content: Markdown table import + 5 tests (round-trip, 460/460)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/content/md-import.sx

@@ -3,11 +3,12 @@
 ;; A line-based parser, the inverse of markdown.sx's asMarkdown. Confined to the
 ;; adapter boundary: the core knows nothing about Markdown. Handles ATX headings
 ;; (#..######), fenced code (```lang), blockquotes (> ), unordered (- / * ) and
-;; ordered (1. ) lists, thematic breaks (--- / ***), and paragraphs (consecutive
-;; plain lines joined with a space). Block ids are assigned sequentially b0,b1…
+;; ordered (1. ) lists, thematic breaks (--- / ***), pipe tables (header row +
+;; --- separator row + body rows), and paragraphs (consecutive plain lines joined
+;; with a space). Block ids are assigned sequentially b0,b1…
 ;;
-;; Requires (loaded by harness): block.sx, doc.sx (and markdown.sx for the
-;; adapter's export side).
+;; Requires (loaded by harness): block.sx, doc.sx, table.sx (mk-table); and
+;; markdown.sx for the adapter's export side.
 
 (define md/-id (fn (i) (str "b" i)))
 (define md/-blank? (fn (s) (= s "")))
@@ -118,6 +119,70 @@
   md/-drop-ul
   (fn (line) (substring line 2 (string-length line))))
 
+;; ── table detection ──
+(define md/-pipe-row? (fn (line) (ct-starts-with? (trim line) "|")))
+(define md/-sep-char? (fn (ch) (ct-in? ch (list "-" ":" "|" " "))))
+(define
+  md/-all-sep?
+  (fn
+    (s i)
+    (if
+      (>= i (string-length s))
+      true
+      (if
+        (md/-sep-char? (substring s i (+ i 1)))
+        (md/-all-sep? s (+ i 1))
+        false))))
+(define
+  md/-has-dash?
+  (fn
+    (s i)
+    (if
+      (>= i (string-length s))
+      false
+      (if
+        (= (substring s i (+ i 1)) "-")
+        true
+        (md/-has-dash? s (+ i 1))))))
+(define
+  md/-sep-row?
+  (fn
+    (line)
+    (and
+      (md/-pipe-row? line)
+      (md/-all-sep? (trim line) 0)
+      (md/-has-dash? line 0))))
+(define
+  md/-table-start?
+  (fn
+    (lines)
+    (and
+      (md/-pipe-row? (first lines))
+      (> (len lines) 1)
+      (md/-sep-row? (nth lines 1)))))
+(define
+  md/-strip-pipes
+  (fn
+    (s0)
+    (let
+      ((s (trim s0)))
+      (let
+        ((a (if (ct-starts-with? s "|") (substring s 1 (string-length s)) s)))
+        (if
+          (and
+            (> (string-length a) 0)
+            (=
+              (substring
+                a
+                (- (string-length a) 1)
+                (string-length a))
+              "|"))
+          (substring a 0 (- (string-length a) 1))
+          a)))))
+(define
+  md/-cells
+  (fn (line) (map (fn (c) (trim c)) (split (md/-strip-pipes line) "|"))))
+
 (define
   md/-plain?
   (fn
@@ -168,6 +233,41 @@
       (else
         (md/-code-collect (rest lines) lang (cons (first lines) body) i acc)))))
 
+(define
+  md/-table-body
+  (fn
+    (lines headers rows i acc)
+    (if
+      (= (len lines) 0)
+      (md/-walk
+        lines
+        (+ i 1)
+        (cons (mk-table (md/-id i) headers (reverse rows)) acc))
+      (let
+        ((line (first lines)))
+        (if
+          (md/-pipe-row? line)
+          (md/-table-body
+            (rest lines)
+            headers
+            (cons (md/-cells line) rows)
+            i
+            acc)
+          (md/-walk
+            lines
+            (+ i 1)
+            (cons (mk-table (md/-id i) headers (reverse rows)) acc)))))))
+(define
+  md/-table
+  (fn
+    (lines i acc)
+    (md/-table-body
+      (rest (rest lines))
+      (md/-cells (first lines))
+      (list)
+      i
+      acc)))
+
 (define
   md/-list-collect
   (fn
@@ -256,6 +356,7 @@
               (rest lines)
               (+ i 1)
               (cons (mk-divider (md/-id i)) acc)))
+          ((md/-table-start? lines) (md/-table lines i acc))
           ((md/-ul? line) (md/-list-collect lines (list) i acc false))
           ((md/-ol? line) (md/-list-collect lines (list) i acc true))
           (else (md/-para-collect lines (list) i acc)))))))