FEAT: Implement ??

Co-authored-by: Greg Caban <[email protected]>
mozilla · Aug 29, 2024 · a8d4621 · a8d4621
1 parent 4e6523b
commit a8d4621
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Showing 6 changed files with 85 additions and 6 deletions.
diff --git a/rhino/src/main/java/org/mozilla/javascript/IRFactory.java b/rhino/src/main/java/org/mozilla/javascript/IRFactory.java
@@ -2038,6 +2038,23 @@ private static Node createBinary(int nodeType, Node left, Node right) {
                     }
                     break;
                 }
+
+            case Token.NULLISH_COALESCING:
+                {
+                    // foo ?? default =>
+                    //     (foo == undefined || foo == null) ? foo (left) : default (right)
+
+                    Node undefinedNode = new Name(0, "undefined");
+                    Node nullNode = new Node(Token.NULL);
+
+                    Node conditional =
+                            new Node(
+                                    Token.OR,
+                                    new Node(Token.SHEQ, nullNode, left),
+                                    new Node(Token.SHEQ, undefinedNode, left));
+
+                    return new Node(Token.HOOK, conditional, right, left);
+                }
         }
 
         return new Node(nodeType, left, right);

diff --git a/rhino/src/main/java/org/mozilla/javascript/Parser.java b/rhino/src/main/java/org/mozilla/javascript/Parser.java
@@ -2370,7 +2370,7 @@ private AstNode assignExpr() throws IOException {
     }
 
     private AstNode condExpr() throws IOException {
-        AstNode pn = orExpr();
+        AstNode pn = nullishCoalescingExpr();
         if (matchToken(Token.HOOK, true)) {
             int line = ts.lineno;
             int qmarkPos = ts.tokenBeg, colonPos = -1;
@@ -2402,6 +2402,15 @@ private AstNode condExpr() throws IOException {
         return pn;
     }
 
+    private AstNode nullishCoalescingExpr() throws IOException {
+        AstNode pn = orExpr();
+        if (matchToken(Token.NULLISH_COALESCING, true)) {
+            int opPos = ts.tokenBeg;
+            pn = new InfixExpression(Token.NULLISH_COALESCING, pn, nullishCoalescingExpr(), opPos);
+        }
+        return pn;
+    }
+
     private AstNode orExpr() throws IOException {
         AstNode pn = andExpr();
         if (matchToken(Token.OR, true)) {

diff --git a/rhino/src/main/java/org/mozilla/javascript/Token.java b/rhino/src/main/java/org/mozilla/javascript/Token.java
@@ -227,7 +227,8 @@ public static enum CommentType {
             TEMPLATE_LITERAL_SUBST = 173, // template literal - substitution
             TAGGED_TEMPLATE_LITERAL = 174, // template literal - tagged/handler
             DOTDOTDOT = 175, // spread/rest ...
-            LAST_TOKEN = 175;
+            NULLISH_COALESCING = 176, // nullish coalescing (??)
+            LAST_TOKEN = 176;
 
     /**
      * Returns a name for the token. If Rhino is compiled with certain hardcoded debugging flags in
@@ -462,6 +463,8 @@ public static String typeToName(int token) {
                 return "COLON";
             case OR:
                 return "OR";
+            case NULLISH_COALESCING:
+                return "NULLISH_COALESCING";
             case AND:
                 return "AND";
             case INC:

diff --git a/rhino/src/main/java/org/mozilla/javascript/TokenStream.java b/rhino/src/main/java/org/mozilla/javascript/TokenStream.java
@@ -1146,6 +1146,9 @@ && peekChar() == '!'
                 case ',':
                     return Token.COMMA;
                 case '?':
+                    if (matchChar('?')) {
+                        return Token.NULLISH_COALESCING;
+                    }
                     return Token.HOOK;
                 case ':':
                     if (matchChar(':')) {

diff --git a/tests/src/test/java/org/mozilla/javascript/tests/NullishCoalescingOpTest.java b/tests/src/test/java/org/mozilla/javascript/tests/NullishCoalescingOpTest.java
@@ -0,0 +1,49 @@
+package org.mozilla.javascript.tests;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.mozilla.javascript.Context;
+import org.mozilla.javascript.Scriptable;
+
+public class NullishCoalescingOpTest {
+
+    @Test
+    public void testNullishColascingBasic() {
+        try (Context cx = Context.enter()) {
+            Scriptable scope = cx.initStandardObjects();
+            cx.setLanguageVersion(Context.VERSION_ES6);
+
+            String script = "null ?? 'default string'";
+            Assert.assertEquals(
+                    "default string",
+                    cx.evaluateString(scope, script, "nullish coalescing basic", 0, null));
+
+            String script2 = "undefined ?? 'default string'";
+            Assert.assertEquals(
+                    "default string",
+                    cx.evaluateString(scope, script2, "nullish coalescing basic", 0, null));
+        }
+    }
+
+    @Test
+    public void testNullishColascingPrecedence() {
+        try (Context cx = Context.enter()) {
+            Scriptable scope = cx.initStandardObjects();
+            cx.setLanguageVersion(Context.VERSION_ES6);
+            cx.setOptimizationLevel(-1);
+
+            String script1 = "3 == 3 ? 'yes' ?? 'default string' : 'no'";
+            Assert.assertEquals(
+                    "yes", cx.evaluateString(scope, script1, "nullish coalescing basic", 0, null));
+
+            String script3 = "3 || null ?? 'default string'";
+            Assert.assertEquals(
+                    3.0, cx.evaluateString(scope, script3, "nullish coalescing basic", 0, null));
+
+            String script2 = "3 && null ?? 'default string'";
+            Assert.assertEquals(
+                    "default string",
+                    cx.evaluateString(scope, script2, "nullish coalescing basic", 0, null));
+        }
+    }
+}
diff --git a/tests/testsrc/test262.properties b/tests/testsrc/test262.properties
@@ -4616,8 +4616,7 @@ language/expressions/compound-assignment 137/454 (30.18%)
 
 language/expressions/concatenation 0/5 (0.0%)
 
-language/expressions/conditional 3/22 (13.64%)
-    coalesce-expr-ternary.js
+language/expressions/conditional 2/22 (9.09%)
     tco-cond.js {unsupported: [tail-call-optimization]}
     tco-pos.js {unsupported: [tail-call-optimization]}
 
@@ -5282,7 +5281,7 @@ language/expressions/new 41/59 (69.49%)
 
 ~language/expressions/new.target
 
-language/expressions/object 866/1169 (74.08%)
+language/expressions/object 865/1169 (73.99%)
     dstr/async-gen-meth-ary-init-iter-close.js {unsupported: [async-iteration, async]}
     dstr/async-gen-meth-ary-init-iter-get-err.js {unsupported: [async-iteration]}
     dstr/async-gen-meth-ary-init-iter-get-err-array-prototype.js {unsupported: [async-iteration]}
@@ -6090,7 +6089,6 @@ language/expressions/object 866/1169 (74.08%)
     cpn-obj-lit-computed-property-name-from-assignment-expression-logical-or.js
     cpn-obj-lit-computed-property-name-from-async-arrow-function-expression.js
     cpn-obj-lit-computed-property-name-from-await-expression.js {unsupported: [module, async]}
-    cpn-obj-lit-computed-property-name-from-expression-coalesce.js
     cpn-obj-lit-computed-property-name-from-yield-expression.js
     fn-name-accessor-get.js
     fn-name-accessor-set.js