support template literals (#4601)

1 files changed, 28 insertions, 0 deletions

diff --git a/lib/ast.js b/lib/ast.js
index 1a09d4de..5bfe7be1 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -1418,6 +1418,34 @@ var AST_This = DEFNODE("This", null, {
     },
 }, AST_Symbol);
 
+var AST_Template = DEFNODE("Template", "expressions strings tag", {
+    $documentation: "A template literal, i.e. tag`str1${expr1}...strN${exprN}strN+1`",
+    $propdoc: {
+        expressions: "[AST_Node*] the placeholder expressions",
+        strings: "[string*] the interpolating text segments",
+        tag: "[AST_Node] tag function, or null if absent",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            if (node.tag) node.tag.walk(visitor);
+            node.expressions.forEach(function(expr) {
+                expr.walk(visitor);
+            });
+        });
+    },
+    _validate: function() {
+        if (this.expressions.length + 1 != this.strings.length) {
+            throw new Error("malformed template with " + this.expressions.length + " placeholder(s) but " + this.strings.length + " text segment(s)");
+        }
+        must_be_expressions(this, "expressions");
+        this.strings.forEach(function(string) {
+            if (typeof string != "string") throw new Error("strings must contain string");
+        });
+        if (this.tag != null) must_be_expression(this, "tag");
+    },
+});
+
 var AST_Constant = DEFNODE("Constant", null, {
     $documentation: "Base class for all constants",
 });