Add validator convenience function

src/codegen.jl

@@ -87,6 +87,32 @@ end
 
 const DefaultCodeGenContext = CodeGenContext()
 
+"""
+    generate_validator_function(name::Symbol, machine::Machine, goto=false)
+
+Generate code that, when evaluated, defines a function named `name`, which takes a
+single argument `data`, interpreted as a sequence of bytes.
+The function returns `nothing` if `data` matches `Machine`, else the index of the first
+invalid byte. If the machine reached unexpected EOF, returns `sizeof(data) + 1`.
+If `goto`, the function uses the faster but more complicated `:goto` code.
+"""
+function generate_validator_function(name::Symbol, machine::Machine, goto::Bool=false)
+    ctx = goto ? CodeGenContext(generator=:goto) : DefaultCodeGenContext
+    return quote
+        """
+            $($(name))(data)::Union{Int, Nothing}
+
+        Checks if `data`, interpreted as a bytearray, conforms to the given `Automa.Machine`.
+        Returns `nothing` if it does, else the byte index of the first invalid byte.
+        If the machine reached unexpected EOF, returns `sizeof(data) + 1`.
+        """
+        function $(name)(data)
+            $(generate_code(ctx, machine))
+            iszero(cs) ? nothing : p
+        end
+    end
+end
+
 """
     generate_code([::CodeGenContext], machine::Machine, actions=nothing)::Expr
 

test/runtests.jl

@@ -86,6 +86,7 @@ include("test17.jl")
 include("test18.jl")
 include("simd.jl")
 include("unicode.jl")
+include("validator.jl")
 
 module TestFASTA
 using Test

test/validator.jl

@@ -0,0 +1,36 @@
+module Validator
+
+import Automa
+import Automa.RegExp: @re_str
+using Test
+
+@testset "Validator" begin
+    machine = let
+        Automa.compile(re"a(bc)*|(def)|x+" | re"def" | re"x+")
+    end
+    eval(Automa.generate_validator_function(:foobar, machine, false))
+    eval(Automa.generate_validator_function(:barfoo, machine, true))
+
+    for good_data in [
+        "def"
+        "abc"
+        "abcbcbcbcbc"
+        "x"
+        "xxxxxx"
+    ]
+        @test foobar(good_data) === barfoo(good_data) === nothing
+    end
+
+    for bad_data in [
+        "",
+        "abcabc",
+        "abcbb",
+        "abcbcb",
+        "defdef",
+        "xabc"
+    ]
+        @test foobar(bad_data) === barfoo(bad_data) !== nothing
+    end
+end
+
+end # module