From f451a7ad79165dda0d3f7fa7a56b3841eeba8174 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Sun, 7 Aug 2022 20:42:18 +0100
Subject: [PATCH] implement `--expression` (#5607)

---
 README.md                    |  8 ++---
 bin/uglifyjs                 |  2 ++
 lib/compress.js              | 29 ++++++++++++++++
 lib/minify.js                | 20 +++++------
 test/compress.js             | 66 ++++++++++++++++++++++++------------
 test/compress/directives.js  | 23 ++++++++++---
 test/compress/issue-281.js   |  8 +++--
 test/compress/issue-640.js   | 10 ++++--
 test/mocha/cli.js            | 21 ++++++++++--
 test/mocha/number-literal.js |  6 ++--
 10 files changed, 143 insertions(+), 50 deletions(-)

diff --git a/README.md b/README.md
index 03ac0314..265a43c5 100644
--- a/README.md
+++ b/README.md
@@ -54,8 +54,6 @@ a double dash to prevent input files being used as option arguments:
                                                 modules and Userscripts that may
                                                 be anonymous function wrapped (IIFE)
                                                 by the .user.js engine `caller`.
-                                `expression`  Parse a single expression, rather than
-                                              a program (for parsing JSON).
                                 `spidermonkey`  Assume input files are SpiderMonkey
                                                 AST format (as JSON).
     -c, --compress [options]    Enable compressor/specify compressor options:
@@ -111,6 +109,8 @@ a double dash to prevent input files being used as option arguments:
     -d, --define <expr>[=value] Global definitions.
     -e, --enclose [arg[:value]] Embed everything in a big function, with configurable
                                 argument(s) & value(s).
+    --expression                Parse a single expression, rather than a program
+                                (for parsing JSON).
     --ie                        Support non-standard Internet Explorer.
                                 Equivalent to setting `ie: true` in `minify()`
                                 for `compress`, `mangle` and `output` options.
@@ -504,6 +504,8 @@ if (result.error) throw result.error;
 - `compress` (default: `{}`) — pass `false` to skip compressing entirely.
   Pass an object to specify custom [compress options](#compress-options).
 
+- `expression` (default: `false`) — parse as a single expression, e.g. JSON.
+
 - `ie` (default: `false`) — enable workarounds for Internet Explorer bugs.
 
 - `keep_fargs` (default: `false`) — pass `true` to prevent discarding or mangling
@@ -633,8 +635,6 @@ to be `false` and all symbol names will be omitted.
 
 - `bare_returns` (default: `false`) — support top level `return` statements
 
-- `expression` (default: `false`) — parse as a single expression, e.g. JSON
-
 - `html5_comments` (default: `true`) — process HTML comment as workaround for
   browsers which do not recognise `<script>` tags
 
diff --git a/bin/uglifyjs b/bin/uglifyjs
index 304d84de..680e3bb0 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -104,6 +104,7 @@ function process_option(name, no_value) {
                 "  --config-file <file>                     Read minify() options from JSON file.",
                 "  -d, --define <expr>[=value]              Global definitions.",
                 "  -e, --enclose [arg[,...][:value[,...]]]  Embed everything in a big function, with configurable argument(s) & value(s).",
+                "  --expression                             Parse a single expression, rather than a program.",
                 "  --ie                                     Support non-standard Internet Explorer.",
                 "  --keep-fargs                             Do not mangle/drop function arguments.",
                 "  --keep-fnames                            Do not mangle/drop function names. Useful for code relying on Function.prototype.name.",
@@ -151,6 +152,7 @@ function process_option(name, no_value) {
         options[name] = read_value();
         break;
       case "annotations":
+      case "expression":
       case "ie":
       case "ie8":
       case "module":
diff --git a/lib/compress.js b/lib/compress.js
index 3e57882d..f28e4daa 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -343,6 +343,35 @@ Compressor.prototype.compress = function(node) {
         });
         self.transform(tt);
     });
+    AST_Toplevel.DEFMETHOD("unwrap_expression", function() {
+        var self = this;
+        switch (self.body.length) {
+          case 0:
+            return make_node(AST_UnaryPrefix, self, {
+                operator: "void",
+                expression: make_node(AST_Number, self, { value: 0 }),
+            });
+          case 1:
+            var stat = self.body[0];
+            if (stat instanceof AST_Directive) return make_node(AST_String, self, stat);
+            if (stat instanceof AST_SimpleStatement) return stat.body;
+          default:
+            return make_node(AST_Call, self, {
+                expression: make_node(AST_Function, self, {
+                    argnames: [],
+                    body: self.body,
+                }).init_vars(self),
+                args: [],
+            });
+        }
+        return self;
+    });
+    AST_Node.DEFMETHOD("wrap_expression", function() {
+        var self = this;
+        if (!is_statement(self)) self = make_node(AST_SimpleStatement, self, { body: self });
+        if (!(self instanceof AST_Toplevel)) self = make_node(AST_Toplevel, self, { body: [ self ] });
+        return self;
+    });
 
     function read_property(obj, node) {
         var key = node.get_property();
diff --git a/lib/minify.js b/lib/minify.js
index 2e9c3325..4ef4211f 100644
--- a/lib/minify.js
+++ b/lib/minify.js
@@ -76,6 +76,7 @@ function minify(files, options) {
             annotations: undefined,
             compress: {},
             enclose: false,
+            expression: false,
             ie: false,
             ie8: false,
             keep_fargs: false,
@@ -98,6 +99,7 @@ function minify(files, options) {
         if (options.validate) AST_Node.enable_validation();
         var timings = options.timings && { start: Date.now() };
         if (options.annotations !== undefined) set_shorthand("annotations", options, [ "compress", "output" ]);
+        if (options.expression) set_shorthand("expression", options, [ "compress", "parse" ]);
         if (options.ie8) options.ie = options.ie || options.ie8;
         if (options.ie) set_shorthand("ie", options, [ "compress", "mangle", "output", "rename" ]);
         if (options.keep_fargs) set_shorthand("keep_fargs", options, [ "compress", "mangle", "rename" ]);
@@ -153,13 +155,11 @@ function minify(files, options) {
         }, options.warnings == "verbose");
         if (timings) timings.parse = Date.now();
         var toplevel;
-        if (files instanceof AST_Toplevel) {
+        options.parse = options.parse || {};
+        if (files instanceof AST_Node) {
             toplevel = files;
         } else {
-            if (typeof files == "string") {
-                files = [ files ];
-            }
-            options.parse = options.parse || {};
+            if (typeof files == "string") files = [ files ];
             options.parse.toplevel = null;
             var source_map_content = options.sourceMap && options.sourceMap.content;
             if (typeof source_map_content == "string" && source_map_content != "inline") {
@@ -171,17 +171,14 @@ function minify(files, options) {
                 options.parse.toplevel = toplevel = parse(files[name], options.parse);
                 if (source_map_content == "inline") {
                     var inlined_content = read_source_map(name, toplevel);
-                    if (inlined_content) {
-                        options.sourceMap.orig[name] = parse_source_map(inlined_content);
-                    }
+                    if (inlined_content) options.sourceMap.orig[name] = parse_source_map(inlined_content);
                 } else if (source_map_content) {
                     options.sourceMap.orig[name] = source_map_content;
                 }
             }
         }
-        if (quoted_props) {
-            reserve_quoted_keys(toplevel, quoted_props);
-        }
+        if (options.parse.expression) toplevel = toplevel.wrap_expression();
+        if (quoted_props) reserve_quoted_keys(toplevel, quoted_props);
         [ "enclose", "wrap" ].forEach(function(action) {
             var option = options[action];
             if (!option) return;
@@ -209,6 +206,7 @@ function minify(files, options) {
         }
         if (timings) timings.properties = Date.now();
         if (options.mangle && options.mangle.properties) mangle_properties(toplevel, options.mangle.properties);
+        if (options.parse.expression) toplevel = toplevel.unwrap_expression();
         if (timings) timings.output = Date.now();
         var result = {};
         var output = defaults(options.output, {
diff --git a/test/compress.js b/test/compress.js
index 8d9a7348..1cd64534 100644
--- a/test/compress.js
+++ b/test/compress.js
@@ -60,8 +60,9 @@ function log() {
     console.log("%s", tmpl.apply(null, arguments));
 }
 
-function make_code(ast, options) {
+function make_code(ast, options, expression) {
     var stream = U.OutputStream(options);
+    if (expression) ast = ast.clone(true).unwrap_expression();
     ast.print(stream);
     return stream.get();
 }
@@ -178,9 +179,18 @@ function parse_test(file) {
 
 // Try to reminify original input with standard options
 // to see if it matches expect_stdout.
-function reminify(orig_options, input_code, input_formatted, stdout) {
+function reminify(expression, orig_options, input_code, input_formatted, stdout) {
     for (var i = 0; i < minify_options.length; i++) {
         var options = JSON.parse(minify_options[i]);
+        if (expression) {
+            if (!options.parse || typeof options.parse != "object") options.parse = {};
+            options.parse.expression = true;
+            if (options.compress == null) options.compress = {};
+            if (options.compress) {
+                if (typeof options.compress != "object") options.compress = {};
+                options.compress.expression = true;
+            }
+        }
         [
             "keep_fargs",
             "keep_fnames",
@@ -210,7 +220,7 @@ function reminify(orig_options, input_code, input_formatted, stdout) {
         } else {
             var toplevel = sandbox.has_toplevel(options);
             var expected = stdout[toplevel ? 1 : 0];
-            var actual = sandbox.run_code(result.code, toplevel);
+            var actual = run_code(expression, result.code, toplevel);
             if (typeof expected != "string" && typeof actual != "string" && expected.name == actual.name) {
                 actual = expected;
             }
@@ -245,18 +255,23 @@ function reminify(orig_options, input_code, input_formatted, stdout) {
     return true;
 }
 
+function run_code(expression, code, toplevel) {
+    return sandbox.run_code(expression ? "console.log(" + code + ");" : code, toplevel);
+}
+
 function test_case(test) {
     log("    Running test [{name}]", { name: test.name });
     U.AST_Node.enable_validation();
     var output_options = test.beautify || {};
     var expect;
     if (test.expect) {
-        expect = make_code(to_toplevel(test.expect, test.mangle), output_options);
+        expect = to_toplevel(test.expect, test.mangle, test.expression);
+        expect = make_code(expect, output_options, test.expression);
     } else {
         expect = test.expect_exact;
     }
-    var input = to_toplevel(test.input, test.mangle);
-    var input_code = make_code(input);
+    var input = to_toplevel(test.input, test.mangle, test.expression);
+    var input_code = make_code(input, {}, test.expression);
     var input_formatted = make_code(test.input, {
         annotations: true,
         beautify: true,
@@ -266,7 +281,7 @@ function test_case(test) {
     });
     try {
         input.validate_ast();
-        U.parse(input_code);
+        U.parse(input_code, { expression: test.expression });
     } catch (ex) {
         log([
             "!!! Cannot parse input",
@@ -310,7 +325,7 @@ function test_case(test) {
         output.mangle_names(test.mangle);
         if (test.mangle.properties) U.mangle_properties(output, test.mangle.properties);
     }
-    var output_code = make_code(output, output_options);
+    var output_code = make_code(output, output_options, test.expression);
     U.AST_Node.log_function();
     if (expect != output_code) {
         log([
@@ -333,7 +348,7 @@ function test_case(test) {
     // expect == output
     try {
         output.validate_ast();
-        U.parse(output_code);
+        U.parse(output_code, { expression: test.expression });
     } catch (ex) {
         log([
             "!!! Test matched expected result but cannot parse output",
@@ -377,7 +392,7 @@ function test_case(test) {
         }
     }
     if (test.expect_stdout && (!test.node_version || semver.satisfies(process.version, test.node_version))) {
-        var stdout = [ sandbox.run_code(input_code), sandbox.run_code(input_code, true) ];
+        var stdout = [ run_code(test.expression, input_code), run_code(test.expression, input_code, true) ];
         var toplevel = sandbox.has_toplevel({
             compress: test.options,
             mangle: test.mangle
@@ -406,7 +421,7 @@ function test_case(test) {
             });
             return false;
         }
-        actual = sandbox.run_code(output_code, toplevel);
+        actual = run_code(test.expression, output_code, toplevel);
         if (!sandbox.same_stdout(test.expect_stdout, actual)) {
             log([
                 "!!! failed",
@@ -427,7 +442,7 @@ function test_case(test) {
             });
             return false;
         }
-        if (!reminify(test.options, input_code, input_formatted, stdout)) {
+        if (!reminify(test.expression, test.options, input_code, input_formatted, stdout)) {
             return false;
         }
     }
@@ -438,20 +453,29 @@ function tmpl() {
     return U.string_template.apply(null, arguments);
 }
 
-function to_toplevel(input, mangle_options) {
+function to_toplevel(input, mangle_options, expression) {
     if (!(input instanceof U.AST_BlockStatement)) throw new Error("Unsupported input syntax");
-    var directive = true;
     var offset = input.start.line;
     var tokens = [];
-    var toplevel = new U.AST_Toplevel(input.transform(new U.TreeTransformer(function(node) {
+    input.walk(new U.TreeWalker(function(node) {
         if (U.push_uniq(tokens, node.start)) node.start.line -= offset;
-        if (!directive || node === input) return;
-        if (node instanceof U.AST_SimpleStatement && node.body instanceof U.AST_String) {
-            return new U.AST_Directive(node.body);
-        } else {
+    }));
+    var toplevel;
+    if (!expression) {
+        var directive = true;
+        toplevel = new U.AST_Toplevel(input.transform(new U.TreeTransformer(function(node) {
+            if (!directive) return node;
+            if (node === input) return;
+            if (node instanceof U.AST_SimpleStatement && node.body instanceof U.AST_String) {
+                return new U.AST_Directive(node.body);
+            }
             directive = false;
-        }
-    })));
+        })));
+    } else if (input.body.length == 1) {
+        toplevel = input.body[0].wrap_expression();
+    } else {
+        throw new Error("Invalid expression");
+    }
     toplevel.figure_out_scope(mangle_options);
     return toplevel;
 }
diff --git a/test/compress/directives.js b/test/compress/directives.js
index 6e3fd131..0d1ad31e 100644
--- a/test/compress/directives.js
+++ b/test/compress/directives.js
@@ -131,19 +131,34 @@ valid_after_invalid_2: {
 }
 
 issue_5368_1: {
+    expression = true
     options = {
         directives: true,
         expression: true,
     }
     input: {
-        "foo";
-    }
-    expect: {
-        "foo";
+        "foo"
     }
+    expect_exact: '"foo"'
+    expect_stdout: "foo"
 }
 
 issue_5368_2: {
+    expression = true
+    options = {
+        directives: true,
+        expression: true,
+    }
+    input: {
+        (function() {
+            "foo";
+        })()
+    }
+    expect_exact: "function(){}()"
+    expect_stdout: "undefined"
+}
+
+issue_5368_3: {
     options = {
         directives: true,
         expression: true,
diff --git a/test/compress/issue-281.js b/test/compress/issue-281.js
index 240c8b1a..649eb255 100644
--- a/test/compress/issue-281.js
+++ b/test/compress/issue-281.js
@@ -108,6 +108,7 @@ safe_undefined: {
 }
 
 negate_iife_3: {
+    expression = true
     options = {
         conditionals: true,
         expression: true,
@@ -123,6 +124,7 @@ negate_iife_3: {
 }
 
 negate_iife_3_off: {
+    expression = true
     options = {
         conditionals: true,
         expression: true,
@@ -203,6 +205,7 @@ negate_iife_5_off: {
 }
 
 issue_1254_negate_iife_true: {
+    expression = true
     options = {
         expression: true,
         inline: true,
@@ -215,11 +218,12 @@ issue_1254_negate_iife_true: {
             };
         })()();
     }
-    expect_exact: 'void console.log("test");'
+    expect_exact: 'void console.log("test")'
     expect_stdout: true
 }
 
 issue_1254_negate_iife_nested: {
+    expression = true
     options = {
         expression: true,
         inline: true,
@@ -232,7 +236,7 @@ issue_1254_negate_iife_nested: {
             };
         })()()()()();
     }
-    expect_exact: '(void console.log("test"))()()();'
+    expect_exact: '(void console.log("test"))()()()'
 }
 
 negate_iife_issue_1073: {
diff --git a/test/compress/issue-640.js b/test/compress/issue-640.js
index 6f443841..8c893de8 100644
--- a/test/compress/issue-640.js
+++ b/test/compress/issue-640.js
@@ -68,6 +68,7 @@ drop_console_2: {
 }
 
 drop_value: {
+    expression = true
     options = {
         expression: true,
         side_effects: true,
@@ -106,6 +107,7 @@ wrongly_optimized: {
 }
 
 negate_iife_1: {
+    expression = true
     options = {
         expression: true,
         negate_iife: true,
@@ -119,6 +121,7 @@ negate_iife_1: {
 }
 
 negate_iife_3: {
+    expression = true
     options = {
         conditionals: true,
         expression: true,
@@ -133,6 +136,7 @@ negate_iife_3: {
 }
 
 negate_iife_3_off: {
+    expression = true
     options = {
         conditionals: true,
         expression: true,
@@ -215,6 +219,7 @@ negate_iife_5_off: {
 }
 
 issue_1254_negate_iife_true: {
+    expression = true
     options = {
         expression: true,
         negate_iife: true,
@@ -226,11 +231,12 @@ issue_1254_negate_iife_true: {
             };
         })()();
     }
-    expect_exact: '(function(){return function(){console.log("test")}})()();'
+    expect_exact: 'function(){return function(){console.log("test")}}()()'
     expect_stdout: true
 }
 
 issue_1254_negate_iife_nested: {
+    expression = true
     options = {
         expression: true,
         negate_iife: true,
@@ -242,7 +248,7 @@ issue_1254_negate_iife_nested: {
             };
         })()()()()();
     }
-    expect_exact: '(function(){return function(){console.log("test")}})()()()()();'
+    expect_exact: 'function(){return function(){console.log("test")}}()()()()()'
     expect_stdout: true
 }
 
diff --git a/test/mocha/cli.js b/test/mocha/cli.js
index 34b97101..bc3f4c88 100644
--- a/test/mocha/cli.js
+++ b/test/mocha/cli.js
@@ -53,6 +53,23 @@ describe("bin/uglifyjs", function() {
             done();
         });
     });
+    it("Should work with --expression", function(done) {
+        exec([
+            uglifyjscmd,
+            "--expression",
+            "--compress",
+            "--mangle",
+        ].join(" "), function(err, stdout) {
+            if (err) throw err;
+            assert.strictEqual(stdout, "function(n){for(;n(););return 42}(A)\n");
+            done();
+        }).stdin.end([
+            "function(x) {",
+            "    while (x()) {}",
+            "    return 42;",
+            "}(A)",
+        ].join("\n"));
+    });
     it("Should work with --source-map names=true", function(done) {
         exec([
             uglifyjscmd,
@@ -69,7 +86,7 @@ describe("bin/uglifyjs", function() {
                 "    q: b",
                 "};",
                 "//# sourceMappingURL=data:application/json;charset=utf-8;base64,",
-            ].join("\n")
+            ].join("\n");
             assert.strictEqual(stdout.slice(0, expected.length), expected);
             var map = JSON.parse(to_ascii(stdout.slice(expected.length).trim()));
             assert.deepEqual(map.names, [ "obj", "p", "a", "q", "b" ]);
@@ -97,7 +114,7 @@ describe("bin/uglifyjs", function() {
                 "    q: b",
                 "};",
                 "//# sourceMappingURL=data:application/json;charset=utf-8;base64,",
-            ].join("\n")
+            ].join("\n");
             assert.strictEqual(stdout.slice(0, expected.length), expected);
             var map = JSON.parse(to_ascii(stdout.slice(expected.length).trim()));
             assert.deepEqual(map.names, []);
diff --git a/test/mocha/number-literal.js b/test/mocha/number-literal.js
index 61c3a6d6..e17e5ef9 100644
--- a/test/mocha/number-literal.js
+++ b/test/mocha/number-literal.js
@@ -50,12 +50,10 @@ describe("Number literals", function() {
             "0.000_000_004_2e+1_0-0B101_010+0x2_A-0o5_2+4_2",
         ].forEach(function(code) {
             var result = UglifyJS.minify(code, {
-                compress: {
-                    expression: true,
-                },
+                expression: true,
             });
             if (result.error) throw result.error;
-            assert.strictEqual(result.code, "42;");
+            assert.strictEqual(result.code, "42");
         });
     });
     it("Should reject invalid use of underscore", function() {