Complete Iterator interface implementation

Ref: https://docs.julialang.org/en/v1/manual/interfaces/#man-interface-iteration

src/IR/Iterators.jl

@@ -7,6 +7,9 @@ struct BlockIterator
     region::Region
 end
 
+Base.IteratorSize(::Core.Type{BlockIterator}) = Base.SizeUnknown()
+Base.eltype(::BlockIterator) = Block
+
 function Base.iterate(it::BlockIterator)
     reg = it.region
     raw_block = API.mlirRegionGetFirstBlock(reg)
@@ -37,6 +40,9 @@ struct RegionIterator
     op::Operation
 end
 
+Base.eltype(::RegionIterator) = Region
+Base.length(it::RegionIterator) = nregions(it.op)
+
 function Base.iterate(it::RegionIterator)
     raw_region = API.mlirOperationGetFirstRegion(it.op)
     if mlirIsNull(raw_region)
@@ -66,6 +72,9 @@ struct OperationIterator
     block::Block
 end
 
+Base.IteratorSize(::Core.Type{OperationIterator}) = Base.SizeUnknown()
+Base.eltype(::OperationIterator) = Operation
+
 function Base.iterate(it::OperationIterator)
     raw_op = API.mlirBlockGetFirstOperation(it.block)
     if mlirIsNull(raw_op)

test/ir.jl

@@ -31,3 +31,34 @@ end
         @test_throws AssertionError IR.Module(arith.constant(; value=true, result=IR.Type(Bool)))
     end
 end
+
+@testset "Iterators" begin
+    IR.context!(IR.Context()) do
+        if LLVM.version() >= v"15"
+            IR.load_all_available_dialects()
+        end
+        IR.get_or_load_dialect!(IR.DialectHandle(:func))
+        mod = parse(IR.Module, """
+        module {
+            func.func @f() {
+                return
+            }
+        }
+        """)
+        b = IR.body(mod)
+
+        ops = collect(IR.OperationIterator(b))
+        @test ops isa Vector{Operation}
+        @test length(ops) == 1
+
+        op = only(ops)
+        regions = collect(IR.RegionIterator(op))
+        @test regions isa Vector{Region}
+        @test length(regions) == 1
+
+        region = only(regions)
+        blocks = collect(IR.BlockIterator(region))
+        @test blocks isa Vector{Block}
+        @test length(blocks) == 1
+    end
+end