include-code-files: Initial import

Author: b3

include-code-files/Makefile

@@ -0,0 +1,10 @@
+DIFF ?= diff --strip-trailing-cr -u
+
+test: sample.md include-code-files.lua
+	@pandoc --lua-filter=include-code-files.lua --to=native $< \
+	    | $(DIFF) expected.native -
+
+expected.native: sample.md include-code-files.lua
+	pandoc --lua-filter=include-code-files.lua --output $@ $<
+
+.PHONY: test

include-code-files/README.md

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+# include-code-files
+
+Filter to include code from source files.
+
+The filter is largely inspired by [pandoc-include-code](https://github.com/owickstrom/pandoc-include-code).
+
+## Usage
+
+The filter recognizes code blocks with the `include` attribute present. It
+swaps the content of the code block with contents from a file.
+
+### Including Files
+
+The simplest way to use this filter is to include an entire file:
+
+    ```{include="hello.c"}
+    ```
+
+You can still use other attributes, and classes, to control the code blocks:
+
+    ```{.c include="hello.c" numberLines}
+    ```
+
+### Ranges
+
+If you want to include a specific range of lines, use `startLine` and `endLine`:
+
+    ```{include="hello.c" startLine=35 endLine=80}
+    ```
+
+### Dedent
+
+Using the `dedent` attribute, you can have whitespaces removed on each line,
+where possible (non-whitespace character will not be removed even if they occur
+in the dedent area).
+
+    ```{include="hello.c" dedent=4}
+    ```
+
+### Line Numbers
+
+If you include the `numberLines` class in your code block, and use `include`,
+the `startFrom` attribute will be added with respect to the included code's
+location in the source file.
+
+    ```{include="hello.c" startLine=35 endLine=80 .numberLines}
+    ```
+
+## Example
+
+An HTML can be produced with this command:
+
+    pandoc --lua-filter=include-code-files.lua sample.md --output result.html
+

include-code-files/expected.native

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+[Header 1 ("inclusion",[],[]) [Str "Inclusion"]
+,CodeBlock ("",["lua","numberLines"],[]) "--- include-code-files.lua \8211 filter to include code from source files\n---\n--- Copyright: \169 2020 Bruno BEAUFILS\n--- License:   MIT \8211 see LICENSE file for details\n\n--- Dedent a line\nlocal function dedent (line, n)\n  return line:sub(1,n):gsub(\" \",\"\") .. line:sub(n+1)\nend\n\n--- Filter function for code blocks\nlocal function transclude (cb)\n  if cb.attributes.include then\n    local content = \"\"\n    local fh = io.open(cb.attributes.include)\n    if not fh then\n      io.stderr:write(\"Cannot open file \" .. cb.attributes.include .. \" | Skipping includes\\n\")\n    else\n      local number = 1\n      local start = 1\n      if cb.attributes.startLine then\n        cb.attributes.startFrom = cb.attributes.startLine\n        start = tonumber(cb.attributes.startLine)\n      end\n      for line in fh:lines (\"L\")\n      do\n        if cb.attributes.dedent then\n          line = dedent(line, cb.attributes.dedent)\n        end\n        if number >= start then\n          if not cb.attributes.endLine or number <= tonumber(cb.attributes.endLine) then\n            content = content .. line\n          end\n        end\n        number = number + 1\n      end \n      fh:close()\n    end     \n    -- remove key-value pair for used keys\n    cb.attributes.include = nil\n    cb.attributes.startLine = nil\n    cb.attributes.endLine = nil\n    cb.attributes.dedent = nil\n    -- return final code block\n    return pandoc.CodeBlock(content, cb.attr)\n  end\nend\n\nreturn {\n  { CodeBlock = transclude }\n}\n"
+,Header 1 ("ranges",[],[]) [Str "Ranges"]
+,CodeBlock ("",["lua","numberLines"],[("startFrom","7")]) "local function dedent (line, n)\n  return line:sub(1,n):gsub(\" \",\"\") .. line:sub(n+1)\nend\n"
+,Header 1 ("detent",[],[]) [Str "Detent"]
+,Para [Code ("",[],[]) "detent",Space,Str "removes",Space,Str "specified",Space,Str "number",Space,Str "of",Space,Str "whitespaces",Space,Str "(and",Space,Str "only",SoftBreak,Str "whitespaces)",Space,Str "from",Space,Str "beginning",Space,Str "of",Space,Str "each",Space,Str "line"]
+,CodeBlock ("",["lua","bash","numberLines"],[("startFrom","8")]) "return line:sub(1,n):gsub(\" \",\"\") .. line:sub(n+1)\n"
+,CodeBlock ("",["lua","numberLines"],[("startFrom","50")]) "{CodeBlock = transclude }\n"]

include-code-files/include-code-files.lua

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+--- include-code-files.lua – filter to include code from source files
+---
+--- Copyright: © 2020 Bruno BEAUFILS
+--- License:   MIT – see LICENSE file for details
+
+--- Dedent a line
+local function dedent (line, n)
+  return line:sub(1,n):gsub(" ","") .. line:sub(n+1)
+end
+
+--- Filter function for code blocks
+local function transclude (cb)
+  if cb.attributes.include then
+    local content = ""
+    local fh = io.open(cb.attributes.include)
+    if not fh then
+      io.stderr:write("Cannot open file " .. cb.attributes.include .. " | Skipping includes\n")
+    else
+      local number = 1
+      local start = 1
+      if cb.attributes.startLine then
+        cb.attributes.startFrom = cb.attributes.startLine
+        start = tonumber(cb.attributes.startLine)
+      end
+      for line in fh:lines ("L")
+      do
+        if cb.attributes.dedent then
+          line = dedent(line, cb.attributes.dedent)
+        end
+        if number >= start then
+          if not cb.attributes.endLine or number <= tonumber(cb.attributes.endLine) then
+            content = content .. line
+          end
+        end
+        number = number + 1
+      end 
+      fh:close()
+    end     
+    -- remove key-value pair for used keys
+    cb.attributes.include = nil
+    cb.attributes.startLine = nil
+    cb.attributes.endLine = nil
+    cb.attributes.dedent = nil
+    -- return final code block
+    return pandoc.CodeBlock(content, cb.attr)
+  end
+end
+
+return {
+  { CodeBlock = transclude }
+}

include-code-files/sample.md

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+---
+author: me
+title: Including Hello World
+---
+
+# Inclusion
+
+``` {include="include-code-files.lua" .lua .numberLines}
+```
+
+# Ranges
+
+``` {include="include-code-files.lua" .lua startLine=7 endLine=9 .numberLines}
+```
+
+# Detent
+
+`detent` removes specified number of whitespaces (and only
+whitespaces) from beginning of each line
+
+``` {include="include-code-files.lua" .lua startLine=8 endLine=8 dedent=4 .bash .numberLines}
+```
+
+``` {include="include-code-files.lua" .lua startLine=50 endLine=50 dedent=5 .numberLines}
+```
+