bytes: make search linear and splits consistent

lib/bytes/tokenize_test.ww

@@ -4,6 +4,7 @@ package bytes_test;
 
 import bytes;
 import os;
+import test;
 
 // ref/hare/bytes/tokenize.ha:258. Hare's @test fn tokenize / rtokenize
 // drives the iterator through an expected-token sequence and asserts
@@ -286,6 +287,15 @@ fn expect_tok(toks: [][]u8, i: i32, want: []u8) void = {
 	expect_tok(t6, 1, d[3:5]);
 	expect_tok(t6, 2, d[6:8]);
 	os.free(t6.ptr: *void, (t6.cap: u64) * 24u64);
+
+	let t7: [][]u8 = bytes.splitn(b[0:5], zd[0:1], 0);
+	assert(!(t7.len != 0 || t7.cap != 0));
+};
+
+@test fn splitn_negative_aborts() void = {
+	test.expectabort();
+	let in: [1]u8; let delim: [1]u8; delim[0] = 1u8;
+	bytes.splitn(in[0:1], delim[0:1], -1);
 };
 
 @test fn rsplitn_cases() void = {
@@ -307,17 +317,15 @@ fn expect_tok(toks: [][]u8, i: i32, want: []u8) void = {
 	expect_tok(t1, 3, a[18:22]);
 	os.free(t1.ptr: *void, (t1.cap: u64) * 24u64);
 
-	// n > token count — done short-circuit returns the toks in
-	// reverse-iteration order (last token first). Mirrors Hare's
-	// behavior at ref/hare/bytes/tokenize.ha:196-199 where the
-	// reverse-step is gated behind the n-1 loop completion.
+	// n > token count still returns input order. The result order must not
+	// change merely because the limit exceeds the number of tokens.
 	let b: [5]u8; b[0] = 1u8; b[1] = 0u8; b[2] = 2u8; b[3] = 0u8; b[4] = 3u8;
 	let zd: [1]u8; zd[0] = 0u8;
 	let t2: [][]u8 = bytes.rsplitn(b[0:5], zd[0:1], 10);
 	assert(!(t2.len != 3));
-	expect_tok(t2, 0, b[4:5]);
+	expect_tok(t2, 0, b[0:1]);
 	expect_tok(t2, 1, b[2:3]);
-	expect_tok(t2, 2, b[0:1]);
+	expect_tok(t2, 2, b[4:5]);
 	os.free(t2.ptr: *void, (t2.cap: u64) * 24u64);
 
 	// n == 1 — single slot holding the whole input as remainder.
@@ -336,6 +344,15 @@ fn expect_tok(toks: [][]u8, i: i32, want: []u8) void = {
 	assert(!(t4.len != 1));
 	expect_tok(t4, 0, c[0:3]);
 	os.free(t4.ptr: *void, (t4.cap: u64) * 24u64);
+
+	let t5: [][]u8 = bytes.rsplitn(b[0:5], zd[0:1], 0);
+	assert(!(t5.len != 0 || t5.cap != 0));
+};
+
+@test fn rsplitn_negative_aborts() void = {
+	test.expectabort();
+	let in: [1]u8; let delim: [1]u8; delim[0] = 1u8;
+	bytes.rsplitn(in[0:1], delim[0:1], -1);
 };
 
 @test fn split_cases() void = {