Add ability to filter potential demo cards (#149)

src/generate.jl

@@ -46,6 +46,8 @@ Processing pipeline:
 * `credit::Bool`: `true` to show a "This page is generated by ..." info. By default it's `true`.
 * `throw_error::Bool`: `true` to throw an error when the julia demo build fails; otherwise it will
   continue the build with warnings.
+* `filter_function::Function`: the function is passed each potential `DemoCard`, and the
+  card is excluded if the function returns false. By default, all potential cards are included.
 
 # Examples
 
@@ -92,7 +94,8 @@ function makedemos(source::String, templates::Union{Dict, Nothing} = nothing;
                    branch::String = "gh-pages",
                    edit_branch::String = "master",
                    credit = true,
-                   throw_error = false)
+                   throw_error = false,
+                   filter_function = x -> true)
 
     if !(basename(pwd()) == "docs" || basename(root) == "docs" || root == preview_build_dir())
         # special cases that warnings are not printed:
@@ -110,7 +113,7 @@ function makedemos(source::String, templates::Union{Dict, Nothing} = nothing;
         startswith(source, root) || throw(ArgumentError("invalid demo page source $page_root"))
     end
 
-    page = DemoPage(page_root)
+    page = DemoPage(page_root, filter_function)
 
     relative_root = basename(page)
 

src/types/page.jl

@@ -105,7 +105,7 @@ end
 
 basename(page::DemoPage) = basename(page.root)
 
-function DemoPage(root::String)::DemoPage
+function DemoPage(root::String, filter_func=x -> true)::DemoPage
     root = replace(root, r"[/\\]" => Base.Filesystem.path_separator) # windows compatibility
     isdir(root) || throw(ArgumentError("page root does not exist: $(root)"))
     root = rstrip(root, '/') # otherwise basename(root) will returns `""`
@@ -133,7 +133,7 @@ function DemoPage(root::String)::DemoPage
     config = parse(Val(:Markdown), template_file)
     config = merge(json_config, config) # template has higher priority over config file
 
-    sections = filter(map(DemoSection, section_paths)) do sec
+    sections = filter(map(p -> DemoSection(p, filter_func), section_paths)) do sec
         empty_section = isempty(sec.cards) && isempty(sec.subsections)
         if empty_section
             @warn "Empty section detected, remove from the demo page tree." section=relpath(sec.root, root)

src/types/section.jl

@@ -88,7 +88,7 @@ end
 
 basename(sec::DemoSection) = basename(sec.root)
 
-function DemoSection(root::String)::DemoSection
+function DemoSection(root::String, filter_func=x -> true)::DemoSection
     root = replace(root, r"[/\\]" => Base.Filesystem.path_separator) # windows compatibility
     isdir(root) || throw(ArgumentError("section root should be a valid dir, instead it's $(root)"))
 
@@ -108,14 +108,14 @@ function DemoSection(root::String)::DemoSection
     # throw warnings for it.
     cards = map(democard, card_paths)
     unmatches = filter(cards) do x
-        x isa UnmatchedCard
+        x isa UnmatchedCard || !filter_func(x)
     end
     if !isempty(unmatches)
         msg = join(map(basename, unmatches), "\", \"")
         @warn "skip unmatched file: \"$msg\"" section_dir=root
     end
     cards = filter!(cards) do x
-        !(x isa UnmatchedCard)
+        !(x isa UnmatchedCard || !filter_func(x))
     end
 
     section = DemoSection(root,