1 files changed, 104 insertions, 36 deletions

diff --git a/lib/std/Io/Reader.zig b/lib/std/Io/Reader.zig
index 6ed0230317..e2344e959e 100644
--- a/lib/std/Io/Reader.zig
+++ b/lib/std/Io/Reader.zig
@@ -481,7 +481,6 @@ pub fn readVecAll(r: *Reader, data: [][]u8) Error!void {
 /// is returned instead.
 ///
 /// See also:
-/// * `peek`
 /// * `toss`
 pub fn peek(r: *Reader, n: usize) Error![]u8 {
     try r.fill(n);
@@ -732,7 +731,7 @@ pub const DelimiterError = error{
 };
 
 /// Returns a slice of the next bytes of buffered data from the stream until
-/// `sentinel` is found, advancing the seek position.
+/// `sentinel` is found, advancing the seek position past the sentinel.
 ///
 /// Returned slice has a sentinel.
 ///
@@ -765,7 +764,7 @@ pub fn peekSentinel(r: *Reader, comptime sentinel: u8) DelimiterError![:sentinel
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
-/// `delimiter` is found, advancing the seek position.
+/// `delimiter` is found, advancing the seek position past the delimiter.
 ///
 /// Returned slice includes the delimiter as the last byte.
 ///
@@ -793,31 +792,42 @@ pub fn takeDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
 /// * `peekDelimiterExclusive`
 /// * `takeDelimiterInclusive`
 pub fn peekDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
-    const buffer = r.buffer[0..r.end];
-    const seek = r.seek;
-    if (std.mem.indexOfScalarPos(u8, buffer, seek, delimiter)) |end| {
-        @branchHint(.likely);
-        return buffer[seek .. end + 1];
+    {
+        const contents = r.buffer[0..r.end];
+        const seek = r.seek;
+        if (std.mem.findScalarPos(u8, contents, seek, delimiter)) |end| {
+            @branchHint(.likely);
+            return contents[seek .. end + 1];
+        }
     }
-    // TODO take a parameter for max search length rather than relying on buffer capacity
-    try rebase(r, r.buffer.len);
-    while (r.buffer.len - r.end != 0) {
-        const end_cap = r.buffer[r.end..];
-        var writer: Writer = .fixed(end_cap);
-        const n = r.vtable.stream(r, &writer, .limited(end_cap.len)) catch |err| switch (err) {
-            error.WriteFailed => unreachable,
-            else => |e| return e,
-        };
-        r.end += n;
-        if (std.mem.indexOfScalarPos(u8, end_cap[0..n], 0, delimiter)) |end| {
-            return r.buffer[0 .. r.end - n + end + 1];
+    while (true) {
+        const content_len = r.end - r.seek;
+        if (r.buffer.len - content_len == 0) break;
+        try fillMore(r);
+        const seek = r.seek;
+        const contents = r.buffer[0..r.end];
+        if (std.mem.findScalarPos(u8, contents, seek + content_len, delimiter)) |end| {
+            return contents[seek .. end + 1];
         }
     }
-    return error.StreamTooLong;
+    // It might or might not be end of stream. There is no more buffer space
+    // left to disambiguate. If `StreamTooLong` was added to `RebaseError` then
+    // this logic could be replaced by removing the exit condition from the
+    // above while loop. That error code would represent when `buffer` capacity
+    // is too small for an operation, replacing the current use of asserts.
+    var failing_writer = Writer.failing;
+    while (r.vtable.stream(r, &failing_writer, .limited(1))) |n| {
+        assert(n == 0);
+    } else |err| switch (err) {
+        error.WriteFailed => return error.StreamTooLong,
+        error.ReadFailed => |e| return e,
+        error.EndOfStream => |e| return e,
+    }
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
-/// `delimiter` is found, advancing the seek position up to the delimiter.
+/// `delimiter` is found, advancing the seek position up to (but not past)
+/// the delimiter.
 ///
 /// Returned slice excludes the delimiter. End-of-stream is treated equivalent
 /// to a delimiter, unless it would result in a length 0 return value, in which
@@ -831,20 +841,13 @@ pub fn peekDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
 /// Invalidates previously returned values from `peek`.
 ///
 /// See also:
+/// * `takeDelimiter`
 /// * `takeDelimiterInclusive`
 /// * `peekDelimiterExclusive`
 pub fn takeDelimiterExclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
-    const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
-        error.EndOfStream => {
-            const remaining = r.buffer[r.seek..r.end];
-            if (remaining.len == 0) return error.EndOfStream;
-            r.toss(remaining.len);
-            return remaining;
-        },
-        else => |e| return e,
-    };
+    const result = try r.peekDelimiterExclusive(delimiter);
     r.toss(result.len);
-    return result[0 .. result.len - 1];
+    return result;
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
@@ -865,7 +868,7 @@ pub fn takeDelimiterExclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
 /// * `takeDelimiterInclusive`
 /// * `takeDelimiterExclusive`
 pub fn takeDelimiter(r: *Reader, delimiter: u8) error{ ReadFailed, StreamTooLong }!?[]u8 {
-    const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
+    const inclusive = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
         error.EndOfStream => {
             const remaining = r.buffer[r.seek..r.end];
             if (remaining.len == 0) return null;
@@ -874,8 +877,8 @@ pub fn takeDelimiter(r: *Reader, delimiter: u8) error{ ReadFailed, StreamTooLong
         },
         else => |e| return e,
     };
-    r.toss(result.len + 1);
-    return result[0 .. result.len - 1];
+    r.toss(inclusive.len);
+    return inclusive[0 .. inclusive.len - 1];
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
@@ -1402,6 +1405,9 @@ test peekSentinel {
     var r: Reader = .fixed("ab\nc");
     try testing.expectEqualStrings("ab", try r.peekSentinel('\n'));
     try testing.expectEqualStrings("ab", try r.peekSentinel('\n'));
+    r.toss(3);
+    try testing.expectError(error.EndOfStream, r.peekSentinel('\n'));
+    try testing.expectEqualStrings("c", try r.peek(1));
 }
 
 test takeDelimiterInclusive {
@@ -1416,22 +1422,52 @@ test peekDelimiterInclusive {
     try testing.expectEqualStrings("ab\n", try r.peekDelimiterInclusive('\n'));
     r.toss(3);
     try testing.expectError(error.EndOfStream, r.peekDelimiterInclusive('\n'));
+    try testing.expectEqualStrings("c", try r.peek(1));
 }
 
 test takeDelimiterExclusive {
     var r: Reader = .fixed("ab\nc");
+
     try testing.expectEqualStrings("ab", try r.takeDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("", try r.takeDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("", try r.takeDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("\n", try r.take(1));
+
     try testing.expectEqualStrings("c", try r.takeDelimiterExclusive('\n'));
     try testing.expectError(error.EndOfStream, r.takeDelimiterExclusive('\n'));
 }
 
 test peekDelimiterExclusive {
     var r: Reader = .fixed("ab\nc");
+
     try testing.expectEqualStrings("ab", try r.peekDelimiterExclusive('\n'));
     try testing.expectEqualStrings("ab", try r.peekDelimiterExclusive('\n'));
-    r.toss(3);
+    r.toss(2);
+    try testing.expectEqualStrings("", try r.peekDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("\n", try r.take(1));
+
     try testing.expectEqualStrings("c", try r.peekDelimiterExclusive('\n'));
     try testing.expectEqualStrings("c", try r.peekDelimiterExclusive('\n'));
+    r.toss(1);
+    try testing.expectError(error.EndOfStream, r.peekDelimiterExclusive('\n'));
+}
+
+test takeDelimiter {
+    var r: Reader = .fixed("ab\nc\n\nd");
+    try testing.expectEqualStrings("ab", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("c", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("d", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
+
+    r = .fixed("ab\nc\n\nd\n"); // one trailing newline does not affect behavior
+    try testing.expectEqualStrings("ab", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("c", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("d", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
 }
 
 test streamDelimiter {
@@ -1601,6 +1637,18 @@ test "readSliceShort with smaller buffer than Reader" {
     try testing.expectEqualStrings(str, &buf);
 }
 
+test "readSliceShort with indirect reader" {
+    var r: Reader = .fixed("HelloFren");
+    var ri_buf: [3]u8 = undefined;
+    var ri: std.testing.ReaderIndirect = .init(&r, &ri_buf);
+    var buf: [5]u8 = undefined;
+    try testing.expectEqual(5, try ri.interface.readSliceShort(&buf));
+    try testing.expectEqualStrings("Hello", buf[0..5]);
+    try testing.expectEqual(4, try ri.interface.readSliceShort(&buf));
+    try testing.expectEqualStrings("Fren", buf[0..4]);
+    try testing.expectEqual(0, try ri.interface.readSliceShort(&buf));
+}
+
 test readVec {
     var r: Reader = .fixed(std.ascii.letters);
     var flat_buffer: [52]u8 = undefined;
@@ -1701,6 +1749,26 @@ test "takeDelimiterInclusive when it rebases" {
     }
 }
 
+test "takeDelimiterInclusive on an indirect reader when it rebases" {
+    const written_line = "ABCDEFGHIJKLMNOPQRSTUVWXYZ\n";
+    var buffer: [128]u8 = undefined;
+    var tr: std.testing.Reader = .init(&buffer, &.{
+        .{ .buffer = written_line[0..4] },
+        .{ .buffer = written_line[4..] },
+        .{ .buffer = written_line },
+        .{ .buffer = written_line },
+        .{ .buffer = written_line },
+        .{ .buffer = written_line },
+        .{ .buffer = written_line },
+    });
+    var indirect_buffer: [128]u8 = undefined;
+    var tri: std.testing.ReaderIndirect = .init(&tr.interface, &indirect_buffer);
+    const r = &tri.interface;
+    for (0..6) |_| {
+        try std.testing.expectEqualStrings(written_line, try r.takeDelimiterInclusive('\n'));
+    }
+}
+
 test "takeStruct and peekStruct packed" {
     var r: Reader = .fixed(&.{ 0b11110000, 0b00110011 });
     const S = packed struct(u16) { a: u2, b: u6, c: u7, d: u1 };