Method prevOffset

src/utils/Cursor.ts:1478–1485

(offset: number)

  }

  prevOffset(offset: number): number {
    if (offset <= 0) return 0

    return this.withCache(`prev:${offset}`, () => {
      const boundaries = this.getGraphemeBoundaries()
      return this.binarySearchBoundary(boundaries, offset, false)
    })
  }

  /**
   * Snap an arbitrary code-unit offset to the start of the containing grapheme.