renamed get- to compute-columns-widths

src/core/renderer.typ

@@ -1,119 +1,156 @@
-#import "/src/cetz.typ": canvas, draw
-#import "utils.typ": get-participants-i, get-style, normalize-units
-#import "group.typ"
-#import "participant.typ"
+#import "/src/cetz.typ" as cetz: canvas, draw
+#import "utils.typ": get-participants-i, get-style, normalize-units, is-elmt
+#import "../group.typ"
+#import "../participant.typ"
 #import participant: PAR-SPECIALS
-#import "sequence.typ"
-#import "separator.typ"
-#import "sync.typ"
-#import "consts.typ": *
-#import "note.typ" as note: get-note-box
+#import "../sequence.typ"
+#import "../separator.typ"
+#import "../sync.typ"
+#import "../consts.typ": *
+#import "../note.typ" as note: get-note-box
 
 #let DEBUG-INVISIBLE = false
 
-#let get-columns-width(participants, elements) = {
-  participants = participants.map(p => {
+#let init-lifelines(participants) = {
+  return participants.map(p => {
     p.insert("lifeline-lvl", 0)
     p.insert("max-lifelines", 0)
     p
   })
-  let pars-i = get-participants-i(participants)
-  let cells = ()
+}
 
-  // Unwrap syncs
+#let unwrap-syncs(elements) = {
   let i = 0
   while i < elements.len() {
     let elmt = elements.at(i)
     if elmt.type == "sync" {
-      elements = elements.slice(0, i + 1) + elmt.elmts + elements.slice(i + 1)
+      elements = (
+        elements.slice(0, i + 1) +
+        elmt.elmts +
+        elements.slice(i + 1)
+      )
     }
     i += 1
   }
+  return elements
+}
 
-  // Compute max lifeline levels
+#let seq-update-lifelines(participants, pars-i, seq) = {
+  let participants = participants
+  let com = if seq.comment == none {""} else {seq.comment}
+  let i1 = pars-i.at(seq.p1)
+  let i2 = pars-i.at(seq.p2)
+  let cell = (
+    elmt: seq,
+    i1: calc.min(i1, i2),
+    i2: calc.max(i1, i2),
+    cell: box(com, inset: 3pt)
+  )
+
+  if seq.disable-src or seq.destroy-src {
+    let p = participants.at(i1)
+    p.lifeline-lvl -= 1
+    participants.at(i1) = p
+  }
+  if seq.disable-dst {
+    let p = participants.at(i2)
+    p.lifeline-lvl -= 1
+    participants.at(i2) = p
+  }
+  if seq.enable-dst {
+    let p = participants.at(i2)
+    p.lifeline-lvl += 1
+    p.max-lifelines = calc.max(p.max-lifelines, p.lifeline-lvl)
+    participants.at(i2) = p
+  }
+
+  return (participants, cell)
+}
+
+#let evt-update-lifelines(participants, pars-i, evt) = {
+  let par-name = evt.participant
+  let i = pars-i.at(par-name)
+  let par = participants.at(i)
+  if evt.event == "disable" or evt.event == "destroy" {
+    par.lifeline-lvl -= 1
+  
+  } else if evt.event == "enable" {
+    par.lifeline-lvl += 1
+    par.max-lifelines = calc.max(par.max-lifelines, par.lifeline-lvl)
+  }
+  participants.at(i) = par
+  return participants
+}
+
+#let note-get-cell(note) = {
+  let (p1, p2) = (none, none)
+  let cell = none
+  if note.side == "left" {
+    p1 = "["
+    p2 = note.pos
+    cell = get-note-box(note)
+  } else if note.side == "right" {
+    p1 = note.pos
+    p2 = "]"
+    cell = get-note-box(note)
+  } else if note.side == "over" and note.aligned-with != none {
+    let box1 = get-note-box(note)
+    let box2 = get-note-box(note.aligned-with)
+    let m1 = measure(box1)
+    let m2 = measure(box2)
+    cell = box(
+      width: (m1.width + m2.width) / 2,
+      height: calc.max(m1.height, m2.height)
+    )
+    p1 = note.pos
+    p2 = note.aligned-with.pos
+  } else {
+    return none
+  }
+
+  let i1 = pars-i.at(p1)
+  let i2 = pars-i.at(p2)
+  cell = (
+    elmt: note,
+    i1: calc.min(i1, i2),
+    i2: calc.max(i1, i2),
+    cell: cell
+  )
+
+  return cell
+}
+
+#let compute-max-lifeline-levels(participants, elements, pars-i) = {
+  let cells = ()
   for elmt in elements {
     if elmt.type == "seq" {
-      let com = if elmt.comment == none {""} else {elmt.comment}
-      let i1 = pars-i.at(elmt.p1)
-      let i2 = pars-i.at(elmt.p2)
-      cells.push(
-        (
-          elmt: elmt,
-          i1: calc.min(i1, i2),
-          i2: calc.max(i1, i2),
-          cell: box(com, inset: 3pt)
-        )
+      let cell
+      (participants, cell) = seq-update-lifelines(
+        participants,
+        pars-i,
+        elmt
       )
-
-      if elmt.disable-src or elmt.destroy-src {
-        let p = participants.at(i1)
-        p.lifeline-lvl -= 1
-        participants.at(i1) = p
-      }
-      if elmt.disable-dst {
-        let p = participants.at(i2)
-        p.lifeline-lvl -= 1
-        participants.at(i2) = p
-      }
-      if elmt.enable-dst {
-        let p = participants.at(i2)
-        p.lifeline-lvl += 1
-        p.max-lifelines = calc.max(p.max-lifelines, p.lifeline-lvl)
-        participants.at(i2) = p
-      }
+      cells.push(cell)
     } else if elmt.type == "evt" {
-      let par-name = elmt.participant
-      let i = pars-i.at(par-name)
-      let par = participants.at(i)
-      if elmt.event == "disable" or elmt.event == "destroy" {
-        par.lifeline-lvl -= 1
-      
-      } else if elmt.event == "enable" {
-        par.lifeline-lvl += 1
-        par.max-lifelines = calc.max(par.max-lifelines, par.lifeline-lvl)
-      }
-      participants.at(i) = par
+      participants = evt-update-lifelines(
+        participants,
+        pars-i,
+        elmt
+      )
     
     } else if elmt.type == "note" {
-      let (p1, p2) = (none, none)
-      let cell = none
-      if elmt.side == "left" {
-        p1 = "["
-        p2 = elmt.pos
-        cell = get-note-box(elmt)
-      } else if elmt.side == "right" {
-        p1 = elmt.pos
-        p2 = "]"
-        cell = get-note-box(elmt)
-      } else if elmt.side == "over" {
-        if elmt.aligned-with != none {
-          let box1 = get-note-box(elmt)
-          let box2 = get-note-box(elmt.aligned-with)
-          let m1 = measure(box1)
-          let m2 = measure(box2)
-          cell = box(width: (m1.width + m2.width) / 2, height: calc.max(m1.height, m2.height))
-          p1 = elmt.pos
-          p2 = elmt.aligned-with.pos
-        }
-      }
-
-      if p1 != none and p2 != none and cell != none {
-        let i1 = pars-i.at(p1)
-        let i2 = pars-i.at(p2)
-        cells.push(
-          (
-            elmt: elmt,
-            i1: calc.min(i1, i2),
-            i2: calc.max(i1, i2),
-            cell: cell
-          )
-        )
+      let cell = note-get-cell(elmt)
+      if cell != none {
+        cells.push(cell)
       }
     }
   }
 
-  // Compute column widths
-  // Compute minimum widths for participant names and shapes
+  return (participants, elements, cells)
+}
+
+/// Compute minimum widths for participant names and shapes
+#let participants-min-col-widths(participants) = {
   let widths = ()
   for i in range(participants.len() - 1) {
     let p1 = participants.at(i)
@@ -124,11 +161,15 @@
     let w2 = m2.width
     widths.push(w1 / 2pt + w2 / 2pt + PAR-SPACE)
   }
+  return widths
+}
 
-  // Compute minimum width for over notes
-  for n in elements.filter(e => (e.type == "note" and
-                                 e.side == "over" and 
-                                 type(e.pos) == str)) {
+/// Compute minimum width for over notes
+#let notes-min-col-widths(elements, widths, pars-i) = {
+  let widths = widths
+  let notes = elements.filter(e => e.type == "note")
+  for n in notes.filter(e => (e.side == "over" and 
+                              type(e.pos) == str)) {
     
     let m = note.get-size(n)
     let i = pars-i.at(n.pos)
@@ -146,8 +187,12 @@
       )
     }
   }
+  return widths
+}
 
-  // Compute minimum width for simple sequences (spanning 1 column)
+/// Compute minimum width for simple sequences (spanning 1 column)
+#let simple-seq-min-col-widths(cells, widths) = {
+  let widths = widths
   for cell in cells.filter(c => c.i2 - c.i1 == 1) {
     let m = measure(cell.cell)
     widths.at(cell.i1) = calc.max(
@@ -155,9 +200,14 @@
       m.width / 1pt + COMMENT-PAD
     )
   }
+  return widths
+}
 
-  // Compute minimum width for self sequences
-  for cell in cells.filter(c => c.elmt.type == "seq" and c.i1 == c.i2) {
+/// Compute minimum width for self sequences
+#let self-seq-min-col-widths(cells, widths) = {
+  let widths = widths
+  for cell in cells.filter(c => (c.elmt.type == "seq" and
+                                 c.i1 == c.i2)) {
     let m = measure(cell.cell)
     let i = cell.i1
     if cell.elmt.flip {
@@ -170,72 +220,112 @@
       )
     }
   }
+  return widths
+}
 
-  // Compute remaining widths for longer sequences (spanning multiple columns)
+/// Compute remaining widths for longer sequences (spanning multiple columns)
+#let long-seq-min-col-widths(cells, widths) = {
+  let widths = widths
   let multicol-cells = cells.filter(c => c.i2 - c.i1 > 1)
   multicol-cells = multicol-cells.sorted(key: c => {
     c.i1 * 1000 + c.i2
   })
   for cell in multicol-cells {
     let m = measure(cell.cell)
+    let width = (
+      m.width / 1pt +
+      COMMENT-PAD -
+      widths.slice(cell.i1, cell.i2 - 1).sum()
+    )
     widths.at(cell.i2 - 1) = calc.max(
-      widths.at(cell.i2 - 1),
-      m.width / 1pt + COMMENT-PAD - widths.slice(cell.i1, cell.i2 - 1).sum()
+      widths.at(cell.i2 - 1), width
     )
   }
+  return widths
+}
 
-  // Add lifeline widths
-  for (i, w) in widths.enumerate() {
+/// Add lifeline widths
+#let col-widths-add-lifelines(participants, widths) = {
+  return widths.enumerate().map(((i, w)) => {
     let p1 = participants.at(i)
     let p2 = participants.at(i + 1)
-    let w = w + p1.max-lifelines * LIFELINE-W / 2
+    w += p1.max-lifelines * LIFELINE-W / 2
     if p2.max-lifelines != 0 {
       w += LIFELINE-W / 2
     }
-    widths.at(i) = w
-  }
+    return w
+  })
+}
 
-  for elmt in elements {
-    if elmt.type == "col" {
-      let i1 = pars-i.at(elmt.p1)
-      let i2 = pars-i.at(elmt.p2)
-      if calc.abs(i1 - i2) != 1 {
-        let i-min = calc.min(i1, i2)
-        let i-max = calc.max(i1, i2)
-        let others = pars-i.pairs()
-                           .sorted(key: p => p.last())
-                           .slice(i-min + 1, i-max)
-                           .map(p => "'" + p.first() + "'")
-                           .join(", ")
-        panic(
-          "Column participants must be consecutive (participants (" +
-          others +
-          ") are in between)"
-        )
-      }
-      let i = calc.min(i1, i2)
-
-      if elmt.width != auto {
-        widths.at(i) = normalize-units(elmt.width)
-      }
-
-      let width = widths.at(i)
-      width = calc.max(width, normalize-units(elmt.min-width))
-      if elmt.max-width != none {
-        width = calc.min(width, normalize-units(elmt.max-width))
-      }
-      widths.at(i) = width + normalize-units(elmt.margin)
+#let process-col-elements(elements, widths, pars-i) = {
+  let widths = widths
+  let cols = elements.filter(e => e.type == "col")
+  for col in cols {
+    let i1 = pars-i.at(col.p1)
+    let i2 = pars-i.at(col.p2)
+    if calc.abs(i1 - i2) != 1 {
+      let i-min = calc.min(i1, i2)
+      let i-max = calc.max(i1, i2)
+      let others = pars-i.pairs()
+                         .sorted(key: p => p.last())
+                         .slice(i-min + 1, i-max)
+                         .map(p => "'" + p.first() + "'")
+                         .join(", ")
+      panic(
+        "Column participants must be consecutive (participants (" +
+        others +
+        ") are in between)"
+      )
     }
-  }
+    let i = calc.min(i1, i2)
 
+    let width = widths.at(i)
+
+    if col.width != auto {
+      width = normalize-units(col.width)
+    }
+
+    width = calc.max(
+      width,
+      normalize-units(col.min-width)
+    )
+    if col.max-width != none {
+      width = calc.min(
+        width,
+        normalize-units(col.max-width)
+      )
+    }
+    widths.at(i) = width + normalize-units(col.margin)
+  }
+  return widths
+}
+
+#let compute-columns-width(participants, elements, pars-i) = {
+  elements = elements.filter(is-elmt)
+  elements = unwrap-syncs(elements)
+
+  let cells
+  (participants, elements, cells) = compute-max-lifeline-levels(participants, elements, pars-i)
+
+  let widths = participants-min-col-widths(participants)
+  widths = notes-min-col-widths(elements, widths, pars-i)
+  widths = simple-seq-min-col-widths(cells, widths)
+  widths = self-seq-min-col-widths(cells, widths)
+  widths = long-seq-min-col-widths(cells, widths)
+  widths = col-widths-add-lifelines(participants, widths)
+  widths = process-col-elements(elements, widths, pars-i)
   return widths
 }
 
 #let render(participants, elements) = context canvas(length: 1pt, {
+  let participants = participants
+  let elements = elements
+
   let shapes = ()
+  participants = init-lifelines(participants)
   let pars-i = get-participants-i(participants)
 
-  let widths = get-columns-width(participants, elements)
+  let widths = compute-columns-width(participants, elements, pars-i)
 
   // Compute each column's X position
   let x-pos = (0,)
@@ -267,8 +357,11 @@
 
   // Draw elemnts
   for elmt in elements {
+    if not is-elmt(elmt) {
+      shapes.push(elmt)
+
     // Sequences
-    if elmt.type == "seq" {
+    } else if elmt.type == "seq" {
       let shps
       (y, lifelines, shps) = draw-seq(elmt, y, lifelines)
       shapes += shps

src/core/setup.typ

@@ -0,0 +1,317 @@
+#import "utils.typ": is-elmt, get-group-span
+#import "../participant.typ": _exists as par-exists, _par
+
+#let flatten-group(elmts, i) = {
+  let group = elmts.at(i)
+  elmts.at(i) = group
+  return (
+    elmts.slice(0, i + 1) +
+    group.elmts +
+    ((
+      type: "grp-end",
+      start-i: i
+    ),) +
+    elmts.slice(i+1)
+  )
+}
+
+#let update-group-children(elmts, i) = {
+  let elmts = elmts
+  let group-end = elmts.at(i)
+  
+  elmts.at(group-end.start-i).elmts = elmts.slice(group-end.start-i + 1, i)
+  return elmts
+}
+
+#let convert-return(elmts, i, activation-history) = {
+  if activation-history.len() == 0 {
+    panic("Cannot return if no lifeline is activated")
+  }
+  let elmts = elmts
+  let activation-history = activation-history
+  let ret = elmts.at(i)
+  let seq = activation-history.pop()
+  elmts.at(i) = _seq(
+    seq.p2, seq.p1,
+    comment: ret.comment,
+    disable-src: true,
+    dashed: true
+  ).first()
+  return (elmts, activation-history)
+}
+
+#let unwrap-containers(elmts) = {
+  let elmts = elmts
+  let i = 0
+  let activation-history = ()
+
+  // Flatten groups + convert returns
+  while i < elmts.len() {
+    let elmt = elmts.at(i)
+    if not is-elmt(elmt) {
+      i += 1
+      continue
+    }
+
+    if elmt.type == "grp" {
+      elmts = flatten-group(elmts, i)
+
+    } else if elmt.type == "seq" {
+      if elmt.enable-dst {
+        activation-history.push(elmt)
+      }
+    
+    } else if elmt.type == "evt" {
+      if elmt.event == "enable" {
+        for elmt2 in elmts.slice(0, i).rev() {
+          if elmt2.type == "seq" {
+            activation-history.push(elmt2)
+            break
+          }
+        }
+      }
+    
+    } else if elmt.type == "ret" {
+      (elmts, activation-history) = convert-return(elmts, i, activation-history)
+    }
+    i += 1
+  }
+
+  return (elmts, activation-history)
+}
+
+
+#let prepare-seq-participants(ctx, seq) = {
+  let ctx = ctx
+  if not par-exists(ctx.participants, seq.p1) {
+    ctx.participants.push(_par(seq.p1).first())
+  }
+  if not par-exists(ctx.participants, seq.p2) {
+    ctx.participants.push(_par(
+      seq.p2,
+      from-start: not seq.create-dst
+    ).first())
+  
+  } else if seq.create-dst {
+    let i = ctx.participants.position(p => p.name == seq.p2)
+    ctx.participants.at(i).from-start = false
+  }
+
+  let p1 = seq.p1
+  let p2 = seq.p2
+  if seq.p1 == "?" {
+    p1 = "?" + seq.p2
+  }
+  if seq.p2 == "?" {
+    p2 = seq.p1 + "?"
+  }
+  ctx.linked.push(p1)
+  ctx.linked.push(p2)
+  ctx.last-seq = (
+    elmt: seq,
+    i: ctx.i,
+    p1: p1,
+    p2: p2
+  )
+  return ctx
+}
+
+#let prepare-note-participants(ctx, note) = {
+  let ctx = ctx
+  let note = note
+  note.insert(
+    "linked",
+    note.pos == none and note.side != "across"
+  )
+  if note.pos == none and note.side != "across" {
+    let names = ctx.participants.map(p => p.name)
+    let i1 = names.position(n => n == ctx.last-seq.p1)
+    let i2 = names.position(n => n == ctx.last-seq.p2)
+    let pars = (
+      (i1, ctx.last-seq.p1),
+      (i2, ctx.last-seq.p2)
+    ).sorted(key: p => p.first())
+
+    if note.side == "left" {
+      note.pos = pars.first().last()
+    } else if note.side == "right" {
+      note.pos = pars.last().last()
+    }
+
+    let seq = last-seq.note
+    seq.insert("linked-note", note)
+    ctx.elmts.at(last-seq.i) = seq
+  }
+  if note.aligned {
+    let n = last-note.note
+    n.aligned-with = note
+    ctx.elmts.at(last-note.i) = n
+  }
+  if note.side == "left" {
+    ctx.linked.push("[")
+  } else if note.side == "right" {
+    ctx.linked.push("]")
+  }
+
+  let pars = none
+  if type(note.pos) == str {
+    pars = (note.pos,)
+  } else if type(note.pos) == array {
+    pars = note.pos
+  }
+  if pars != none {
+    for par in pars {
+      if not par-exists(ctx.participants, par) {
+        participants.push(_par(par).first())
+      }
+    }
+  }
+
+  ctx.elmts.at(ctx.i) = note
+
+  ctx.last-note = (
+    elmt: note,
+    i: ctx.i
+  )
+
+  return ctx
+}
+
+#let prepare-evt-participants(ctx, evt) = {
+  let par = evt.participant
+  if not par-exists(ctx.participants, par) {
+    let p = _par(
+      par,
+      from-start: evt.event != "create"
+    ).first()
+    ctx.participants.push(p)
+  
+  } else if evt.event == "create" {
+    let i = ctx.participants.position(p => p.name == par)
+    ctx.participants.at(i).from-start = false
+  }
+  return ctx
+}
+
+#let normalize-special-participants(elmt) = {
+  if elmt.p1 == "?" {
+    elmt.p1 = "?" + elmt.p2
+  } else if elmt.p2 == "?" {
+    elmt.p2 = elmt.p1 + "?"
+  }
+  return elmt
+}
+
+#let prepare-participants(elmts) = {
+  let ctx = (
+    linked: (),
+    last-seq: none,
+    last-note: none,
+    participants: (),
+    elmts: elmts,
+    i: 0
+  )
+
+  for (i, elmt) in ctx.elmts.enumerate() {
+    ctx.i = i
+    if not is-elmt(elmt) {
+      continue
+    }
+
+    if elmt.type == "par" {
+      ctx.participants.push(elmt)
+
+    } else if elmt.type == "seq" {
+      ctx = prepare-seq-participants(ctx, elmt)
+    
+    } else if elmt.type == "note" {
+      ctx = prepare-note-participants(ctx, elmt)
+    
+    } else if elmt.type == "evt" {
+      ctx = prepare-evt-participants(ctx, elmt)
+    }
+  }
+  ctx.linked = ctx.linked.dedup()
+
+  let pars = ctx.participants
+  let participants = ()
+  
+  if "[" in ctx.linked {
+    participants.push(_par("[", invisible: true).first())
+  }
+  
+  for (i, p) in pars.enumerate() {
+    let before = _par(
+      "?" + p.name,
+      invisible: true
+    ).first()
+    let after = _par(
+      p.name + "?",
+      invisible: true
+    ).first()
+    
+    if before.name in ctx.linked {
+      if participants.len() == 0 or not participants.last().name.ends-with("?") {
+        participants.push(before)
+      } else {
+        participants.insert(-1, before)
+      }
+    }
+
+    participants.push(p)
+
+    if after.name in ctx.linked {
+      participants.push(after)
+    }
+  }
+  if "]" in ctx.linked {
+    participants.push(_par(
+      "]",
+      invisible: true
+    ).first())
+  }
+
+  return (ctx.elmts, participants)
+}
+
+#let finalize-setup(elmts, participants) = {
+  for (i, p) in participants.enumerate() {
+    p.insert("i", i)
+    participants.at(i) = p
+  }
+
+  let containers = ()
+
+  for (i, elmt) in elmts.enumerate() {
+    if not is-elmt(elmt) {
+      continue
+    }
+    if elmt.type == "seq" {
+      elmts.at(i) = normalize-special-participants(elmt)
+    } else if elmt.type == "grp-end" {
+      // Put back elements in group because they might have changed
+      elmts = update-group-children(elmts, i)
+    } else if elmt.type in ("grp", "alt") {
+      containers.push(i)
+    }
+  }
+
+  // Compute groups spans (horizontal)
+  for i in containers {
+    let elmt = elmts.at(i)
+    let (min-i, max-i) = get-group-span(participants, elmt)
+    elmts.at(i).insert("min-i", min-i)
+    elmts.at(i).insert("max-i", max-i)
+  }
+
+  return (elmts, participants)
+}
+
+#let setup(elements) = {
+  let (elmts, activation-history) = unwrap-containers(elements)
+  
+  let participants
+  (elmts, participants) = prepare-participants(elmts)
+
+  return finalize-setup(elmts, participants)
+}

src/core/utils.typ

@@ -1,3 +1,13 @@
+#let is-elmt(elmt) = {
+  if type(elmt) != dictionary {
+    return false
+  }
+  if "type" not in elmt {
+    return false
+  }
+  return true
+}
+
 #let normalize-units(value) = {
   if type(value) == int or type(value) == float {
     return value

src/diagram.typ

@@ -1,8 +1,10 @@
-#import "utils.typ": get-group-span, fit-canvas
-#import "renderer.typ": render
+#import "core/utils.typ": fit-canvas
+#import "core/renderer.typ": render
 #import "participant.typ" as participant: _par, PAR-SPECIALS
 #import "sequence.typ": _seq
 
+#import "core/setup.typ": setup
+
 #let _gap(size: 20) = {
   return ((
     type: "gap",
@@ -36,214 +38,7 @@
     return
   }
   
-  let participants = ()
-  let elmts = elements
-  let i = 0
-
-  let activation-history = ()
-
-  // Flatten groups + convert returns
-  while i < elmts.len() {
-    let elmt = elmts.at(i)
-    if elmt.type == "grp" {
-      elmt.elmts = elmt.elmts.map(e => {
-        if e.type == "seq" {
-          if e.p1 == "?" {
-            e.p1 = "?" + e.p2
-          } else if e.p2 == "?" {
-            e.p2 = e.p1 + "?"
-          }
-        }
-        e
-      })
-      elmts.at(i) = elmt
-      elmts = (
-        elmts.slice(0, i + 1) +
-        elmt.elmts +
-        ((
-          type: "grp-end",
-          start-i: i
-        ),) +
-        elmts.slice(i+1)
-      )
-    } else if elmt.type == "grp-end" {
-      // Put back elements in group because they might have changed
-      elmts.at(elmt.start-i).elmts = elmts.slice(elmt.start-i + 1, i)
-
-    } else if elmt.type == "seq" {
-      if elmt.enable-dst {
-        activation-history.push(elmt)
-      }
-    } else if elmt.type == "evt" {
-      if elmt.event == "enable" {
-        for elmt2 in elmts.slice(0, i).rev() {
-          if elmt2.type == "seq" {
-            activation-history.push(elmt2)
-            break
-          }
-        }
-      }
-    } else if elmt.type == "ret" {
-      if activation-history.len() == 0 {
-        panic("Cannot return if no lifeline is activated")
-      }
-      let seq = activation-history.pop()
-      elmts.at(i) = _seq(
-        seq.p2, seq.p1,
-        comment: elmt.comment,
-        disable-src: true,
-        dashed: true
-      ).first()
-    }
-    i += 1
-  }
-
-  // List participants
-  let linked = ()
-  let last-seq = none
-  let last-note = none
-  for (i, elmt) in elmts.enumerate() {
-    if elmt.type == "par" {
-      participants.push(elmt)
-    } else if elmt.type == "seq" {
-      if not participant._exists(participants, elmt.p1) {
-        participants.push(_par(elmt.p1).first())
-      }
-      if not participant._exists(participants, elmt.p2) {
-        let par = _par(elmt.p2, from-start: not elmt.create-dst).first()
-        participants.push(par)
-      
-      } else if elmt.create-dst {
-        let i = participants.position(p => p.name == elmt.p2)
-        participants.at(i).from-start = false
-      }
-
-      let p1 = elmt.p1
-      let p2 = elmt.p2
-      if elmt.p1 == "?" {
-        p1 = "?" + elmt.p2
-      }
-      if elmt.p2 == "?" {
-        p2 = elmt.p1 + "?"
-      }
-      linked.push(p1)
-      linked.push(p2)
-      last-seq = (
-        elmt: elmt,
-        i: i,
-        p1: p1,
-        p2: p2
-      )
-    } else if elmt.type == "note" {
-      elmt.insert("linked", elmt.pos == none and elmt.side != "across")
-      if elmt.pos == none and elmt.side != "across" {
-        let names = participants.map(p => p.name)
-        let i1 = names.position(n => n == last-seq.p1)
-        let i2 = names.position(n => n == last-seq.p2)
-        let pars = ((i1, last-seq.p1), (i2, last-seq.p2)).sorted(key: p => p.first())
-        if elmt.side == "left" {
-          elmt.pos = pars.first().last()
-        } else if elmt.side == "right" {
-          elmt.pos = pars.last().last()
-        }
-
-        let seq = last-seq.elmt
-        seq.insert("linked-note", elmt)
-        elmts.at(last-seq.i) = seq
-      }
-      if elmt.aligned {
-        let n = last-note.elmt
-        n.aligned-with = elmt
-        elmts.at(last-note.i) = n
-      }
-      elmts.at(i) = elmt
-      if elmt.side == "left" {
-        linked.push("[")
-      } else if elmt.side == "right" {
-        linked.push("]")
-      }
-
-      let pars = none
-      if type(elmt.pos) == str {
-        pars = (elmt.pos,)
-      } else if type(elmt.pos) == array {
-        pars = elmt.pos
-      }
-      if pars != none {
-        for par in pars {
-          if not participant._exists(participants, par) {
-            participants.push(_par(par).first())
-          }
-        }
-      }
-
-      last-note = (
-        elmt: elmt,
-        i: i
-      )
-    } else if elmt.type == "evt" {
-      let par = elmt.participant
-      if not participant._exists(participants, par) {
-        let p = _par(par, from-start: elmt.event != "create").first()
-        participants.push(p)
-      
-      } else if elmt.event == "create" {
-        let i = participants.position(p => p.name == par)
-        participants.at(i).from-start = false
-      }
-    }
-  }
-  linked = linked.dedup()
-
-  let pars = participants
-  participants = ()
-  
-  if "[" in linked {
-    participants.push(_par("[", invisible: true).first())
-  }
-  
-  for (i, p) in pars.enumerate() {
-    let before = _par("?" + p.name, invisible: true).first()
-    let after = _par(p.name + "?", invisible: true).first()
-    
-    if before.name in linked {
-      if participants.len() == 0 or not participants.last().name.ends-with("?") {
-        participants.push(before)
-      } else {
-        participants.insert(-1, before)
-      }
-    }
-
-    participants.push(p)
-
-    if after.name in linked {
-      participants.push(after)
-    }
-  }
-  if "]" in linked {
-    participants.push(_par("]", invisible: true).first())
-  }
-
-  // Add index to participant
-  for (i, p) in participants.enumerate() {
-    p.insert("i", i)
-    participants.at(i) = p
-  }
-
-  // Compute groups spans (horizontal)
-  for (i, elmt) in elmts.enumerate() {
-    if elmt.type == "grp" or elmt.type == "alt" {
-      let (min-i, max-i) = get-group-span(participants, elmt)
-      elmts.at(i).insert("min-i", min-i)
-      elmts.at(i).insert("max-i", max-i)
-    } else if elmt.type == "seq" {
-      if elmt.p1 == "?" {
-        elmts.at(i).p1 = "?" + elmt.p2
-      } else if elmt.p2 == "?" {
-        elmts.at(i).p2 = elmt.p1 + "?"
-      }
-    }
-  }
+  let (elmts, participants) = setup(elements)
 
   let canvas = render(participants, elmts)
   fit-canvas(canvas, width: width)