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util: improve symbol to string tag #27342

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866d008
util: improve `Symbol.toStringTag` handling
BridgeAR Apr 22, 2019
d6d6624
util: rename setIteratorBraces to getIteratorBraces
BridgeAR Apr 22, 2019
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35 changes: 21 additions & 14 deletions lib/internal/util/inspect.js
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Original file line number Diff line number Diff line change
Expand Up @@ -560,22 +560,20 @@ function formatValue(ctx, value, recurseTimes, typedArray) {
return formatRaw(ctx, value, recurseTimes, typedArray);
}

function setIteratorBraces(type, tag) {
if (tag !== `${type} Iterator`) {
if (tag !== '')
tag += '] [';
tag += `${type} Iterator`;
}
return [`[${tag}] {`, '}'];
}

function formatRaw(ctx, value, recurseTimes, typedArray) {
let keys;

const constructor = getConstructorName(value, ctx);
let tag = value[Symbol.toStringTag];
if (typeof tag !== 'string')
// Only list the tag in case it's non-enumerable / not an own property.
// Otherwise we'd print this twice.
if (typeof tag !== 'string' ||
tag !== '' &&
(ctx.showHidden ? hasOwnProperty : propertyIsEnumerable)(
value, Symbol.toStringTag
)) {
tag = '';
}
let base = '';
let formatter = getEmptyFormatArray;
let braces;
Expand Down Expand Up @@ -623,11 +621,11 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
extrasType = kArrayExtrasType;
} else if (isMapIterator(value)) {
keys = getKeys(value, ctx.showHidden);
braces = setIteratorBraces('Map', tag);
braces = getIteratorBraces('Map', tag);
formatter = formatIterator;
} else if (isSetIterator(value)) {
keys = getKeys(value, ctx.showHidden);
braces = setIteratorBraces('Set', tag);
braces = getIteratorBraces('Set', tag);
formatter = formatIterator;
} else {
noIterator = true;
Expand Down Expand Up @@ -747,10 +745,10 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
}
}
if (isMapIterator(value)) {
braces = setIteratorBraces('Map', tag);
braces = getIteratorBraces('Map', tag);
formatter = formatIterator;
} else if (isSetIterator(value)) {
braces = setIteratorBraces('Set', tag);
braces = getIteratorBraces('Set', tag);
formatter = formatIterator;
// Handle other regular objects again.
} else if (keys.length === 0) {
Expand Down Expand Up @@ -811,6 +809,15 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
return res;
}

function getIteratorBraces(type, tag) {
if (tag !== `${type} Iterator`) {
if (tag !== '')
tag += '] [';
tag += `${type} Iterator`;
}
return [`[${tag}] {`, '}'];
}

function formatError(err, constructor, tag, ctx) {
// TODO(BridgeAR): Always show the error code if present.
let stack = err.stack || ErrorPrototype.toString(err);
Expand Down
16 changes: 14 additions & 2 deletions test/parallel/test-util-inspect.js
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Expand Up @@ -1264,8 +1264,20 @@ util.inspect(process);

{
// @@toStringTag
assert.strictEqual(util.inspect({ [Symbol.toStringTag]: 'a' }),
"Object [a] { [Symbol(Symbol.toStringTag)]: 'a' }");
const obj = { [Symbol.toStringTag]: 'a' };
assert.strictEqual(
util.inspect(obj),
"{ [Symbol(Symbol.toStringTag)]: 'a' }"
);
Object.defineProperty(obj, Symbol.toStringTag, {
value: 'a',
enumerable: false
});
assert.strictEqual(util.inspect(obj), 'Object [a] {}');
assert.strictEqual(
util.inspect(obj, { showHidden: true }),
"{ [Symbol(Symbol.toStringTag)]: 'a' }"
);

class Foo {
constructor() {
Expand Down