From f85c4cd79f6dc5466ecf7f760efda455655b6995 Mon Sep 17 00:00:00 2001
From: Samuel Goad <53803593+ellipse12@users.noreply.github.com>
Date: Fri, 9 Aug 2024 15:10:46 -0600
Subject: [PATCH] Update string_iterator.c3 to include extra convenience
 methods (#1327)

Update string_iterator.c3 to include extra convenience methods

Added peek: returns the next character without incrementing current
Added has_next: checks if the iterator has another element
Added get: gets the current element (the same one that was returned with the previous call to next).
---
 lib/std/core/string_iterator.c3          | 40 +++++++++++++++++++-----
 test/unit/stdlib/core/string_iterator.c3 | 35 +++++++++++++++++++++
 2 files changed, 68 insertions(+), 7 deletions(-)
 create mode 100644 test/unit/stdlib/core/string_iterator.c3

diff --git a/lib/std/core/string_iterator.c3 b/lib/std/core/string_iterator.c3
index 299e0fd4d..abd7aa4a3 100644
--- a/lib/std/core/string_iterator.c3
+++ b/lib/std/core/string_iterator.c3
@@ -13,11 +13,37 @@ fn void StringIterator.reset(&self)
 
 fn Char32! StringIterator.next(&self)
 {
-	usz len = self.utf8.len;
-	usz current = self.current;
-	if (current >= len) return IteratorResult.NO_MORE_ELEMENT?;
-	usz read = (len - current < 4 ? len - current : 4);
-	Char32 res = conv::utf8_to_char32(&self.utf8[current], &read)!;
-	self.current += read;
-	return res;
+    usz len = self.utf8.len;
+    usz current = self.current;
+    if (current >= len) return IteratorResult.NO_MORE_ELEMENT?;
+    usz read = (len - current < 4 ? len - current : 4);
+    Char32 res = conv::utf8_to_char32(&self.utf8[current], &read)!;
+    self.current += read;
+    return res;
+}
+
+fn Char32! StringIterator.peek(&self)
+{
+    usz len = self.utf8.len;
+    usz current = self.current;
+    if (current >= len) return IteratorResult.NO_MORE_ELEMENT?;
+    usz read = (len - current < 4 ? len - current : 4);
+    Char32 res = conv::utf8_to_char32(&self.utf8[current], &read)!;
+    return res;
+}
+
+fn bool StringIterator.has_next(&self)
+{
+    return self.current < self.utf8.len;
+}
+
+fn Char32! StringIterator.get(&self)
+{
+    usz len = self.utf8.len;
+    usz current = self.current;
+    usz read = (len - current < 4 ? len - current : 4);
+    usz index = current > read ? current - read : 0;
+    if (index >= len) return IteratorResult.NO_MORE_ELEMENT?;
+    Char32 res = conv::utf8_to_char32(&self.utf8[index], &read)!;
+    return res;
 }
diff --git a/test/unit/stdlib/core/string_iterator.c3 b/test/unit/stdlib/core/string_iterator.c3
new file mode 100644
index 000000000..4b9615d4d
--- /dev/null
+++ b/test/unit/stdlib/core/string_iterator.c3
@@ -0,0 +1,35 @@
+module std::core::test::string_iterator::tests @test;
+
+fn void test_at_start()
+{
+    String test = "abcd";
+    StringIterator iterator = test.iterator();
+    assert(iterator.get()! == 'a');
+    assert(iterator.peek()! == 'a');
+    iterator.next()!;
+    assert(iterator.next()! == 'b');
+    assert(iterator.has_next());
+}
+
+
+fn void test_general()
+{ 
+    String test = "åƦs1";
+    StringIterator iterator = test.iterator();
+    assert(iterator.get()! == 'å');
+    iterator.next()!;
+    assert(iterator.peek()! == 'Ʀ');
+    assert(iterator.next()! == 'Ʀ');
+    iterator.reset();
+    assert(iterator.current == 0);
+}
+
+fn void test_end()
+{
+    String test = "åƦ";
+    StringIterator iterator = test.iterator();
+    assert(@ok(iterator.next()));
+    assert(iterator.peek()! == 'Ʀ');
+    assert(@ok(iterator.next()));
+    assert(@catch(iterator.next()));
+}