From 7c3f0e6aa4b2e8c4570e5027ac7d661e1080617c Mon Sep 17 00:00:00 2001
From: Timothee Cour <timothee.cour2@gmail.com>
Date: Thu, 3 Jun 2021 16:05:19 -0700
Subject: [PATCH] use strscans

---
 tests/tools/tnimdigger.nim | 11 +++++++++++
 tools/nimdigger.nim        | 23 ++++++++++-------------
 2 files changed, 21 insertions(+), 13 deletions(-)
 create mode 100644 tests/tools/tnimdigger.nim

diff --git a/tests/tools/tnimdigger.nim b/tests/tools/tnimdigger.nim
new file mode 100644
index 0000000000000..d2d307277b2d9
--- /dev/null
+++ b/tests/tools/tnimdigger.nim
@@ -0,0 +1,11 @@
+import tools/nimdigger {.all.}
+
+block: # parseNimGitTag
+  doAssert parseNimGitTag("v1.4.2") == (1, 4, 2)
+  doAssertRaises(ValueError): discard parseNimGitTag("v1.4")
+  doAssertRaises(ValueError): discard parseNimGitTag("v1.4.2a")
+  doAssertRaises(ValueError): discard parseNimGitTag("av1.4.2")
+
+block: # isGitNimTag
+  doAssert isGitNimTag("v1.4.2")
+  doAssert not isGitNimTag("v1.4.2a")
diff --git a/tools/nimdigger.nim b/tools/nimdigger.nim
index 421490a7eb062..401e07f0657d4 100644
--- a/tools/nimdigger.nim
+++ b/tools/nimdigger.nim
@@ -185,21 +185,18 @@ proc gitIsAncestorOf(dir: string, rev1, rev2: string): bool =
   gitCheck(dir)
   execShellCmd(fmt"git -C {dir.quoteShell} merge-base --is-ancestor {rev1} {rev2}") == 0
 
-proc isGitNimTag(tag: string): bool =
-  if not tag.startsWith "v":
-    return false
-  let ver = tag[1..^1].split(".")
-  return ver.len == 3
+import std/strscans
 
 proc parseNimGitTag(tag: string): (int, int, int) =
-  doAssert tag.isGitNimTag, tag
-  let ver = tag[1..^1].split(".")
-  template impl(i) =
-    # improve pending https://github.com/nim-lang/Nim/pull/18038
-    result[i] = ver[i].parseInt
-  impl 0
-  impl 1
-  impl 2
+  if not scanf(tag, "v$i.$i.$i$.", result[0], result[1], result[2]):
+    raise newException(ValueError, tag)
+
+proc isGitNimTag(tag: string): bool =
+  try:
+    discard parseNimGitTag(tag)
+    return true
+  except ValueError:
+    return false
 
 proc toNimCsourcesExe(binDir: string, name: string, rev: string): string =
   let rev2 = rev.replace(".", "_")