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const Limited = @This();
const std = @import("../../std.zig");
const Reader = std.Io.Reader;
const Writer = std.Io.Writer;
const Limit = std.Io.Limit;
unlimited: *Reader,
remaining: Limit,
interface: Reader,
pub fn init(reader: *Reader, limit: Limit, buffer: []u8) Limited {
return .{
.unlimited = reader,
.remaining = limit,
.interface = .{
.vtable = &.{
.stream = stream,
.discard = discard,
},
.buffer = buffer,
.seek = 0,
.end = 0,
},
};
}
fn stream(r: *Reader, w: *Writer, limit: Limit) Reader.StreamError!usize {
const l: *Limited = @fieldParentPtr("interface", r);
if (l.remaining == .nothing) return error.EndOfStream;
const combined_limit = limit.min(l.remaining);
const n = try l.unlimited.stream(w, combined_limit);
l.remaining = l.remaining.subtract(n).?;
return n;
}
test stream {
var orig_buf: [10]u8 = undefined;
@memcpy(&orig_buf, "test bytes");
var fixed: std.Io.Reader = .fixed(&orig_buf);
var limit_buf: [1]u8 = undefined;
var limited: std.Io.Reader.Limited = .init(&fixed, @enumFromInt(4), &limit_buf);
var result_buf: [10]u8 = undefined;
var fixed_writer: std.Io.Writer = .fixed(&result_buf);
const streamed = try limited.interface.stream(&fixed_writer, @enumFromInt(7));
try std.testing.expect(streamed == 4);
try std.testing.expectEqualStrings("test", result_buf[0..streamed]);
}
fn discard(r: *Reader, limit: Limit) Reader.Error!usize {
const l: *Limited = @fieldParentPtr("interface", r);
if (l.remaining == .nothing) return error.EndOfStream;
const combined_limit = limit.min(l.remaining);
const n = try l.unlimited.discard(combined_limit);
l.remaining = l.remaining.subtract(n).?;
return n;
}
test "end of stream, read, hit limit exactly" {
var f: Reader = .fixed("i'm dying");
var l = f.limited(.limited(4), &.{});
const r = &l.interface;
var buf: [2]u8 = undefined;
try r.readSliceAll(&buf);
try r.readSliceAll(&buf);
try std.testing.expectError(error.EndOfStream, l.interface.readSliceAll(&buf));
}
test "end of stream, read, hit limit after partial read" {
var f: Reader = .fixed("i'm dying");
var l = f.limited(.limited(5), &.{});
const r = &l.interface;
var buf: [2]u8 = undefined;
try r.readSliceAll(&buf);
try r.readSliceAll(&buf);
try std.testing.expectError(error.EndOfStream, l.interface.readSliceAll(&buf));
}
test "end of stream, discard, hit limit exactly" {
var f: Reader = .fixed("i'm dying");
var l = f.limited(.limited(4), &.{});
const r = &l.interface;
try r.discardAll(2);
try r.discardAll(2);
try std.testing.expectError(error.EndOfStream, l.interface.discardAll(2));
}
test "end of stream, discard, hit limit after partial read" {
var f: Reader = .fixed("i'm dying");
var l = f.limited(.limited(5), &.{});
const r = &l.interface;
try r.discardAll(2);
try r.discardAll(2);
try std.testing.expectError(error.EndOfStream, l.interface.discardAll(2));
}
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