Add bounds checking to list

Fixes #417.

.gitignore

@@ -1,3 +1,4 @@
+Manifest.toml
 deps/deps.jl
 docs/build
 docs/gh-pages

src/methods.jl

@@ -152,8 +152,15 @@ function iterate(s::RObject{S}, state) where S<:VectorListSxp
     state += 1
     (RObject(s[state]), state)
 end
-getindex(r::RObject{S}, I...) where S<:VectorListSxp = RObject(getindex(sexp(r), I...))
 
+Base.checkbounds(::Type{Bool}, r::RObject{S}, i::Integer) where S<:VectorListSxp =
+    1 <= i <= length(r)
+Base.checkbounds(r::RObject{S}, i) where S<:VectorListSxp =
+    checkbounds(Bool, r, i) ? nothing : throw(BoundsError(r, i))
+function getindex(r::RObject{S}, i::Integer) where S<:VectorListSxp
+    @boundscheck checkbounds(r, i)
+    RObject(getindex(sexp(r), i))
+end
 
 # StrSxp
 

test/basic.jl

@@ -32,6 +32,9 @@ globalEnv[:y] = RObject([4,5,6])
 @test isna(R"list(a=1, b=NA)", 1) == false
 @test isna(R"list(a=1, b=NA)", 2) == true
 
+@test R"list(1,2)"[1] isa RObject
+@test_throws BoundsError R"list(1,2)"[3]
+
 @test length(R"mtcars") == 11
 @test size(R"mtcars") == (32, 11)