From 82716427165106cb17f596c191b4e64edc9e1687 Mon Sep 17 00:00:00 2001
From: Nathanael Jones <nathanael.jones@gmail.com>
Date: Sat, 23 May 2015 11:35:41 -0400
Subject: [PATCH] Add SemVerHelper.isValidSemVer(string) Allows build scripts
 to check if a git tag or input string is a semver.

---
 src/app/FakeLib/SemVerHelper.fs             | 12 +++++++++++
 src/test/Test.FAKECore/SemVerHelperSpecs.cs | 24 +++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/src/app/FakeLib/SemVerHelper.fs b/src/app/FakeLib/SemVerHelper.fs
index c782ce8fd36..134dc791f11 100644
--- a/src/app/FakeLib/SemVerHelper.fs
+++ b/src/app/FakeLib/SemVerHelper.fs
@@ -76,6 +76,15 @@ type SemVerInfo =
                     0
             | _ -> invalidArg "yobj" "cannot compare values of different types"
 
+
+let private SemVerPattern = "^(?:0|[1-9][0-9]*)\.(?:0|[1-9][0-9]*)\.(?:0|[1-9][0-9]*)(?:-[\da-zA-Z\-]+(?:\.[\da-zA-Z\-]+)*)?(?:\+[\da-zA-Z\-]+(?:\.[\da-zA-Z\-]+)*)?$"
+
+/// Returns true if input appears to be a parsable semver string
+let isValidSemVer input =
+    let m = Regex.Match(input, SemVerPattern)
+    if m.Success then true
+    else false
+
 /// Parses the given version string into a SemVerInfo which can be printed using ToString() or compared
 /// according to the rules described in the [SemVer docs](http://semver.org/).
 /// ## Sample
@@ -100,3 +109,6 @@ let parse version =
       PreRelease = PreRelease.TryParse preRelease
       Build = if l > 3 then splitted.[3] else "" 
     }
+
+
+
diff --git a/src/test/Test.FAKECore/SemVerHelperSpecs.cs b/src/test/Test.FAKECore/SemVerHelperSpecs.cs
index 0e543b265dc..8a3de15ba47 100644
--- a/src/test/Test.FAKECore/SemVerHelperSpecs.cs
+++ b/src/test/Test.FAKECore/SemVerHelperSpecs.cs
@@ -33,6 +33,30 @@ public class when_parsing_semver_strings_and_printing_the_result
             () => SemVerHelper.parse("1.2.3-foo").ToString().ShouldEqual("1.2.3-foo");
     }
 
+    public class when_validating_semver_strings
+    {
+        It should_validate_0_1_2 =
+            () => SemVerHelper.isValidSemVer("0.1.2").ShouldEqual(true);
+
+        It should_validate_alpha_beta_versions =
+            () => SemVerHelper.isValidSemVer("1.0.0-alpha.beta").ShouldEqual(true);
+
+        It should_validate_prerelease_versions_without_build =
+            () => SemVerHelper.isValidSemVer("1.2.3-foo").ShouldEqual(true);
+
+        It should_reject_leading_zeros = 
+            () => SemVerHelper.isValidSemVer("01.02.03").ShouldEqual(false);
+
+        It should_require_3_numbers = 
+            () => SemVerHelper.isValidSemVer("1.2").ShouldEqual(false);
+
+        It should_reject_leading_v = 
+            () => SemVerHelper.isValidSemVer("v1.2.0").ShouldEqual(false);
+
+
+    }
+
+
     public class when_parsing_semver_strings
     {
         static SemVerHelper.SemVerInfo semVer;