Improve iteration for multiple documents in one file.

src/YAML.jl

@@ -131,6 +131,9 @@ function iterate(it::YAMLDocIterator, _ = nothing)
     return doc, nothing
 end
 
+Base.IteratorSize(::Type{YAMLDocIterator}) = Base.SizeUnknown()
+Base.IteratorEltype(::Type{YAMLDocIterator}) = Base.EltypeUnknown()
+
 """
     load_all(x::Union{AbstractString, IO}) -> YAMLDocIterator
 
@@ -161,8 +164,8 @@ load_file(filename::AbstractString, args...; kwargs...) =
 Parse the YAML file `filename`, and return corresponding YAML documents.
 """
 load_all_file(filename::AbstractString, args...; kwargs...) =
-    open(filename, "r") do input
-        load_all(input, args...; kwargs...)
+    open(filename, "r") do f
+        io = IOBuffer(read(f))
+        load_all(io, args...; kwargs...)
     end
-
 end  # module

test/runtests.jl

@@ -239,25 +239,59 @@ const encodings = [
     @test YAML.load(IOBuffer(data)) == "test"
 end
 
-@testset "multi_doc_bom" begin
-    iterable = YAML.load_all("""
+const multidoc_contents = """
 \ufeff---\r
 test: 1
 \ufeff---
 test: 2
 
 \ufeff---
 test: 3
-""")
+\ufeff---
+42
+"""
+
+@testset "multi_doc_bom" begin
+    iterable = YAML.load_all(multidoc_contents)
     (val, state) = iterate(iterable)
     @test isequal(val, Dict("test" => 1))
     (val, state) = iterate(iterable, state)
     @test isequal(val, Dict("test" => 2))
     (val, state) = iterate(iterable, state)
     @test isequal(val, Dict("test" => 3))
+    (val, state) = iterate(iterable, state)
+    @test isequal(val, 42)
     @test iterate(iterable, state) === nothing
 end
 
+@testset "multi_doc_file" begin
+    fname = tempname() # cleanup=true, file will be deleted on process exit
+    open(fname, "w") do f
+        write(f, multidoc_contents)
+    end
+    iterable = YAML.load_all_file(fname)
+    (val, state) = iterate(iterable)
+    @test isequal(val, Dict("test" => 1))
+    (val, state) = iterate(iterable, state)
+    @test isequal(val, Dict("test" => 2))
+    (val, state) = iterate(iterable, state)
+    @test isequal(val, Dict("test" => 3))
+    (val, state) = iterate(iterable, state)
+    @test isequal(val, 42)
+    @test iterate(iterable, state) === nothing
+end
+
+@testset "multi_doc_iteration_protocol" begin
+    fname = tempname() # cleanup=true, file will be deleted on process exit
+    open(fname, "w") do f
+        write(f, multidoc_contents)
+    end
+    iterable = YAML.load_all_file(fname)
+    @test Base.IteratorSize(YAML.YAMLDocIterator) == Base.SizeUnknown()
+    @test Base.IteratorEltype(YAML.YAMLDocIterator) == Base.EltypeUnknown()
+    @test length(collect(iterable)) == 4
+end
+
 # test that an OrderedDict is written in the correct order
 using OrderedCollections, DataStructures
 @test strip(YAML.yaml(OrderedDict(:c => 3, :b => 2, :a => 1))) == join(["c: 3", "b: 2", "a: 1"], "\n")