hare

commit 9761fd06e2d4cd37ea1ff6a1b7e877c2bcd39ee5
parent 13fbc8fd10abea66171d93ab308edb01e0ab6f93
Author: Sebastian <sebastian@sebsite.pw>
Date:   Tue, 22 Feb 2022 18:50:04 -0500

strings: add strcmp function

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

Diffstat:
M
stdlib.mk
 | 
2
++
A
strings/strcmp.ha
 | 
38
++++++++++++++++++++++++++++++++++++++

2 files changed, 40 insertions(+), 0 deletions(-)
diff --git a/stdlib.mk b/stdlib.mk
@@ -1620,6 +1620,7 @@ stdlib_strings_any_srcs= \
 	$(STDLIB)/strings/cstrings.ha \
 	$(STDLIB)/strings/dup.ha \
 	$(STDLIB)/strings/iter.ha \
+	$(STDLIB)/strings/strcmp.ha \
 	$(STDLIB)/strings/sub.ha \
 	$(STDLIB)/strings/suffix.ha \
 	$(STDLIB)/strings/tokenize.ha \
@@ -3488,6 +3489,7 @@ testlib_strings_any_srcs= \
 	$(STDLIB)/strings/cstrings.ha \
 	$(STDLIB)/strings/dup.ha \
 	$(STDLIB)/strings/iter.ha \
+	$(STDLIB)/strings/strcmp.ha \
 	$(STDLIB)/strings/sub.ha \
 	$(STDLIB)/strings/suffix.ha \
 	$(STDLIB)/strings/tokenize.ha \
diff --git a/strings/strcmp.ha b/strings/strcmp.ha
@@ -0,0 +1,38 @@
+// Compares two strings by their Unicode codepoint sort order. Zero is returned
+// if the strings are equal, a negative value if a is less than b, or a positive
+// value if a is greater than b.
+export fn strcmp(a: str, b: str) int = {
+	let a = iter(a), b = iter(b);
+	for (true) {
+		let ra = match (next(&a)) {
+		case void =>
+			match (next(&b)) {
+			case void =>
+				return 0;
+			case rune =>
+				return -1;
+			};
+		case let r: rune =>
+			yield r;
+		};
+		let rb = match (next(&b)) {
+		case void =>
+			return 1;
+		case let r: rune =>
+			yield r;
+		};
+		if (ra != rb) {
+			return ra: u32: int - rb: u32: int;
+		};
+	};
+	abort("unreachable");
+};
+
+@test fn strcmp() void = {
+	assert(strcmp("ABC", "ABC") == 0);
+	assert(strcmp("ABC", "AB") > 0);
+	assert(strcmp("AB", "ABC") < 0);
+	assert(strcmp("BCD", "ABC") > 0);
+	assert(strcmp("ABC", "こんにちは") < 0);
+	assert(strcmp("ABC", "abc") < 0);
+};