97 lines
1.8 KiB
Go
97 lines
1.8 KiB
Go
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package event
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import (
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"strings"
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"unicode"
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)
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// ParseRange parses a Range.
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func ParseRange(src string) (*Range, string) {
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var from, to Position
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from, src = parsePosition(src)
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if from == nil {
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return nil, src
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}
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var ok bool
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if src, ok = strings.CutPrefix(src, ","); !ok {
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return &Range{From: from}, src
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}
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to, src = parsePosition(src)
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return &Range{From: from, To: to}, src
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}
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func parsePosition(src string) (Position, string) {
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var pos Position
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var offset int64
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src = strings.TrimLeftFunc(src, unicode.IsSpace)
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if src == "" {
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return nil, src
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}
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switch src[0] {
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case '.':
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src = src[1:]
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fallthrough
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case '-', '+':
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pos = Relative{}
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case '$':
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pos = End{}
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src = src[1:]
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case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
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offset, src = parseNum(src)
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pos = Absolute{offset}
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case '\'':
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if len(src) == 1 {
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return nil, src
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}
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switch src[1] {
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case '<':
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pos = VisualStart{}
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case '>':
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pos = VisualEnd{}
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default:
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return nil, src
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}
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src = src[2:]
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default:
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return nil, src
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}
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for src != "" {
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src = strings.TrimLeftFunc(src, unicode.IsSpace)
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if src == "" {
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break
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}
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sign := int64(1)
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switch src[0] {
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case '-':
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sign = -1
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fallthrough
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case '+':
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offset, src = parseNum(src[1:])
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pos = pos.add(sign * offset)
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default:
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return pos, src
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}
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}
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return pos, src
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}
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func parseNum(src string) (int64, string) {
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offset, radix, ishex := int64(0), int64(10), false
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if src, ishex = strings.CutPrefix(src, "0x"); ishex {
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radix = 16
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}
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for src != "" {
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c := src[0]
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switch {
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case '0' <= c && c <= '9':
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offset = offset*radix + int64(c-'0')
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case ('A' <= c && c <= 'F' || 'a' <= c && c <= 'f') && ishex:
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offset = offset*radix + int64(c|('a'-'A')-'a'+10)
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default:
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return offset, src
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}
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src = src[1:]
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}
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return offset, src
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}
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