Merge pull request #21 from git-chglog/feat/next-tag

Add `--next-tag` flag (EXPERIMENTAL)

README.md

@@ -154,7 +154,7 @@ USAGE:
 
     There are the following specification methods for <tag query>.
 
-    1. <old>..<new> - Commit contained in <new> tags from <old>.
+    1. <old>..<new> - Commit contained in <old> tags from <new>.
     2. <name>..     - Commit from the <name> to the latest tag.
     3. ..<name>     - Commit from the oldest tag to <name>.
     4. <name>       - Commit contained in <name>.
@@ -163,6 +163,7 @@ OPTIONS:
   --init                    generate the git-chglog configuration file in interactive
   --config value, -c value  specifies a different configuration file to pick up (default: ".chglog/config.yml")
   --output value, -o value  output path and filename for the changelogs. If not specified, output to stdout
+  --next-tag value          treat unreleased commits as specified tags (EXPERIMENTAL)
   --silent                  disable stdout output
   --no-color                disable color output [$NO_COLOR]
   --no-emoji                disable emoji output [$NO_EMOJI]
@@ -486,6 +487,25 @@ See godoc [RenderData][doc-render-data] for available variables.
   By displaying it on the standard output, it makes it easy to change the contents.
 </details>
 
+<details>
+  <summary>Can I commit CHANGELOG changes before creating tags?</summary>
+
+  Yes, it can be solved by using the `--next-tag` flag.
+
+  For example, let's say you want to upgrade your project to `2.0.0`.  
+  You can create CHANGELOG containing `2.0.0` as follows.
+
+  ```bash
+  $ git-chglog --next-tag 2.0.0 -o CHANGELOG.md
+  $ git commit -am "release 2.0.0"
+  $ git tag 2.0.0
+  ```
+
+  The point to notice is that before actually creating a tag with git, it is conveying the next version with `--next-tag` :+1:
+
+  This is a step that is necessary for project operation in many cases.
+</details>
+
 
 
 

chglog.go

@@ -16,6 +16,7 @@ import (
 // Options is an option used to process commits
 type Options struct {
 	Processor            Processor
+	NextTag              string              // Treat unreleased commits as specified tags (EXPERIMENTAL)
 	CommitFilters        map[string][]string // Filter by using `Commit` properties and values. Filtering is not done by specifying an empty value
 	CommitSortBy         string              // Property name to use for sorting `Commit` (e.g. `Scope`)
 	CommitGroupBy        string              // Property name of `Commit` to be grouped into `CommitGroup` (e.g. `Type`)
@@ -150,18 +151,30 @@ func (gen *Generator) Generate(w io.Writer, query string) error {
 }
 
 func (gen *Generator) readVersions(tags []*Tag, first string) ([]*Version, error) {
+	next := gen.config.Options.NextTag
 	versions := []*Version{}
 
 	for i, tag := range tags {
-		var rev string
-
-		if i+1 < len(tags) {
-			rev = tags[i+1].Name + ".." + tag.Name
+		var (
+			isNext = next == tag.Name
+			rev    string
+		)
+
+		if isNext {
+			if tag.Previous != nil {
+				rev = tag.Previous.Name + "..HEAD"
+			} else {
+				rev = "HEAD"
+			}
 		} else {
-			if first != "" {
-				rev = first + ".." + tag.Name
+			if i+1 < len(tags) {
+				rev = tags[i+1].Name + ".." + tag.Name
 			} else {
-				rev = tag.Name
+				if first != "" {
+					rev = first + ".." + tag.Name
+				} else {
+					rev = tag.Name
+				}
 			}
 		}
 
@@ -180,12 +193,21 @@ func (gen *Generator) readVersions(tags []*Tag, first string) ([]*Version, error
 			RevertCommits: revertCommits,
 			NoteGroups:    noteGroups,
 		})
+
+		// Instead of `getTags()`, assign the date to the tag
+		if isNext {
+			tag.Date = commits[0].Author.Date
+		}
 	}
 
 	return versions, nil
 }
 
 func (gen *Generator) readUnreleased(tags []*Tag) (*Unreleased, error) {
+	if gen.config.Options.NextTag != "" {
+		return &Unreleased{}, nil
+	}
+
 	rev := "HEAD"
 
 	if len(tags) > 0 {
@@ -216,6 +238,33 @@ func (gen *Generator) getTags(query string) ([]*Tag, string, error) {
 		return nil, "", err
 	}
 
+	next := gen.config.Options.NextTag
+	if next != "" {
+		for _, tag := range tags {
+			if next == tag.Name {
+				return nil, "", fmt.Errorf("\"%s\" tag already exists", next)
+			}
+		}
+
+		var previous *RelateTag
+		if len(tags) > 0 {
+			previous = &RelateTag{
+				Name:    tags[0].Name,
+				Subject: tags[0].Subject,
+				Date:    tags[0].Date,
+			}
+		}
+
+		// Assign the date with `readVersions()`
+		tags = append([]*Tag{
+			&Tag{
+				Name:     next,
+				Subject:  next,
+				Previous: previous,
+			},
+		}, tags...)
+	}
+
 	if len(tags) == 0 {
 		return nil, "", errors.New("git-tag does not exist")
 	}