Filemedium importancesource

tabstops.ts

ink/tabstops.ts

47
Lines
1113
Bytes
1
Exports
2
Imports
10
Keywords

What this is

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Beginner explanation

This file is one piece of the larger system. Its name, directory, imports, and exports show where it fits. Start by reading the exports and related files first.

How it is used

Start from the exports list and related files. Those are the easiest clues for where this file fits into the system.

Expert explanation

Architecturally, this file intersects with ui-flow. It contains 47 lines, 2 detected imports, and 1 detected exports.

Important relationships

Detected exports

  • expandTabs

Keywords

columnresultparttexttokenstringwidthintervaltokenizertokenselse

Detected imports

  • ./stringWidth.js
  • ./termio/tokenize.js

Source notes

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Full source

// Tab expansion, inspired by Ghostty's Tabstops.zig
// Uses 8-column intervals (POSIX default, hardcoded in terminals like Ghostty)

import { stringWidth } from './stringWidth.js'
import { createTokenizer } from './termio/tokenize.js'

const DEFAULT_TAB_INTERVAL = 8

export function expandTabs(
  text: string,
  interval = DEFAULT_TAB_INTERVAL,
): string {
  if (!text.includes('\t')) {
    return text
  }

  const tokenizer = createTokenizer()
  const tokens = tokenizer.feed(text)
  tokens.push(...tokenizer.flush())

  let result = ''
  let column = 0

  for (const token of tokens) {
    if (token.type === 'sequence') {
      result += token.value
    } else {
      const parts = token.value.split(/(\t|\n)/)
      for (const part of parts) {
        if (part === '\t') {
          const spaces = interval - (column % interval)
          result += ' '.repeat(spaces)
          column += spaces
        } else if (part === '\n') {
          result += part
          column = 0
        } else {
          result += part
          column += stringWidth(part)
        }
      }
    }
  }

  return result
}