support completions for command aliases (#669)

* support completions for command aliases

* try newer version of shellcheck

* initialize aliashash only when BASH_VERSION > 3

Author: rajatjindal

.circleci/config.yml

@@ -13,7 +13,7 @@ base: &base
         name: "All Commands"
         command: |
           mkdir -p bin
-          curl -Lso bin/shellcheck https://github.com/caarlos0/shellcheck-docker/releases/download/v0.4.3/shellcheck
+          curl -Lso bin/shellcheck https://github.com/caarlos0/shellcheck-docker/releases/download/v0.4.6/shellcheck
           chmod +x bin/shellcheck
           go get -t -v ./...
           PATH=$PATH:$PWD/bin go test -v ./...

bash_completions.go

@@ -251,6 +251,14 @@ __%[1]s_handle_word()
         __%[1]s_handle_command
     elif [[ $c -eq 0 ]]; then
         __%[1]s_handle_command
+    elif __%[1]s_contains_word "${words[c]}" "${command_aliases[@]}"; then
+        # aliashash variable is an associative array which is only supported in bash > 3.
+        if [[ -z "${BASH_VERSION}" || "${BASH_VERSINFO[0]}" -gt 3 ]]; then
+            words[c]=${aliashash[${words[c]}]}
+            __%[1]s_handle_command
+        else
+            __%[1]s_handle_noun
+        fi
     else
         __%[1]s_handle_noun
     fi
@@ -266,6 +274,7 @@ func writePostscript(buf *bytes.Buffer, name string) {
 	buf.WriteString(fmt.Sprintf(`{
     local cur prev words cword
     declare -A flaghash 2>/dev/null || :
+    declare -A aliashash 2>/dev/null || :
     if declare -F _init_completion >/dev/null 2>&1; then
         _init_completion -s || return
     else
@@ -305,6 +314,7 @@ func writeCommands(buf *bytes.Buffer, cmd *Command) {
 			continue
 		}
 		buf.WriteString(fmt.Sprintf("    commands+=(%q)\n", c.Name()))
+		writeCmdAliases(buf, c)
 	}
 	buf.WriteString("\n")
 }
@@ -443,6 +453,21 @@ func writeRequiredNouns(buf *bytes.Buffer, cmd *Command) {
 	}
 }
 
+func writeCmdAliases(buf *bytes.Buffer, cmd *Command) {
+	if len(cmd.Aliases) == 0 {
+		return
+	}
+
+	sort.Sort(sort.StringSlice(cmd.Aliases))
+
+	buf.WriteString(fmt.Sprint(`    if [[ -z "${BASH_VERSION}" || "${BASH_VERSINFO[0]}" -gt 3 ]]; then`, "\n"))
+	for _, value := range cmd.Aliases {
+		buf.WriteString(fmt.Sprintf("        command_aliases+=(%q)\n", value))
+		buf.WriteString(fmt.Sprintf("        aliashash[%q]=%q\n", value, cmd.Name()))
+	}
+	buf.WriteString(`    fi`)
+	buf.WriteString("\n")
+}
 func writeArgAliases(buf *bytes.Buffer, cmd *Command) {
 	buf.WriteString("    noun_aliases=()\n")
 	sort.Sort(sort.StringSlice(cmd.ArgAliases))
@@ -469,6 +494,10 @@ func gen(buf *bytes.Buffer, cmd *Command) {
 	}
 
 	buf.WriteString(fmt.Sprintf("    last_command=%q\n", commandName))
+	buf.WriteString("\n")
+	buf.WriteString("    command_aliases=()\n")
+	buf.WriteString("\n")
+
 	writeCommands(buf, cmd)
 	writeFlags(buf, cmd)
 	writeRequiredFlag(buf, cmd)