expand parameters

Conflicts:
	test/compress/harmony.js

lib/ast.js

@@ -363,10 +363,27 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     }
 }, AST_Scope);
 
+// TODO besides parameters and function calls, expansions can go in
+// arrays, array destructuring parameters, and array destructuring
+// assignment. But I'm not adding this right now because I'm trying
+// to do the most minimal and independent changesets.
+var AST_Expansion = DEFNODE("AST_Expansion", "symbol", {
+    $documentation: "An expandible argument, such as ...rest",
+    $propdoc: {
+        symbol: "AST_SymbolFunarg the name of the argument as a SymbolFunarg"
+    },
+    _walk: function(visitor) {
+        var self = this;
+        return visitor._visit(this, function(){
+            self.symbol.walk(visitor);
+        });
+    }
+});
+
 var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
     $documentation: "A set of arrow function parameters or a sequence expression. This is used because when the parser sees a \"(\" it could be the start of a seq, or the start of a parameter list of an arrow function.",
     $propdoc: {
-        expressions: "[AST_Expression|AST_Destructuring*] array of expressions or argument names or destructurings."
+        expressions: "[AST_Expression|AST_Destructuring|AST_Expansion*] array of expressions or argument names or destructurings."
     },
     as_params: function (croak) {
         // We don't want anything which doesn't belong in a destructuring
@@ -398,6 +415,8 @@ var AST_ArrowParametersOrSeq = DEFNODE("ArrowParametersOrSeq", "expressions", {
                     start: ex.start,
                     end: ex.end
                 });
+            } else if (ex instanceof AST_Expansion) {
+                return ex;
             } else if (ex instanceof AST_Array) {
                 if (ex.elements.length === 0)
                     croak("Invalid destructuring function parameter", ex.start.line, ex.start.col);
@@ -421,7 +440,7 @@ var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments", {
     $documentation: "Base class for functions",
     $propdoc: {
         name: "[AST_SymbolDeclaration?] the name of this function",
-        argnames: "[AST_SymbolFunarg|AST_Destructuring*] array of function arguments or destructurings",
+        argnames: "[AST_SymbolFunarg|AST_Destructuring|AST_Expansion*] array of function arguments, destructurings, or expanding arguments",
         uses_arguments: "[boolean/S] tells whether this function accesses the arguments array"
     },
     args_as_names: function () {
@@ -431,6 +450,9 @@ var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments", {
             if (parm instanceof AST_SymbolFunarg) {
                 out.push(parm);
             }
+            if (parm instanceof AST_Expansion) {
+                out.push(parm.symbol);
+            }
         }));
         return out;
     },

lib/compress.js

@@ -1107,6 +1107,9 @@ merge(Compressor.prototype, {
                                     break;
                                 } else {
                                     var sym = a[i];
+                                    if (sym instanceof AST_Expansion) {
+                                        sym = sym.symbol;
+                                    }
                                     if (sym.unreferenced()) {
                                         a.pop();
                                         compressor.warn("Dropping unused function argument {name} [{file}:{line},{col}]", {

lib/output.js

@@ -607,6 +607,11 @@ function OutputStream(options) {
         output.semicolon();
     });
 
+    DEFPRINT(AST_Expansion, function (self, output) {
+        output.print('...');
+        self.symbol.print(output);
+    });
+
     DEFPRINT(AST_Destructuring, function (self, output) {
         output.print(self.is_array ? "[" : "{");
         var first = true;

lib/parse.js

@@ -526,9 +526,16 @@ function tokenizer($TEXT, filename, html5_comments) {
 
     function handle_dot() {
         next();
-        return is_digit(peek().charCodeAt(0))
-            ? read_num(".")
-            : token("punc", ".");
+        if (is_digit(peek().charCodeAt(0))) {
+            return read_num(".");
+        }
+        if (peek() === ".") {
+            next();  // Consume second dot
+            next();  // Consume third dot
+            return token("expand", "...");
+        }
+
+        return token("punc", ".");
     };
 
     function read_word() {
@@ -1034,7 +1041,16 @@ function parse($TEXT, options) {
         S.in_parameters = true;
         while (!is("punc", ")")) {
             if (first) first = false; else expect(",");
-            a.push(expression(false));
+            if (is("expand", "...")) {
+                next();
+                a.push(new AST_Expansion({
+                    start: prev(),
+                    symbol: as_symbol(AST_SymbolFunarg),
+                    end: S.token,
+                }));
+            } else {
+                a.push(expression(false));
+            }
         }
         S.in_parameters = false;
         var end = S.token
@@ -1475,13 +1491,32 @@ function parse($TEXT, options) {
             return subscripts(new AST_Call({
                 start      : start,
                 expression : expr,
-                args       : expr_list(")"),
+                args       : call_args(),
                 end        : prev()
             }), true);
         }
         return expr;
     };
 
+    var call_args = embed_tokens(function call_args() {
+        var first = true;
+        var args = [];
+        while (!is("punc", ")")) {
+            if (first) first = false; else expect(",");
+            if (is("expand", "...")) {
+                next();
+                args.push(new AST_Expansion({
+                    start: prev(),
+                    symbol: as_symbol(AST_SymbolFunarg)
+                }));
+            } else {
+                args.push(expression(false));
+            }
+        }
+        next();
+        return args;
+    });
+
     var maybe_unary = function(allow_calls) {
         var start = S.token;
         if (is("operator") && UNARY_PREFIX(start.value)) {

test/compress/expansions.js

@@ -0,0 +1,17 @@
+
+expand_arguments: {
+    input: {
+        func(a, ...rest);
+        func(...all);
+    }
+    expect_exact: "func(a,...rest);func(...all);"
+}
+
+expand_parameters: {
+    input: {
+        (function (a, ...b){});
+        (function (...args){});
+    }
+    expect_exact: "(function(a,...b){});(function(...args){});"
+}
+