Add minlevel option

Closes: #8

Makefile

@@ -19,7 +19,7 @@ endif
 # Ensure that the `test` target is run each time it's called.
 .PHONY: test
 test: test-default test-no-citeproc test-refs-name test-section-level \
-	test-unnumbered-section
+	test-unnumbered-section test-minlevel
 
 # Test that running the filter on the sample input document yields
 # the expected output.
@@ -32,7 +32,7 @@ test-%: $(FILTER_FILE) test/input.md test/input-unnumbered-section.md \
 # Update files that contain the expected test output
 .PHONY: update-expected update-%
 update-expected: update-default update-no-citeproc update-refs-name \
-	update-section-level update-unnumbered-section
+	update-section-level update-unnumbered-section update-minlevel
 update-%: $(FILTER_FILE) \
 		test/input.md \
 		test/input-unnumbered-section.md \

README.md

@@ -101,6 +101,11 @@ nested below the `section-bibliographies` value:
     (so if it occurs at the end of a level-1 section, it will
     receive a level-2 header, and so on).
 
+`section-bibiliograpies.minlevel`
+:   Sets the minimum section level at which bibliographies will be
+    produced. The default is 1. Higher numbers will leave
+    top-level sections unprocessed.
+
 `section-bibliographies.bibliography`
 :   Behaves like `bibliography` in the context of this filter.
     This variable exists because pandoc automatically invokes

_extensions/section-bibliographies/section-bibliographies.lua

@@ -146,6 +146,10 @@ local function create_section_bibliography (meta, opts)
     if not header or not suffix or opts.level < header.level then
       -- Don't do anything for deeply-nested sections.
       return div, false
+    elseif header.level < opts.minlevel then
+      -- Don't process sections above minlevel
+      div.content = div.content:map(process_div)
+      return div, false
     elseif opts.level == header.level then
       div.content = section_citeproc(div.content, suffix)
       return adjust_refs_components(div), false
@@ -199,12 +203,20 @@ local function get_options (meta)
   opts.bibliography = opts.bibliography
     or meta['section-bibs-bibliography']
     or meta['bibliography']
-  opts.level = opts.level
+  opts.level = tonumber(opts.level)
     or tonumber(meta['section-bibs-level'])
     or 1
+  opts.minlevel = tonumber(opts.minlevel)
+    or 1
   opts.references = opts.references
     or meta['references']
 
+  -- sanity check
+  if opts.level < opts.minlevel then
+    warn('level cannot be smaller than minlevel, setting minlevel = level')
+    opts.minlevel = opts.level
+  end
+
   return opts
 end