses when not used at top level.
   # (At top level, ImportDeclaration will match first.)
   "import" ArgumentsWithTrailingMemberExpressions CallExpressionRest*:rest ->
@@ -5315,19 +5317,25 @@ ImportDeclaration
       type: "ImportDeclaration",
       children: [imp, $0.slice(1)],
     }
-  Import __ TypeKeyword __ ImportClause:imports __ FromClause:from -> { type: "ImportDeclaration", ts: true, children: $0, imports, from }
-  Import __ Operator OperatorBehavior?:behavior __ OperatorNamedImports:imports __ FromClause:from ->
+  ( ( Import __ ) / ImpliedImport ):i Operator OperatorBehavior?:behavior __:ws1 OperatorNamedImports:imports __:ws2 FromClause:from ->
     imports.specifiers.forEach((spec) => {
       state.operators.set(spec.binding.name, spec.behavior ?? behavior)
     })
     return {
       type: "ImportDeclaration",
-      children: [$1, $2, trimFirstSpace($5), imports, $7, from],
-        // omit $3 = Operator and $4 = OperatorBehavior
+      children: [i, trimFirstSpace(ws1), imports, ws2, from],
+        // omit $2 = Operator and $3 = OperatorBehavior
+      imports,
+      from,
+    }
+  Import __ ( TypeKeyword __ )?:t ImportClause:imports __ FromClause:from ->
+    return {
+      type: "ImportDeclaration",
+      children: $0,
       imports,
       from,
+      ts: !!t,
     }
-  Import __ ImportClause:imports __ FromClause:from -> { type: "ImportDeclaration", children: $0, imports, from }
   Import __ ModuleSpecifier:module -> { type: "ImportDeclaration", children: $0, module }
   # NOTE: Added import shorthand
   # NOTE: Not adding $loc to source map here yet because it will point to the start of the identifier
@@ -5341,16 +5349,25 @@ ImportDeclaration
     }
     const children = [i, t, imports, w, from]
     return { type: "ImportDeclaration", ts: !!t, children, imports, from }
-  ImpliedImport:i Operator OperatorBehavior?:behavior __ OperatorNamedImports:imports __ FromClause:from ->
+  # NOTE: [from] ... import ... reverse syntax
+  ImpliedFromClause:from __:fws Import:i __:iws Operator OperatorBehavior?:behavior __:ows OperatorNamedImports:imports ->
     imports.specifiers.forEach((spec) => {
       state.operators.set(spec.binding.name, spec.behavior ?? behavior)
     })
     return {
       type: "ImportDeclaration",
-      children: [$1, trimFirstSpace($4), imports, $6, from],
-        // omit $2 = Operator and $3 = OperatorBehavior
+      children: [i, iws, trimFirstSpace(ows), imports, fws, from],
+        // omit Operator and OperatorBehavior
+      imports,
+      from,
+    }
+  ImpliedFromClause:from __:fws Import:i __:iws ( TypeKeyword __ )?:t ImportClause:imports ->
+    return {
+      type: "ImportDeclaration",
+      children: [ i, iws, t, imports, fws, from ],
       imports,
       from,
+      ts: !!t,
     }
 
 ImpliedImport
@@ -5419,6 +5436,15 @@ FromClause
     if (!Array.isArray(module)) return $0
     return [ $1, $2, ...module ]
 
+ImpliedFromClause
+  ( ( From __ ) / ImpliedFrom ) ModuleSpecifier:module ->
+    if (!Array.isArray(module)) return $0
+    return [ $1, ...module ]
+
+ImpliedFrom
+  "" ->
+    return { $loc, token: "from " }
+
 # https://github.com/tc39/proposal-import-assertions
 # https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-5.html#import-assertions
 # https://github.com/tc39/proposal-import-attributes
@@ -5531,10 +5557,11 @@ UnprocessedModuleSpecifier
   UnquotedSpecifier
 
 UnquotedSpecifier
-  # Currently allowing all characters except for whitespace, double quotes, and semi-colon
+  # Currently allowing most non-whitespace characters
+  # Forbidding ; (statement separator), = (assignment), > (function arrow)
   # It may make sense to restrict this to only allow characters that are valid in a module specifier
   # Also consider URLs
-  /[^;"\s]+/:spec ->
+  /[^;"\s=>]+/:spec ->
     return { $loc, token: `"${spec}"` }
 
 # https://262.ecma-international.org/#prod-ImportedBinding
@@ -5583,8 +5610,15 @@ ExportDeclaration
   # NOTE: Using Expression to allow If/Switch expressions
   Decorators? Export __ Default __ ( HoistableDeclaration / ClassDeclaration / InterfaceDeclaration / MaybeNestedExpression ):declaration ->
     return { type: "ExportDeclaration", declaration, ts: declaration.ts, children: $0 }
-  Export __ ExportFromClause __ FromClause ->
-    return { type: "ExportDeclaration", ts: $3.ts, children: $0 }
+  Export __ ExportFromClause:exports __ FromClause ->
+    return { type: "ExportDeclaration", ts: exports.ts, children: $0 }
+  # NOTE: [from] ... export ... reverse syntax
+  ImpliedFromClause:from __:fws Export:e __:ews ExportFromClause:exports ->
+    return {
+      type: "ExportDeclaration",
+      ts: exports.ts,
+      children: [ e, ews, exports, " ", from, trimFirstSpace(fws) ],
+    }
   # NOTE: Declaration and VariableStatement should come before NamedExports
   # so that NamedExports doesn't grab function, async, type, var, etc.
   # NOTE: TS decorators come before `export` keyword but TC39 stage 3 decorators proposal come after

test/export.civet

@@ -273,3 +273,48 @@ describe "export", ->
     ---
     export { s } from "./stuff.json" with {type: "json"}
   """
+
+  describe "from ... export", ->
+    testCase """
+      top-level explicit from
+      ---
+      from "./module" export {x}
+      from ./module export {y}
+      from node:fs export { readFile }
+      from ./module export * as module
+      from ./module export a, b
+      from ./module export type T1, T2
+      from ./module export type { Type1, Type2 }
+      from ./package.json with {type: "json"} export { version }
+      ---
+      export {x} from "./module"
+      export {y} from "./module"
+      export { readFile } from "node:fs"
+      export * as module from "./module"
+      export {a, b} from "./module"
+      export type {T1, T2} from "./module"
+      export type { Type1, Type2 } from "./module"
+      export { version } from "./package.json" with {type: "json"}
+    """
+
+    testCase """
+      top-level implicit from
+      ---
+      from "./module" export {x}
+      from ./module export {y}
+      from node:fs export { readFile }
+      from ./module export * as module
+      from ./module export a, b
+      from ./module export type T1, T2
+      from ./module export type { Type1, Type2 }
+      from ./package.json with {type: "json"} export { version }
+      ---
+      export {x} from "./module"
+      export {y} from "./module"
+      export { readFile } from "node:fs"
+      export * as module from "./module"
+      export {a, b} from "./module"
+      export type {T1, T2} from "./module"
+      export type { Type1, Type2 } from "./module"
+      export { version } from "./package.json" with {type: "json"}
+    """

test/import.civet

@@ -442,3 +442,94 @@ describe "import", ->
           import "./foo.json"
           ${keyword}({type: "json"})
         ```
+
+  describe "from ... import", ->
+    testCase """
+      top-level explicit from
+      ---
+      from "./module" import {x}
+      from ./module import {y}
+      from node:fs import { readFile }
+      from ./module import * as module
+      from ./module import moduleDefault
+      from ./module import type Type
+      from ./module import type { Type1, Type2 }
+      from ./package.json with {type: "json"} import { version }
+      from ./operators import operator {a, b}
+      ---
+      import {x} from "./module"
+      import {y} from "./module"
+      import { readFile } from "node:fs"
+      import * as module from "./module"
+      import moduleDefault from "./module"
+      import type Type from "./module"
+      import type { Type1, Type2 } from "./module"
+      import { version } from "./package.json" with {type: "json"}
+      import {a, b} from "./operators"
+    """
+
+    testCase """
+      top-level implicit from
+      ---
+      "./module" import {x}
+      ./module import {y}
+      node:fs import { readFile }
+      ./module import * as module
+      ./module import moduleDefault
+      ./module import type Type
+      ./module import type { Type1, Type2 }
+      ./package.json with {type: "json"} import { version }
+      ./operators import operator {a, b}
+      ---
+      import {x} from "./module"
+      import {y} from "./module"
+      import { readFile } from "node:fs"
+      import * as module from "./module"
+      import moduleDefault from "./module"
+      import type Type from "./module"
+      import type { Type1, Type2 } from "./module"
+      import { version } from "./package.json" with {type: "json"}
+      import {a, b} from "./operators"
+    """
+
+    testCase """
+      dynamic declaration explicit from
+      ---
+      =>
+        from "./module" import {x}
+        from ./module import {y}
+        from node:fs import { readFile }
+        from ./module import * as module
+        from ./module import moduleDefault
+        from ./package.json with {type: "json"} import { version }
+      ---
+      async () => {
+        const {x} = await import("./module")
+        const {y} = await import("./module")
+        const {readFile} = await import("node:fs")
+        const module = await import("./module")
+        const moduleDefault = (await import("./module")).default
+        const {version} = await import("./package.json", {with:{type: "json"}});return {version}
+      }
+    """
+
+    testCase """
+      dynamic declaration implicit from
+      ---
+      =>
+        "./module" import {x}
+        ./module import {y}
+        node:fs import { readFile }
+        ./module import * as module
+        ./module import moduleDefault
+        ./package.json with {type: "json"} import { version }
+      ---
+      async () => {
+        const {x} = await import("./module")
+        const {y} = await import("./module")
+        const {readFile} = await import("node:fs")
+        const module = await import("./module")
+        const moduleDefault = (await import("./module")).default
+        const {version} = await import("./package.json", {with:{type: "json"}});return {version}
+      }
+    """