Initial project import

tools/v/vlib/io/reader.v

@@ -0,0 +1,91 @@
+module io
+
+// Eof error means that we reach the end of the stream.
+pub struct Eof {
+	Error
+}
+
+// NotExpected is a generic error that means that we receave a not expected error.
+pub struct NotExpected {
+	cause string
+	code  int
+}
+
+fn (err NotExpected) msg() string {
+	return err.cause
+}
+
+fn (err NotExpected) code() int {
+	return err.code
+}
+
+// Reader represents a stream of data that can be read.
+pub interface Reader {
+	// read reads up to buf.len bytes and places
+	// them into buf.
+	// A type that implements this should return
+	// `io.Eof` on end of stream (EOF) instead of just returning 0
+mut:
+	read(mut buf []u8) !int
+}
+
+pub const read_all_len = 10 * 1024
+pub const read_all_grow_len = 1024
+
+// ReadAllConfig allows options to be passed for the behaviour
+// of read_all.
+pub struct ReadAllConfig {
+pub:
+	read_to_end_of_stream bool
+	reader                Reader
+}
+
+// read_all reads all bytes from a reader until either a 0 length read
+// or if read_to_end_of_stream is true then the end of the stream (`none`).
+pub fn read_all(config ReadAllConfig) ![]u8 {
+	mut r := config.reader
+	read_till_eof := config.read_to_end_of_stream
+
+	mut b := []u8{len: read_all_len}
+	mut read := 0
+	for {
+		new_read := r.read(mut b[read..]) or { break }
+		if new_read < 0 {
+			return error('io.read_all: reader returned a negative read count (${new_read})')
+		}
+		read += new_read
+		if !read_till_eof && new_read == 0 {
+			break
+		}
+		if b.len == read {
+			unsafe { b.grow_len(read_all_grow_len) }
+		}
+	}
+	return b[..read]
+}
+
+// read_any reads any available bytes from a reader
+// (until the reader returns a read of 0 length).
+pub fn read_any(mut r Reader) ![]u8 {
+	mut b := []u8{len: read_all_len}
+	mut read := 0
+	for {
+		new_read := r.read(mut b[read..]) or { return error('none') }
+		if new_read < 0 {
+			return error('io.read_any: reader returned a negative read count (${new_read})')
+		}
+		read += new_read
+		if new_read == 0 {
+			break
+		}
+		if b.len == read {
+			unsafe { b.grow_len(read_all_grow_len) }
+		}
+	}
+	return b[..read]
+}
+
+// RandomReader represents a stream of readable data from at a random location.
+pub interface RandomReader {
+	read_from(pos u64, mut buf []u8) !int
+}