output formatting. includes paragraph reflowing

1 files changed, 38 insertions, 2 deletions

diff --git a/rst_helpers.lua b/rst_helpers.lua
index b30370a..f7eb950 100644
--- a/rst_helpers.lua
+++ b/rst_helpers.lua
@@ -29,10 +29,10 @@ end
 --helpers.dbg_write = dbg_write
 local dbg_write = helpers.dbg_writef
 
-local patterns  = {}
+helpers.patterns  = {}
 
 do
-    local p = patterns
+    local p = helpers.patterns
     p.dash   = P"-"
     p.equals = P"="
     p.plus   = P"+"
@@ -701,5 +701,41 @@ do
     helpers.list.successor = suc
 end
 
+helpers.string = {}
+
+do
+    -- This grammar inside the function is slightly faster than the same as an upvalue
+    -- with the value of “width” repeatedly given via lpeg.Carg(). This holds
+    -- for repeated calls as well.
+    local ulen = utf.len
+    function helpers.string.wrapat (str, width)
+        local linelength = 0
+        local wrap = P{
+            [1] = "wrapper",
+
+            wrapper       = Cs(V"nowhitespace"^0 * (Cs(V"wrapme") + V"other")^1),
+            whitespace    = S" \t\v" + P"\n" / function() linelength = 0 end,
+            nowhitespace  = 1 - V"whitespace",
+            ignore        = P"\\type{"  * (1 - P"}")^1 * P"}",
+            other            = Cmt(V"whitespace"^1 * (V"ignore" + (1 - V"whitespace")^1), function(s,i,w)
+                                   linelength = linelength + ulen(w)
+                                   return true
+                               end),
+            wrapme = Cmt(V"whitespace"^1 * (1 - V"whitespace" - V"ignore")^1, function(s,i,w)
+                        local lw = ulen(w)
+                        if linelength + lw > width then
+                            linelength = lw
+                            return true
+                        end
+                        return false
+                    --end) / function (word) return "\n" .. match(V"whitespace"^1 * C((1 - V"whitespace")^1), word) end,
+                    end) / function (word) return "\n" .. word:match("[^%s]+") end,
+        }
+
+        local reflowed = wrap:match(str)
+        return reflowed
+    end
+end
+
 return helpers