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util: improve function inspection
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This commit contains the following changes:

1) Add null prototype support for functions.
2) Safely detect async and generator functions.
3) Mark anonymous functions as such instead of just leaving out the
   name.

PR-URL: nodejs#27227
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
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BridgeAR committed May 5, 2019
1 parent a758f9b commit e56eaea
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Showing 7 changed files with 101 additions and 30 deletions.
37 changes: 30 additions & 7 deletions lib/internal/util/inspect.js
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,8 @@ const {
} = require('internal/errors');

const {
isAsyncFunction,
isGeneratorFunction,
isAnyArrayBuffer,
isArrayBuffer,
isArgumentsObject,
Expand Down Expand Up @@ -642,14 +644,9 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
return `${braces[0]}}`;
}
} else if (typeof value === 'function') {
const type = constructor || tag || 'Function';
let name = `${type}`;
if (value.name && typeof value.name === 'string') {
name += `: ${value.name}`;
}
base = getFunctionBase(value, constructor, tag);
if (keys.length === 0)
return ctx.stylize(`[${name}]`, 'special');
base = `[${name}]`;
return ctx.stylize(base, 'special');
} else if (isRegExp(value)) {
// Make RegExps say that they are RegExps
base = RegExpPrototype.toString(
Expand Down Expand Up @@ -834,6 +831,32 @@ function getBoxedBase(value, ctx, keys, constructor, tag) {
return ctx.stylize(base, type.toLowerCase());
}

function getFunctionBase(value, constructor, tag) {
let type = 'Function';
if (isAsyncFunction(value)) {
type = 'AsyncFunction';
} else if (isGeneratorFunction(value)) {
type = 'GeneratorFunction';
}
let base = `[${type}`;
if (constructor === null) {
base += ' (null prototype)';
}
if (value.name === '') {
base += ' (anonymous)';
} else {
base += `: ${value.name}`;
}
base += ']';
if (constructor !== type && constructor !== null) {
base += ` ${constructor}`;
}
if (tag !== '' && constructor !== tag) {
base += ` [${tag}]`;
}
return base;
}

function formatError(err, constructor, tag, ctx) {
// TODO(BridgeAR): Always show the error code if present.
let stack = err.stack || ErrorPrototype.toString(err);
Expand Down
4 changes: 2 additions & 2 deletions test/parallel/test-assert.js
Original file line number Diff line number Diff line change
Expand Up @@ -289,7 +289,7 @@ testAssertionMessage(undefined, 'undefined');
testAssertionMessage(-Infinity, '-Infinity');
testAssertionMessage([1, 2, 3], '[\n+ 1,\n+ 2,\n+ 3\n+ ]');
testAssertionMessage(function f() {}, '[Function: f]');
testAssertionMessage(function() {}, '[Function]');
testAssertionMessage(function() {}, '[Function (anonymous)]');
testAssertionMessage(circular, '{\n+ x: [Circular],\n+ y: 1\n+ }');
testAssertionMessage({ a: undefined, b: null },
'{\n+ a: undefined,\n+ b: null\n+ }');
Expand Down Expand Up @@ -597,7 +597,7 @@ assert.throws(
'\n' +
'+ {}\n' +
'- {\n' +
'- [Symbol(nodejs.util.inspect.custom)]: [Function],\n' +
'- [Symbol(nodejs.util.inspect.custom)]: [Function (anonymous)],\n' +
"- loop: 'forever'\n" +
'- }'
});
Expand Down
2 changes: 1 addition & 1 deletion test/parallel/test-console-table.js
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ test(undefined, 'undefined\n');
test(false, 'false\n');
test('hi', 'hi\n');
test(Symbol(), 'Symbol()\n');
test(function() {}, '[Function]\n');
test(function() {}, '[Function (anonymous)]\n');

test([1, 2, 3], `
┌─────────┬────────┐
Expand Down
2 changes: 1 addition & 1 deletion test/parallel/test-repl.js
Original file line number Diff line number Diff line change
Expand Up @@ -308,7 +308,7 @@ const errorTests = [
// Functions should not evaluate twice (#2773)
{
send: 'var I = [1,2,3,function() {}]; I.pop()',
expect: '[Function]'
expect: '[Function (anonymous)]'
},
// Multiline object
{
Expand Down
6 changes: 3 additions & 3 deletions test/parallel/test-util-format.js
Original file line number Diff line number Diff line change
Expand Up @@ -293,7 +293,7 @@ assert.strictEqual(util.format('abc%', 1), 'abc% 1');

// Additional arguments after format specifiers
assert.strictEqual(util.format('%i', 1, 'number'), '1 number');
assert.strictEqual(util.format('%i', 1, () => {}), '1 [Function]');
assert.strictEqual(util.format('%i', 1, () => {}), '1 [Function (anonymous)]');

{
const o = {};
Expand Down Expand Up @@ -344,8 +344,8 @@ assert.strictEqual(util.format('1', '1'), '1 1');
assert.strictEqual(util.format(1, '1'), '1 1');
assert.strictEqual(util.format('1', 1), '1 1');
assert.strictEqual(util.format(1, -0), '1 -0');
assert.strictEqual(util.format('1', () => {}), '1 [Function]');
assert.strictEqual(util.format(1, () => {}), '1 [Function]');
assert.strictEqual(util.format('1', () => {}), '1 [Function (anonymous)]');
assert.strictEqual(util.format(1, () => {}), '1 [Function (anonymous)]');
assert.strictEqual(util.format('1', "'"), "1 '");
assert.strictEqual(util.format(1, "'"), "1 '");
assert.strictEqual(util.format('1', 'number'), '1 number');
Expand Down
4 changes: 2 additions & 2 deletions test/parallel/test-util-inspect-proxy.js
Original file line number Diff line number Diff line change
Expand Up @@ -144,7 +144,7 @@ const proxy11 = new Proxy(() => {}, {
return proxy11;
}
});
const expected10 = '[Function]';
const expected11 = '[Function]';
const expected10 = '[Function (anonymous)]';
const expected11 = '[Function (anonymous)]';
assert.strictEqual(util.inspect(proxy10), expected10);
assert.strictEqual(util.inspect(proxy11), expected11);
76 changes: 62 additions & 14 deletions test/parallel/test-util-inspect.js
Original file line number Diff line number Diff line change
Expand Up @@ -33,11 +33,51 @@ assert.strictEqual(util.inspect(1), '1');
assert.strictEqual(util.inspect(false), 'false');
assert.strictEqual(util.inspect(''), "''");
assert.strictEqual(util.inspect('hello'), "'hello'");
assert.strictEqual(util.inspect(function() {}), '[Function]');
assert.strictEqual(util.inspect(() => {}), '[Function]');
assert.strictEqual(util.inspect(async function() {}), '[AsyncFunction]');
assert.strictEqual(util.inspect(async () => {}), '[AsyncFunction]');
assert.strictEqual(util.inspect(function*() {}), '[GeneratorFunction]');
assert.strictEqual(util.inspect(function abc() {}), '[Function: abc]');
assert.strictEqual(util.inspect(() => {}), '[Function (anonymous)]');
assert.strictEqual(
util.inspect(async function() {}),
'[AsyncFunction (anonymous)]'
);
assert.strictEqual(util.inspect(async () => {}), '[AsyncFunction (anonymous)]');

// Special function inspection.
{
const fn = (() => function*() {})();
assert.strictEqual(
util.inspect(fn),
'[GeneratorFunction (anonymous)]'
);
Object.setPrototypeOf(fn, Object.getPrototypeOf(async () => {}));
assert.strictEqual(
util.inspect(fn),
'[GeneratorFunction (anonymous)] AsyncFunction'
);
Object.defineProperty(fn, 'name', { value: 5, configurable: true });
assert.strictEqual(
util.inspect(fn),
'[GeneratorFunction: 5] AsyncFunction'
);
Object.defineProperty(fn, Symbol.toStringTag, {
value: 'Foobar',
configurable: true
});
assert.strictEqual(
util.inspect({ ['5']: fn }),
"{ '5': [GeneratorFunction: 5] AsyncFunction [Foobar] }"
);
Object.defineProperty(fn, 'name', { value: '5', configurable: true });
Object.setPrototypeOf(fn, null);
assert.strictEqual(
util.inspect(fn),
'[GeneratorFunction (null prototype): 5] [Foobar]'
);
assert.strictEqual(
util.inspect({ ['5']: fn }),
"{ '5': [GeneratorFunction (null prototype): 5] [Foobar] }"
);
}

assert.strictEqual(util.inspect(undefined), 'undefined');
assert.strictEqual(util.inspect(null), 'null');
assert.strictEqual(util.inspect(/foo(bar\n)?/gi), '/foo(bar\\n)?/gi');
Expand All @@ -59,8 +99,9 @@ assert.strictEqual(util.inspect({}), '{}');
assert.strictEqual(util.inspect({ a: 1 }), '{ a: 1 }');
assert.strictEqual(util.inspect({ a: function() {} }), '{ a: [Function: a] }');
assert.strictEqual(util.inspect({ a: () => {} }), '{ a: [Function: a] }');
assert.strictEqual(util.inspect({ a: async function() {} }),
'{ a: [AsyncFunction: a] }');
// eslint-disable-next-line func-name-matching
assert.strictEqual(util.inspect({ a: async function abc() {} }),
'{ a: [AsyncFunction: abc] }');
assert.strictEqual(util.inspect({ a: async () => {} }),
'{ a: [AsyncFunction: a] }');
assert.strictEqual(util.inspect({ a: function*() {} }),
Expand Down Expand Up @@ -411,7 +452,10 @@ assert.strictEqual(
{
const value = (() => function() {})();
value.aprop = 42;
assert.strictEqual(util.inspect(value), '[Function] { aprop: 42 }');
assert.strictEqual(
util.inspect(value),
'[Function (anonymous)] { aprop: 42 }'
);
}

// Regular expressions with properties.
Expand Down Expand Up @@ -1441,7 +1485,7 @@ util.inspect(process);
out = util.inspect(o, { compact: false, breakLength: 3 });
expect = [
'{',
' a: [Function],',
' a: [Function (anonymous)],',
' b: [Number: 3]',
'}'
].join('\n');
Expand All @@ -1450,7 +1494,7 @@ util.inspect(process);
out = util.inspect(o, { compact: false, breakLength: 3, showHidden: true });
expect = [
'{',
' a: [Function] {',
' a: [Function (anonymous)] {',
' [length]: 0,',
" [name]: ''",
' },',
Expand Down Expand Up @@ -1767,8 +1811,8 @@ assert.strictEqual(util.inspect('"\'${a}'), "'\"\\'${a}'");
[new Number(55), '[Number: 55]'],
[Object(BigInt(55)), '[BigInt: 55n]'],
[Object(Symbol('foo')), '[Symbol: Symbol(foo)]'],
[function() {}, '[Function]'],
[() => {}, '[Function]'],
[function() {}, '[Function (anonymous)]'],
[() => {}, '[Function (anonymous)]'],
[[1, 2], '[ 1, 2 ]'],
[[, , 5, , , , ], '[ <2 empty items>, 5, <3 empty items> ]'],
[{ a: 5 }, '{ a: 5 }'],
Expand Down Expand Up @@ -1957,10 +2001,14 @@ assert.strictEqual(
let value = (function() { return function() {}; })();
Object.setPrototypeOf(value, null);
Object.setPrototypeOf(obj, value);
assert.strictEqual(util.inspect(obj), '<[Function]> { a: true }');
assert.strictEqual(
util.inspect(obj),
'<[Function (null prototype) (anonymous)]> { a: true }'
);
assert.strictEqual(
util.inspect(obj, { colors: true }),
'<\u001b[36m[Function]\u001b[39m> { a: \u001b[33mtrue\u001b[39m }'
'<\u001b[36m[Function (null prototype) (anonymous)]\u001b[39m> ' +
'{ a: \u001b[33mtrue\u001b[39m }'
);

obj = { a: true };
Expand Down

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