add fallback isvalid

Author: stevengj

src/StringViews.jl

@@ -67,6 +67,7 @@ Base.typemin(::Type{StringView{Vector{UInt8}}}) = StringView(Vector{UInt8}(undef
 Base.typemin(::T) where {T<:StringView} = typemin(T)
 
 Base.isvalid(s::DenseStringView) = ccall(:u8_isvalid, Int32, (Ptr{UInt8}, Int), s, sizeof(s)) ≠ 0
+Base.isvalid(s::StringView) = all(isvalid, s)
 Base.isvalid(::Type{String}, s::StringView) = isvalid(s)
 
 function Base.isascii(s::StringView)

test/runtests.jl

@@ -3,6 +3,7 @@ using StringViews, Test
 b = Vector{UInt8}("foobar")
 s = StringView(b)
 abc = StringView(0x61:0x63)
+invalid = StringView([0x8b, 0x52, 0x9b, 0x8d])
 
 @testset "Construction/conversion" begin
     @test StringView(s) === s
@@ -41,6 +42,11 @@ abc = StringView(0x61:0x63)
 
     @test Base.print_to_string(s) == "foobar"
     @test Base.print_to_string(abc) == "abc"
+
+    @test isvalid(s)
+    @test isvalid(abc)
+    @test !isvalid(invalid)
+    @test !invoke(isvalid, Tuple{StringView}, invalid)
 end
 
 @testset "regular expressions" begin