From fd4caf7a9cbfaa482d8cc77d2bc8cd00e8bc256a Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Sun, 7 Feb 2021 22:44:20 +0000
Subject: support generator functions (#4620)

---
 lib/output.js | 55 ++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 38 insertions(+), 17 deletions(-)

(limited to 'lib/output.js')

diff --git a/lib/output.js b/lib/output.js
index a171c7e7..b2213f74 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -673,7 +673,9 @@ function OutputStream(options) {
         }
     }
     PARENS(AST_AsyncFunction, needs_parens_function);
+    PARENS(AST_AsyncGeneratorFunction, needs_parens_function);
     PARENS(AST_Function, needs_parens_function);
+    PARENS(AST_GeneratorFunction, needs_parens_function);
 
     // same goes for an object literal, because otherwise it would be
     // interpreted as a block of code.
@@ -682,14 +684,19 @@ function OutputStream(options) {
     }
     PARENS(AST_Object, needs_parens_obj);
 
-    PARENS(AST_Unary, function(output) {
+    function needs_parens_unary(output) {
         var p = output.parent();
         // (-x) ** y
         if (p instanceof AST_Binary) return p.operator == "**" && p.left === this;
-        // (x++).toString(3)
-        // (typeof x).length
-        return (p instanceof AST_Call || p instanceof AST_PropAccess) && p.expression === this;
-    });
+        // (await x)(y)
+        // new (await x)
+        if (p instanceof AST_Call) return p.expression === this;
+        // (x++)[y]
+        // (typeof x).y
+        if (p instanceof AST_PropAccess) return p.expression === this;
+    }
+    PARENS(AST_Await, needs_parens_unary);
+    PARENS(AST_Unary, needs_parens_unary);
 
     PARENS(AST_Sequence, function(output) {
         var p = output.parent();
@@ -719,7 +726,9 @@ function OutputStream(options) {
             // !(foo, bar, baz)
             || p instanceof AST_Unary
             // var a = (1, 2), b = a + a; ---> b == 4
-            || p instanceof AST_VarDef;
+            || p instanceof AST_VarDef
+            // yield (foo, bar)
+            || p instanceof AST_Yield;
     });
 
     PARENS(AST_Binary, function(output) {
@@ -826,17 +835,8 @@ function OutputStream(options) {
     PARENS(AST_Conditional, function(output) {
         return needs_parens_assign_cond(this, output);
     });
-
-    PARENS(AST_Await, function(output) {
-        var p = output.parent();
-        // (await x) ** y
-        if (p instanceof AST_Binary) return p.operator == "**" && p.left === this;
-        // new (await foo)
-        // (await foo)(bar)
-        if (p instanceof AST_Call) return p.expression === this;
-        // (await foo).prop
-        // (await foo)["prop"]
-        if (p instanceof AST_PropAccess) return p.expression === this;
+    PARENS(AST_Yield, function(output) {
+        return needs_parens_assign_cond(this, output);
     });
 
     /* -----[ PRINTERS ]----- */
@@ -1061,6 +1061,20 @@ function OutputStream(options) {
     }
     DEFPRINT(AST_AsyncDefun, print_async);
     DEFPRINT(AST_AsyncFunction, print_async);
+    function print_async_generator(output) {
+        output.print("async");
+        output.space();
+        output.print("function*");
+        print_lambda(this, output);
+    }
+    DEFPRINT(AST_AsyncGeneratorDefun, print_async_generator);
+    DEFPRINT(AST_AsyncGeneratorFunction, print_async_generator);
+    function print_generator(output) {
+        output.print("function*");
+        print_lambda(this, output);
+    }
+    DEFPRINT(AST_GeneratorDefun, print_generator);
+    DEFPRINT(AST_GeneratorFunction, print_generator);
 
     /* -----[ jumps ]----- */
     function print_jump(kind, prop) {
@@ -1360,6 +1374,13 @@ function OutputStream(options) {
         output.space();
         this.expression.print(output);
     });
+    DEFPRINT(AST_Yield, function(output) {
+        output.print(this.nested ? "yield*" : "yield");
+        if (this.expression) {
+            output.space();
+            this.expression.print(output);
+        }
+    });
 
     /* -----[ literals ]----- */
     DEFPRINT(AST_Array, function(output) {
-- 
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