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const std = @import("../std.zig");
const io = std.io;
const mem = std.mem;
const assert = std.debug.assert;
/// Used to detect if the data written to a stream differs from a source buffer
pub fn ChangeDetectionStream(comptime WriterType: type) type {
return struct {
const Self = @This();
pub const Error = WriterType.Error;
pub const Writer = io.Writer(*Self, Error, write);
anything_changed: bool,
underlying_writer: WriterType,
source_index: usize,
source: []const u8,
pub fn writer(self: *Self) Writer {
return .{ .context = self };
}
fn write(self: *Self, bytes: []const u8) Error!usize {
if (!self.anything_changed) {
const end = self.source_index + bytes.len;
if (end > self.source.len) {
self.anything_changed = true;
} else {
const src_slice = self.source[self.source_index..end];
self.source_index += bytes.len;
if (!mem.eql(u8, bytes, src_slice)) {
self.anything_changed = true;
}
}
}
return self.underlying_writer.write(bytes);
}
pub fn changeDetected(self: *Self) bool {
return self.anything_changed or (self.source_index != self.source.len);
}
};
}
pub fn changeDetectionStream(
source: []const u8,
underlying_writer: anytype,
) ChangeDetectionStream(@TypeOf(underlying_writer)) {
return ChangeDetectionStream(@TypeOf(underlying_writer)){
.anything_changed = false,
.underlying_writer = underlying_writer,
.source_index = 0,
.source = source,
};
}
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