repl: support eof, define object with fields (#24784)

For `nim secret`:

- **fix(repl): eof(ctrl-D/Z) and ctrl-C were ignored**
- **feat(repl): continueLine  figures section, constr, bool ops**

---------

Co-authored-by: ringabout <43030857+ringabout@users.noreply.github.com>
(cherry picked from commit d573578b28)

compiler/llstream.nim

@@ -11,7 +11,7 @@
 
 import
   pathutils
-
+import std/strutils
 when defined(nimPreviewSlimSystem):
   import std/syncio
 
@@ -86,6 +86,47 @@ const
   LineContinuationOprs = {'+', '-', '*', '/', '\\', '<', '>', '!', '?', '^',
                           '|', '%', '&', '$', '@', '~', ','}
   AdditionalLineContinuationOprs = {'#', ':', '='}
+  LineContinuationTokens = [
+    "let", "var", "const", "type",  # section
+    "object", "tuple",
+    # from ./layouter.oprSet
+    "div", "mod", "shl", "shr", "in", "notin", "is",
+    "isnot", "not", "of", "as", "from", "..", "and", "or", "xor", 
+  ]  # must be all `nimIdentNormalized`-ed
+
+proc eqIdent(a, bNormalized: string): bool =
+  a.nimIdentNormalize == bNormalized
+
+proc endsWithIdent(s, subs: string): bool =
+  let le = subs.len
+  if le > s.len: return false
+  s[^le .. ^1].eqIdent subs
+
+proc continuesWithIdent(s, subs: string, start: int): bool =
+  s.substr(start, start+subs.high).eqIdent subs
+
+proc endsWithIdent(s, subs: string, endIdx: var int): bool =
+  endIdx.dec subs.len
+  result = s.continuesWithIdent(subs, endIdx+1)
+
+proc containsObjectOf(x: string): bool =
+  const sep = ' '
+  var idx = x.rfind(sep)
+  if idx == -1: return
+  template eatWord(word) =  
+    while x[idx] == sep: idx.dec
+    result = x.endsWithIdent(word, idx)
+    if not result: return
+  eatWord "of"
+  eatWord "object"
+  result = true
+
+proc endsWithLineContinuationToken(x: string): bool =
+  result = false
+  for tok in LineContinuationTokens:
+    if x.endsWithIdent(tok):
+      return true
+  result = x.containsObjectOf
 
 proc endsWithOpr*(x: string): bool =
   result = x.endsWith(LineContinuationOprs)
@@ -93,7 +134,9 @@ proc endsWithOpr*(x: string): bool =
 proc continueLine(line: string, inTripleString: bool): bool {.inline.} =
   result = inTripleString or line.len > 0 and (
         line[0] == ' ' or
-        line.endsWith(LineContinuationOprs+AdditionalLineContinuationOprs))
+        line.endsWith(LineContinuationOprs+AdditionalLineContinuationOprs) or
+        line.endsWithLineContinuationToken()
+      )
 
 proc countTriples(s: string): int =
   result = 0
@@ -109,7 +152,10 @@ proc llReadFromStdin(s: PLLStream, buf: pointer, bufLen: int): int =
   s.rd = 0
   var line = newStringOfCap(120)
   var triples = 0
-  while readLineFromStdin(if s.s.len == 0: ">>> " else: "... ", line):
+  while true:
+    if not readLineFromStdin(if s.s.len == 0: ">>> " else: "... ", line):
+      # now readLineFromStdin meets EOF (ctrl-D/Z) or ctrl-C
+      quit()
     s.s.add(line)
     s.s.add("\n")
     inc triples, countTriples(line)