snippet.js
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'use strict';
var common = require('./common');
// get snippet for a single line, respecting maxLength
function getLine(buffer, lineStart, lineEnd, position, maxLineLength) {
var head = '';
var tail = '';
var maxHalfLength = Math.floor(maxLineLength / 2) - 1;
if (position - lineStart > maxHalfLength) {
head = ' ... ';
lineStart = position - maxHalfLength + head.length;
}
if (lineEnd - position > maxHalfLength) {
tail = ' ...';
lineEnd = position + maxHalfLength - tail.length;
}
return {
str: head + buffer.slice(lineStart, lineEnd).replace(/\t/g, '→') + tail,
pos: position - lineStart + head.length // relative position
};
}
function padStart(string, max) {
return common.repeat(' ', max - string.length) + string;
}
function makeSnippet(mark, options) {
options = Object.create(options || null);
if (!mark.buffer) return null;
if (!options.maxLength) options.maxLength = 79;
if (typeof options.indent !== 'number') options.indent = 1;
if (typeof options.linesBefore !== 'number') options.linesBefore = 3;
if (typeof options.linesAfter !== 'number') options.linesAfter = 2;
var re = /\r?\n|\r|\0/g;
var lineStarts = [ 0 ];
var lineEnds = [];
var match;
var foundLineNo = -1;
while ((match = re.exec(mark.buffer))) {
lineEnds.push(match.index);
lineStarts.push(match.index + match[0].length);
if (mark.position <= match.index && foundLineNo < 0) {
foundLineNo = lineStarts.length - 2;
}
}
if (foundLineNo < 0) foundLineNo = lineStarts.length - 1;
var result = '', i, line;
var lineNoLength = Math.min(mark.line + options.linesAfter, lineEnds.length).toString().length;
var maxLineLength = options.maxLength - (options.indent + lineNoLength + 3);
for (i = 1; i <= options.linesBefore; i++) {
if (foundLineNo - i < 0) break;
line = getLine(
mark.buffer,
lineStarts[foundLineNo - i],
lineEnds[foundLineNo - i],
mark.position - (lineStarts[foundLineNo] - lineStarts[foundLineNo - i]),
maxLineLength
);
result = common.repeat(' ', options.indent) + padStart((mark.line - i + 1).toString(), lineNoLength) +
' | ' + line.str + '\n' + result;
}
line = getLine(mark.buffer, lineStarts[foundLineNo], lineEnds[foundLineNo], mark.position, maxLineLength);
result += common.repeat(' ', options.indent) + padStart((mark.line + 1).toString(), lineNoLength) +
' | ' + line.str + '\n';
result += common.repeat('-', options.indent + lineNoLength + 3 + line.pos) + '^' + '\n';
for (i = 1; i <= options.linesAfter; i++) {
if (foundLineNo + i >= lineEnds.length) break;
line = getLine(
mark.buffer,
lineStarts[foundLineNo + i],
lineEnds[foundLineNo + i],
mark.position - (lineStarts[foundLineNo] - lineStarts[foundLineNo + i]),
maxLineLength
);
result += common.repeat(' ', options.indent) + padStart((mark.line + i + 1).toString(), lineNoLength) +
' | ' + line.str + '\n';
}
return result.replace(/\n$/, '');
}
module.exports = makeSnippet;