hare

commit 7dd938696a1871fb37571a7e3fe752c8be2280e4
parent 90e7993b3629d1334cb71f1248d3700f6eea7992
Author: Drew DeVault <sir@cmpwn.com>
Date:   Thu, 25 Feb 2021 14:09:50 -0500

strio: add strio::join

Diffstat:
M
strio/ops.ha
 | 
46
+++++++++++++++++++++++++++++++++++++++++++---

1 file changed, 43 insertions(+), 3 deletions(-)
diff --git a/strio/ops.ha b/strio/ops.ha
@@ -2,7 +2,8 @@ use io;
 use strings;
 
 // Appends zero or more strings to an [io::stream]. The stream needn't be a
-// strio stream, but it's often efficient if it is.
+// strio stream, but it's often efficient if it is. Returns the number of bytes
+// written, or an error.
 export fn concat(st: *io::stream, strs: str...) (size | io::error) = {
 	let n = 0z;
 	for (let i = 0z; i < len(strs); i += 1) {
@@ -20,7 +21,46 @@ export fn concat(st: *io::stream, strs: str...) (size | io::error) = {
 @test fn concat() void = {
 	let st = dynamic();
 	defer io::close(st);
-	concat(st, "hello");
-	concat(st, " ", "world");
+	concat(st, "hello") as size;
+	concat(st, " ", "world") as size;
 	assert(string(st) == "hello world");
 };
+
+// Joins several strings together by a delimiter and writes them to a stream.
+// The stream needn't be a strio stream, but it's often more efficient if it is.
+// Returns the number of bytes written, or an error.
+export fn join(st: *io::stream, delim: str, strs: str...) (size | io::error) = {
+	let n = 0z;
+	let delim = strings::to_utf8(delim);
+	for (let i = 0z; i < len(strs); i += 1) {
+		let q = 0z;
+		let buf = strings::to_utf8(strs[i]);
+		for (q < len(buf)) {
+			let w = io::write(st, buf[q..])?;
+			n += w;
+			q -= w;
+		};
+		if (i + 1 < len(strs)) {
+			let q = 0z;
+			for (q < len(delim)) {
+				let w = io::write(st, delim[q..])?;
+				n += w;
+				q -= w;
+			};
+		};
+	};
+	return n;
+};
+
+@test fn join() void = {
+	let st = dynamic();
+	defer io::close(st);
+	join(st, "::", "hello", "world") as size;
+	assert(string(st) == "hello::world");
+	truncate(st);
+	join(st, "::") as size;
+	assert(string(st) == "");
+	truncate(st);
+	join(st, "::", "foo") as size;
+	assert(string(st) == "foo");
+};