Support old Nim 0.18 (#33)

* support nim 0.18

* put checks back

* fix checks

Author: nitely

.travis.yml

@@ -1,6 +1,7 @@
 services:
   - docker
 env:
+  - NIM=0.18.0
   - NIM=0.19.0
 before_install:
   - docker pull nimlang/nim:$NIM

CHANGELOG.md

@@ -1,4 +1,9 @@
-v0.9.0
+v0.10.0 (unreleased)
+==================
+
+* Add Nim 0.18 support back
+
+v0.9.0 (unreleased)
 ==================
 
 * Drop Nim 0.18 support

regex.nimble

@@ -1,13 +1,13 @@
 # Package
 
-version = "0.9.1"
+version = "0.10.0"
 author = "Esteban Castro Borsani (@nitely)"
 description = "Linear time regex matching"
 license = "MIT"
 srcDir = "src"
 skipDirs = @["tests"]
 
-requires "nim >= 0.19.0"
+requires "nim >= 0.18.0"
 requires "unicodedb >= 0.6.0 & < 0.7"
 requires "unicodeplus >= 0.4.0 & < 0.5"
 

src/regex.nim

@@ -2182,7 +2182,10 @@ proc populateCaptures(
   # then calculate slices for each match
   # (a group can have multiple matches).
   # Note the given `capture` is in reverse order (leaf to root)
-  result.groups.setLen(gc)
+  if result.groups.len == 0:  # todo: remove in Nim 0.18.1
+    result.groups = newSeq[Slice[int]](gc)
+  else:
+    result.groups.setLen(gc)
   var
     curr = cIdx
     ci = 0
@@ -2200,7 +2203,10 @@ proc populateCaptures(
     else:
       g.b = -1  # 0 .. -1
   assert ci mod 2 == 0
-  result.captures.setLen(ci div 2)
+  if result.captures.len == 0:  # todo: remove in Nim 0.18.1
+    result.captures = newSeq[Slice[int]](ci div 2)
+  else:
+    result.captures.setLen(ci div 2)
   curr = cIdx
   while curr != 0:
     let
@@ -2853,7 +2859,7 @@ when defined(forceRegexAtRuntime):
   proc re*(s: string): Regex {.inline.} =
     toPattern(s)
 else:
-  proc re*(s: static string): Regex {.inline.} =
+  proc re*(s: static[string]): Regex {.inline.} =
     ## Parse and compile a regular expression at compile-time
     const pattern = toPattern(s)
     pattern