91 lines
1.9 KiB
V
91 lines
1.9 KiB
V
module utf8
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struct Utf8State {
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mut:
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index int
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subindex int
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failed bool
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}
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// validate_str reports if str consists of valid UTF-8 runes
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pub fn validate_str(str string) bool {
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return validate(str.str, str.len)
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}
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// validate reports if data consists of valid UTF-8 runes
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pub fn validate(data &u8, len int) bool {
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mut state := Utf8State{}
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for i := 0; i < len; i++ {
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s := unsafe { data[i] }
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if s == 0 {
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break
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}
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state.next_state(s)
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if state.failed {
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return false
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}
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}
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return !state.failed && state.subindex <= 0
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}
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fn (mut s Utf8State) seq(r0 bool, r1 bool, is_tail bool) bool {
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if s.subindex == 0 || (s.index > 1 && s.subindex == 1) || (s.index >= 6 && s.subindex == 2) {
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if (s.subindex == 0 && r0) || (s.subindex == 1 && r1) || (s.subindex == 2 && is_tail) {
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s.subindex++
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return true
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}
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} else {
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s.failed = true
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if is_tail {
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s.index = 0
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s.subindex = 0
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s.failed = false
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}
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return true
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}
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s.index++
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s.subindex = 0
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return false
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}
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fn (mut s Utf8State) next_state(c u8) {
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// sequence 1
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if s.index == 0 {
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if (c >= 0x00 + 1 && c <= 0x7F) || c == 0x00 {
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return
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}
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s.index++
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s.subindex = 0
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}
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is_tail := c >= 0x80 && c <= 0xBF
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// sequence 2
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if s.index == 1 && s.seq(c >= 0xC2 && c <= 0xDF, false, is_tail) {
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return
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}
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// sequence 3
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if s.index == 2 && s.seq(c == 0xE0, c >= 0xA0 && c <= 0xBF, is_tail) {
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return
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}
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if s.index == 3 && s.seq(c >= 0xE1 && c <= 0xEC, c >= 0x80 && c <= 0xBF, is_tail) {
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return
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}
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if s.index == 4 && s.seq(c == 0xED, c >= 0x80 && c <= 0x9F, is_tail) {
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return
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}
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if s.index == 5 && s.seq(c >= 0xEE && c <= 0xEF, c >= 0x80 && c <= 0xBF, is_tail) {
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return
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}
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// sequence 4
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if s.index == 6 && s.seq(c == 0xF0, c >= 0x90 && c <= 0xBF, is_tail) {
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return
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}
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if s.index == 7 && s.seq(c >= 0xF1 && c <= 0xF3, c >= 0x80 && c <= 0xBF, is_tail) {
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return
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}
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if s.index == 8 && s.seq(c == 0xF4, c >= 0x80 && c <= 0x8F, is_tail) {
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return
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}
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// we should never reach here
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s.failed = true
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}
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