fixed and completed arrow tips

src/sequence.typ

@@ -16,10 +16,34 @@
     "/": (symbol: ">", fill: color, harpoon: true),
     "//": (symbol: "straight", harpoon: true),
     "x": none,
-    "o": (symbol: "o"),
+    "o": none,
   ).at(sym)
 }
 
+#let reverse-arrow-mark(mark) = {
+  if type(mark) == array {
+    return mark.map(m => reverse-arrow-mark(m))
+  }
+  let mark2 = mark
+  if type(mark) == dictionary and mark.at("harpoon", default: false) {
+    let flipped = mark.at("flip", default: false)
+    mark2.insert("flip", not flipped)
+  }
+  return mark2
+}
+
+#let is-tip-of-type(type_, tip) = {
+  if type(tip) == str and tip == type_ {
+    return true
+  }
+  if type(tip) == array and tip.contains(type_) {
+    return true
+  }
+  return false
+}
+#let is-circle-tip = is-tip-of-type.with("o")
+#let is-cross-tip = is-tip-of-type.with("x")
+
 #let _seq(
   p1,
   p2,
@@ -175,6 +199,15 @@
     shapes += shps
   }
 
+  let flip-mark = end-info.i <= start-info.i
+  if elmt.flip {
+    flip-mark = not flip-mark
+  }
+  if flip-mark {
+    style.mark.end = reverse-arrow-mark(style.mark.end)
+  }
+
+  let pts
   if elmt.p1 == elmt.p2 {
     if elmt.flip {
       x1 = start-info.lx
@@ -197,12 +230,11 @@
       )
     }
 
-    shapes += draw.line(
+    pts = (
       (x1, start-info.y),
       (x-mid, start-info.y),
       (x-mid, end-info.y),
-      (x2, end-info.y),
-      ..style
+      (x2, end-info.y)
     )
 
   } else {
@@ -219,12 +251,58 @@
       )
     }
 
-    shapes += draw.line(
+    pts = (
       (x1, start-info.y),
-      (x2, end-info.y),
-      ..style
+      (x2, end-info.y)
     )
   }
+
+  // Start circle tip
+  if is-circle-tip(elmt.start-tip) {
+    shapes += draw.circle(pts.first(), radius: CIRCLE-TIP-RADIUS, stroke: elmt.color, fill: none, name: "_circle-start-tip")
+    pts.at(0) = "_circle-start-tip"
+  
+  // Start cross tip
+  } else if is-cross-tip(elmt.start-tip) {
+    let size = CROSS-TIP-SIZE
+    let cross-pt = (pts.first(), size * 2, pts.at(1))
+    shapes += draw.line(
+      (rel: (-size, -size), to: cross-pt),
+      (rel: (size, size), to: cross-pt),
+      stroke: elmt.color + 1.5pt
+    )
+    shapes += draw.line(
+      (rel: (-size, size), to: cross-pt),
+      (rel: (size, -size), to: cross-pt),
+      stroke: elmt.color + 1.5pt
+    )
+    pts.at(0) = cross-pt
+  }
+
+  // End circle tip
+  if is-circle-tip(elmt.end-tip) {
+    shapes += draw.circle(pts.last(), radius: 3, stroke: elmt.color, fill: none, name: "_circle-end-tip")
+    pts.at(pts.len() - 1) = "_circle-end-tip"
+  
+  // End cross tip
+  } else if is-cross-tip(elmt.end-tip) {
+    let size = CROSS-TIP-SIZE
+    let cross-pt = (pts.last(), size * 2, pts.at(pts.len() - 2))
+    shapes += draw.line(
+      (rel: (-size, -size), to: cross-pt),
+      (rel: (size, size), to: cross-pt),
+      stroke: elmt.color + 1.5pt
+    )
+    shapes += draw.line(
+      (rel: (-size, size), to: cross-pt),
+      (rel: (size, -size), to: cross-pt),
+      stroke: elmt.color + 1.5pt
+    )
+    pts.at(pts.len() - 1) = cross-pt
+  }
+
+  shapes += draw.line(..pts, ..style)
+
   if elmt.enable-dst {
     let dst-line = lifelines.at(i2)
     dst-line.lines.push(("enable", end-info.y, elmt.lifeline-style))