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diff --git a/doc/markdown_rst.md b/doc/markdown_rst.md new file mode 100644 index 000000000..c7977f75a --- /dev/null +++ b/doc/markdown_rst.md @@ -0,0 +1,349 @@ +========================================== +Nim-flavored Markdown and reStructuredText +========================================== + +:Author: Andrey Makarov +:Version: |nimversion| + +.. default-role:: code +.. include:: rstcommon.rst +.. contents:: + +.. importdoc:: docgen.md + +Both `Markdown`:idx: (md) and `reStructuredText`:idx: (RST) are markup +languages whose goal is to typeset texts with complex structure, +formatting and references using simple plaintext representation. + +Command line usage +================== + +Usage (to convert Markdown into HTML): + + ```cmd + nim md2html markdown_rst.md + ``` + +Output: + + You're reading it! + +The `md2tex`:option: command is invoked identically to `md2html`:option:, +but outputs a ``.tex`` file instead of ``.html``. + +These tools embedded into Nim compiler; the compiler can output +the result to HTML [^html] or Latex [^latex]. + +[^html]: commands `nim doc`:cmd: for ``*.nim`` files and + `nim rst2html`:cmd: for ``*.rst`` files + +[^latex]: commands `nim doc2tex`:cmd: for ``*.nim`` and + `nim rst2tex`:cmd: for ``*.rst``. + +Full list of supported commands: + +=================== ====================== ============ ============== +command runs on... input format output format +=================== ====================== ============ ============== +`nim md2html`:cmd: standalone md files ``.md`` ``.html`` HTML +`nim md2tex`:cmd: same same ``.tex`` LaTeX +`nim rst2html`:cmd: standalone rst files ``.rst`` ``.html`` HTML +`nim rst2tex`:cmd: same same ``.tex`` LaTeX +`nim doc`:cmd: documentation comments ``.nim`` ``.html`` HTML +`nim doc2tex`:cmd: same same ``.tex`` LaTeX +`nim jsondoc`:cmd: same same ``.json`` JSON +=================== ====================== ============ ============== + + +Basic markup +============ + +If you are new to Markdown/RST please consider reading the following: + +1) [Markdown Basic Syntax] +2) a long specification of Markdown: [CommonMark Spec] +3) a short [quick introduction] to RST +4) an [RST reference]: a comprehensive cheatsheet for RST +5) a more formal 50-page [RST specification]. + +Features +-------- + +A large subset is implemented with some [limitations] and +[additional Nim-specific features]. + +Supported common RST/Markdown features: + +* body elements + + sections + + transitions + + paragraphs + + bullet lists using \+, \*, \- + + enumerated lists using arabic numerals or alphabet + characters: 1. ... 2. ... *or* a. ... b. ... *or* A. ... B. ... + + footnotes (including manually numbered, auto-numbered, auto-numbered + with label, and auto-symbol footnotes) and citations + + field lists + + option lists + + quoted literal blocks + + line blocks + + simple tables + + directives (see official documentation in [RST directives list]): + - ``image``, ``figure`` for including images and videos + - ``code`` + - ``contents`` (table of contents), ``container``, ``raw`` + - ``include`` + - admonitions: "attention", "caution", "danger", "error", "hint", + "important", "note", "tip", "warning", "admonition" + - substitution definitions: `replace` and `image` + + comments +* inline markup + + *emphasis*, **strong emphasis**, + ``inline literals``, hyperlink references (including embedded URI), + substitution references, standalone hyperlinks, + internal links (inline and outline) + + \`interpreted text\` with roles ``:literal:``, ``:strong:``, + ``emphasis``, ``:sub:``/``:subscript:``, ``:sup:``/``:superscript:`` + (see [RST roles list] for description). + + inline internal targets + +RST mode only features +---------------------- + ++ RST syntax for definition lists (that is additional indentation after + a definition line) ++ indented literal blocks starting from ``::`` + +Markdown-specific features +-------------------------- + +* Markdown tables +* Markdown code blocks. For them the same additional arguments as for RST + code blocks can be provided (e.g. `test` or `number-lines`) but with + a one-line syntax like this: + + ```nim test number-lines=10 + echo "ok" + ``` +* Markdown links ``[...](...)`` +* Pandoc syntax for automatic links ``[...]``, see [Referencing] for description +* Pandoc syntax for footnotes, including ``[^10]`` (manually numbered) + and ``[^someName]`` (auto-numbered with a label) +* Markdown literal blocks indented by 4 or more spaces +* Markdown headlines +* Markdown block quotes +* Markdown syntax for definition lists +* using ``1`` as auto-enumerator in enumerated lists like RST ``#`` + (auto-enumerator ``1`` can not be used with ``#`` in the same list) + +Additional Nim-specific features +-------------------------------- + +* referencing to definitions in external files, see + [Markup external referencing] section +* directives: ``code-block`` [^Sphinx], ``title``, + ``index`` [^Sphinx] +* predefined roles + - ``:nim:`` (default), ``:c:`` (C programming language), + ``:python:``, ``:yaml:``, ``:java:``, ``:cpp:`` (C++), ``:csharp`` (C#). + That is every language that [highlite](highlite.html) supports. + They turn on appropriate syntax highlighting in inline code. + + .. Note:: default role for Nim files is ``:nim:``, + for ``*.rst`` it's currently ``:literal:``. + + - generic command line highlighting roles: + - ``:cmd:`` for commands and common shells syntax + - ``:console:`` the same for interactive sessions + (commands should be prepended by ``$``) + - ``:program:`` for executable names [^Sphinx] + (one can just use ``:cmd:`` on single word) + - ``:option:`` for command line options [^Sphinx] + - ``:tok:``, a role for highlighting of programming language tokens +* ***triple emphasis*** (bold and italic) using \*\*\* +* ``:idx:`` role for \`interpreted text\` to include the link to this + text into an index (example: [Nim index]). +* double slash `//` in option lists serves as a prefix for any option that + starts from a word (without any leading symbols like `-`, `--`, `/`): + + //compile compile the project + //doc generate documentation + + Here the dummy `//` will disappear, while options `compile`:option: + and `doc`:option: will be left in the final document. +* emoji / smiley symbols + +[^Sphinx]: similar but different from the directives of + Python [Sphinx directives] and [Sphinx roles] extensions + +.. Note:: By default Nim has ``roSupportMarkdown`` and + ``roSupportRawDirective`` turned **on**. + +.. warning:: Using Nim-specific features can cause other Markdown and + RST implementations to fail on your document. + +Referencing +=========== + +To be able to copy and share links Nim generates anchors for all +main document elements: + +* headlines (including document title) +* footnotes +* explicitly set anchors: RST internal cross-references and + inline internal targets +* Nim symbols (external referencing), see [Nim DocGen Tools Guide] for details. + +But direct use of those anchors have 2 problems: + +1. the anchors are usually mangled (e.g. spaces substituted to minus + signs, etc). +2. manual usage of anchors is not checked, so it's easy to get broken + links inside your project if e.g. spelling has changed for a heading + or you use a wrong relative path to your document. + +That's why Nim implementation has syntax for using +*original* labels for referencing. +Such referencing can be either local/internal or external: + +* Local referencing (inside any given file) is defined by + RST standard or Pandoc Markdown User guide. +* External (cross-document) referencing is a Nim-specific feature, + though it's not really different from local referencing by its syntax. + +Markup local referencing +------------------------ + +There are 2 syntax option available for referencing to objects +inside any given file, e.g. for headlines: + + Markdown RST + + Some headline Some headline + ============= ============= + + Ref. [Some headline] Ref. `Some headline`_ + + +Markup external referencing +--------------------------- + +The syntax is the same as for local referencing, but the anchors are +saved in ``.idx`` files, so one needs to generate them beforehand, +and they should be loaded by an `.. importdoc::` directive. +E.g. if we want to reference section "Some headline" in ``file1.md`` +from ``file2.md``, then ``file2.md`` may look like: + +``` +.. importdoc:: file1.md + +Ref. [Some headline] +``` + +```cmd +nim md2html --index:only file1.md # creates ``htmldocs/file1.idx`` +nim md2html file2.md # creates ``htmldocs/file2.html`` +``` + +To allow cross-references between any files in any order (especially, if +circular references are present), it's strongly recommended +to make a run for creating all the indexes first: + +```cmd +nim md2html --index:only file1.md # creates ``htmldocs/file1.idx`` +nim md2html --index:only file2.md # creates ``htmldocs/file2.idx`` +nim md2html file1.md # creates ``htmldocs/file1.html`` +nim md2html file2.md # creates ``htmldocs/file2.html`` +``` + +and then one can freely reference any objects as if these 2 documents +are actually 1 file. + +Other +===== + +Idiosyncrasies +-------------- + +Currently we do **not** aim at 100% Markdown or RST compatibility in inline +markup recognition rules because that would provide very little user value. +This parser has 2 modes for inline markup: + +1) Markdown-like mode which is enabled by `roPreferMarkdown` option + (turned **on** by default). + + .. Note:: RST features like directives are still turned **on** + +2) Compatibility mode which is RST rules. + +.. Note:: in both modes the parser interpretes text between single + backticks (code) identically: + backslash does not escape; the only exception: ``\`` folowed by ` + does escape so that we can always input a single backtick ` in + inline code. However that makes impossible to input code with + ``\`` at the end in *single* backticks, one must use *double* + backticks: + + `\` -- WRONG + ``\`` -- GOOD + So single backticks can always be input: `\`` will turn to ` code + +.. Attention:: + We don't support some obviously poor design choices of Markdown (or RST). + + - no support for the rule of 2 spaces causing a line break in Markdown + (use RST "line blocks" syntax for making line breaks) + + - interpretation of Markdown block quotes is also slightly different, + e.g. case + + >>> foo + > bar + >>baz + + is a single 3rd-level quote `foo bar baz` in original Markdown, while + in Nim we naturally see it as 3rd-level quote `foo` + 1st level `bar` + + 2nd level `baz`: + + >>> foo + > bar + >>baz + +Limitations +----------- + +* no Unicode support in character width calculations +* body elements + - no roman numerals in enumerated lists + - no doctest blocks + - no grid tables + - some directives are missing (check official [RST directives list]): + ``parsed-literal``, ``sidebar``, ``topic``, ``math``, ``rubric``, + ``epigraph``, ``highlights``, ``pull-quote``, ``compound``, + ``table``, ``csv-table``, ``list-table``, ``section-numbering``, + ``header``, ``footer``, ``meta``, ``class`` + - no ``role`` directives and no custom interpreted text roles + - some standard roles are not supported (check [RST roles list]) + - no generic admonition support +* inline markup + - no simple-inline-markup + - no embedded aliases + +Additional resources +-------------------- + +* See [Nim DocGen Tools Guide](docgen.html) for the details about + `nim doc`:cmd: command and idiosyncrasies of documentation markup in + ``.nim`` files and Nim programming language projects. +* See also documentation for [rst module](rst.html) -- Nim RST/Markdown parser. + +.. _Markdown Basic Syntax: https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax +.. _CommonMark Spec: https://spec.commonmark.org/0.30 +.. _quick introduction: https://docutils.sourceforge.io/docs/user/rst/quickstart.html +.. _RST reference: https://docutils.sourceforge.io/docs/user/rst/quickref.html +.. _RST specification: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html +.. _RST directives list: https://docutils.sourceforge.io/docs/ref/rst/directives.html +.. _RST roles list: https://docutils.sourceforge.io/docs/ref/rst/roles.html +.. _Nim index: https://nim-lang.org/docs/theindex.html +.. _Sphinx directives: https://www.sphinx-doc.org/en/master/usage/restructuredtext/directives.html +.. _Sphinx roles: https://www.sphinx-doc.org/en/master/usage/restructuredtext/roles.html |