support arrow function (#4385)

1 files changed, 114 insertions, 42 deletions

diff --git a/lib/parse.js b/lib/parse.js
index c65b2f42..f760d0de 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -569,6 +569,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
             }
             if (is_digit(code)) return read_num();
             if (PUNC_CHARS[ch]) return token("punc", next());
+            if (looking_at("=>")) return token("punc", next() + next());
             if (OPERATOR_CHARS[ch]) return read_operator();
             if (code == 92 || !NON_IDENTIFIER_CHARS[ch]) return read_word();
             break;
@@ -634,7 +635,7 @@ var PRECEDENCE = function(a, ret) {
     ["*", "/", "%"]
 ], {});
 
-var ATOMIC_START_TOKEN = makePredicate("atom num string regexp name");
+var ATOMIC_START_TOKEN = makePredicate("atom num regexp string");
 
 /* -----[ Parser ]----- */
 
@@ -741,7 +742,7 @@ function parse($TEXT, options) {
 
     function parenthesised() {
         expect("(");
-        var exp = expression(true);
+        var exp = expression();
         expect(")");
         return exp;
     }
@@ -769,7 +770,7 @@ function parse($TEXT, options) {
         switch (S.token.type) {
           case "string":
             var dir = S.in_directives;
-            var body = expression(true);
+            var body = expression();
             if (dir) {
                 if (body instanceof AST_String) {
                     var value = body.start.raw.slice(1, -1);
@@ -887,7 +888,7 @@ function parse($TEXT, options) {
                 if (is("punc", ";")) {
                     next();
                 } else if (!can_insert_semicolon()) {
-                    value = expression(true);
+                    value = expression();
                     semicolon();
                 }
                 return new AST_Return({
@@ -905,7 +906,7 @@ function parse($TEXT, options) {
                 next();
                 if (has_newline_before(S.token))
                     croak("Illegal newline after 'throw'");
-                var value = expression(true);
+                var value = expression();
                 semicolon();
                 return new AST_Throw({
                     value: value
@@ -956,9 +957,7 @@ function parse($TEXT, options) {
             // https://github.com/mishoo/UglifyJS/issues/287
             label.references.forEach(function(ref) {
                 if (ref instanceof AST_Continue) {
-                    ref = ref.label.start;
-                    croak("Continue label `" + label.name + "` refers to non-IterationStatement.",
-                          ref.line, ref.col, ref.pos);
+                    token_error(ref.label.start, "Continue label `" + label.name + "` must refer to IterationStatement");
                 }
             });
         }
@@ -966,7 +965,7 @@ function parse($TEXT, options) {
     }
 
     function simple_statement() {
-        var body = expression(true);
+        var body = expression();
         semicolon();
         return new AST_SimpleStatement({ body: body });
     }
@@ -980,7 +979,7 @@ function parse($TEXT, options) {
             ldef = find_if(function(l) {
                 return l.name == label.name;
             }, S.labels);
-            if (!ldef) croak("Undefined label " + label.name);
+            if (!ldef) token_error(label.start, "Undefined label " + label.name);
             label.thedef = ldef;
         } else if (S.in_loop == 0) croak(type.TYPE + " not inside a loop or switch");
         semicolon();
@@ -999,13 +998,14 @@ function parse($TEXT, options) {
                 ? (next(), let_(true))
                 : is("keyword", "var")
                 ? (next(), var_(true))
-                : expression(true, true);
+                : expression(true);
             if (is("operator", "in")) {
                 if (init instanceof AST_Definitions) {
-                    if (init.definitions.length > 1)
-                        croak("Only one variable declaration allowed in for..in loop", init.start.line, init.start.col, init.start.pos);
+                    if (init.definitions.length > 1) {
+                        token_error(init.start, "Only one variable declaration allowed in for..in loop");
+                    }
                 } else if (!(is_assignable(init) || (init = to_destructured(init)) instanceof AST_Destructured)) {
-                    croak("Invalid left-hand side in for..in loop", init.start.line, init.start.col, init.start.pos);
+                    token_error(init.start, "Invalid left-hand side in for..in loop");
                 }
                 next();
                 return for_in(init);
@@ -1016,9 +1016,9 @@ function parse($TEXT, options) {
 
     function regular_for(init) {
         expect(";");
-        var test = is("punc", ";") ? null : expression(true);
+        var test = is("punc", ";") ? null : expression();
         expect(";");
-        var step = is("punc", ")") ? null : expression(true);
+        var step = is("punc", ")") ? null : expression();
         expect(")");
         return new AST_For({
             init      : init,
@@ -1029,7 +1029,7 @@ function parse($TEXT, options) {
     }
 
     function for_in(init) {
-        var obj = expression(true);
+        var obj = expression();
         expect(")");
         return new AST_ForIn({
             init   : init,
@@ -1038,6 +1038,71 @@ function parse($TEXT, options) {
         });
     }
 
+    function to_funarg(node) {
+        if (node instanceof AST_Array) return new AST_DestructuredArray({
+            start: node.start,
+            elements: node.elements.map(function(node) {
+                return node instanceof AST_Hole ? node : to_funarg(node);
+            }),
+            end: node.end,
+        });
+        if (node instanceof AST_Object) return new AST_DestructuredObject({
+            start: node.start,
+            properties: node.properties.map(function(prop) {
+                if (!(prop instanceof AST_ObjectKeyVal)) token_error(prop.start, "Invalid destructuring assignment");
+                return new AST_DestructuredKeyVal({
+                    start: prop.start,
+                    key: prop.key,
+                    value: to_funarg(prop.value),
+                    end: prop.end,
+                });
+            }),
+            end: node.end,
+        });
+        if (node instanceof AST_SymbolRef) return new AST_SymbolFunarg(node);
+        token_error(node.start, "Invalid arrow parameter");
+    }
+
+    function arrow(exprs, start) {
+        var was_async = S.in_async;
+        S.in_async = false;
+        var was_funarg = S.in_funarg;
+        S.in_funarg = S.in_function;
+        var argnames = exprs.map(to_funarg);
+        S.in_funarg = was_funarg;
+        expect("=>");
+        var body, value;
+        var loop = S.in_loop;
+        var labels = S.labels;
+        ++S.in_function;
+        S.in_directives = true;
+        S.input.push_directives_stack();
+        S.in_loop = 0;
+        S.labels = [];
+        if (is("punc", "{")) {
+            body = block_();
+            value = null;
+            if (S.input.has_directive("use strict")) {
+                argnames.forEach(strict_verify_symbol);
+            }
+        } else {
+            body = [];
+            value = maybe_assign();
+        }
+        S.input.pop_directives_stack();
+        --S.in_function;
+        S.in_loop = loop;
+        S.labels = labels;
+        S.in_async = was_async;
+        return new AST_Arrow({
+            start: start,
+            argnames: argnames,
+            body: body,
+            value: value,
+            end: prev(),
+        });
+    }
+
     var function_ = function(ctor) {
         var was_async = S.in_async;
         var name;
@@ -1118,7 +1183,7 @@ function parse($TEXT, options) {
                 cur = [];
                 branch = new AST_Case({
                     start      : (tmp = S.token, next(), tmp),
-                    expression : expression(true),
+                    expression : expression(),
                     body       : cur
                 });
                 a.push(branch);
@@ -1187,7 +1252,7 @@ function parse($TEXT, options) {
             var value = null;
             if (is("operator", "=")) {
                 next();
-                value = expression(false, no_in);
+                value = maybe_assign(no_in);
             } else if (!no_in && (type === AST_SymbolConst || name instanceof AST_Destructured)) {
                 croak("Missing initializer in declaration");
             }
@@ -1251,9 +1316,6 @@ function parse($TEXT, options) {
     function as_atom_node() {
         var tok = S.token, ret;
         switch (tok.type) {
-          case "name":
-            ret = _make_symbol(AST_SymbolRef, tok);
-            break;
           case "num":
             ret = new AST_Number({ start: tok, end: tok, value: tok.value });
             break;
@@ -1295,7 +1357,11 @@ function parse($TEXT, options) {
             switch (start.value) {
               case "(":
                 next();
-                var ex = expression(true);
+                if (is("punc", ")")) {
+                    next();
+                    return arrow([], start);
+                }
+                var ex = expression(false, true);
                 var len = start.comments_before.length;
                 [].unshift.apply(ex.start.comments_before, start.comments_before);
                 start.comments_before.length = 0;
@@ -1318,6 +1384,7 @@ function parse($TEXT, options) {
                 end.comments_after = ex.end.comments_after;
                 ex.end = end;
                 if (ex instanceof AST_Call) mark_pure(ex);
+                if (is("punc", "=>")) return arrow(ex instanceof AST_Sequence ? ex.expressions : [ ex ], start);
                 return subscripts(ex, allow_calls);
               case "[":
                 return subscripts(array_(), allow_calls);
@@ -1340,6 +1407,11 @@ function parse($TEXT, options) {
             func.end = prev();
             return subscripts(func, allow_calls);
         }
+        if (is("name")) {
+            var sym = _make_symbol(AST_SymbolRef, start);
+            next();
+            return is("punc", "=>") ? arrow([ sym ], start) : subscripts(sym, allow_calls);
+        }
         if (ATOMIC_START_TOKEN[S.token.type]) {
             return subscripts(as_atom_node(), allow_calls);
         }
@@ -1347,14 +1419,14 @@ function parse($TEXT, options) {
     };
 
     function expr_list(closing, allow_trailing_comma, allow_empty, parser) {
-        if (!parser) parser = expression;
+        if (!parser) parser = maybe_assign;
         var first = true, a = [];
         while (!is("punc", closing)) {
             if (first) first = false; else expect(",");
             if (allow_trailing_comma && is("punc", closing)) break;
             if (allow_empty && is("punc", ",")) {
                 a.push(new AST_Hole({ start: S.token, end: S.token }));
-            } else if (parser === expression && is("operator", "...")) {
+            } else if (parser === maybe_assign && is("operator", "...")) {
                 a.push(new AST_Spread({
                     start: S.token,
                     expression: (next(), parser()),
@@ -1391,7 +1463,7 @@ function parse($TEXT, options) {
                 next();
                 a.push(new AST_Spread({
                     start: start,
-                    expression: expression(false),
+                    expression: maybe_assign(),
                     end: prev(),
                 }));
                 continue;
@@ -1440,7 +1512,7 @@ function parse($TEXT, options) {
             a.push(new AST_ObjectKeyVal({
                 start: start,
                 key: key,
-                value: expression(false),
+                value: maybe_assign(),
                 end: prev(),
             }));
         }
@@ -1463,7 +1535,7 @@ function parse($TEXT, options) {
           case "punc":
             if (tmp.value != "[") unexpected();
             next();
-            var key = expression(false);
+            var key = maybe_assign();
             expect("]");
             return key;
           default:
@@ -1490,7 +1562,7 @@ function parse($TEXT, options) {
 
     function strict_verify_symbol(sym) {
         if (sym.name == "arguments" || sym.name == "eval")
-            croak("Unexpected " + sym.name + " in strict mode", sym.start.line, sym.start.col, sym.start.pos);
+            token_error(sym.start, "Unexpected " + sym.name + " in strict mode");
     }
 
     function as_symbol(type, noerror) {
@@ -1580,7 +1652,7 @@ function parse($TEXT, options) {
         }
         if (is("punc", "[")) {
             next();
-            var prop = expression(true);
+            var prop = expression();
             expect("]");
             return subscripts(new AST_Sub({
                 start      : start,
@@ -1629,11 +1701,11 @@ function parse($TEXT, options) {
           case "++":
           case "--":
             if (!is_assignable(expr))
-                croak("Invalid use of " + op + " operator", token.line, token.col, token.pos);
+                token_error(token, "Invalid use of " + op + " operator");
             break;
           case "delete":
             if (expr instanceof AST_SymbolRef && S.input.has_directive("use strict"))
-                croak("Calling delete on expression not allowed in strict mode", expr.start.line, expr.start.col, expr.start.pos);
+                token_error(expr.start, "Calling delete on expression not allowed in strict mode");
             break;
         }
         return new ctor({ operator: op, expression: expr });
@@ -1679,13 +1751,13 @@ function parse($TEXT, options) {
         var expr = expr_ops(no_in);
         if (is("operator", "?")) {
             next();
-            var yes = expression(false);
+            var yes = maybe_assign();
             expect(":");
             return new AST_Conditional({
                 start       : start,
                 condition   : expr,
                 consequent  : yes,
-                alternative : expression(false, no_in),
+                alternative : maybe_assign(no_in),
                 end         : prev()
             });
         }
@@ -1728,7 +1800,7 @@ function parse($TEXT, options) {
         });
     }
 
-    var maybe_assign = function(no_in) {
+    function maybe_assign(no_in) {
         var start = S.token;
         var left = maybe_conditional(no_in), val = S.token.value;
         if (is("operator") && ASSIGNMENT[val]) {
@@ -1745,23 +1817,23 @@ function parse($TEXT, options) {
             croak("Invalid assignment");
         }
         return left;
-    };
+    }
 
-    var expression = function(commas, no_in) {
+    function expression(no_in, maybe_arrow) {
         var start = S.token;
         var exprs = [];
         while (true) {
             exprs.push(maybe_assign(no_in));
-            if (!commas || !is("punc", ",")) break;
+            if (!is("punc", ",")) break;
             next();
-            commas = true;
+            if (maybe_arrow && is("punc", ")") && is_token(peek(), "punc", "=>")) break;
         }
         return exprs.length == 1 ? exprs[0] : new AST_Sequence({
             start       : start,
             expressions : exprs,
-            end         : peek()
+            end         : prev()
         });
-    };
+    }
 
     function in_loop(cont) {
         ++S.in_loop;
@@ -1772,7 +1844,7 @@ function parse($TEXT, options) {
 
     if (options.expression) {
         handle_regexp();
-        return expression(true);
+        return expression();
     }
 
     return function() {