77 lines
1.9 KiB
V
77 lines
1.9 KiB
V
module io
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// Reader represents a stream of data that can be read
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pub interface Reader {
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// read reads up to buf.len bytes and places
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// them into buf.
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// A type that implements this should return
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// `none` on end of stream (EOF) instead of just returning 0
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read(mut buf []byte) ?int
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}
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// make_reader is a temp that converts a type to a reader
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// (e.g. for use in struct initialisation)
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// (this shouldnt need to be a thing but until coercion gets made better
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// it is required)
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[deprecated: 'use just `x` instead of `io.make_reader(x)`. Interfaces are now checked against all types.']
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[deprecated_after: '2021-05-27']
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pub fn make_reader(r Reader) Reader {
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return r
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}
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const (
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read_all_len = 10 * 1024
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read_all_grow_len = 1024
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)
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// ReadAllConfig allows options to be passed for the behaviour
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// of read_all
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pub struct ReadAllConfig {
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reader Reader
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read_to_end_of_stream bool
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}
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// read_all reads all bytes from a reader until either a 0 length read
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// or if read_to_end_of_stream is true then the end of the stream (`none`)
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pub fn read_all(config ReadAllConfig) ?[]byte {
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r := config.reader
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read_till_eof := config.read_to_end_of_stream
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mut b := []byte{len: io.read_all_len}
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mut read := 0
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for {
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new_read := r.read(mut b[read..]) or { break }
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read += new_read
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if !read_till_eof && read == 0 {
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break
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}
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if b.len == read {
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unsafe { b.grow_len(io.read_all_grow_len) }
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}
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}
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return b[..read]
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}
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// read_any reads any available bytes from a reader
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// (until the reader returns a read of 0 length)
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pub fn read_any(r Reader) ?[]byte {
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mut b := []byte{len: io.read_all_len}
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mut read := 0
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for {
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new_read := r.read(mut b[read..]) or { break }
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read += new_read
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if new_read == 0 {
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break
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}
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if b.len == read {
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unsafe { b.grow_len(io.read_all_grow_len) }
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}
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}
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return b[..read]
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}
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// RandomReader represents a stream of data that can be read from at a random location
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interface RandomReader {
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read_from(pos u64, mut buf []byte) ?int
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}
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