58 lines
1.4 KiB
V
58 lines
1.4 KiB
V
import io
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struct StringReader {
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text string
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mut:
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place int
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}
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fn imin(a int, b int) int {
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return if a < b { a } else { b }
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}
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fn (mut s StringReader) read(mut buf []byte) ?int {
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$if debug {
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eprintln('>>>> StringReader.read output buf.len: $buf.len')
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}
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if s.place > s.text.len + 1 {
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return none
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}
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mut howmany := imin(buf.len, s.text.len - s.place)
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xxx := s.text[s.place..s.place + howmany].bytes()
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read := copy(buf, xxx)
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s.place += read
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return read
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}
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fn read_from_string(text string, capacity int) []byte {
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mut str := StringReader{
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text: text
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}
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mut stream := io.new_buffered_reader(reader: io.make_reader(str), cap: capacity)
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//
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mut buf := []byte{len: 1}
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mut res := []byte{}
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mut i := 0
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for {
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z := stream.read(mut buf) or { break }
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res << buf
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$if debug {
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println('capacity: $capacity, i: $i, buf: $buf | z: $z')
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}
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i++
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}
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return res
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}
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pub fn test_reading_from_a_string() {
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for capacity in 1 .. 1000 {
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assert read_from_string('a', capacity) == [byte(`a`)]
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assert read_from_string('ab', capacity) == [byte(`a`), `b`]
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assert read_from_string('abc', capacity) == [byte(`a`), `b`, `c`]
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assert read_from_string('abcde', capacity) == [byte(`a`), `b`, `c`, `d`, `e`]
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large_string_bytes := []byte{len: 1000, init: `x`}
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large_string := large_string_bytes.bytestr()
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assert read_from_string(large_string, capacity) == large_string_bytes
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}
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}
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