59 lines
1.8 KiB
TypeScript
59 lines
1.8 KiB
TypeScript
const range: number = 2
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export function generateCodeFrame(
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source: string,
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start = 0,
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end = source.length
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): string {
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// Split the content into individual lines but capture the newline sequence
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// that separated each line. This is important because the actual sequence is
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// needed to properly take into account the full line length for offset
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// comparison
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let lines = source.split(/(\r?\n)/)
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// Separate the lines and newline sequences into separate arrays for easier referencing
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const newlineSequences = lines.filter((_, idx) => idx % 2 === 1)
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lines = lines.filter((_, idx) => idx % 2 === 0)
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let count = 0
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const res: string[] = []
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for (let i = 0; i < lines.length; i++) {
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count +=
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lines[i].length +
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((newlineSequences[i] && newlineSequences[i].length) || 0)
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if (count >= start) {
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for (let j = i - range; j <= i + range || end > count; j++) {
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if (j < 0 || j >= lines.length) continue
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const line = j + 1
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res.push(
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`${line}${' '.repeat(Math.max(3 - String(line).length, 0))}| ${
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lines[j]
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}`
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)
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const lineLength = lines[j].length
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const newLineSeqLength =
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(newlineSequences[j] && newlineSequences[j].length) || 0
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if (j === i) {
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// push underline
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const pad = start - (count - (lineLength + newLineSeqLength))
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const length = Math.max(
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1,
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end > count ? lineLength - pad : end - start
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)
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res.push(` | ` + ' '.repeat(pad) + '^'.repeat(length))
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} else if (j > i) {
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if (end > count) {
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const length = Math.max(Math.min(end - count, lineLength), 1)
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res.push(` | ` + '^'.repeat(length))
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}
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count += lineLength + newLineSeqLength
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}
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}
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break
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}
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}
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return res.join('\n')
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}
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