add keep_comments to Literate.script to keep markdown as comments in script output

src/Literate.jl

@@ -200,9 +200,12 @@ Keyword arguments:
 - `documenter`: boolean that says if the source contains Documenter.jl specific things
   to filter out during script generation. Defaults to `true`. See the the manual
   section on [Interaction with Documenter](@ref Interaction-with-Documenter).
+- `keep_comments`: boolean that, if set to `true`, keeps markdown lines (`#'`)
+  as comments in the output script. Defaults to `false`.
 """
 function script(inputfile, outputdir; preprocess = identity, postprocess = identity,
-                name = filename(inputfile), documenter = true, kwargs...)
+                name = filename(inputfile), documenter = true,
+                keep_comments::Bool=false, kwargs...)
     # normalize paths
     inputfile = realpath(abspath(inputfile))
     mkpath(outputdir)
@@ -226,6 +229,11 @@ function script(inputfile, outputdir; preprocess = identity, postprocess = ident
                 write(ioscript, line, '\n')
             end
             write(ioscript, '\n') # add a newline between each chunk
+        elseif isa(chunk, MDChunk) && keep_comments
+            for line in chunk.lines
+                write(ioscript, "#' ", line, '\n')
+            end
+            write(ioscript, '\n') # add a newline between each chunk
         end
     end
 

test/runtests.jl

@@ -240,6 +240,13 @@ content = """
             @test occursin("name: foobar", script)
             @test !occursin("name: inputfile", script)
             @test !occursin("name: @__NAME__", script)
+
+            # keep_comments
+            Literate.script(inputfile, outdir, keep_comments = true)
+            script = read(joinpath(outdir, "inputfile.jl"), String)
+            @test occursin("#' # Example", script)
+            @test occursin("#' foo, bar", script)
+            @test occursin("#' \\int f(x) dx", script)
         end
     end
 end