8000 util,console: colorize regexp groups, character classes, etc · nodejs/node@fdef072 · GitHub
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util,console: colorize regexp groups, character classes, etc
This adds a parser to parse the regular expression and to highlight different parts of a regular expression in case colors are active. It is a one time pass algorithm and should therefore not cause too much overhead during parsing. As side effect, it is now possible to create individual styles to colorize inspected values values as a user likes. This might for example be expanded to numbers with numeric separators, highlighting the separators or decimal points different. It would in theory also be possible to return a changed string. That is however not the intention for this API as it is only triggered in case colors are active. PR-URL: #59710 Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com> Reviewed-By: Jordan Harband <ljharb@gmail.com>
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‎doc/api/util.md‎

Lines changed: 22 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -847,6 +847,11 @@ stream.write('With ES6');
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<!-- YAML
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added: v0.3.0
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changes:
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- version:
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- REPLACEME
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pr-url: https://github.com/nodejs/node/pull/59710
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description: The util.inspect.styles.regexp style is now a method that is
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invoked for coloring the stringified regular expression.
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- version:
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- v17.3.0
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- v16.14.0
@@ -1297,7 +1302,12 @@ The default styles and associated colors are:
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* `name`: (no styling)
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* `null`: `bold`
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* `number`: `yellow`
1300-
* `regexp`: `red`
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* `regexp`: A method that colors character classes, groups, assertions, and
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other parts for improved readability. To customize the coloring, change the
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`colors` property. It is set to
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`['red', 'green', 'yellow', 'cyan', 'magenta']` by default and may be
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adjusted as needed. The array is repetitively iterated through depending on
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the "depth".
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* `special`: `cyan` (e.g., `Proxies`)
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* `string`: `green`
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* `symbol`: `green`
@@ -1309,6 +1319,17 @@ terminals. To verify color support use [`tty.hasColors()`][].
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Predefined control codes are listed below (grouped as "Modifiers", "Foreground
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colors", and "Background colors").
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#### Complex custom coloring
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It is possible to define a method as style. It receives the stringified value
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of the input. It is invoked in case coloring is active and the type is
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inspected.
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Example: `util.inspect.styles.regexp(value)`
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* `value` {string} The string representation of the input type.
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* Returns: {string} The adjusted representation of `object`.
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#### Modifiers
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Modifier support varies throughout different terminals. They will mostly be

‎lib/internal/util/inspect.js‎

Lines changed: 257 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -502,7 +502,6 @@ defineColorAlias('inverse', 'swapColors');
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defineColorAlias('inverse', 'swapcolors');
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defineColorAlias('doubleunderline', 'doubleUnderline');
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505-
// TODO(BridgeAR): Add function style support for more complex styles.
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// Don't use 'blue' not visible on cmd.exe
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inspect.styles = ObjectAssign({ __proto__: null }, {
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special: 'cyan',
@@ -515,11 +514,259 @@ inspect.styles = ObjectAssign({ __proto__: null }, {
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symbol: 'green',
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date: 'magenta',
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// "name": intentionally not styling
518-
// TODO(BridgeAR): Highlight regular expressions properly.
519-
regexp: 'red',
517+
regexp: highlightRegExp,
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module: 'underline',
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});
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// Define the palette for RegExp group depth highlighting. Can be changed by users.
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inspect.styles.regexp.colors = ['green', 'red', 'yellow', 'cyan', 'magenta'];
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const highlightRegExpColors = inspect.styles.regexp.colors.slice();
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/**
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* Colorize a JavaScript RegExp pattern per ECMAScript grammar.
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* This is a tolerant single-pass highlighter using heuristics in some cases.
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* It supports: groups (named/unnamed, lookaround), assertions, alternation,
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* quantifiers, escapes (incl. Unicode properties), character classes and
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* backreferences.
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* @param {string} regexpString
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* @returns {string}
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*/
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function highlightRegExp(regexpString) {
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let out = '';
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let i = 0;
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let depth = 0;
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let inClass = false;
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// TODO(BridgeAR): Add group type tracking. That allows to increase the depth
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// in case the same type is next to each other.
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// let groupType = 0;
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// Verify palette and update cache if user changed colors
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const paletteNames = highlightRegExp.colors?.length > 0 ?
547+
highlightRegExp.colors :
548+
highlightRegExpColors;
549+
550+
const palette = paletteNames.reduce((acc, name) => {
551+
const color = inspect.colors[name];
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if (color) acc.push([`\u001b[${color[0]}m`, `\u001b[${color[1]}m`]);
553+
return acc;
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}, []);
555+
556+
function writeGroup(start, end, decreaseDepth = 1) {
557+
let seq = '';
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i++;
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// Only checking for the closing delimiter is a fast heuristic for regular
560+
// expressions without the u or v flag. A safer check would verify that the
561+
// read characters are all alphanumeric.
562+
while (i < regexpString.length && regexpString[i] !== end) {
563+
seq += regexpString[i++];
564+
}
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if (i < regexpString.length) {
566+
depth -= decreaseDepth;
567+
write(start);
568+
writeDepth(seq, 1, 1);
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write(end);
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depth += decreaseDepth;
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} else {
572+
// The group is not closed which would lead to mistakes in the output.
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// This is a workaround to prevent output from being corrupted.
574+
writeDepth(start, 1, -seq.length);
575+
}
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}
577+
578+
const write = (str) => {
579+
const idx = depth % palette.length;
580+
// Safeguard against bugs in the implementation.
581+
const color = palette[idx] ?? palette[0];
582+
out += color[0] + str + color[1];
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return idx;
584+
};
585+
586+
function writeDepth(str, incDepth, incI) {
587+
depth += incDepth;
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write(str);
589+
depth -= incDepth;
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i += incI;
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}
592+
593+
// Opening '/'
594+
write('/');
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depth++;
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i = 1;
597+
598+
// Parse pattern until next unescaped '/'
599+
while (i < regexpString.length) {
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const ch = regexpString[i];
601+
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if (inClass) {
603+
if (ch === '\\') {
604+
let seq = '\\';
605+
i++;
606+
if (i < regexpString.length) {
607+
seq += regexpString[i++];
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const next = seq[1];
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if (next === 'u' && regexpString[i] === '{') {
610+
writeGroup(`${seq}{`, '}', 0);
611+
continue;
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} else if ((next === 'p' || next === 'P') && regexpString[i] === '{') {
613+
writeGroup(`${seq}{`, '}', 0);
614+
continue;
615+
} else if (seq[1] === 'x') {
616+
seq += regexpString.slice(i, i + 2);
617+
i += 2;
618+
}
619+
}
620+
write(seq);
621+
} else if (ch === ']') {
622+
depth--;
623+
write(']');
624+
i++;
625+
inClass = false;
626+
} else if (ch === '-' && regexpString[i - 1] !== '[' &&
627+
i + 1 < regexpString.length && regexpString[i + 1] !== ']') {
628+
writeDepth('-', 1, 1);
629+
} else {
630+
write(ch);
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i++;
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}
633+
} else if (ch === '[') {
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// Enter class
635+
write('[');
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depth++;
637+
i++;
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inClass = true;
639+
} else if (ch === '(') {
640+
write('(');
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depth++;
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i++;
643+
if (i < regexpString.length && regexpString[i] === '?') {
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// Assertions and named groups
645+
i++;
646+
const a = i < regexpString.length ? regexpString[i] : '';
647+
if (a === ':' || a === '=' || a === '!') {
648+
writeDepth(`?${a}`, -1, 1);
649+
} else {
650+
const b = i + 1 < regexpString.length ? regexpString[i + 1] : '';
651+
if (a === '<' && (b === '=' || b === '!')) {
652+
writeDepth(`?<${b}`, -1, 2);
653+
} else if (a === '<') {
654+
// Named capture: write '?<name>' as a single colored token
655+
i++; // consume '<'
656+
const start = i;
657+
while (i < regexpString.length && regexpString[i] !== '>') {
658+
i++;
659+
}
660+
const name = regexpString.slice(start, i);
661+
if (i < regexpString.length && regexpString[i] === '>') {
662+
depth--;
663+
write('?<');
664+
writeDepth(name, 1, 0);
665+
write('>');
666+
depth++;
667+
i++;
668+
} else {
669+
writeDepth('?<', -1, 0);
670+
write(name);
671+
}
672+
} else {
673+
write('?');
674+
}
675+
}
676+
}
677+
} else if (ch === ')') {
678+
depth--;
679+
write(')');
680+
i++;
681+
} else if (ch === '\\') {
682+
let seq = '\\';
683+
i++;
684+
if (i < regexpString.length) {
685+
seq += regexpString[i++];
686+
const next = seq[1];
687+
if (i < regexpString.length) {
688+
if (next === 'u' && regexpString[i] === '{') {
689+
writeGroup(`${seq}{`, '}', 0);
690+
continue;
691+
} else if (next === 'x') {
692+
seq += regexpString.slice(i, i + 2);
693+
i += 2;
694+
} else if (next >= '0' && next <= '9') {
695+
while (i < regexpString.length && regexpString[i] >= '0' && regexpString[i] <= '9') {
696+
seq += regexpString[i++];
697+
}
698+
} else if (next === 'k' && regexpString[i] === '<') {
699+
writeGroup(`${seq}<`, '>');
700+
continue;
701+
} else if ((next === 'p' || next === 'P') && regexpString[i] === '{') {
702+
// Unicode properties
703+
writeGroup(`${seq}{`, '}', 0);
704+
continue;
705+
}
706+
}
707+
}
708+
writeDepth(seq, 1, 0);
709+
} else if (ch === '|' || ch === '+' || ch === '*' || ch === '?' || ch === ',' || ch === '^' || ch === '$') {
710+
writeDepth(ch, 3, 1);
711+
} else if (ch === '{') {
712+
i++;
713+
let digits = '';
714+
while (i < regexpString.length && regexpString[i] >= '0' && regexpString[i] <= '9') {
715+
digits += regexpString[i++];
716+
}
717+
if (digits) {
718+
write('{');
719+
depth++;
720+
writeDepth(digits, 1, 0);
721+
}
722+
if (i < regexpString.length) {
723+
if (regexpString[i] === ',') {
724+
if (!digits) {
725+
write('{');
726+
depth++;
727+
}
728+
write(',');
729+
i++;
730+
} else if (!digits) {
731+
depth += 1;
732+
write('{');
733+
depth -= 1;
734+
continue;
735+
}
736+
}
737+
let digits2 = '';
738+
while (i < regexpString.length && regexpString[i] >= '0' && regexpString[i] <= '9') {
739+
digits2 += regexpString[i++];
740+
}
741+
if (digits2) {
742+
writeDepth(digits2, 1, 0);
743+
}
744+
if (i < regexpString.length && regexpString[i] === '}') {
745+
depth--;
746+
write('}');
747+
i++;
748+
}
749+
if (i < regexpString.length && regexpString[i] === '?') {
750+
writeDepth('?', 3, 1);
751+
}
752+
} else if (ch === '.') {
753+
writeDepth(ch, 2, 1);
754+
} else if (ch === '/') {
755+
// Stop at closing delimiter (unescaped, outside of character class)
756+
break;
757+
} else {
758+
writeDepth(ch, 1, 1);
759+
}
760+
}
761+
762+
// Closing delimiter and flags
763+
writeDepth('/', -1, 1);
764+
if (i < regexpString.length) {
765+
write(regexpString.slice(i));
766+
}
767+
return out;
768+
}
769+
523770
function addQuotes(str, quotes) {
524771
if (quotes === -1) {
525772
return `"${str}"`;
@@ -606,8 +853,12 @@ function stylizeWithColor(str, styleType) {
606853
const style = inspect.styles[styleType];
607854
if (style !== undefined) {
608855
const color = inspect.colors[style];
609-
if (color !== undefined)
856+
if (color !== undefined) {
610857
return `\u001b[${color[0]}m${str}\u001b[${color[1]}m`;
858+
}
859+
if (typeof style === 'function') {
860+
return style(str);
861+
}
611862
}
612863
return str;
613864
}
@@ -1048,9 +1299,10 @@ function formatRaw(ctx, value, recurseTimes, typedArray) {
10481299
const prefix = getPrefix(constructor, tag, 'RegExp');
10491300
if (prefix !== 'RegExp ')
10501301
base = `${prefix}${base}`;
1302+
base = ctx.stylize(base, 'regexp');
10511303
if ((keys.length === 0 && protoProps === undefined) ||
10521304
(recurseTimes > ctx.depth && ctx.depth !== null)) {
1053-
return ctx.stylize(base, 'regexp');
1305+
return base;
10541306
}
10551307
} else if (isDate(value)) {
10561308
// Make dates with properties first say the date

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