remove AST_ArrowParametersOrSeq (#1997)

lib/ast.js

@@ -355,79 +355,6 @@ var AST_Expansion = DEFNODE("Expansion", "expression", {
     }
 });
 
-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|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
-        var root = this;
-        return this.expressions.map(function to_fun_args(ex, _, __, default_seen_above) {
-            var insert_default = function(ex, default_value) {
-                if (default_value) {
-                    return new AST_DefaultAssign({
-                        start: ex.start,
-                        left: ex,
-                        operator: "=",
-                        right: default_value,
-                        end: default_value.end
-                    });
-                }
-                return ex;
-            }
-            if (ex instanceof AST_Object) {
-                return insert_default(new AST_Destructuring({
-                    start: ex.start,
-                    end: ex.end,
-                    is_array: false,
-                    names: ex.properties.map(to_fun_args)
-                }), default_seen_above);
-            } else if (ex instanceof AST_ObjectKeyVal) {
-                if (ex.key instanceof AST_SymbolRef) {
-                    ex.key = to_fun_args(ex.key, 0, [ex.key]);
-                }
-                ex.value = to_fun_args(ex.value, 0, [ex.key]);
-                return insert_default(ex, default_seen_above);
-            } else if (ex instanceof AST_Hole) {
-                return ex;
-            } else if (ex instanceof AST_Destructuring) {
-                ex.names = ex.names.map(to_fun_args);
-                return insert_default(ex, default_seen_above);
-            } else if (ex instanceof AST_SymbolRef) {
-                return insert_default(new AST_SymbolFunarg({
-                    name: ex.name,
-                    start: ex.start,
-                    end: ex.end
-                }), default_seen_above);
-            } else if (ex instanceof AST_Expansion) {
-                ex.expression = to_fun_args(ex.expression);
-                return insert_default(ex, default_seen_above);
-            } else if (ex instanceof AST_Array) {
-                return insert_default(new AST_Destructuring({
-                    start: ex.start,
-                    end: ex.end,
-                    is_array: true,
-                    names: ex.elements.map(to_fun_args)
-                }), default_seen_above);
-            } else if (ex instanceof AST_Assign) {
-                return insert_default(to_fun_args(ex.left, undefined, undefined, ex.right), default_seen_above);
-            } else if (ex instanceof AST_DefaultAssign) {
-                ex.left = to_fun_args(ex.left, 0, [ex.left]);
-                return ex;
-            } else {
-                croak("Invalid function parameter", ex.start.line, ex.start.col);
-            }
-        });
-    },
-    as_expr: function() {
-        var exprs = this.expressions;
-        return exprs.length == 1 ? exprs[0] : new AST_Sequence({
-            expressions: exprs
-        });
-    }
-});
-
 var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments is_generator", {
     $documentation: "Base class for functions",
     $propdoc: {

lib/parse.js

@@ -1272,26 +1272,17 @@ function parse($TEXT, options) {
         });
     };
 
-    var arrow_function = function(args) {
+    var arrow_function = function(start, argnames) {
         if (S.token.nlb) {
             croak("Unexpected newline before arrow (=>)");
         }
 
         expect_token("arrow", "=>");
 
-        var argnames;
+        var body = _function_body(is("punc", "{"));
-        if (typeof args.length === 'number') {
-            argnames = args;
-        } else {
-            argnames = args.as_params(croak);
-        }
-
-        var body = is("punc", "{") ?
-            _function_body(true) :
-            _function_body(false);
 
         return new AST_Arrow({
-            start    : args.start,
+            start    : start,
             end      : body.end,
             argnames : argnames,
             body     : body
@@ -1615,8 +1606,6 @@ function parse($TEXT, options) {
     }
 
     function params_or_seq_() {
-        var start = S.token
-        expect("(");
         var first = true;
         var a = [];
         while (!is("punc", ")")) {
@@ -1626,23 +1615,17 @@ function parse($TEXT, options) {
                 next();
                 a.push(new AST_Expansion({
                     start: prev(),
-                    expression: expression(false),
+                    expression: expression(),
                     end: S.token,
                 }));
                 if (!is("punc", ")")) {
                     unexpected(spread_token);
                 }
             } else {
-                a.push(expression(false));
+                a.push(expression());
             }
         }
-        var end = S.token
+        return a;
-        next();
-        return new AST_ArrowParametersOrSeq({
-            start: start,
-            end: end,
-            expressions: a
-        });
     }
 
     function _function_body(block, generator, name, args) {
@@ -1931,6 +1914,63 @@ function parse($TEXT, options) {
         return ret;
     };
 
+    function to_fun_args(ex, _, __, default_seen_above) {
+        var insert_default = function(ex, default_value) {
+            if (default_value) {
+                return new AST_DefaultAssign({
+                    start: ex.start,
+                    left: ex,
+                    operator: "=",
+                    right: default_value,
+                    end: default_value.end
+                });
+            }
+            return ex;
+        }
+        if (ex instanceof AST_Object) {
+            return insert_default(new AST_Destructuring({
+                start: ex.start,
+                end: ex.end,
+                is_array: false,
+                names: ex.properties.map(to_fun_args)
+            }), default_seen_above);
+        } else if (ex instanceof AST_ObjectKeyVal) {
+            if (ex.key instanceof AST_SymbolRef) {
+                ex.key = to_fun_args(ex.key, 0, [ex.key]);
+            }
+            ex.value = to_fun_args(ex.value, 0, [ex.key]);
+            return insert_default(ex, default_seen_above);
+        } else if (ex instanceof AST_Hole) {
+            return ex;
+        } else if (ex instanceof AST_Destructuring) {
+            ex.names = ex.names.map(to_fun_args);
+            return insert_default(ex, default_seen_above);
+        } else if (ex instanceof AST_SymbolRef) {
+            return insert_default(new AST_SymbolFunarg({
+                name: ex.name,
+                start: ex.start,
+                end: ex.end
+            }), default_seen_above);
+        } else if (ex instanceof AST_Expansion) {
+            ex.expression = to_fun_args(ex.expression);
+            return insert_default(ex, default_seen_above);
+        } else if (ex instanceof AST_Array) {
+            return insert_default(new AST_Destructuring({
+                start: ex.start,
+                end: ex.end,
+                is_array: true,
+                names: ex.elements.map(to_fun_args)
+            }), default_seen_above);
+        } else if (ex instanceof AST_Assign) {
+            return insert_default(to_fun_args(ex.left, undefined, undefined, ex.right), default_seen_above);
+        } else if (ex instanceof AST_DefaultAssign) {
+            ex.left = to_fun_args(ex.left, 0, [ex.left]);
+            return ex;
+        } else {
+            croak("Invalid function parameter", ex.start.line, ex.start.col);
+        }
+    }
+
     var expr_atom = function(allow_calls) {
         if (is("operator", "new")) {
             return new_(allow_calls);
@@ -1939,13 +1979,15 @@ function parse($TEXT, options) {
         if (is("punc")) {
             switch (start.value) {
               case "(":
-                var ex = params_or_seq_();
+                next();
+                var exprs = params_or_seq_();
+                expect(")");
                 if (is("arrow", "=>")) {
-                    ex.start = start;
+                    return arrow_function(start, exprs.map(to_fun_args));
-                    ex.end = S.token;
-                    return arrow_function(ex);
                 }
-                ex = ex.as_expr(croak);
+                var ex = exprs.length == 1 ? exprs[0] : new AST_Sequence({
+                    expressions: exprs
+                });
                 ex.start = start;
                 ex.end = S.token;
                 return subscripts(ex, allow_calls);
@@ -2668,7 +2710,7 @@ function parse($TEXT, options) {
         if (start.type == "punc" && start.value == "(" && peek().value == ")") {
             next();
             next();
-            return arrow_function([]);
+            return arrow_function(start, []);
         }
 
         if (is("name") && is_token(peek(), "arrow")) {
@@ -2678,7 +2720,7 @@ function parse($TEXT, options) {
                 end: start,
             });
             next();
-            return arrow_function([param])
+            return arrow_function(start, [param]);
         }
 
         var left = maybe_conditional(no_in);
@@ -2709,16 +2751,7 @@ function parse($TEXT, options) {
             next();
             commas = true;
         }
-        if (exprs.length == 1) {
+        return exprs.length == 1 ? exprs[0] : new AST_Sequence({
-            var expr = exprs[0];
-            if (!(expr instanceof AST_SymbolRef) || !is("arrow", "=>")) return expr;
-            return arrow_function(new AST_ArrowParametersOrSeq({
-                start: expr.start,
-                end: expr.end,
-                expressions: [expr]
-            }));
-        }
-        return new AST_Sequence({
             start       : start,
             expressions : exprs,
             end         : peek()