add multiline tab editing

closes antonmedv#97

codejar.ts

@@ -237,7 +237,8 @@ export function CodeJar(editor: HTMLElement, highlight: (e: HTMLElement, pos?: P
  const text = toString()
  const before = text.slice(0, start)
  const after = text.slice(end)
- return {before, after}
+ const within = text.slice(start, end)
+ return {before, after, within}
  }
 
  function handleNewLine(event: KeyboardEvent) {
@@ -303,25 +304,31 @@ export function CodeJar(editor: HTMLElement, highlight: (e: HTMLElement, pos?: P
  }
 
  function handleTabCharacters(event: KeyboardEvent) {
- if (event.key === 'Tab') {
- event.preventDefault()
- if (event.shiftKey) {
- const {before} = aroundCursor()
- const [padding, start] = findPadding(before)
- if (padding.length > 0) {
- const pos = save()
- // Remove full length tab or just remaining padding
- const len = Math.min(options.tab.length, padding.length)
- restore({start, end: start + len})
- insert('') // deletes the selection
- pos.start -= len
- pos.end -= len
- restore(pos)
- }
- } else {
- insert(options.tab)
- }
+ if (event.key !== 'Tab') return
+ event.preventDefault()
+ const pos = save()
+ if (!event.shiftKey && pos.start === pos.end) {
+ insert(options.tab)
+ return
  }
+
+ let {before, after, within} = aroundCursor()
+
+ const i = Math.max(0, before.lastIndexOf('\n'))
+ const j = Math.min(Infinity, after.indexOf('\n'))
+ within = before.slice(i) + within + after.slice(0, j)
+ before = before.slice(0, i)
+ after = after.slice(j)
+
+ const replaced = event.shiftKey
+ ? within.replace(new RegExp(`^[\\t ]{0,${options.tab.length}}`, 'gm'), '')
+ : within.replace(/^/gm, options.tab)
+ editor.textContent = before + replaced + after
+
+ const len = replaced.length - within.length
+ pos.start += len
+ pos.end += len
+ restore(pos)
  }
 
  function handleUndoRedo(event: KeyboardEvent) {