added bidirectional relationships

https://github.com/RicardoNiepel/C4-PlantUML/issues/43

.vscode/C4.code-snippets

@@ -257,6 +257,24 @@
 		],
 		"description": "Add unidirectional Relationship with Technology to C4 diagram"
 	},
+	"C4_Relationship_Bi": {
+		"scope": "diagram",
+		"prefix": "Bidirectional Relationship",
+		"body": [
+			"BiRel(${1:from_alias}, ${2:to_alias}, \"${3:label}\")",
+			"$0"
+		],
+		"description": "Add bidirectional Relationship to C4 diagram"
+	},
+	"C4_Relationship_Bi_Techn": {
+		"scope": "diagram",
+		"prefix": "Bidirectional Relationship with Technology",
+		"body": [
+			"BiRel(${1:from_alias}, ${2:to_alias}, \"${3:label}\", \"${4:technology}\")",
+			"$0"
+		],
+		"description": "Add bidirectional Relationship with Technology to C4 diagram"
+	},
 	"C4_Relationship_Index": {
 		"scope": "diagram",
 		"prefix": "Relationship with Index",

C4.puml

@@ -94,6 +94,12 @@ Rel_($from, $to, $label, "-->>")
 !unquoted function Rel($from, $to, $label, $techn)
 Rel_($from, $to, $label, $techn, "-->>")
 !endfunction
+!unquoted function BiRel($from, $to, $label)
+Rel_($from, $to, $label, "<<-->>")
+!endfunction
+!unquoted function BiRel($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-->>")
+!endfunction
 
 !unquoted function Rel_Back($from, $to, $label)
 Rel_($from, $to, $label, "<<--")
@@ -128,6 +134,18 @@ Rel_($from, $to, $label, "-DOWN->>")
 !unquoted function Rel_Down($from, $to, $label, $techn)
 Rel_($from, $to, $label, $techn, "-DOWN->>")
 !endfunction
+!unquoted function BiRel_D($from, $to, $label)
+Rel_($from, $to, $label, "<<-DOWN->>")
+!endfunction
+!unquoted function BiRel_D($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-DOWN->>")
+!endfunction
+!unquoted function BiRel_Down($from, $to, $label)
+Rel_($from, $to, $label, "<<-DOWN->>")
+!endfunction
+!unquoted function BiRel_Down($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-DOWN->>")
+!endfunction
 
 !unquoted function Rel_U($from, $to, $label)
 Rel_($from, $to, $label, "-UP->>")
@@ -141,6 +159,18 @@ Rel_($from, $to, $label, "-UP->>")
 !unquoted function Rel_Up($from, $to, $label, $techn)
 Rel_($from, $to, $label, $techn, "-UP->>")
 !endfunction
+!unquoted function BiRel_U($from, $to, $label)
+Rel_($from, $to, $label, "<<-UP->>")
+!endfunction
+!unquoted function BiRel_U($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-UP->>")
+!endfunction
+!unquoted function BiRel_Up($from, $to, $label)
+Rel_($from, $to, $label, "<<-UP->>")
+!endfunction
+!unquoted function BiRel_Up($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-UP->>")
+!endfunction
 
 !unquoted function Rel_L($from, $to, $label)
 Rel_($from, $to, $label, "-LEFT->>")
@@ -154,6 +184,18 @@ Rel_($from, $to, $label, "-LEFT->>")
 !unquoted function Rel_Left($from, $to, $label, $techn)
 Rel_($from, $to, $label, $techn, "-LEFT->>")
 !endfunction
+!unquoted function BiRel_L($from, $to, $label)
+Rel_($from, $to, $label, "<<-LEFT->>")
+!endfunction
+!unquoted function BiRel_L($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-LEFT->>")
+!endfunction
+!unquoted function BiRel_Left($from, $to, $label)
+Rel_($from, $to, $label, "<<-LEFT->>")
+!endfunction
+!unquoted function BiRel_Left($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-LEFT->>")
+!endfunction
 
 !unquoted function Rel_R($from, $to, $label)
 Rel_($from, $to, $label, "-RIGHT->>")
@@ -167,6 +209,18 @@ Rel_($from, $to, $label, "-RIGHT->>")
 !unquoted function Rel_Right($from, $to, $label, $techn)
 Rel_($from, $to, $label, $techn, "-RIGHT->>")
 !endfunction
+!unquoted function BiRel_R($from, $to, $label)
+Rel_($from, $to, $label, "<<-RIGHT->>")
+!endfunction
+!unquoted function BiRel_R($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-RIGHT->>")
+!endfunction
+!unquoted function BiRel_Right($from, $to, $label)
+Rel_($from, $to, $label, "<<-RIGHT->>")
+!endfunction
+!unquoted function BiRel_Right($from, $to, $label, $techn)
+Rel_($from, $to, $label, $techn, "<<-RIGHT->>")
+!endfunction
 
 ' Layout Helpers
 ' ##################################