Function ComputePositionMap

internal/ast/positionmap.go:40–60

ComputePositionMap builds a PositionMap for the given text.

(text string)

// ComputePositionMap builds a PositionMap for the given text.
func ComputePositionMap(text string) *PositionMap {
	pm := &PositionMap{}
	delta := 0
	for i := 0; i < len(text); {
		b := text[i]
		if b < utf8.RuneSelf {
			i++
			continue
		}
		r, size := stringutil.DecodeJSStringRune(text[i:])
		utf16Size := 1
		if r >= 0x10000 {
			utf16Size = 2
		}
		delta += size - utf16Size
		pm.entries = append(pm.entries, positionMapEntry{utf8Pos: i + size, delta: delta})
		i += size
	}
	pm.asciiOnly = len(pm.entries) == 0
	return pm
}

// IsAsciiOnly returns true if the text is ASCII-only,
// meaning UTF-8 and UTF-16 offsets are identical.