hare

commit c929eb16a3d1a99d54acfc055778b30367fc2bec
parent 81f1b58d3ec9c41568677179b86052a077506ebe
Author: Sebastian <sebastian@sebsite.pw>
Date:   Tue, 17 Oct 2023 21:09:47 -0400

bufio: allow unreading more than scan.readout

Signed-off-by: Sebastian <sebastian@sebsite.pw>

Diffstat:
M
bufio/scanner.ha
 | 
15
++++++++++++---
M
bufio/scanner_test+test.ha
 | 
6
+++++-

2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/bufio/scanner.ha b/bufio/scanner.ha
@@ -271,9 +271,18 @@ fn scan_unread(scan: *scanner, buf: []u8) void = {
 	if (len(buf) == 0) {
 		return;
 	};
-	assert(len(buf) <= scan.readout);
-	scan.buffer[scan.readout - len(buf)..scan.readout] = buf;
-	scan.readout -= len(buf);
+	if (len(buf) <= scan.readout) {
+		scan.buffer[scan.readout - len(buf)..scan.readout] = buf;
+		scan.readout -= len(buf);
+	} else {
+		const n = len(buf) - scan.readout;
+		assert(n < scan.maxread - scan.pending,
+			"Attempted to unread more data than buffer has available");
+		scan.buffer[n..] = scan.buffer[..len(scan.buffer) - n];
+		scan.pending += n;
+		scan.buffer[..len(buf)] = buf;
+		scan.readout = 0;
+	};
 };
 
 // Reads a single byte from an [[io::handle]].
diff --git a/bufio/scanner_test+test.ha b/bufio/scanner_test+test.ha
@@ -158,8 +158,12 @@ use strings;
 	let l = scan_line(&scanner)! as const str;
 	assert(l == "See?");
 
+	let b = scan_rune(&scanner) as rune;
+	unreadrune(&scanner, b);
+	unreadrune(&scanner, ' ');
+	unread(&scanner, strings::toutf8("I'm"));
 	let l = scan_line(&scanner)! as const str;
-	assert(l == "Done!");
+	assert(l == "I'm Done!");
 
 	assert(scan_line(&scanner) is io::EOF);
 };