feat: implements --tags

Implements `--tags`, which lists all tags in use.

cmd/cheat/cmd_tags.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/cheat/cheat/internal/config"
+	"github.com/cheat/cheat/internal/sheets"
+)
+
+// cmdTags lists all tags in use.
+func cmdTags(opts map[string]interface{}, conf config.Config) {
+
+	// load the cheatsheets
+	cheatsheets, err := sheets.Load(conf.Cheatpaths)
+	if err != nil {
+		fmt.Fprintln(os.Stderr, fmt.Sprintf("failed to list cheatsheets: %v", err))
+		os.Exit(1)
+	}
+
+	// write sheet tags to stdout
+	for _, tag := range sheets.Tags(cheatsheets) {
+		fmt.Println(tag)
+	}
+}

cmd/cheat/docopt.txt

@@ -11,6 +11,7 @@ Options:
   -r --regex            Treat search <phrase> as a regex
   -s --search=<phrase>  Search cheatsheets for <phrase>
   -t --tag=<tag>        Return only sheets matching <tag>
+  -T --tags             List all tags in use
   -v --version          Print the version number
 
 Examples:
@@ -33,6 +34,9 @@ Examples:
   To list all available cheatsheets:
     cheat -l
 
+  To list all tags in use:
+    cheat -T
+
   To list available cheatsheets that are tagged as "personal":
     cheat -l -t personal
 

cmd/cheat/main.go

@@ -76,6 +76,9 @@ func main() {
 	case opts["--list"].(bool):
 		cmd = cmdList
 
+	case opts["--tags"].(bool):
+		cmd = cmdTags
+
 	case opts["--search"] != nil:
 		cmd = cmdSearch
 

cmd/cheat/str_usage.go

@@ -20,6 +20,7 @@ Options:
   -r --regex            Treat search <phrase> as a regex
   -s --search=<phrase>  Search cheatsheets for <phrase>
   -t --tag=<tag>        Return only sheets matching <tag>
+  -T --tags             List all tags in use
   -v --version          Print the version number
 
 Examples:

internal/sheets/tags.go

@@ -0,0 +1,36 @@
+package sheets
+
+import (
+	"sort"
+
+	"github.com/cheat/cheat/internal/sheet"
+)
+
+// Tags returns a slice of all tags in use in any sheet
+func Tags(cheatpaths []map[string]sheet.Sheet) []string {
+
+	// create a map of all tags in use in any sheet
+	tags := make(map[string]bool)
+
+	// iterate over all tags on all sheets on all cheatpaths
+	for _, path := range cheatpaths {
+		for _, sheet := range path {
+			for _, tag := range sheet.Tags {
+				tags[tag] = true
+			}
+		}
+	}
+
+	// restructure the map into a slice
+	sorted := []string{}
+	for tag := range tags {
+		sorted = append(sorted, tag)
+	}
+
+	// sort the slice
+	sort.Slice(sorted, func(i, j int) bool {
+		return sorted[i] < sorted[j]
+	})
+
+	return sorted
+}

internal/sheets/tags_test.go

@@ -0,0 +1,51 @@
+package sheets
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/davecgh/go-spew/spew"
+
+	"github.com/cheat/cheat/internal/sheet"
+)
+
+// TestTags asserts that cheetsheet tags are properly returned
+func TestTags(t *testing.T) {
+
+	// mock cheatsheets available on multiple cheatpaths
+	cheatpaths := []map[string]sheet.Sheet{
+
+		// mock community cheatsheets
+		map[string]sheet.Sheet{
+			"foo": sheet.Sheet{Title: "foo", Tags: []string{"alpha"}},
+			"bar": sheet.Sheet{Title: "bar", Tags: []string{"alpha", "bravo"}},
+		},
+
+		// mock local cheatsheets
+		map[string]sheet.Sheet{
+			"bar": sheet.Sheet{Title: "bar", Tags: []string{"bravo", "charlie"}},
+			"baz": sheet.Sheet{Title: "baz", Tags: []string{"delta"}},
+		},
+	}
+
+	// consolidate the cheatsheets
+	tags := Tags(cheatpaths)
+
+	// specify the expected output
+	want := []string{
+		"alpha",
+		"bravo",
+		"charlie",
+		"delta",
+	}
+
+	// assert that the cheatsheets properly consolidated
+	if !reflect.DeepEqual(tags, want) {
+		t.Errorf(
+			"failed to return tags: want:\n%s, got:\n%s",
+			spew.Sdump(want),
+			spew.Sdump(tags),
+		)
+	}
+
+}