block labels

examples/programs/yield/main.bro

@@ -174,6 +174,72 @@ loop_none_first :: func() i32 {
 	return 2
 }
 
+# --- labels: value blocks + outer-loop yield/break (milestone 20.7) -----------
+
+# A labeled value block: `yield :blk` exits the block (past a nested `if`) with a
+# value. Every path must yield.
+lblock :: func(sel i32) i32 {
+	r :: blk: {
+		base :: 10
+		if (sel == 0) {
+			yield :blk base
+		} else {
+			yield :blk base * 2
+		}
+	}
+	return r
+}
+
+# An early `yield :blk` skips the rest of the block; the value is captured before
+# the block's defer runs.
+lblock_defer :: func() i32 {
+	r :: blk: {
+		n i32 = 5
+		defer n = 999
+		if (true) yield :blk n
+		yield :blk 0
+	}
+	return r # 5, not 999
+}
+
+# A labeled block whose `{T, none}` yields resolve the result to an optional.
+lblock_optional :: func(present i32) i32 {
+	r :: blk: {
+		if (present == 0) yield :blk none
+		yield :blk 8
+	}
+	if r |v| {
+		return v
+	}
+	return -1
+}
+
+# `yield :outer v` exits an OUTER value loop from inside an inner loop.
+yield_outer :: func(target i32) i32 {
+	found :: for 0..3 |row| outer: {
+		for 0..3 |col| {
+			if (row * 3 + col == target) yield :outer (row * 10 + col)
+		}
+		yield none
+	}
+	if found |v| {
+		return v
+	}
+	return -1
+}
+
+# Plain `break :outer` exits an outer loop from an inner loop.
+break_outer :: func() i32 {
+	count i32 = 0
+	for 0..3 |a| outer: {
+		for 0..3 |b| {
+			count += 1
+			if (a == 1 and b == 1) break :outer
+		}
+	}
+	return count # 5
+}
+
 main :: func() i32 {
 	if (basic() != 42) return 101
 	if (typed() != 100) return 102
@@ -201,5 +267,14 @@ main :: func() i32 {
 	if (orelse_value(none) != 7) return 121
 	if (loop_none_first() != 0) return 122
 
+	if (lblock(0) != 10) return 123
+	if (lblock(1) != 20) return 124
+	if (lblock_defer() != 5) return 125
+	if (lblock_optional(0) != -1) return 126
+	if (lblock_optional(1) != 8) return 127
+	if (yield_outer(4) != 11) return 128
+	if (yield_outer(99) != -1) return 129
+	if (break_outer() != 5) return 130
+
 	return 42
 }