Implement #hide EOL token to filter lines after execution in markdown…

…(...).

docs/src/fileformat.md

@@ -57,10 +57,20 @@ certain lines:
 - `#src `: line exclusive to the source code and thus filtered out unconditionally.
 
 Lines *starting* or *ending* with one of these tokens are filtered out in the
-[preprocessing step](@ref Pre-processing).
+[preprocessing step](@ref Pre-processing). In addition, for markdown output, lines
+ending with `#hide` are filtered out similar to Documenter.jl.
+
+
+!!! note "Difference between `#src` and `#hide`"
+    `#src` and `#hide` are quite similar. The only difference is that `#src` lines
+    are filtered out *before* execution (if `execute=true`) and `#hide` lines
+    are filtered out *after* execution.
+
+!!! compat "Literate 2.6"
+    The `#hide` token requires at least Literate version 2.6.
 
 !!! compat "Literate 2.3"
-    Filter tokens at the end of the line requires at least Literate version 2.3.
+    Filter tokens at the *end of the line* requires at least Literate version 2.3.
 
 !!! tip
     The tokens can also be negated, for example a line starting with `#!nb` would

src/Literate.jl

@@ -421,20 +421,26 @@ function markdown(inputfile, outputdir=pwd(); config::Dict=Dict(), kwargs...)
                 write(iomd, line.second, '\n') # skip indent here
             end
         else # isa(chunk, CodeChunk)
+            iocode = IOBuffer()
             codefence = config["codefence"]::Pair
-            write(iomd, codefence.first)
+            write(iocode, codefence.first)
             # make sure the code block is finalized if we are printing to ```@example
             if chunk.continued && startswith(codefence.first, "```@example") && config["documenter"]::Bool
-                write(iomd, "; continued = true")
+                write(iocode, "; continued = true")
             end
-            write(iomd, '\n')
+            write(iocode, '\n')
             for line in chunk.lines
-                write(iomd, line, '\n')
+                # filter out trailing #hide (unless leaving it for Documenter)
+                if !(endswith(line, "#hide") && !(config["documenter"]::Bool))
+                    write(iocode, line, '\n')
+                end
             end
             if config["documenter"]::Bool && REPL.ends_with_semicolon(chunk.lines[end])
-                write(iomd, "nothing #hide\n")
+                write(iocode, "nothing #hide\n")
             end
-            write(iomd, codefence.second, '\n')
+            write(iocode, codefence.second, '\n')
+            write_code = !(all(l -> endswith(l, "#hide"), chunk.lines) && !(config["documenter"]::Bool))
+            write_code && write(iomd, seekstart(iocode))
             if config["execute"]::Bool
                 execute_markdown!(iomd, sb, join(chunk.lines, '\n'), outputdir)
             end

test/runtests.jl

@@ -236,6 +236,14 @@ content = """
     # Semicolon output supression
     1 + 1;
 
+    # Completely hidden
+    hidden = 12     #hide
+    hidden * hidden #hide
+
+    # Partially hidden
+    hidden2 = 12      #hide
+    hidden2 * hidden2
+
     #nb # A notebook cell with special metadata
     #nb %% Meta1 {"meta": "data"}
     #nb 1+1
@@ -319,6 +327,12 @@ const GITLAB_ENV = Dict(
 
             1 + 1;
 
+            hidden = 12     #hide
+            hidden * hidden #hide
+
+            hidden2 = 12      #hide
+            hidden2 * hidden2
+
             # This file was generated using Literate.jl, https://github.com/fredrikekre/Literate.jl
 
             """
@@ -528,6 +542,20 @@ end end
             nothing #hide
             ```
 
+            Completely hidden
+
+            ```@example inputfile
+            hidden = 12     #hide
+            hidden * hidden #hide
+            ```
+
+            Partially hidden
+
+            ```@example inputfile
+            hidden2 = 12      #hide
+            hidden2 * hidden2
+            ```
+
             ---
 
             *This page was generated using [Literate.jl](https://github.com/fredrikekre/Literate.jl).*
@@ -632,6 +660,7 @@ end end
             @test !occursin("```@example", markdown)
             @test !occursin("continued = true", markdown)
             @test !occursin("EditURL", markdown)
+            @test !occursin("#hide", markdown)
 
             # codefence
             Literate.markdown(inputfile, outdir, codefence = "```c" => "```")