rowtable: Implement space as separator

Author: bluss

docs/rowmantic-manual.pdf

@@ -200,10 +200,11 @@ Example from Wikipedia#footnote[https://en.wikipedia.org/wiki/Interlinear_gloss]
 
 ````)
 
-== Double Semicolon Separator
+== Other Separators
 
 #block(sticky: true)[
-  The cell separator can be more than a single character, like in this example.
+  The cell separator is specified as a string with the `separator` argument.
+  It can be more than a single character, like in this example with double semicolon:
 ]
 #show-example(```typst
 #rowtable(
@@ -214,10 +215,25 @@ Example from Wikipedia#footnote[https://en.wikipedia.org/wiki/Interlinear_gloss]
 )
 ```)
 
+Using a space as a separator has special behaviour -- because of how spaces are treated in Typst markup: multiple spaces, tabs, or a (single) newline are all collapsed into just whitespace. Using a space as separator splits on any such whitespace:
+
+#show-example(```typst
+#rowtable(
+  separator: " ",
+  stroke: 0.5pt,
+  [First  Second Third~(3rd)],
+  [Fourth Fifth  Sixth~(6th)],
+)
+```)
+
+The recommended way to insert a literal space in this case is to use ```typst ~```.
+
 
 == Using Other Table Functions
 
-Use the `table` argument to let rowtable pass its result to a different table function rather than the standard one, for example `pillar.table` (shown below) or `zero.ztable`.
+#block(sticky: true)[
+  Use the `table` argument to let rowtable pass its result to a different table function rather than the standard one, for example `pillar.table` (shown below) or `zero.ztable`.
+  ]
 
 #show-example(```typst
 #import "@preview/pillar:0.3.3"

docs/rowmantic-manual.typ

@@ -95,6 +95,9 @@
       } else if contentsep and isfunc(elt, sep.func()) and elt == sep {
         res.push(accum)
         accum = ()
+      } else if (sep == " " or sep == "  ") and isfunc(elt, space) {
+        res.push(accum)
+        accum = ()
       } else {
         accum.push(elt)
       }
@@ -262,7 +265,9 @@
 ///   Arguments to `table` pass through. A `columns` argument to the table is possible but not
 ///   mandatory.
 /// - separator (str): Configurable cell separator in rows. Good choices are `"&"`, `","` or `";"`.
-///   Escape the separator using e.g. ```typst \&```
+///   Escape the separator using e.g. ```typst \&```.
+///   As a special case `" "` will split on consecutive whitespace (one or more spaces, tabs or a newline).
+///   Additionally, using `"  "` (two spaces) will only split on
 /// - separator-eq (none, auto, equation): Cell separator for equations, must be single symbol.
 ///   By default depends on `separator` if possible otherwise falls back to ```typst $&$```.
 ///   Set to ```typc none``` to disable splitting equations.

src/rowtable.typ

@@ -11,6 +11,14 @@
 #assert.eq(row-split([A,B\,C], sep: ","),  ([A], [B#sym.comma;C]))
 #assert.eq(row-split([A&B\&C], sep: "&"),  ([A], [B#sym.amp;C]))
 
+// space as delimiter
+#assert.eq(row-split([A B], sep: " "),  ([A], [B]))
+#assert.eq(row-split([A *B*], sep: " "),  ([A], [*B*]))
+#assert.eq(row-split([A B  C	D E
+F G~H], sep: " "),  ([A], [B], [C], [D], [E], [F], [G~H]))
+// double space as delimiter
+#assert.eq(row-split([A B  C	D E *F*], sep: "  "),  ([A B], [C], [D E], [*F*]))
+
 // table
 #assert.eq(rowtable(), table(columns: 1))
 #assert.eq(rowtable([A & B], [C]), table(columns: 2, [A], [B], [C], []))