59 lines
1.9 KiB
Zig
59 lines
1.9 KiB
Zig
const std = @import("../std.zig");
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const io = std.io;
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const mem = std.mem;
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const assert = std.debug.assert;
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pub fn ChangeDetectionStream(comptime OutStreamType: type) type {
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return struct {
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const Self = @This();
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pub const Error = OutStreamType.Error;
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pub const OutStream = io.OutStream(*Self, Error, write);
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anything_changed: bool = false,
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out_stream: *OutStreamType,
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source_index: usize,
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source: []const u8,
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pub fn init(source: []const u8, out_stream: *OutStreamType) Self {
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return Self{
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.out_stream = out_stream,
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.source_index = 0,
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.source = source,
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};
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}
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pub fn outStream(self: *Self) OutStream {
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return .{ .context = self };
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}
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fn write(self: *Self, bytes: []const u8) Error!usize {
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if (!self.anything_changed) {
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const end = self.source_index + bytes.len;
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if (end > self.source.len) {
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self.anything_changed = true;
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} else {
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const src_slice = self.source[self.source_index..end];
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self.source_index += bytes.len;
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if (!mem.eql(u8, bytes, src_slice)) {
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self.anything_changed = true;
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}
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}
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}
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return self.out_stream.write(bytes);
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}
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pub fn changeDetected(self: *Self) bool {
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return self.anything_changed or (self.source_index != self.source.len);
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}
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};
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}
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pub fn changeDetectionStream(
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source: []const u8,
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underlying_stream: anytype,
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) ChangeDetectionStream(@TypeOf(underlying_stream).Child) {
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comptime assert(@typeInfo(@TypeOf(underlying_stream)) == .Pointer);
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return ChangeDetectionStream(@TypeOf(underlying_stream).Child).init(source, underlying_stream);
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}
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