feat: Add resilient.defn package for styled definition items

examples/manual-packages/packages.sil

@@ -166,6 +166,10 @@ And here it is stating at level 1, i.e. chapters and sections.
 
 \package-documentation{resilient.verbatim}
 
+\section{Definition items}
+
+\package-documentation{resilient.defn}
+
 %%%
 %%% INPUT FORMATS
 %%%

examples/sile-resilient-manual-styles.yml

@@ -93,6 +93,32 @@ code:
       family: "Hack"
       size: "1.4ex"
 
+defn-base:
+  origin: "resilient.defn"
+  style:
+
+defn-desc:
+  inherit: "defn-base"
+  origin: "resilient.defn"
+  style:
+    paragraph:
+      after:
+        skip: "smallskip"
+      before:
+        vbreak: false
+
+defn-term:
+  inherit: "defn-base"
+  origin: "resilient.defn"
+  style:
+    font:
+      weight: 700
+    paragraph:
+      after:
+        vbreak: false
+      before:
+        skip: "smallskip"
+
 dropcap:
   origin: "resilient.book"
   style:

packages/resilient/defn/init.lua

@@ -0,0 +1,149 @@
+--
+-- Definition environment for SILE
+-- Very minimal implementation for Djot/Markdown needs, with styling support.
+-- 2023, Didier Willis
+-- License: MIT
+--
+local ast = require("silex.ast")
+local extractFromTree = ast.extractFromTree
+
+local base = require("packages.resilient.base")
+
+local trimLeft = function (str)
+  return str:gsub("^%s*", "")
+end
+
+local trimRight = function (str)
+  return str:gsub("%s*$", "")
+end
+
+local trim = function (str)
+  return trimRight(trimLeft(str))
+end
+
+local package = pl.class(base)
+package._name = "resilient.defn"
+
+function package:_init (options)
+  base._init(self, options)
+end
+
+function package.declareSettings (_)
+
+  SILE.settings:declare({
+    parameter = "defn.variant",
+    type = "string or nil",
+    default = nil,
+    help = "Definition variant (styling)"
+  })
+
+  SILE.settings:declare({
+    parameter = "defn.indent",
+    type = "measurement",
+    default = SILE.measurement("2em"),
+    help = "Definition description indentation (styling)"
+  })
+
+end
+
+function package:registerCommands ()
+
+  self:registerCommand("defn:internal:term", function (options, content)
+    local variant = options.variant or SILE.settings:get("defn.variant")
+    local style = variant and "defn-term-" .. variant or "defn-term"
+
+    SILE.call("style:apply:paragraph", { name = style }, content)
+  end, "Definition term (internal)")
+
+  self:registerCommand("defn:internal:desc", function (options, content)
+    local variant = options.variant or SILE.settings:get("defn.variant")
+    local style = variant and "defn-desc-" .. variant or "defn-desc"
+
+    SILE.settings:temporarily(function ()
+      local indent = SILE.settings:get("defn.indent"):absolute()
+      local lskip = SILE.settings:get("document.lskip") or SILE.nodefactory.glue()
+      SILE.settings:set("document.lskip", SILE.nodefactory.glue(lskip.width:absolute() + indent))
+      SILE.call("style:apply:paragraph", { name = style }, content)
+    end)
+  end, "Definition block (internal)")
+
+  self:registerCommand("defn", function (options, content)
+    local term = extractFromTree(content, "term")
+    local desc = extractFromTree(content, "desc")
+    if not term then
+      SU.error("Missing term in definition")
+    end
+
+    for _, v in ipairs(content) do
+      -- Just check that there is no unexpected content left
+      if type(v) == "string" then
+        -- All text nodes are ignored in structure tags, but just warn
+        -- if there do not just consist in spaces.
+        local text = trim(v)
+        if text ~= "" then SU.warn("Ignored standalone text ("..text..")") end
+      else
+        SU.error("Definition structure error")
+      end
+    end
+
+    SILE.call("defn:internal:term", options, term)
+    if desc then
+      SILE.call("defn:internal:desc", options, desc)
+    end
+  end, "Definition environment (term and description).")
+
+end
+
+function package:registerStyles ()
+  self:registerStyle("defn-base", {}, {})
+
+  self:registerStyle("defn-term", { inherit = "defn-base" }, {
+    font = { weight = 700 },
+    paragraph = {
+      before = {
+        skip = "smallskip"
+      },
+      after = {
+        vbreak = false
+      }
+    }
+  })
+  self:registerStyle("defn-desc", { inherit = "defn-base" }, {
+    paragraph = {
+      before = {
+        vbreak = false
+      },
+      after = {
+        skip = "smallskip"
+      }
+    }
+  })
+end
+
+package.documentation = [[\begin{document}
+The \autodoc:package{resilient.defn} package is a style-enabled implementation of definition items, containing a term and a description.
+The current implementation is fairly minimal, focused on the needs of Djot and Markdown.
+
+The \autodoc:environment{defn} environment can contain a \autodoc:command[check=false]{\term} and a \autodoc:command[check=false]{\desc} element, and nothing else.
+By default, it looks like this:
+
+\begin{defn}
+  \term{SILE}
+  \desc{A typesetting system.}
+\end{defn}
+
+\begin{defn}
+  \term{re·sil·ient}
+  \desc{A collection of classes and packages for SILE.}
+\end{defn}
+
+The term is styled with the \code{defn-term} paragraph style, and the description is styled with the \code{defn-desc} paragraph style.
+
+The indentation of the description can be controlled with the \autodoc:setting{defn.indent} setting, which defaults to \code{2em}.
+
+The package also exposes a \autodoc:setting{defn.variant} setting, to globally switch to an alternate set of styles, assumed to be named \code{defn-term-⟨\em{variant}⟩} and \code{defn-desc-⟨\em{variant}⟩}.
+To switch styles on a specific definition, the \autodoc:environment{defn} environment also accepts a \autodoc:parameter{variant} option.
+
+\end{document}]]
+
+return package

resilient.sile-2.2.0-1.rockspec

@@ -49,6 +49,7 @@ build = {
     ["sile.packages.resilient.epigraph"]        = "packages/resilient/epigraph/init.lua",
     ["sile.packages.resilient.bookmatters"]     = "packages/resilient/bookmatters/init.lua",
     ["sile.packages.resilient.verbatim"]        = "packages/resilient/verbatim/init.lua",
+    ["sile.packages.resilient.defn"]            = "packages/resilient/defn/init.lua",
 
     ["sile.packages.resilient.bible.usx"]       = "packages/resilient/bible/usx/init.lua",
     ["sile.packages.resilient.bible.tei"]       = "packages/resilient/bible/tei/init.lua",

resilient.sile-dev-1.rockspec

@@ -47,6 +47,7 @@ build = {
     ["sile.packages.resilient.epigraph"]        = "packages/resilient/epigraph/init.lua",
     ["sile.packages.resilient.bookmatters"]     = "packages/resilient/bookmatters/init.lua",
     ["sile.packages.resilient.verbatim"]        = "packages/resilient/verbatim/init.lua",
+    ["sile.packages.resilient.defn"]            = "packages/resilient/defn/init.lua",
 
     ["sile.packages.resilient.bible.usx"]       = "packages/resilient/bible/usx/init.lua",
     ["sile.packages.resilient.bible.tei"]       = "packages/resilient/bible/tei/init.lua",