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1 files changed, 2231 insertions, 0 deletions

diff --git a/src/node_modules/terser/lib/output.js b/src/node_modules/terser/lib/output.js
new file mode 100644
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+++ b/src/node_modules/terser/lib/output.js
@@ -0,0 +1,2231 @@
+/***********************************************************************
+
+  A JavaScript tokenizer / parser / beautifier / compressor.
+  https://github.com/mishoo/UglifyJS2
+
+  -------------------------------- (C) ---------------------------------
+
+                           Author: Mihai Bazon
+                         <mihai.bazon@gmail.com>
+                       http://mihai.bazon.net/blog
+
+  Distributed under the BSD license:
+
+    Copyright 2012 (c) Mihai Bazon <mihai.bazon@gmail.com>
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+
+        * Redistributions of source code must retain the above
+          copyright notice, this list of conditions and the following
+          disclaimer.
+
+        * Redistributions in binary form must reproduce the above
+          copyright notice, this list of conditions and the following
+          disclaimer in the documentation and/or other materials
+          provided with the distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER “AS IS” AND ANY
+    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE
+    LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+    OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
+    TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+    THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+    SUCH DAMAGE.
+
+ ***********************************************************************/
+
+"use strict";
+
+import {
+    defaults,
+    makePredicate,
+    noop,
+    regexp_source_fix,
+    sort_regexp_flags,
+    return_false,
+    return_true,
+} from "./utils/index.js";
+import { first_in_statement, left_is_object } from "./utils/first_in_statement.js";
+import {
+    AST_Array,
+    AST_Arrow,
+    AST_Assign,
+    AST_Await,
+    AST_BigInt,
+    AST_Binary,
+    AST_BlockStatement,
+    AST_Break,
+    AST_Call,
+    AST_Case,
+    AST_Catch,
+    AST_Chain,
+    AST_Class,
+    AST_ClassExpression,
+    AST_ClassProperty,
+    AST_ConciseMethod,
+    AST_Conditional,
+    AST_Const,
+    AST_Constant,
+    AST_Continue,
+    AST_Debugger,
+    AST_Default,
+    AST_DefaultAssign,
+    AST_Definitions,
+    AST_Defun,
+    AST_Destructuring,
+    AST_Directive,
+    AST_Do,
+    AST_Dot,
+    AST_EmptyStatement,
+    AST_Exit,
+    AST_Expansion,
+    AST_Export,
+    AST_Finally,
+    AST_For,
+    AST_ForIn,
+    AST_ForOf,
+    AST_Function,
+    AST_Hole,
+    AST_If,
+    AST_Import,
+    AST_ImportMeta,
+    AST_Jump,
+    AST_LabeledStatement,
+    AST_Lambda,
+    AST_Let,
+    AST_LoopControl,
+    AST_NameMapping,
+    AST_New,
+    AST_NewTarget,
+    AST_Node,
+    AST_Number,
+    AST_Object,
+    AST_ObjectGetter,
+    AST_ObjectKeyVal,
+    AST_ObjectProperty,
+    AST_ObjectSetter,
+    AST_PrefixedTemplateString,
+    AST_PropAccess,
+    AST_RegExp,
+    AST_Return,
+    AST_Scope,
+    AST_Sequence,
+    AST_SimpleStatement,
+    AST_Statement,
+    AST_StatementWithBody,
+    AST_String,
+    AST_Sub,
+    AST_Super,
+    AST_Switch,
+    AST_SwitchBranch,
+    AST_Symbol,
+    AST_SymbolClassProperty,
+    AST_SymbolMethod,
+    AST_SymbolRef,
+    AST_TemplateSegment,
+    AST_TemplateString,
+    AST_This,
+    AST_Throw,
+    AST_Toplevel,
+    AST_Try,
+    AST_Unary,
+    AST_UnaryPostfix,
+    AST_UnaryPrefix,
+    AST_Var,
+    AST_VarDef,
+    AST_While,
+    AST_With,
+    AST_Yield,
+    TreeWalker,
+    walk,
+    walk_abort
+} from "./ast.js";
+import {
+    get_full_char_code,
+    get_full_char,
+    is_identifier_char,
+    is_basic_identifier_string,
+    is_identifier_string,
+    PRECEDENCE,
+    RESERVED_WORDS,
+} from "./parse.js";
+
+const EXPECT_DIRECTIVE = /^$|[;{][\s\n]*$/;
+const CODE_LINE_BREAK = 10;
+const CODE_SPACE = 32;
+
+const r_annotation = /[@#]__(PURE|INLINE|NOINLINE)__/g;
+
+function is_some_comments(comment) {
+    // multiline comment
+    return (
+        (comment.type === "comment2" || comment.type === "comment1")
+        && /@preserve|@lic|@cc_on|^\**!/i.test(comment.value)
+    );
+}
+
+function OutputStream(options) {
+
+    var readonly = !options;
+    options = defaults(options, {
+        ascii_only           : false,
+        beautify             : false,
+        braces               : false,
+        comments             : "some",
+        ecma                 : 5,
+        ie8                  : false,
+        indent_level         : 4,
+        indent_start         : 0,
+        inline_script        : true,
+        keep_numbers         : false,
+        keep_quoted_props    : false,
+        max_line_len         : false,
+        preamble             : null,
+        preserve_annotations : false,
+        quote_keys           : false,
+        quote_style          : 0,
+        safari10             : false,
+        semicolons           : true,
+        shebang              : true,
+        shorthand            : undefined,
+        source_map           : null,
+        webkit               : false,
+        width                : 80,
+        wrap_iife            : false,
+        wrap_func_args       : true,
+    }, true);
+
+    if (options.shorthand === undefined)
+        options.shorthand = options.ecma > 5;
+
+    // Convert comment option to RegExp if neccessary and set up comments filter
+    var comment_filter = return_false; // Default case, throw all comments away
+    if (options.comments) {
+        let comments = options.comments;
+        if (typeof options.comments === "string" && /^\/.*\/[a-zA-Z]*$/.test(options.comments)) {
+            var regex_pos = options.comments.lastIndexOf("/");
+            comments = new RegExp(
+                options.comments.substr(1, regex_pos - 1),
+                options.comments.substr(regex_pos + 1)
+            );
+        }
+        if (comments instanceof RegExp) {
+            comment_filter = function(comment) {
+                return comment.type != "comment5" && comments.test(comment.value);
+            };
+        } else if (typeof comments === "function") {
+            comment_filter = function(comment) {
+                return comment.type != "comment5" && comments(this, comment);
+            };
+        } else if (comments === "some") {
+            comment_filter = is_some_comments;
+        } else { // NOTE includes "all" option
+            comment_filter = return_true;
+        }
+    }
+
+    var indentation = 0;
+    var current_col = 0;
+    var current_line = 1;
+    var current_pos = 0;
+    var OUTPUT = "";
+    let printed_comments = new Set();
+
+    var to_utf8 = options.ascii_only ? function(str, identifier) {
+        if (options.ecma >= 2015 && !options.safari10) {
+            str = str.replace(/[\ud800-\udbff][\udc00-\udfff]/g, function(ch) {
+                var code = get_full_char_code(ch, 0).toString(16);
+                return "\\u{" + code + "}";
+            });
+        }
+        return str.replace(/[\u0000-\u001f\u007f-\uffff]/g, function(ch) {
+            var code = ch.charCodeAt(0).toString(16);
+            if (code.length <= 2 && !identifier) {
+                while (code.length < 2) code = "0" + code;
+                return "\\x" + code;
+            } else {
+                while (code.length < 4) code = "0" + code;
+                return "\\u" + code;
+            }
+        });
+    } : function(str) {
+        return str.replace(/[\ud800-\udbff][\udc00-\udfff]|([\ud800-\udbff]|[\udc00-\udfff])/g, function(match, lone) {
+            if (lone) {
+                return "\\u" + lone.charCodeAt(0).toString(16);
+            }
+            return match;
+        });
+    };
+
+    function make_string(str, quote) {
+        var dq = 0, sq = 0;
+        str = str.replace(/[\\\b\f\n\r\v\t\x22\x27\u2028\u2029\0\ufeff]/g,
+          function(s, i) {
+            switch (s) {
+              case '"': ++dq; return '"';
+              case "'": ++sq; return "'";
+              case "\\": return "\\\\";
+              case "\n": return "\\n";
+              case "\r": return "\\r";
+              case "\t": return "\\t";
+              case "\b": return "\\b";
+              case "\f": return "\\f";
+              case "\x0B": return options.ie8 ? "\\x0B" : "\\v";
+              case "\u2028": return "\\u2028";
+              case "\u2029": return "\\u2029";
+              case "\ufeff": return "\\ufeff";
+              case "\0":
+                  return /[0-9]/.test(get_full_char(str, i+1)) ? "\\x00" : "\\0";
+            }
+            return s;
+        });
+        function quote_single() {
+            return "'" + str.replace(/\x27/g, "\\'") + "'";
+        }
+        function quote_double() {
+            return '"' + str.replace(/\x22/g, '\\"') + '"';
+        }
+        function quote_template() {
+            return "`" + str.replace(/`/g, "\\`") + "`";
+        }
+        str = to_utf8(str);
+        if (quote === "`") return quote_template();
+        switch (options.quote_style) {
+          case 1:
+            return quote_single();
+          case 2:
+            return quote_double();
+          case 3:
+            return quote == "'" ? quote_single() : quote_double();
+          default:
+            return dq > sq ? quote_single() : quote_double();
+        }
+    }
+
+    function encode_string(str, quote) {
+        var ret = make_string(str, quote);
+        if (options.inline_script) {
+            ret = ret.replace(/<\x2f(script)([>\/\t\n\f\r ])/gi, "<\\/$1$2");
+            ret = ret.replace(/\x3c!--/g, "\\x3c!--");
+            ret = ret.replace(/--\x3e/g, "--\\x3e");
+        }
+        return ret;
+    }
+
+    function make_name(name) {
+        name = name.toString();
+        name = to_utf8(name, true);
+        return name;
+    }
+
+    function make_indent(back) {
+        return " ".repeat(options.indent_start + indentation - back * options.indent_level);
+    }
+
+    /* -----[ beautification/minification ]----- */
+
+    var has_parens = false;
+    var might_need_space = false;
+    var might_need_semicolon = false;
+    var might_add_newline = 0;
+    var need_newline_indented = false;
+    var need_space = false;
+    var newline_insert = -1;
+    var last = "";
+    var mapping_token, mapping_name, mappings = options.source_map && [];
+
+    var do_add_mapping = mappings ? function() {
+        mappings.forEach(function(mapping) {
+            try {
+                options.source_map.add(
+                    mapping.token.file,
+                    mapping.line, mapping.col,
+                    mapping.token.line, mapping.token.col,
+                    !mapping.name && mapping.token.type == "name" ? mapping.token.value : mapping.name
+                );
+            } catch(ex) {
+                // Ignore bad mapping
+            }
+        });
+        mappings = [];
+    } : noop;
+
+    var ensure_line_len = options.max_line_len ? function() {
+        if (current_col > options.max_line_len) {
+            if (might_add_newline) {
+                var left = OUTPUT.slice(0, might_add_newline);
+                var right = OUTPUT.slice(might_add_newline);
+                if (mappings) {
+                    var delta = right.length - current_col;
+                    mappings.forEach(function(mapping) {
+                        mapping.line++;
+                        mapping.col += delta;
+                    });
+                }
+                OUTPUT = left + "\n" + right;
+                current_line++;
+                current_pos++;
+                current_col = right.length;
+            }
+        }
+        if (might_add_newline) {
+            might_add_newline = 0;
+            do_add_mapping();
+        }
+    } : noop;
+
+    var requireSemicolonChars = makePredicate("( [ + * / - , . `");
+
+    function print(str) {
+        str = String(str);
+        var ch = get_full_char(str, 0);
+        if (need_newline_indented && ch) {
+            need_newline_indented = false;
+            if (ch !== "\n") {
+                print("\n");
+                indent();
+            }
+        }
+        if (need_space && ch) {
+            need_space = false;
+            if (!/[\s;})]/.test(ch)) {
+                space();
+            }
+        }
+        newline_insert = -1;
+        var prev = last.charAt(last.length - 1);
+        if (might_need_semicolon) {
+            might_need_semicolon = false;
+
+            if (prev === ":" && ch === "}" || (!ch || !";}".includes(ch)) && prev !== ";") {
+                if (options.semicolons || requireSemicolonChars.has(ch)) {
+                    OUTPUT += ";";
+                    current_col++;
+                    current_pos++;
+                } else {
+                    ensure_line_len();
+                    if (current_col > 0) {
+                        OUTPUT += "\n";
+                        current_pos++;
+                        current_line++;
+                        current_col = 0;
+                    }
+
+                    if (/^\s+$/.test(str)) {
+                        // reset the semicolon flag, since we didn't print one
+                        // now and might still have to later
+                        might_need_semicolon = true;
+                    }
+                }
+
+                if (!options.beautify)
+                    might_need_space = false;
+            }
+        }
+
+        if (might_need_space) {
+            if ((is_identifier_char(prev)
+                    && (is_identifier_char(ch) || ch == "\\"))
+                || (ch == "/" && ch == prev)
+                || ((ch == "+" || ch == "-") && ch == last)
+            ) {
+                OUTPUT += " ";
+                current_col++;
+                current_pos++;
+            }
+            might_need_space = false;
+        }
+
+        if (mapping_token) {
+            mappings.push({
+                token: mapping_token,
+                name: mapping_name,
+                line: current_line,
+                col: current_col
+            });
+            mapping_token = false;
+            if (!might_add_newline) do_add_mapping();
+        }
+
+        OUTPUT += str;
+        has_parens = str[str.length - 1] == "(";
+        current_pos += str.length;
+        var a = str.split(/\r?\n/), n = a.length - 1;
+        current_line += n;
+        current_col += a[0].length;
+        if (n > 0) {
+            ensure_line_len();
+            current_col = a[n].length;
+        }
+        last = str;
+    }
+
+    var star = function() {
+        print("*");
+    };
+
+    var space = options.beautify ? function() {
+        print(" ");
+    } : function() {
+        might_need_space = true;
+    };
+
+    var indent = options.beautify ? function(half) {
+        if (options.beautify) {
+            print(make_indent(half ? 0.5 : 0));
+        }
+    } : noop;
+
+    var with_indent = options.beautify ? function(col, cont) {
+        if (col === true) col = next_indent();
+        var save_indentation = indentation;
+        indentation = col;
+        var ret = cont();
+        indentation = save_indentation;
+        return ret;
+    } : function(col, cont) { return cont(); };
+
+    var newline = options.beautify ? function() {
+        if (newline_insert < 0) return print("\n");
+        if (OUTPUT[newline_insert] != "\n") {
+            OUTPUT = OUTPUT.slice(0, newline_insert) + "\n" + OUTPUT.slice(newline_insert);
+            current_pos++;
+            current_line++;
+        }
+        newline_insert++;
+    } : options.max_line_len ? function() {
+        ensure_line_len();
+        might_add_newline = OUTPUT.length;
+    } : noop;
+
+    var semicolon = options.beautify ? function() {
+        print(";");
+    } : function() {
+        might_need_semicolon = true;
+    };
+
+    function force_semicolon() {
+        might_need_semicolon = false;
+        print(";");
+    }
+
+    function next_indent() {
+        return indentation + options.indent_level;
+    }
+
+    function with_block(cont) {
+        var ret;
+        print("{");
+        newline();
+        with_indent(next_indent(), function() {
+            ret = cont();
+        });
+        indent();
+        print("}");
+        return ret;
+    }
+
+    function with_parens(cont) {
+        print("(");
+        //XXX: still nice to have that for argument lists
+        //var ret = with_indent(current_col, cont);
+        var ret = cont();
+        print(")");
+        return ret;
+    }
+
+    function with_square(cont) {
+        print("[");
+        //var ret = with_indent(current_col, cont);
+        var ret = cont();
+        print("]");
+        return ret;
+    }
+
+    function comma() {
+        print(",");
+        space();
+    }
+
+    function colon() {
+        print(":");
+        space();
+    }
+
+    var add_mapping = mappings ? function(token, name) {
+        mapping_token = token;
+        mapping_name = name;
+    } : noop;
+
+    function get() {
+        if (might_add_newline) {
+            ensure_line_len();
+        }
+        return OUTPUT;
+    }
+
+    function has_nlb() {
+        let n = OUTPUT.length - 1;
+        while (n >= 0) {
+            const code = OUTPUT.charCodeAt(n);
+            if (code === CODE_LINE_BREAK) {
+                return true;
+            }
+
+            if (code !== CODE_SPACE) {
+                return false;
+            }
+            n--;
+        }
+        return true;
+    }
+
+    function filter_comment(comment) {
+        if (!options.preserve_annotations) {
+            comment = comment.replace(r_annotation, " ");
+        }
+        if (/^\s*$/.test(comment)) {
+            return "";
+        }
+        return comment.replace(/(<\s*\/\s*)(script)/i, "<\\/$2");
+    }
+
+    function prepend_comments(node) {
+        var self = this;
+        var start = node.start;
+        if (!start) return;
+        var printed_comments = self.printed_comments;
+
+        // There cannot be a newline between return and its value.
+        const return_with_value = node instanceof AST_Exit && node.value;
+
+        if (
+            start.comments_before
+            && printed_comments.has(start.comments_before)
+        ) {
+            if (return_with_value) {
+                start.comments_before = [];
+            } else {
+                return;
+            }
+        }
+
+        var comments = start.comments_before;
+        if (!comments) {
+            comments = start.comments_before = [];
+        }
+        printed_comments.add(comments);
+
+        if (return_with_value) {
+            var tw = new TreeWalker(function(node) {
+                var parent = tw.parent();
+                if (parent instanceof AST_Exit
+                    || parent instanceof AST_Binary && parent.left === node
+                    || parent.TYPE == "Call" && parent.expression === node
+                    || parent instanceof AST_Conditional && parent.condition === node
+                    || parent instanceof AST_Dot && parent.expression === node
+                    || parent instanceof AST_Sequence && parent.expressions[0] === node
+                    || parent instanceof AST_Sub && parent.expression === node
+                    || parent instanceof AST_UnaryPostfix) {
+                    if (!node.start) return;
+                    var text = node.start.comments_before;
+                    if (text && !printed_comments.has(text)) {
+                        printed_comments.add(text);
+                        comments = comments.concat(text);
+                    }
+                } else {
+                    return true;
+                }
+            });
+            tw.push(node);
+            node.value.walk(tw);
+        }
+
+        if (current_pos == 0) {
+            if (comments.length > 0 && options.shebang && comments[0].type === "comment5"
+                && !printed_comments.has(comments[0])) {
+                print("#!" + comments.shift().value + "\n");
+                indent();
+            }
+            var preamble = options.preamble;
+            if (preamble) {
+                print(preamble.replace(/\r\n?|[\n\u2028\u2029]|\s*$/g, "\n"));
+            }
+        }
+
+        comments = comments.filter(comment_filter, node).filter(c => !printed_comments.has(c));
+        if (comments.length == 0) return;
+        var last_nlb = has_nlb();
+        comments.forEach(function(c, i) {
+            printed_comments.add(c);
+            if (!last_nlb) {
+                if (c.nlb) {
+                    print("\n");
+                    indent();
+                    last_nlb = true;
+                } else if (i > 0) {
+                    space();
+                }
+            }
+
+            if (/comment[134]/.test(c.type)) {
+                var value = filter_comment(c.value);
+                if (value) {
+                    print("//" + value + "\n");
+                    indent();
+                }
+                last_nlb = true;
+            } else if (c.type == "comment2") {
+                var value = filter_comment(c.value);
+                if (value) {
+                    print("/*" + value + "*/");
+                }
+                last_nlb = false;
+            }
+        });
+        if (!last_nlb) {
+            if (start.nlb) {
+                print("\n");
+                indent();
+            } else {
+                space();
+            }
+        }
+    }
+
+    function append_comments(node, tail) {
+        var self = this;
+        var token = node.end;
+        if (!token) return;
+        var printed_comments = self.printed_comments;
+        var comments = token[tail ? "comments_before" : "comments_after"];
+        if (!comments || printed_comments.has(comments)) return;
+        if (!(node instanceof AST_Statement || comments.every((c) =>
+            !/comment[134]/.test(c.type)
+        ))) return;
+        printed_comments.add(comments);
+        var insert = OUTPUT.length;
+        comments.filter(comment_filter, node).forEach(function(c, i) {
+            if (printed_comments.has(c)) return;
+            printed_comments.add(c);
+            need_space = false;
+            if (need_newline_indented) {
+                print("\n");
+                indent();
+                need_newline_indented = false;
+            } else if (c.nlb && (i > 0 || !has_nlb())) {
+                print("\n");
+                indent();
+            } else if (i > 0 || !tail) {
+                space();
+            }
+            if (/comment[134]/.test(c.type)) {
+                const value = filter_comment(c.value);
+                if (value) {
+                    print("//" + value);
+                }
+                need_newline_indented = true;
+            } else if (c.type == "comment2") {
+                const value = filter_comment(c.value);
+                if (value) {
+                    print("/*" + value + "*/");
+                }
+                need_space = true;
+            }
+        });
+        if (OUTPUT.length > insert) newline_insert = insert;
+    }
+
+    var stack = [];
+    return {
+        get             : get,
+        toString        : get,
+        indent          : indent,
+        in_directive    : false,
+        use_asm         : null,
+        active_scope    : null,
+        indentation     : function() { return indentation; },
+        current_width   : function() { return current_col - indentation; },
+        should_break    : function() { return options.width && this.current_width() >= options.width; },
+        has_parens      : function() { return has_parens; },
+        newline         : newline,
+        print           : print,
+        star            : star,
+        space           : space,
+        comma           : comma,
+        colon           : colon,
+        last            : function() { return last; },
+        semicolon       : semicolon,
+        force_semicolon : force_semicolon,
+        to_utf8         : to_utf8,
+        print_name      : function(name) { print(make_name(name)); },
+        print_string    : function(str, quote, escape_directive) {
+            var encoded = encode_string(str, quote);
+            if (escape_directive === true && !encoded.includes("\\")) {
+                // Insert semicolons to break directive prologue
+                if (!EXPECT_DIRECTIVE.test(OUTPUT)) {
+                    force_semicolon();
+                }
+                force_semicolon();
+            }
+            print(encoded);
+        },
+        print_template_string_chars: function(str) {
+            var encoded = encode_string(str, "`").replace(/\${/g, "\\${");
+            return print(encoded.substr(1, encoded.length - 2));
+        },
+        encode_string   : encode_string,
+        next_indent     : next_indent,
+        with_indent     : with_indent,
+        with_block      : with_block,
+        with_parens     : with_parens,
+        with_square     : with_square,
+        add_mapping     : add_mapping,
+        option          : function(opt) { return options[opt]; },
+        printed_comments: printed_comments,
+        prepend_comments: readonly ? noop : prepend_comments,
+        append_comments : readonly || comment_filter === return_false ? noop : append_comments,
+        line            : function() { return current_line; },
+        col             : function() { return current_col; },
+        pos             : function() { return current_pos; },
+        push_node       : function(node) { stack.push(node); },
+        pop_node        : function() { return stack.pop(); },
+        parent          : function(n) {
+            return stack[stack.length - 2 - (n || 0)];
+        }
+    };
+
+}
+
+/* -----[ code generators ]----- */
+
+(function() {
+
+    /* -----[ utils ]----- */
+
+    function DEFPRINT(nodetype, generator) {
+        nodetype.DEFMETHOD("_codegen", generator);
+    }
+
+    AST_Node.DEFMETHOD("print", function(output, force_parens) {
+        var self = this, generator = self._codegen;
+        if (self instanceof AST_Scope) {
+            output.active_scope = self;
+        } else if (!output.use_asm && self instanceof AST_Directive && self.value == "use asm") {
+            output.use_asm = output.active_scope;
+        }
+        function doit() {
+            output.prepend_comments(self);
+            self.add_source_map(output);
+            generator(self, output);
+            output.append_comments(self);
+        }
+        output.push_node(self);
+        if (force_parens || self.needs_parens(output)) {
+            output.with_parens(doit);
+        } else {
+            doit();
+        }
+        output.pop_node();
+        if (self === output.use_asm) {
+            output.use_asm = null;
+        }
+    });
+    AST_Node.DEFMETHOD("_print", AST_Node.prototype.print);
+
+    AST_Node.DEFMETHOD("print_to_string", function(options) {
+        var output = OutputStream(options);
+        this.print(output);
+        return output.get();
+    });
+
+    /* -----[ PARENTHESES ]----- */
+
+    function PARENS(nodetype, func) {
+        if (Array.isArray(nodetype)) {
+            nodetype.forEach(function(nodetype) {
+                PARENS(nodetype, func);
+            });
+        } else {
+            nodetype.DEFMETHOD("needs_parens", func);
+        }
+    }
+
+    PARENS(AST_Node, return_false);
+
+    // a function expression needs parens around it when it's provably
+    // the first token to appear in a statement.
+    PARENS(AST_Function, function(output) {
+        if (!output.has_parens() && first_in_statement(output)) {
+            return true;
+        }
+
+        if (output.option("webkit")) {
+            var p = output.parent();
+            if (p instanceof AST_PropAccess && p.expression === this) {
+                return true;
+            }
+        }
+
+        if (output.option("wrap_iife")) {
+            var p = output.parent();
+            if (p instanceof AST_Call && p.expression === this) {
+                return true;
+            }
+        }
+
+        if (output.option("wrap_func_args")) {
+            var p = output.parent();
+            if (p instanceof AST_Call && p.args.includes(this)) {
+                return true;
+            }
+        }
+
+        return false;
+    });
+
+    PARENS(AST_Arrow, function(output) {
+        var p = output.parent();
+
+        if (
+            output.option("wrap_func_args")
+            && p instanceof AST_Call
+            && p.args.includes(this)
+        ) {
+            return true;
+        }
+        return p instanceof AST_PropAccess && p.expression === this;
+    });
+
+    // same goes for an object literal (as in AST_Function), because
+    // otherwise {...} would be interpreted as a block of code.
+    PARENS(AST_Object, function(output) {
+        return !output.has_parens() && first_in_statement(output);
+    });
+
+    PARENS(AST_ClassExpression, first_in_statement);
+
+    PARENS(AST_Unary, function(output) {
+        var p = output.parent();
+        return p instanceof AST_PropAccess && p.expression === this
+            || p instanceof AST_Call && p.expression === this
+            || p instanceof AST_Binary
+                && p.operator === "**"
+                && this instanceof AST_UnaryPrefix
+                && p.left === this
+                && this.operator !== "++"
+                && this.operator !== "--";
+    });
+
+    PARENS(AST_Await, function(output) {
+        var p = output.parent();
+        return p instanceof AST_PropAccess && p.expression === this
+            || p instanceof AST_Call && p.expression === this
+            || output.option("safari10") && p instanceof AST_UnaryPrefix;
+    });
+
+    PARENS(AST_Sequence, function(output) {
+        var p = output.parent();
+        return p instanceof AST_Call                          // (foo, bar)() or foo(1, (2, 3), 4)
+            || p instanceof AST_Unary                         // !(foo, bar, baz)
+            || p instanceof AST_Binary                        // 1 + (2, 3) + 4 ==> 8
+            || p instanceof AST_VarDef                        // var a = (1, 2), b = a + a; ==> b == 4
+            || p instanceof AST_PropAccess                    // (1, {foo:2}).foo or (1, {foo:2})["foo"] ==> 2
+            || p instanceof AST_Array                         // [ 1, (2, 3), 4 ] ==> [ 1, 3, 4 ]
+            || p instanceof AST_ObjectProperty                // { foo: (1, 2) }.foo ==> 2
+            || p instanceof AST_Conditional                   /* (false, true) ? (a = 10, b = 20) : (c = 30)
+                                                               * ==> 20 (side effect, set a := 10 and b := 20) */
+            || p instanceof AST_Arrow                         // x => (x, x)
+            || p instanceof AST_DefaultAssign                 // x => (x = (0, function(){}))
+            || p instanceof AST_Expansion                     // [...(a, b)]
+            || p instanceof AST_ForOf && this === p.object    // for (e of (foo, bar)) {}
+            || p instanceof AST_Yield                         // yield (foo, bar)
+            || p instanceof AST_Export                        // export default (foo, bar)
+        ;
+    });
+
+    PARENS(AST_Binary, function(output) {
+        var p = output.parent();
+        // (foo && bar)()
+        if (p instanceof AST_Call && p.expression === this)
+            return true;
+        // typeof (foo && bar)
+        if (p instanceof AST_Unary)
+            return true;
+        // (foo && bar)["prop"], (foo && bar).prop
+        if (p instanceof AST_PropAccess && p.expression === this)
+            return true;
+        // this deals with precedence: 3 * (2 + 1)
+        if (p instanceof AST_Binary) {
+            const po = p.operator;
+            const so = this.operator;
+
+            if (so === "??" && (po === "||" || po === "&&")) {
+                return true;
+            }
+
+            if (po === "??" && (so === "||" || so === "&&")) {
+                return true;
+            }
+
+            const pp = PRECEDENCE[po];
+            const sp = PRECEDENCE[so];
+            if (pp > sp
+                || (pp == sp
+                    && (this === p.right || po == "**"))) {
+                return true;
+            }
+        }
+    });
+
+    PARENS(AST_Yield, function(output) {
+        var p = output.parent();
+        // (yield 1) + (yield 2)
+        // a = yield 3
+        if (p instanceof AST_Binary && p.operator !== "=")
+            return true;
+        // (yield 1)()
+        // new (yield 1)()
+        if (p instanceof AST_Call && p.expression === this)
+            return true;
+        // (yield 1) ? yield 2 : yield 3
+        if (p instanceof AST_Conditional && p.condition === this)
+            return true;
+        // -(yield 4)
+        if (p instanceof AST_Unary)
+            return true;
+        // (yield x).foo
+        // (yield x)['foo']
+        if (p instanceof AST_PropAccess && p.expression === this)
+            return true;
+    });
+
+    PARENS(AST_PropAccess, function(output) {
+        var p = output.parent();
+        if (p instanceof AST_New && p.expression === this) {
+            // i.e. new (foo.bar().baz)
+            //
+            // if there's one call into this subtree, then we need
+            // parens around it too, otherwise the call will be
+            // interpreted as passing the arguments to the upper New
+            // expression.
+            return walk(this, node => {
+                if (node instanceof AST_Scope) return true;
+                if (node instanceof AST_Call) {
+                    return walk_abort;  // makes walk() return true.
+                }
+            });
+        }
+    });
+
+    PARENS(AST_Call, function(output) {
+        var p = output.parent(), p1;
+        if (p instanceof AST_New && p.expression === this
+            || p instanceof AST_Export && p.is_default && this.expression instanceof AST_Function)
+            return true;
+
+        // workaround for Safari bug.
+        // https://bugs.webkit.org/show_bug.cgi?id=123506
+        return this.expression instanceof AST_Function
+            && p instanceof AST_PropAccess
+            && p.expression === this
+            && (p1 = output.parent(1)) instanceof AST_Assign
+            && p1.left === p;
+    });
+
+    PARENS(AST_New, function(output) {
+        var p = output.parent();
+        if (this.args.length === 0
+            && (p instanceof AST_PropAccess // (new Date).getTime(), (new Date)["getTime"]()
+                || p instanceof AST_Call && p.expression === this)) // (new foo)(bar)
+            return true;
+    });
+
+    PARENS(AST_Number, function(output) {
+        var p = output.parent();
+        if (p instanceof AST_PropAccess && p.expression === this) {
+            var value = this.getValue();
+            if (value < 0 || /^0/.test(make_num(value))) {
+                return true;
+            }
+        }
+    });
+
+    PARENS(AST_BigInt, function(output) {
+        var p = output.parent();
+        if (p instanceof AST_PropAccess && p.expression === this) {
+            var value = this.getValue();
+            if (value.startsWith("-")) {
+                return true;
+            }
+        }
+    });
+
+    PARENS([ AST_Assign, AST_Conditional ], function(output) {
+        var p = output.parent();
+        // !(a = false) → true
+        if (p instanceof AST_Unary)
+            return true;
+        // 1 + (a = 2) + 3 → 6, side effect setting a = 2
+        if (p instanceof AST_Binary && !(p instanceof AST_Assign))
+            return true;
+        // (a = func)() —or— new (a = Object)()
+        if (p instanceof AST_Call && p.expression === this)
+            return true;
+        // (a = foo) ? bar : baz
+        if (p instanceof AST_Conditional && p.condition === this)
+            return true;
+        // (a = foo)["prop"] —or— (a = foo).prop
+        if (p instanceof AST_PropAccess && p.expression === this)
+            return true;
+        // ({a, b} = {a: 1, b: 2}), a destructuring assignment
+        if (this instanceof AST_Assign && this.left instanceof AST_Destructuring && this.left.is_array === false)
+            return true;
+    });
+
+    /* -----[ PRINTERS ]----- */
+
+    DEFPRINT(AST_Directive, function(self, output) {
+        output.print_string(self.value, self.quote);
+        output.semicolon();
+    });
+
+    DEFPRINT(AST_Expansion, function (self, output) {
+        output.print("...");
+        self.expression.print(output);
+    });
+
+    DEFPRINT(AST_Destructuring, function (self, output) {
+        output.print(self.is_array ? "[" : "{");
+        var len = self.names.length;
+        self.names.forEach(function (name, i) {
+            if (i > 0) output.comma();
+            name.print(output);
+            // If the final element is a hole, we need to make sure it
+            // doesn't look like a trailing comma, by inserting an actual
+            // trailing comma.
+            if (i == len - 1 && name instanceof AST_Hole) output.comma();
+        });
+        output.print(self.is_array ? "]" : "}");
+    });
+
+    DEFPRINT(AST_Debugger, function(self, output) {
+        output.print("debugger");
+        output.semicolon();
+    });
+
+    /* -----[ statements ]----- */
+
+    function display_body(body, is_toplevel, output, allow_directives) {
+        var last = body.length - 1;
+        output.in_directive = allow_directives;
+        body.forEach(function(stmt, i) {
+            if (output.in_directive === true && !(stmt instanceof AST_Directive ||
+                stmt instanceof AST_EmptyStatement ||
+                (stmt instanceof AST_SimpleStatement && stmt.body instanceof AST_String)
+            )) {
+                output.in_directive = false;
+            }
+            if (!(stmt instanceof AST_EmptyStatement)) {
+                output.indent();
+                stmt.print(output);
+                if (!(i == last && is_toplevel)) {
+                    output.newline();
+                    if (is_toplevel) output.newline();
+                }
+            }
+            if (output.in_directive === true &&
+                stmt instanceof AST_SimpleStatement &&
+                stmt.body instanceof AST_String
+            ) {
+                output.in_directive = false;
+            }
+        });
+        output.in_directive = false;
+    }
+
+    AST_StatementWithBody.DEFMETHOD("_do_print_body", function(output) {
+        force_statement(this.body, output);
+    });
+
+    DEFPRINT(AST_Statement, function(self, output) {
+        self.body.print(output);
+        output.semicolon();
+    });
+    DEFPRINT(AST_Toplevel, function(self, output) {
+        display_body(self.body, true, output, true);
+        output.print("");
+    });
+    DEFPRINT(AST_LabeledStatement, function(self, output) {
+        self.label.print(output);
+        output.colon();
+        self.body.print(output);
+    });
+    DEFPRINT(AST_SimpleStatement, function(self, output) {
+        self.body.print(output);
+        output.semicolon();
+    });
+    function print_braced_empty(self, output) {
+        output.print("{");
+        output.with_indent(output.next_indent(), function() {
+            output.append_comments(self, true);
+        });
+        output.print("}");
+    }
+    function print_braced(self, output, allow_directives) {
+        if (self.body.length > 0) {
+            output.with_block(function() {
+                display_body(self.body, false, output, allow_directives);
+            });
+        } else print_braced_empty(self, output);
+    }
+    DEFPRINT(AST_BlockStatement, function(self, output) {
+        print_braced(self, output);
+    });
+    DEFPRINT(AST_EmptyStatement, function(self, output) {
+        output.semicolon();
+    });
+    DEFPRINT(AST_Do, function(self, output) {
+        output.print("do");
+        output.space();
+        make_block(self.body, output);
+        output.space();
+        output.print("while");
+        output.space();
+        output.with_parens(function() {
+            self.condition.print(output);
+        });
+        output.semicolon();
+    });
+    DEFPRINT(AST_While, function(self, output) {
+        output.print("while");
+        output.space();
+        output.with_parens(function() {
+            self.condition.print(output);
+        });
+        output.space();
+        self._do_print_body(output);
+    });
+    DEFPRINT(AST_For, function(self, output) {
+        output.print("for");
+        output.space();
+        output.with_parens(function() {
+            if (self.init) {
+                if (self.init instanceof AST_Definitions) {
+                    self.init.print(output);
+                } else {
+                    parenthesize_for_noin(self.init, output, true);
+                }
+                output.print(";");
+                output.space();
+            } else {
+                output.print(";");
+            }
+            if (self.condition) {
+                self.condition.print(output);
+                output.print(";");
+                output.space();
+            } else {
+                output.print(";");
+            }
+            if (self.step) {
+                self.step.print(output);
+            }
+        });
+        output.space();
+        self._do_print_body(output);
+    });
+    DEFPRINT(AST_ForIn, function(self, output) {
+        output.print("for");
+        if (self.await) {
+            output.space();
+            output.print("await");
+        }
+        output.space();
+        output.with_parens(function() {
+            self.init.print(output);
+            output.space();
+            output.print(self instanceof AST_ForOf ? "of" : "in");
+            output.space();
+            self.object.print(output);
+        });
+        output.space();
+        self._do_print_body(output);
+    });
+    DEFPRINT(AST_With, function(self, output) {
+        output.print("with");
+        output.space();
+        output.with_parens(function() {
+            self.expression.print(output);
+        });
+        output.space();
+        self._do_print_body(output);
+    });
+
+    /* -----[ functions ]----- */
+    AST_Lambda.DEFMETHOD("_do_print", function(output, nokeyword) {
+        var self = this;
+        if (!nokeyword) {
+            if (self.async) {
+                output.print("async");
+                output.space();
+            }
+            output.print("function");
+            if (self.is_generator) {
+                output.star();
+            }
+            if (self.name) {
+                output.space();
+            }
+        }
+        if (self.name instanceof AST_Symbol) {
+            self.name.print(output);
+        } else if (nokeyword && self.name instanceof AST_Node) {
+            output.with_square(function() {
+                self.name.print(output); // Computed method name
+            });
+        }
+        output.with_parens(function() {
+            self.argnames.forEach(function(arg, i) {
+                if (i) output.comma();
+                arg.print(output);
+            });
+        });
+        output.space();
+        print_braced(self, output, true);
+    });
+    DEFPRINT(AST_Lambda, function(self, output) {
+        self._do_print(output);
+    });
+
+    DEFPRINT(AST_PrefixedTemplateString, function(self, output) {
+        var tag = self.prefix;
+        var parenthesize_tag = tag instanceof AST_Lambda
+            || tag instanceof AST_Binary
+            || tag instanceof AST_Conditional
+            || tag instanceof AST_Sequence
+            || tag instanceof AST_Unary
+            || tag instanceof AST_Dot && tag.expression instanceof AST_Object;
+        if (parenthesize_tag) output.print("(");
+        self.prefix.print(output);
+        if (parenthesize_tag) output.print(")");
+        self.template_string.print(output);
+    });
+    DEFPRINT(AST_TemplateString, function(self, output) {
+        var is_tagged = output.parent() instanceof AST_PrefixedTemplateString;
+
+        output.print("`");
+        for (var i = 0; i < self.segments.length; i++) {
+            if (!(self.segments[i] instanceof AST_TemplateSegment)) {
+                output.print("${");
+                self.segments[i].print(output);
+                output.print("}");
+            } else if (is_tagged) {
+                output.print(self.segments[i].raw);
+            } else {
+                output.print_template_string_chars(self.segments[i].value);
+            }
+        }
+        output.print("`");
+    });
+    DEFPRINT(AST_TemplateSegment, function(self, output) {
+        output.print_template_string_chars(self.value);
+    });
+
+    AST_Arrow.DEFMETHOD("_do_print", function(output) {
+        var self = this;
+        var parent = output.parent();
+        var needs_parens = (parent instanceof AST_Binary && !(parent instanceof AST_Assign)) ||
+            parent instanceof AST_Unary ||
+            (parent instanceof AST_Call && self === parent.expression);
+        if (needs_parens) { output.print("("); }
+        if (self.async) {
+            output.print("async");
+            output.space();
+        }
+        if (self.argnames.length === 1 && self.argnames[0] instanceof AST_Symbol) {
+            self.argnames[0].print(output);
+        } else {
+            output.with_parens(function() {
+                self.argnames.forEach(function(arg, i) {
+                    if (i) output.comma();
+                    arg.print(output);
+                });
+            });
+        }
+        output.space();
+        output.print("=>");
+        output.space();
+        const first_statement = self.body[0];
+        if (
+            self.body.length === 1
+            && first_statement instanceof AST_Return
+        ) {
+            const returned = first_statement.value;
+            if (!returned) {
+                output.print("{}");
+            } else if (left_is_object(returned)) {
+                output.print("(");
+                returned.print(output);
+                output.print(")");
+            } else {
+                returned.print(output);
+            }
+        } else {
+            print_braced(self, output);
+        }
+        if (needs_parens) { output.print(")"); }
+    });
+
+    /* -----[ exits ]----- */
+    AST_Exit.DEFMETHOD("_do_print", function(output, kind) {
+        output.print(kind);
+        if (this.value) {
+            output.space();
+            const comments = this.value.start.comments_before;
+            if (comments && comments.length && !output.printed_comments.has(comments)) {
+                output.print("(");
+                this.value.print(output);
+                output.print(")");
+            } else {
+                this.value.print(output);
+            }
+        }
+        output.semicolon();
+    });
+    DEFPRINT(AST_Return, function(self, output) {
+        self._do_print(output, "return");
+    });
+    DEFPRINT(AST_Throw, function(self, output) {
+        self._do_print(output, "throw");
+    });
+
+    /* -----[ yield ]----- */
+
+    DEFPRINT(AST_Yield, function(self, output) {
+        var star = self.is_star ? "*" : "";
+        output.print("yield" + star);
+        if (self.expression) {
+            output.space();
+            self.expression.print(output);
+        }
+    });
+
+    DEFPRINT(AST_Await, function(self, output) {
+        output.print("await");
+        output.space();
+        var e = self.expression;
+        var parens = !(
+               e instanceof AST_Call
+            || e instanceof AST_SymbolRef
+            || e instanceof AST_PropAccess
+            || e instanceof AST_Unary
+            || e instanceof AST_Constant
+            || e instanceof AST_Await
+            || e instanceof AST_Object
+        );
+        if (parens) output.print("(");
+        self.expression.print(output);
+        if (parens) output.print(")");
+    });
+
+    /* -----[ loop control ]----- */
+    AST_LoopControl.DEFMETHOD("_do_print", function(output, kind) {
+        output.print(kind);
+        if (this.label) {
+            output.space();
+            this.label.print(output);
+        }
+        output.semicolon();
+    });
+    DEFPRINT(AST_Break, function(self, output) {
+        self._do_print(output, "break");
+    });
+    DEFPRINT(AST_Continue, function(self, output) {
+        self._do_print(output, "continue");
+    });
+
+    /* -----[ if ]----- */
+    function make_then(self, output) {
+        var b = self.body;
+        if (output.option("braces")
+            || output.option("ie8") && b instanceof AST_Do)
+            return make_block(b, output);
+        // The squeezer replaces "block"-s that contain only a single
+        // statement with the statement itself; technically, the AST
+        // is correct, but this can create problems when we output an
+        // IF having an ELSE clause where the THEN clause ends in an
+        // IF *without* an ELSE block (then the outer ELSE would refer
+        // to the inner IF).  This function checks for this case and
+        // adds the block braces if needed.
+        if (!b) return output.force_semicolon();
+        while (true) {
+            if (b instanceof AST_If) {
+                if (!b.alternative) {
+                    make_block(self.body, output);
+                    return;
+                }
+                b = b.alternative;
+            } else if (b instanceof AST_StatementWithBody) {
+                b = b.body;
+            } else break;
+        }
+        force_statement(self.body, output);
+    }
+    DEFPRINT(AST_If, function(self, output) {
+        output.print("if");
+        output.space();
+        output.with_parens(function() {
+            self.condition.print(output);
+        });
+        output.space();
+        if (self.alternative) {
+            make_then(self, output);
+            output.space();
+            output.print("else");
+            output.space();
+            if (self.alternative instanceof AST_If)
+                self.alternative.print(output);
+            else
+                force_statement(self.alternative, output);
+        } else {
+            self._do_print_body(output);
+        }
+    });
+
+    /* -----[ switch ]----- */
+    DEFPRINT(AST_Switch, function(self, output) {
+        output.print("switch");
+        output.space();
+        output.with_parens(function() {
+            self.expression.print(output);
+        });
+        output.space();
+        var last = self.body.length - 1;
+        if (last < 0) print_braced_empty(self, output);
+        else output.with_block(function() {
+            self.body.forEach(function(branch, i) {
+                output.indent(true);
+                branch.print(output);
+                if (i < last && branch.body.length > 0)
+                    output.newline();
+            });
+        });
+    });
+    AST_SwitchBranch.DEFMETHOD("_do_print_body", function(output) {
+        output.newline();
+        this.body.forEach(function(stmt) {
+            output.indent();
+            stmt.print(output);
+            output.newline();
+        });
+    });
+    DEFPRINT(AST_Default, function(self, output) {
+        output.print("default:");
+        self._do_print_body(output);
+    });
+    DEFPRINT(AST_Case, function(self, output) {
+        output.print("case");
+        output.space();
+        self.expression.print(output);
+        output.print(":");
+        self._do_print_body(output);
+    });
+
+    /* -----[ exceptions ]----- */
+    DEFPRINT(AST_Try, function(self, output) {
+        output.print("try");
+        output.space();
+        print_braced(self, output);
+        if (self.bcatch) {
+            output.space();
+            self.bcatch.print(output);
+        }
+        if (self.bfinally) {
+            output.space();
+            self.bfinally.print(output);
+        }
+    });
+    DEFPRINT(AST_Catch, function(self, output) {
+        output.print("catch");
+        if (self.argname) {
+            output.space();
+            output.with_parens(function() {
+                self.argname.print(output);
+            });
+        }
+        output.space();
+        print_braced(self, output);
+    });
+    DEFPRINT(AST_Finally, function(self, output) {
+        output.print("finally");
+        output.space();
+        print_braced(self, output);
+    });
+
+    /* -----[ var/const ]----- */
+    AST_Definitions.DEFMETHOD("_do_print", function(output, kind) {
+        output.print(kind);
+        output.space();
+        this.definitions.forEach(function(def, i) {
+            if (i) output.comma();
+            def.print(output);
+        });
+        var p = output.parent();
+        var in_for = p instanceof AST_For || p instanceof AST_ForIn;
+        var output_semicolon = !in_for || p && p.init !== this;
+        if (output_semicolon)
+            output.semicolon();
+    });
+    DEFPRINT(AST_Let, function(self, output) {
+        self._do_print(output, "let");
+    });
+    DEFPRINT(AST_Var, function(self, output) {
+        self._do_print(output, "var");
+    });
+    DEFPRINT(AST_Const, function(self, output) {
+        self._do_print(output, "const");
+    });
+    DEFPRINT(AST_Import, function(self, output) {
+        output.print("import");
+        output.space();
+        if (self.imported_name) {
+            self.imported_name.print(output);
+        }
+        if (self.imported_name && self.imported_names) {
+            output.print(",");
+            output.space();
+        }
+        if (self.imported_names) {
+            if (self.imported_names.length === 1 && self.imported_names[0].foreign_name.name === "*") {
+                self.imported_names[0].print(output);
+            } else {
+                output.print("{");
+                self.imported_names.forEach(function (name_import, i) {
+                    output.space();
+                    name_import.print(output);
+                    if (i < self.imported_names.length - 1) {
+                        output.print(",");
+                    }
+                });
+                output.space();
+                output.print("}");
+            }
+        }
+        if (self.imported_name || self.imported_names) {
+            output.space();
+            output.print("from");
+            output.space();
+        }
+        self.module_name.print(output);
+        output.semicolon();
+    });
+    DEFPRINT(AST_ImportMeta, function(self, output) {
+        output.print("import.meta");
+    });
+
+    DEFPRINT(AST_NameMapping, function(self, output) {
+        var is_import = output.parent() instanceof AST_Import;
+        var definition = self.name.definition();
+        var names_are_different =
+            (definition && definition.mangled_name || self.name.name) !==
+            self.foreign_name.name;
+        if (names_are_different) {
+            if (is_import) {
+                output.print(self.foreign_name.name);
+            } else {
+                self.name.print(output);
+            }
+            output.space();
+            output.print("as");
+            output.space();
+            if (is_import) {
+                self.name.print(output);
+            } else {
+                output.print(self.foreign_name.name);
+            }
+        } else {
+            self.name.print(output);
+        }
+    });
+
+    DEFPRINT(AST_Export, function(self, output) {
+        output.print("export");
+        output.space();
+        if (self.is_default) {
+            output.print("default");
+            output.space();
+        }
+        if (self.exported_names) {
+            if (self.exported_names.length === 1 && self.exported_names[0].name.name === "*") {
+                self.exported_names[0].print(output);
+            } else {
+                output.print("{");
+                self.exported_names.forEach(function(name_export, i) {
+                    output.space();
+                    name_export.print(output);
+                    if (i < self.exported_names.length - 1) {
+                        output.print(",");
+                    }
+                });
+                output.space();
+                output.print("}");
+            }
+        } else if (self.exported_value) {
+            self.exported_value.print(output);
+        } else if (self.exported_definition) {
+            self.exported_definition.print(output);
+            if (self.exported_definition instanceof AST_Definitions) return;
+        }
+        if (self.module_name) {
+            output.space();
+            output.print("from");
+            output.space();
+            self.module_name.print(output);
+        }
+        if (self.exported_value
+                && !(self.exported_value instanceof AST_Defun ||
+                    self.exported_value instanceof AST_Function ||
+                    self.exported_value instanceof AST_Class)
+            || self.module_name
+            || self.exported_names
+        ) {
+            output.semicolon();
+        }
+    });
+
+    function parenthesize_for_noin(node, output, noin) {
+        var parens = false;
+        // need to take some precautions here:
+        //    https://github.com/mishoo/UglifyJS2/issues/60
+        if (noin) {
+            parens = walk(node, node => {
+                if (node instanceof AST_Scope) return true;
+                if (node instanceof AST_Binary && node.operator == "in") {
+                    return walk_abort;  // makes walk() return true
+                }
+            });
+        }
+        node.print(output, parens);
+    }
+
+    DEFPRINT(AST_VarDef, function(self, output) {
+        self.name.print(output);
+        if (self.value) {
+            output.space();
+            output.print("=");
+            output.space();
+            var p = output.parent(1);
+            var noin = p instanceof AST_For || p instanceof AST_ForIn;
+            parenthesize_for_noin(self.value, output, noin);
+        }
+    });
+
+    /* -----[ other expressions ]----- */
+    DEFPRINT(AST_Call, function(self, output) {
+        self.expression.print(output);
+        if (self instanceof AST_New && self.args.length === 0)
+            return;
+        if (self.expression instanceof AST_Call || self.expression instanceof AST_Lambda) {
+            output.add_mapping(self.start);
+        }
+        if (self.optional) output.print("?.");
+        output.with_parens(function() {
+            self.args.forEach(function(expr, i) {
+                if (i) output.comma();
+                expr.print(output);
+            });
+        });
+    });
+    DEFPRINT(AST_New, function(self, output) {
+        output.print("new");
+        output.space();
+        AST_Call.prototype._codegen(self, output);
+    });
+
+    AST_Sequence.DEFMETHOD("_do_print", function(output) {
+        this.expressions.forEach(function(node, index) {
+            if (index > 0) {
+                output.comma();
+                if (output.should_break()) {
+                    output.newline();
+                    output.indent();
+                }
+            }
+            node.print(output);
+        });
+    });
+    DEFPRINT(AST_Sequence, function(self, output) {
+        self._do_print(output);
+        // var p = output.parent();
+        // if (p instanceof AST_Statement) {
+        //     output.with_indent(output.next_indent(), function(){
+        //         self._do_print(output);
+        //     });
+        // } else {
+        //     self._do_print(output);
+        // }
+    });
+    DEFPRINT(AST_Dot, function(self, output) {
+        var expr = self.expression;
+        expr.print(output);
+        var prop = self.property;
+        var print_computed = RESERVED_WORDS.has(prop)
+            ? output.option("ie8")
+            : !is_identifier_string(
+                prop,
+                output.option("ecma") >= 2015 || output.option("safari10")
+            );
+
+        if (self.optional) output.print("?.");
+
+        if (print_computed) {
+            output.print("[");
+            output.add_mapping(self.end);
+            output.print_string(prop);
+            output.print("]");
+        } else {
+            if (expr instanceof AST_Number && expr.getValue() >= 0) {
+                if (!/[xa-f.)]/i.test(output.last())) {
+                    output.print(".");
+                }
+            }
+            if (!self.optional) output.print(".");
+            // the name after dot would be mapped about here.
+            output.add_mapping(self.end);
+            output.print_name(prop);
+        }
+    });
+    DEFPRINT(AST_Sub, function(self, output) {
+        self.expression.print(output);
+        if (self.optional) output.print("?.");
+        output.print("[");
+        self.property.print(output);
+        output.print("]");
+    });
+    DEFPRINT(AST_Chain, function(self, output) {
+        self.expression.print(output);
+    });
+    DEFPRINT(AST_UnaryPrefix, function(self, output) {
+        var op = self.operator;
+        output.print(op);
+        if (/^[a-z]/i.test(op)
+            || (/[+-]$/.test(op)
+                && self.expression instanceof AST_UnaryPrefix
+                && /^[+-]/.test(self.expression.operator))) {
+            output.space();
+        }
+        self.expression.print(output);
+    });
+    DEFPRINT(AST_UnaryPostfix, function(self, output) {
+        self.expression.print(output);
+        output.print(self.operator);
+    });
+    DEFPRINT(AST_Binary, function(self, output) {
+        var op = self.operator;
+        self.left.print(output);
+        if (op[0] == ">" /* ">>" ">>>" ">" ">=" */
+            && self.left instanceof AST_UnaryPostfix
+            && self.left.operator == "--") {
+            // space is mandatory to avoid outputting -->
+            output.print(" ");
+        } else {
+            // the space is optional depending on "beautify"
+            output.space();
+        }
+        output.print(op);
+        if ((op == "<" || op == "<<")
+            && self.right instanceof AST_UnaryPrefix
+            && self.right.operator == "!"
+            && self.right.expression instanceof AST_UnaryPrefix
+            && self.right.expression.operator == "--") {
+            // space is mandatory to avoid outputting <!--
+            output.print(" ");
+        } else {
+            // the space is optional depending on "beautify"
+            output.space();
+        }
+        self.right.print(output);
+    });
+    DEFPRINT(AST_Conditional, function(self, output) {
+        self.condition.print(output);
+        output.space();
+        output.print("?");
+        output.space();
+        self.consequent.print(output);
+        output.space();
+        output.colon();
+        self.alternative.print(output);
+    });
+
+    /* -----[ literals ]----- */
+    DEFPRINT(AST_Array, function(self, output) {
+        output.with_square(function() {
+            var a = self.elements, len = a.length;
+            if (len > 0) output.space();
+            a.forEach(function(exp, i) {
+                if (i) output.comma();
+                exp.print(output);
+                // If the final element is a hole, we need to make sure it
+                // doesn't look like a trailing comma, by inserting an actual
+                // trailing comma.
+                if (i === len - 1 && exp instanceof AST_Hole)
+                  output.comma();
+            });
+            if (len > 0) output.space();
+        });
+    });
+    DEFPRINT(AST_Object, function(self, output) {
+        if (self.properties.length > 0) output.with_block(function() {
+            self.properties.forEach(function(prop, i) {
+                if (i) {
+                    output.print(",");
+                    output.newline();
+                }
+                output.indent();
+                prop.print(output);
+            });
+            output.newline();
+        });
+        else print_braced_empty(self, output);
+    });
+    DEFPRINT(AST_Class, function(self, output) {
+        output.print("class");
+        output.space();
+        if (self.name) {
+            self.name.print(output);
+            output.space();
+        }
+        if (self.extends) {
+            var parens = (
+                   !(self.extends instanceof AST_SymbolRef)
+                && !(self.extends instanceof AST_PropAccess)
+                && !(self.extends instanceof AST_ClassExpression)
+                && !(self.extends instanceof AST_Function)
+            );
+            output.print("extends");
+            if (parens) {
+                output.print("(");
+            } else {
+                output.space();
+            }
+            self.extends.print(output);
+            if (parens) {
+                output.print(")");
+            } else {
+                output.space();
+            }
+        }
+        if (self.properties.length > 0) output.with_block(function() {
+            self.properties.forEach(function(prop, i) {
+                if (i) {
+                    output.newline();
+                }
+                output.indent();
+                prop.print(output);
+            });
+            output.newline();
+        });
+        else output.print("{}");
+    });
+    DEFPRINT(AST_NewTarget, function(self, output) {
+        output.print("new.target");
+    });
+
+    function print_property_name(key, quote, output) {
+        if (output.option("quote_keys")) {
+            return output.print_string(key);
+        }
+        if ("" + +key == key && key >= 0) {
+            if (output.option("keep_numbers")) {
+                return output.print(key);
+            }
+            return output.print(make_num(key));
+        }
+        var print_string = RESERVED_WORDS.has(key)
+            ? output.option("ie8")
+            : (
+                output.option("ecma") < 2015 || output.option("safari10")
+                    ? !is_basic_identifier_string(key)
+                    : !is_identifier_string(key, true)
+            );
+        if (print_string || (quote && output.option("keep_quoted_props"))) {
+            return output.print_string(key, quote);
+        }
+        return output.print_name(key);
+    }
+
+    DEFPRINT(AST_ObjectKeyVal, function(self, output) {
+        function get_name(self) {
+            var def = self.definition();
+            return def ? def.mangled_name || def.name : self.name;
+        }
+
+        var allowShortHand = output.option("shorthand");
+        if (allowShortHand &&
+            self.value instanceof AST_Symbol &&
+            is_identifier_string(
+                self.key,
+                output.option("ecma") >= 2015 || output.option("safari10")
+            ) &&
+            get_name(self.value) === self.key &&
+            !RESERVED_WORDS.has(self.key)
+        ) {
+            print_property_name(self.key, self.quote, output);
+
+        } else if (allowShortHand &&
+            self.value instanceof AST_DefaultAssign &&
+            self.value.left instanceof AST_Symbol &&
+            is_identifier_string(
+                self.key,
+                output.option("ecma") >= 2015 || output.option("safari10")
+            ) &&
+            get_name(self.value.left) === self.key
+        ) {
+            print_property_name(self.key, self.quote, output);
+            output.space();
+            output.print("=");
+            output.space();
+            self.value.right.print(output);
+        } else {
+            if (!(self.key instanceof AST_Node)) {
+                print_property_name(self.key, self.quote, output);
+            } else {
+                output.with_square(function() {
+                    self.key.print(output);
+                });
+            }
+            output.colon();
+            self.value.print(output);
+        }
+    });
+    DEFPRINT(AST_ClassProperty, (self, output) => {
+        if (self.static) {
+            output.print("static");
+            output.space();
+        }
+
+        if (self.key instanceof AST_SymbolClassProperty) {
+            print_property_name(self.key.name, self.quote, output);
+        } else {
+            output.print("[");
+            self.key.print(output);
+            output.print("]");
+        }
+
+        if (self.value) {
+            output.print("=");
+            self.value.print(output);
+        }
+
+        output.semicolon();
+    });
+    AST_ObjectProperty.DEFMETHOD("_print_getter_setter", function(type, output) {
+        var self = this;
+        if (self.static) {
+            output.print("static");
+            output.space();
+        }
+        if (type) {
+            output.print(type);
+            output.space();
+        }
+        if (self.key instanceof AST_SymbolMethod) {
+            print_property_name(self.key.name, self.quote, output);
+        } else {
+            output.with_square(function() {
+                self.key.print(output);
+            });
+        }
+        self.value._do_print(output, true);
+    });
+    DEFPRINT(AST_ObjectSetter, function(self, output) {
+        self._print_getter_setter("set", output);
+    });
+    DEFPRINT(AST_ObjectGetter, function(self, output) {
+        self._print_getter_setter("get", output);
+    });
+    DEFPRINT(AST_ConciseMethod, function(self, output) {
+        var type;
+        if (self.is_generator && self.async) {
+            type = "async*";
+        } else if (self.is_generator) {
+            type = "*";
+        } else if (self.async) {
+            type = "async";
+        }
+        self._print_getter_setter(type, output);
+    });
+    AST_Symbol.DEFMETHOD("_do_print", function(output) {
+        var def = this.definition();
+        output.print_name(def ? def.mangled_name || def.name : this.name);
+    });
+    DEFPRINT(AST_Symbol, function (self, output) {
+        self._do_print(output);
+    });
+    DEFPRINT(AST_Hole, noop);
+    DEFPRINT(AST_This, function(self, output) {
+        output.print("this");
+    });
+    DEFPRINT(AST_Super, function(self, output) {
+        output.print("super");
+    });
+    DEFPRINT(AST_Constant, function(self, output) {
+        output.print(self.getValue());
+    });
+    DEFPRINT(AST_String, function(self, output) {
+        output.print_string(self.getValue(), self.quote, output.in_directive);
+    });
+    DEFPRINT(AST_Number, function(self, output) {
+        if ((output.option("keep_numbers") || output.use_asm) && self.raw) {
+            output.print(self.raw);
+        } else {
+            output.print(make_num(self.getValue()));
+        }
+    });
+    DEFPRINT(AST_BigInt, function(self, output) {
+        output.print(self.getValue() + "n");
+    });
+
+    const r_slash_script = /(<\s*\/\s*script)/i;
+    const slash_script_replace = (_, $1) => $1.replace("/", "\\/");
+    DEFPRINT(AST_RegExp, function(self, output) {
+        let { source, flags } = self.getValue();
+        source = regexp_source_fix(source);
+        flags = flags ? sort_regexp_flags(flags) : "";
+        source = source.replace(r_slash_script, slash_script_replace);
+        output.print(output.to_utf8(`/${source}/${flags}`));
+        const parent = output.parent();
+        if (
+            parent instanceof AST_Binary
+            && /^\w/.test(parent.operator)
+            && parent.left === self
+        ) {
+            output.print(" ");
+        }
+    });
+
+    function force_statement(stat, output) {
+        if (output.option("braces")) {
+            make_block(stat, output);
+        } else {
+            if (!stat || stat instanceof AST_EmptyStatement)
+                output.force_semicolon();
+            else
+                stat.print(output);
+        }
+    }
+
+    function best_of(a) {
+        var best = a[0], len = best.length;
+        for (var i = 1; i < a.length; ++i) {
+            if (a[i].length < len) {
+                best = a[i];
+                len = best.length;
+            }
+        }
+        return best;
+    }
+
+    function make_num(num) {
+        var str = num.toString(10).replace(/^0\./, ".").replace("e+", "e");
+        var candidates = [ str ];
+        if (Math.floor(num) === num) {
+            if (num < 0) {
+                candidates.push("-0x" + (-num).toString(16).toLowerCase());
+            } else {
+                candidates.push("0x" + num.toString(16).toLowerCase());
+            }
+        }
+        var match, len, digits;
+        if (match = /^\.0+/.exec(str)) {
+            len = match[0].length;
+            digits = str.slice(len);
+            candidates.push(digits + "e-" + (digits.length + len - 1));
+        } else if (match = /0+$/.exec(str)) {
+            len = match[0].length;
+            candidates.push(str.slice(0, -len) + "e" + len);
+        } else if (match = /^(\d)\.(\d+)e(-?\d+)$/.exec(str)) {
+            candidates.push(match[1] + match[2] + "e" + (match[3] - match[2].length));
+        }
+        return best_of(candidates);
+    }
+
+    function make_block(stmt, output) {
+        if (!stmt || stmt instanceof AST_EmptyStatement)
+            output.print("{}");
+        else if (stmt instanceof AST_BlockStatement)
+            stmt.print(output);
+        else output.with_block(function() {
+            output.indent();
+            stmt.print(output);
+            output.newline();
+        });
+    }
+
+    /* -----[ source map generators ]----- */
+
+    function DEFMAP(nodetype, generator) {
+        nodetype.forEach(function(nodetype) {
+            nodetype.DEFMETHOD("add_source_map", generator);
+        });
+    }
+
+    DEFMAP([
+        // We could easily add info for ALL nodes, but it seems to me that
+        // would be quite wasteful, hence this noop in the base class.
+        AST_Node,
+        // since the label symbol will mark it
+        AST_LabeledStatement,
+        AST_Toplevel,
+    ], noop);
+
+    // XXX: I'm not exactly sure if we need it for all of these nodes,
+    // or if we should add even more.
+    DEFMAP([
+        AST_Array,
+        AST_BlockStatement,
+        AST_Catch,
+        AST_Class,
+        AST_Constant,
+        AST_Debugger,
+        AST_Definitions,
+        AST_Directive,
+        AST_Finally,
+        AST_Jump,
+        AST_Lambda,
+        AST_New,
+        AST_Object,
+        AST_StatementWithBody,
+        AST_Symbol,
+        AST_Switch,
+        AST_SwitchBranch,
+        AST_TemplateString,
+        AST_TemplateSegment,
+        AST_Try,
+    ], function(output) {
+        output.add_mapping(this.start);
+    });
+
+    DEFMAP([
+        AST_ObjectGetter,
+        AST_ObjectSetter,
+    ], function(output) {
+        output.add_mapping(this.start, this.key.name);
+    });
+
+    DEFMAP([ AST_ObjectProperty ], function(output) {
+        output.add_mapping(this.start, this.key);
+    });
+})();
+
+export {
+    OutputStream,
+};