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Add -B, -A, and -C options to grep (#1206)
Adds the -B (before context), -A (after context), and -C (before+after context) options to grep. Example usage: ``` grep -B <num> [args...] grep -A <num> [args...] ```
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‎README.md‎

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Original file line numberDiff line numberDiff line change
@@ -419,12 +419,18 @@ Available options:
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+ `-l`: Print only filenames of matching files.
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+ `-i`: Ignore case.
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+ `-n`: Print line numbers.
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+ `-B <num>`: Show `<num>` lines before each result.
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+ `-A <num>`: Show `<num>` lines after each result.
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+ `-C <num>`: Show `<num>` lines before and after each result. -B and -A override this option.
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Examples:
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```javascript
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grep('-v', 'GLOBAL_VARIABLE', '*.js');
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grep('GLOBAL_VARIABLE', '*.js');
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grep('-B', 3, 'GLOBAL_VARIABLE', '*.js');
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grep({ '-B': 3 }, 'GLOBAL_VARIABLE', '*.js');
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grep({ '-B': 3, '-C': 2 }, 'GLOBAL_VARIABLE', '*.js');
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```
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Reads input string from given files and returns a

‎src/grep.js‎

Lines changed: 120 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,9 @@ common.register('grep', _grep, {
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'l': 'nameOnly',
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'i': 'ignoreCase',
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'n': 'lineNumber',
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'B': 'beforeContext',
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'A': 'afterContext',
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'C': 'context',
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},
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});
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@@ -22,12 +25,18 @@ common.register('grep', _grep, {
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//@ + `-l`: Print only filenames of matching files.
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//@ + `-i`: Ignore case.
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//@ + `-n`: Print line numbers.
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//@ + `-B <num>`: Show `<num>` lines before each result.
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//@ + `-A <num>`: Show `<num>` lines after each result.
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//@ + `-C <num>`: Show `<num>` lines before and after each result. -B and -A override this option.
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//@
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//@ Examples:
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//@
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//@ ```javascript
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//@ grep('-v', 'GLOBAL_VARIABLE', '*.js');
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//@ grep('GLOBAL_VARIABLE', '*.js');
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//@ grep('-B', 3, 'GLOBAL_VARIABLE', '*.js');
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//@ grep({ '-B': 3 }, 'GLOBAL_VARIABLE', '*.js');
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//@ grep({ '-B': 3, '-C': 2 }, 'GLOBAL_VARIABLE', '*.js');
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//@ ```
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//@
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//@ Reads input string from given files and returns a
@@ -39,7 +48,41 @@ function _grep(options, regex, files) {
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if (!files && !pipe) common.error('no paths given', 2);
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files = [].slice.call(arguments, 2);
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var idx = 2;
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var contextError = ': invalid context length argument';
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// If the option has been found but not read, copy value from arguments
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if (options.beforeContext === true) {
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idx = 3;
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options.beforeContext = Number(arguments[1]);
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if (options.beforeContext < 0) {
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common.error(options.beforeContext + contextError, 2);
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}
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}
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if (options.afterContext === true) {
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idx = 3;
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options.afterContext = Number(arguments[1]);
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if (options.afterContext < 0) {
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common.error(options.afterContext + contextError, 2);
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}
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}
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if (options.context === true) {
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idx = 3;
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options.context = Number(arguments[1]);
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if (options.context < 0) {
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common.error(options.context + contextError, 2);
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}
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}
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// If before or after not given but context is, update values
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if (typeof options.context === 'number') {
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if (options.beforeContext === false) {
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options.beforeContext = options.context;
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}
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if (options.afterContext === false) {
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options.afterContext = options.context;
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}
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}
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regex = arguments[idx - 1];
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files = [].slice.call(arguments, idx);
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if (pipe) {
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files.unshift('-');
@@ -62,23 +105,94 @@ function _grep(options, regex, files) {
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}
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} else {
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var lines = contents.split('\n');
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var matches = [];
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lines.forEach(function (line, index) {
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var matched = line.match(regex);
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if ((options.inverse && !matched) || (!options.inverse && matched)) {
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var result = line;
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if (options.lineNumber) {
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result = '' + (index + 1) + ':' + line;
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var lineNumber = index + 1;
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var result = {};
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if (matches.length > 0) {
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// If the last result intersects, combine them
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var last = matches[matches.length - 1];
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var minimumLineNumber = Math.max(
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1,
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lineNumber - options.beforeContext - 1,
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);
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if (
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last.hasOwnProperty('' + lineNumber) ||
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last.hasOwnProperty('' + minimumLineNumber)
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) {
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result = last;
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}
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}
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result[lineNumber] = {
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line,
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match: true,
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};
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if (options.beforeContext > 0) {
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// Store the lines with their line numbers to check for overlap
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lines
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.slice(Math.max(index - options.beforeContext, 0), index)
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.forEach(function (v, i, a) {
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var lineNum = '' + (index - a.length + i + 1);
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if (!result.hasOwnProperty(lineNum)) {
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result[lineNum] = { line: v, match: false };
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}
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});
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}
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if (options.afterContext > 0) {
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// Store the lines with their line numbers to check for overlap
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lines
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.slice(
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index + 1,
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Math.min(index + options.afterContext + 1, lines.length - 1),
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)
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.forEach(function (v, i) {
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var lineNum = '' + (index + 1 + i + 1);
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if (!result.hasOwnProperty(lineNum)) {
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result[lineNum] = { line: v, match: false };
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}
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});
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}
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// Only add the result if it's new
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if (!matches.includes(result)) {
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matches.push(result);
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}
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grep.push(result);
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}
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});
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// Loop through the matches and add them to the output
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Array.prototype.push.apply(
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grep,
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matches.map(function (result) {
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return Object.entries(result)
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.map(function (entry) {
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var lineNumber = entry[0];
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var line = entry[1].line;
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var match = entry[1].match;
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return options.lineNumber
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? lineNumber + (match ? ':' : '-') + line
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: line;
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})
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.join('\n');
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}),
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);
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}
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});
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if (grep.length === 0 && common.state.errorCode !== 2) {
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// We didn't hit the error above, but pattern didn't match
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common.error('', { silent: true });
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}
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return grep.join('\n') + '\n';
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var separator = '\n';
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if (
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typeof options.beforeContext === 'number' ||
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typeof options.afterContext === 'number'
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) {
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separator = '\n--\n';
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}
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return grep.join(separator) + '\n';
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}
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module.exports = _grep;

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