Add semver and semverCompare.

README.md

@@ -281,6 +281,13 @@ string is passed in, functions will attempt to conver with
        {{ derivePassword 1 "long" "password" "user" "example.com" }}
        ```
 
+## SemVer Functions:
+
+These functions provide version parsing and comparisons for SemVer 2 version
+strings.
+
+- semver: Parse a semantic version and return a Version object.
+- semverCompare: Compare a SemVer range to a particular version.
 
 ## Principles:
 

doc.go

@@ -213,5 +213,13 @@ Crypto Functions:
 	  Given parameters (in order) are:
           `counter` (starting with 1), `password_type` (maximum, long, medium, short, basic, or pin), `password`,
            `user`, and `site`
+
+SemVer Functions:
+
+These functions provide version parsing and comparisons for SemVer 2 version
+strings.
+
+	- semver: Parse a semantic version and return a Version object.
+	- semverCompare: Compare a SemVer range to a particular version.
 */
 package sprig

functions.go

@@ -243,4 +243,8 @@ var genericMap = map[string]interface{}{
 
 	// UUIDs:
 	"uuidv4": uuidv4,
+
+	// SemVer:
+	"semver":        semver,
+	"semverCompare": semverCompare,
 }

glide.yaml

@@ -6,3 +6,5 @@ import:
 - package: golang.org/x/crypto
   subpackages:
   - scrypt
+- package: github.com/Masterminds/semver
+  version: v1.2.2

semver.go

@@ -0,0 +1,23 @@
+package sprig
+
+import (
+	sv2 "github.com/Masterminds/semver"
+)
+
+func semverCompare(constraint, version string) (bool, error) {
+	c, err := sv2.NewConstraint(constraint)
+	if err != nil {
+		return false, err
+	}
+
+	v, err := sv2.NewVersion(version)
+	if err != nil {
+		return false, err
+	}
+
+	return c.Check(v), nil
+}
+
+func semver(version string) (*sv2.Version, error) {
+	return sv2.NewVersion(version)
+}

semver_test.go

@@ -0,0 +1,31 @@
+package sprig
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSemverCompare(t *testing.T) {
+	tests := map[string]string{
+		`{{ semverCompare "1.2.3" "1.2.3" }}`:  `true`,
+		`{{ semverCompare "^1.2.0" "1.2.3" }}`: `true`,
+		`{{ semverCompare "^1.2.0" "2.2.3" }}`: `false`,
+	}
+	for tpl, expect := range tests {
+		assert.NoError(t, runt(tpl, expect))
+	}
+}
+
+func TestSemver(t *testing.T) {
+	tests := map[string]string{
+		`{{ $s := semver "1.2.3-beta.1+c0ff33" }}{{ $s.Prerelease }}`: "beta.1",
+		`{{ $s := semver "1.2.3-beta.1+c0ff33" }}{{ $s.Major}}`:       "1",
+		`{{ semver "1.2.3" | (semver "1.2.3").Compare }}`:             `0`,
+		`{{ semver "1.2.3" | (semver "1.3.3").Compare }}`:             `1`,
+		`{{ semver "1.4.3" | (semver "1.2.3").Compare }}`:             `-1`,
+	}
+	for tpl, expect := range tests {
+		assert.NoError(t, runt(tpl, expect))
+	}
+}