From 40ee0cfd165ebbd81ce3915d5d55c530ae89eff3 Mon Sep 17 00:00:00 2001
From: walle250ai <chentong250ai@gmail.com>
Date: Tue, 28 Apr 2026 20:51:59 +0800
Subject: [PATCH] feat: add IsPrerelease and IsStable methods to Version

---
 version.go      | 30 +++++++++++++++
 version_test.go | 99 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)

diff --git a/version.go b/version.go
index 2627f13..5993625 100644
--- a/version.go
+++ b/version.go
@@ -366,6 +366,17 @@ func (v Version) Metadata() string {
 	return v.metadata
 }
 
+// IsPrerelease returns true if the version has a prerelease identifier.
+func (v *Version) IsPrerelease() bool {
+	return v.Prerelease() != ""
+}
+
+// IsStable returns true if the version is a stable release.
+// A version is stable when Major >= 1 and there's no prerelease identifier.
+func (v *Version) IsStable() bool {
+	return v.Major() >= 1 && v.Prerelease() == ""
+}
+
 // originalVPrefix returns the original 'v' prefix if any.
 func (v Version) originalVPrefix() string {
 	// Note, only lowercase v is supported as a prefix by the parser.
@@ -500,6 +511,25 @@ func (v *Version) Equal(o *Version) bool {
 	return v.Compare(o) == 0
 }
 
+// Diff returns the difference type between two versions.
+// It returns "major", "minor", "patch", "prerelease", or "" if the versions
+// are equal. Metadata differences are ignored.
+func (v *Version) Diff(o *Version) string {
+	if v.Major() != o.Major() {
+		return "major"
+	}
+	if v.Minor() != o.Minor() {
+		return "minor"
+	}
+	if v.Patch() != o.Patch() {
+		return "patch"
+	}
+	if v.Prerelease() != o.Prerelease() {
+		return "prerelease"
+	}
+	return ""
+}
+
 // Compare compares this version to another one. It returns -1, 0, or 1 if
 // the version smaller, equal, or larger than the other version.
 //
diff --git a/version_test.go b/version_test.go
index 03980ec..a25dde5 100644
--- a/version_test.go
+++ b/version_test.go
@@ -1027,6 +1027,105 @@ func TestValidateMetadata(t *testing.T) {
 	}
 }
 
+func TestDiff(t *testing.T) {
+	tests := []struct {
+		v1       string
+		v2       string
+		expected string
+	}{
+		{"1.2.3", "2.2.3", "major"},
+		{"1.2.3", "1.3.3", "minor"},
+		{"1.2.3", "1.2.4", "patch"},
+		{"1.2.3", "1.2.3-alpha", "prerelease"},
+		{"1.2.3-alpha", "1.2.3-beta", "prerelease"},
+		{"1.2.3-alpha.1", "1.2.3-alpha.2", "prerelease"},
+		{"1.2.3", "1.2.3", ""},
+		{"1.2.3+foo", "1.2.3+bar", ""},
+		{"1.2.3-alpha+foo", "1.2.3-alpha+bar", ""},
+	}
+
+	for _, tc := range tests {
+		v1, err := NewVersion(tc.v1)
+		if err != nil {
+			t.Errorf("Error parsing version: %s", err)
+		}
+
+		v2, err := NewVersion(tc.v2)
+		if err != nil {
+			t.Errorf("Error parsing version: %s", err)
+		}
+
+		a := v1.Diff(v2)
+		e := tc.expected
+		if a != e {
+			t.Errorf(
+				"Diff of '%s' and '%s' failed. Expected '%s', got '%s'",
+				tc.v1, tc.v2, e, a,
+			)
+		}
+	}
+}
+
+func TestIsPrerelease(t *testing.T) {
+	tests := []struct {
+		version  string
+		expected bool
+	}{
+		{"1.2.3", false},
+		{"1.2.3-alpha", true},
+		{"1.2.3-alpha.1", true},
+		{"0.3.7", false},
+		{"0.3.7-beta", true},
+		{"1.2.3-x.7.z.92", true},
+	}
+
+	for _, tc := range tests {
+		v, err := NewVersion(tc.version)
+		if err != nil {
+			t.Errorf("Error parsing version: %s", err)
+		}
+
+		a := v.IsPrerelease()
+		e := tc.expected
+		if a != e {
+			t.Errorf(
+				"IsPrerelease of '%s' failed. Expected '%t', got '%t'",
+				tc.version, e, a,
+			)
+		}
+	}
+}
+
+func TestIsStable(t *testing.T) {
+	tests := []struct {
+		version  string
+		expected bool
+	}{
+		{"0.1.0", false},
+		{"0.9.9", false},
+		{"1.0.0", true},
+		{"1.0.0-beta", false},
+		{"2.3.4", true},
+		{"1.2.3-alpha.1", false},
+	}
+
+	for _, tc := range tests {
+		v, err := NewVersion(tc.version)
+		if err != nil {
+			t.Errorf("Error parsing version: %s", err)
+		}
+
+		a := v.IsStable()
+		e := tc.expected
+		if a != e {
+			t.Errorf(
+				"IsStable of '%s' failed. Expected '%t', got '%t'",
+				tc.version, e, a,
+			)
+		}
+	}
+}
+
 func FuzzNewVersion(f *testing.F) {
 	testcases := []string{"v1.2.3", " ", "......", "1", "1.2.3-beta.1", "1.2.3+foo", "2.3.4-alpha.1+bar", "lorem ipsum"}