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util: improve display of iterators and weak entries
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This adds the number of not visible elements when inspecting iterators
while exceeding `maxArrayLength`.
It also fixes a edge case with `maxArrayLength` and the map.entries()
iterator. Now the whole entry will be visible instead of only the key
but not the value of the first entry.
Besides that it uses a slighly better algorithm that improves the
performance by skipping unnecessary steps.

PR-URL: #20961
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
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@BridgeAR @rvagg
BridgeAR authored and rvagg committed Aug 15, 2018
1 parent d95a22c commit b171fa2
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Showing 4 changed files with 89 additions and 70 deletions.
9 changes: 6 additions & 3 deletions lib/console.js
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Original file line number Diff line number Diff line change
Expand Up @@ -360,8 +360,11 @@ Console.prototype.table = function(tabularData, properties) {
const mapIter = isMapIterator(tabularData);
let isKeyValue = false;
let i = 0;
if (mapIter)
[ tabularData, isKeyValue ] = previewEntries(tabularData);
if (mapIter) {
const res = previewEntries(tabularData, true);
tabularData = res[0];
isKeyValue = res[1];
}

if (isKeyValue || isMap(tabularData)) {
const keys = [];
Expand Down Expand Up @@ -391,7 +394,7 @@ Console.prototype.table = function(tabularData, properties) {

const setIter = isSetIterator(tabularData);
if (setIter)
[ tabularData ] = previewEntries(tabularData);
tabularData = previewEntries(tabularData);

const setlike = setIter || (mapIter && !isKeyValue) || isSet(tabularData);
if (setlike) {
Expand Down
98 changes: 54 additions & 44 deletions lib/util.js
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Original file line number Diff line number Diff line change
Expand Up @@ -115,6 +115,10 @@ const meta = [
'', '', '', '', '', '', '', '', '', '',
'', '', '', '', '', '', '', '\\\\'
];
// Constants to map the iterator state.
const kWeak = 0;
const kIterator = 1;
const kMapEntries = 2;

const escapeFn = (str) => meta[str.charCodeAt(0)];

Expand Down Expand Up @@ -982,77 +986,83 @@ function formatMap(ctx, value, recurseTimes, keys) {
return output;
}

function formatWeakSet(ctx, value, recurseTimes, keys) {
function formatSetIterInner(ctx, value, recurseTimes, keys, entries, state) {
const maxArrayLength = Math.max(ctx.maxArrayLength, 0);
const [ entries ] = previewEntries(value).slice(0, maxArrayLength + 1);
const maxLength = Math.min(maxArrayLength, entries.length);
let output = new Array(maxLength);
for (var i = 0; i < maxLength; ++i)
output[i] = formatValue(ctx, entries[i], recurseTimes);
// Sort all entries to have a halfway reliable output (if more entries than
// retrieved ones exist, we can not reliably return the same output).
output = output.sort();
if (entries.length > maxArrayLength)
output.push('... more items');
if (state === kWeak) {
// Sort all entries to have a halfway reliable output (if more entries than
// retrieved ones exist, we can not reliably return the same output).
output = output.sort();
}
const remaining = entries.length - maxLength;
if (remaining > 0) {
output.push(`... ${remaining} more item${remaining > 1 ? 's' : ''}`);
}
for (i = 0; i < keys.length; i++)
output.push(formatProperty(ctx, value, recurseTimes, keys[i], 0));
return output;
}

function formatWeakMap(ctx, value, recurseTimes, keys) {
function formatMapIterInner(ctx, value, recurseTimes, keys, entries, state) {
const maxArrayLength = Math.max(ctx.maxArrayLength, 0);
const [ entries ] = previewEntries(value).slice(0, (maxArrayLength + 1) * 2);
// Entries exist as [key1, val1, key2, val2, ...]
const remainder = entries.length / 2 > maxArrayLength;
const len = entries.length / 2 - (remainder ? 1 : 0);
const len = entries.length / 2;
const remaining = len - maxArrayLength;
const maxLength = Math.min(maxArrayLength, len);
let output = new Array(maxLength);
for (var i = 0; i < maxLength; i++) {
let start = '';
let end = '';
let middle = ' => ';
let i = 0;
if (state === kMapEntries) {
start = '[ ';
end = ' ]';
middle = ', ';
}
for (; i < maxLength; i++) {
const pos = i * 2;
output[i] = `${formatValue(ctx, entries[pos], recurseTimes)} => ` +
formatValue(ctx, entries[pos + 1], recurseTimes);
output[i] = `${start}${formatValue(ctx, entries[pos], recurseTimes)}` +
`${middle}${formatValue(ctx, entries[pos + 1], recurseTimes)}${end}`;
}
if (state === kWeak) {
// Sort all entries to have a halfway reliable output (if more entries
// than retrieved ones exist, we can not reliably return the same output).
output = output.sort();
}
if (remaining > 0) {
output.push(`... ${remaining} more item${remaining > 1 ? 's' : ''}`);
}
// Sort all entries to have a halfway reliable output (if more entries than
// retrieved ones exist, we can not reliably return the same output).
output = output.sort();
if (remainder > 0)
output.push('... more items');
for (i = 0; i < keys.length; i++)
output.push(formatProperty(ctx, value, recurseTimes, keys[i], 0));
return output;
}

function zip2(list) {
const ret = Array(list.length / 2);
for (var i = 0; i < ret.length; ++i)
ret[i] = [list[2 * i], list[2 * i + 1]];
return ret;
function formatWeakSet(ctx, value, recurseTimes, keys) {
const entries = previewEntries(value);
return formatSetIterInner(ctx, value, recurseTimes, keys, entries, kWeak);
}

function formatCollectionIterator(ctx, value, recurseTimes, keys) {
const output = [];
var [ entries, isKeyValue ] = previewEntries(value);
if (isKeyValue)
entries = zip2(entries);
for (const entry of entries) {
if (ctx.maxArrayLength === output.length) {
output.push('... more items');
break;
}
output.push(formatValue(ctx, entry, recurseTimes));
}
for (var n = 0; n < keys.length; n++) {
output.push(formatProperty(ctx, value, recurseTimes, keys[n], 0));
}
return output;
function formatWeakMap(ctx, value, recurseTimes, keys) {
const entries = previewEntries(value);
return formatMapIterInner(ctx, value, recurseTimes, keys, entries, kWeak);
}

function formatMapIterator(ctx, value, recurseTimes, keys) {
return formatCollectionIterator(ctx, value, recurseTimes, keys);
function formatSetIterator(ctx, value, recurseTimes, keys) {
const entries = previewEntries(value);
return formatSetIterInner(ctx, value, recurseTimes, keys, entries, kIterator);
}

function formatSetIterator(ctx, value, recurseTimes, keys) {
return formatCollectionIterator(ctx, value, recurseTimes, keys);
function formatMapIterator(ctx, value, recurseTimes, keys) {
const [entries, isKeyValue] = previewEntries(value, true);
if (isKeyValue) {
return formatMapIterInner(
ctx, value, recurseTimes, keys, entries, kMapEntries);
}

return formatSetIterInner(ctx, value, recurseTimes, keys, entries, kIterator);
}

function formatPromise(ctx, value, recurseTimes, keys) {
Expand Down
3 changes: 3 additions & 0 deletions src/node_util.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,9 @@ static void PreviewEntries(const FunctionCallbackInfo<Value>& args) {
Local<Array> entries;
if (!args[0].As<Object>()->PreviewEntries(&is_key_value).ToLocal(&entries))
return;
// Fast path for WeakMap, WeakSet and Set iterators.
if (args.Length() == 1)
return args.GetReturnValue().Set(entries);
Local<Array> ret = Array::New(env->isolate(), 2);
ret->Set(env->context(), 0, entries).FromJust();
ret->Set(env->context(), 1, v8::Boolean::New(env->isolate(), is_key_value))
Expand Down
49 changes: 26 additions & 23 deletions test/parallel/test-util-inspect.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -447,13 +447,15 @@ assert.strictEqual(util.inspect(-5e-324), '-5e-324');
{
const map = new Map();
map.set(1, 2);
const [ vals ] = previewEntries(map.entries());
const valsOutput = [];
for (const o of vals) {
valsOutput.push(o);
}

assert.strictEqual(util.inspect(valsOutput), '[ 1, 2 ]');
// Passing only a single argument to indicate a set iterator.
const valsSetIterator = previewEntries(map.entries());
// Passing through true to indicate a map iterator.
const valsMapIterEntries = previewEntries(map.entries(), true);
const valsMapIterKeys = previewEntries(map.keys(), true);

assert.strictEqual(util.inspect(valsSetIterator), '[ 1, 2 ]');
assert.strictEqual(util.inspect(valsMapIterEntries), '[ [ 1, 2 ], true ]');
assert.strictEqual(util.inspect(valsMapIterKeys), '[ [ 1 ], false ]');
}

// Test for other constructors in different context.
Expand Down Expand Up @@ -965,18 +967,19 @@ if (typeof Symbol !== 'undefined') {
// Test Map iterators.
{
const map = new Map([['foo', 'bar']]);
assert.strictEqual(util.inspect(map.keys()), "[Map Iterator] { 'foo' }");
assert.strictEqual(util.inspect(map.values()), "[Map Iterator] { 'bar' }");
assert.strictEqual(util.inspect(map.entries()),
"[Map Iterator] { [ 'foo', 'bar' ] }");
assert.strictEqual(util.inspect(map.keys()), '[Map Iterator] { \'foo\' }');
assert.strictEqual(util.inspect(map.values()), '[Map Iterator] { \'bar\' }');
map.set('A', 'B!');
assert.strictEqual(util.inspect(map.entries(), { maxArrayLength: 1 }),
"[Map Iterator] { [ 'foo', 'bar' ], ... 1 more item }");
// Make sure the iterator doesn't get consumed.
const keys = map.keys();
assert.strictEqual(util.inspect(keys), "[Map Iterator] { 'foo' }");
assert.strictEqual(util.inspect(keys), "[Map Iterator] { 'foo' }");
assert.strictEqual(util.inspect(keys), "[Map Iterator] { 'foo', 'A' }");
assert.strictEqual(util.inspect(keys), "[Map Iterator] { 'foo', 'A' }");
keys.extra = true;
assert.strictEqual(
util.inspect(keys, { maxArrayLength: 0 }),
'[Map Iterator] { ... more items, extra: true }');
'[Map Iterator] { ... 2 more items, extra: true }');
}

// Test Set iterators.
Expand All @@ -992,7 +995,7 @@ if (typeof Symbol !== 'undefined') {
keys.extra = true;
assert.strictEqual(
util.inspect(keys, { maxArrayLength: 1 }),
'[Set Iterator] { 1, ... more items, extra: true }');
'[Set Iterator] { 1, ... 1 more item, extra: true }');
}

// Test alignment of items in container.
Expand Down Expand Up @@ -1413,17 +1416,17 @@ util.inspect(process);
assert.strictEqual(out, expect);

out = util.inspect(weakMap, { maxArrayLength: 0, showHidden: true });
expect = 'WeakMap { ... more items }';
expect = 'WeakMap { ... 2 more items }';
assert.strictEqual(out, expect);

weakMap.extra = true;
out = util.inspect(weakMap, { maxArrayLength: 1, showHidden: true });
// It is not possible to determine the output reliable.
expect = 'WeakMap { [ [length]: 0 ] => {}, ... more items, extra: true }';
const expectAlt = 'WeakMap { {} => [ [length]: 0 ], ... more items, ' +
expect = 'WeakMap { [ [length]: 0 ] => {}, ... 1 more item, extra: true }';
const expectAlt = 'WeakMap { {} => [ [length]: 0 ], ... 1 more item, ' +
'extra: true }';
assert(out === expect || out === expectAlt,
`Found "${out}" rather than "${expect}" or "${expectAlt}"`);
`Found: "${out}"\nrather than: "${expect}"\nor: "${expectAlt}"`);
}

{ // Test WeakSet
Expand All @@ -1437,17 +1440,17 @@ util.inspect(process);
assert.strictEqual(out, expect);

out = util.inspect(weakSet, { maxArrayLength: -2, showHidden: true });
expect = 'WeakSet { ... more items }';
expect = 'WeakSet { ... 2 more items }';
assert.strictEqual(out, expect);

weakSet.extra = true;
out = util.inspect(weakSet, { maxArrayLength: 1, showHidden: true });
// It is not possible to determine the output reliable.
expect = 'WeakSet { {}, ... more items, extra: true }';
const expectAlt = 'WeakSet { [ 1, [length]: 1 ], ... more items, ' +
expect = 'WeakSet { {}, ... 1 more item, extra: true }';
const expectAlt = 'WeakSet { [ 1, [length]: 1 ], ... 1 more item, ' +
'extra: true }';
assert(out === expect || out === expectAlt,
`Found "${out}" rather than "${expect}" or "${expectAlt}"`);
`Found: "${out}"\nrather than: "${expect}"\nor: "${expectAlt}"`);
}

{ // Test argument objects.
Expand Down

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