1119 Add ability to define return type for methods

Updated ClassRenderer to check for `[]` to indicate return type for method. Small refactor to split out logic for determining method display text and style. Updated documentation

docs/classDiagram.md

@@ -105,7 +105,7 @@ Naming convention: a class name should be composed of alphanumeric (unicode allo
 
 UML provides mechanisms to represent class members, such as attributes and methods, and additional information about them.
 
-Mermaid distinguishes between attributes and functions/methods based on if the **parenthesis** `()` are present or not. The ones with `()` are treated as functions/methods, and others as attributes.
+Mermaid distinguishes between attributes and functions/methods based on if the **parenthesis** `()` are present or not. The ones with `()` are treated as functions/methods, and others as attributes. To indicate a return type for a method, enclose the type within **square brackets** `[]`
 
 
 There are two ways to define the members of a class, and regardless of whichever syntax is used to define the members, the output will still be same. The two different ways are :
@@ -115,15 +115,15 @@ There are two ways to define the members of a class, and regardless of whichever
   class BankAccount
   BankAccount : +String owner
   BankAccount : +BigDecimal balance
-  BankAccount : +deposit(amount)
-  BankAccount : +withdrawl(amount)
+  BankAccount : +deposit(amount) [bool]
+  BankAccount : +withdrawal(amount)
   ```
   ```  mermaid
     classDiagram
     class BankAccount
     BankAccount : +String owner
     BankAccount : +BigDecimal balance
-    BankAccount : +deposit(amount)
+    BankAccount : +deposit(amount) : bool
     BankAccount : +withdrawl(amount)
 ```
 
@@ -132,7 +132,7 @@ There are two ways to define the members of a class, and regardless of whichever
 class BankAccount{
     +String owner
     +BigDecimal balance
-    +deposit(amount)
+    +deposit(amount) [bool]
     +withdrawl(amount)
 }
 ```
@@ -141,7 +141,7 @@ class BankAccount{
     class BankAccount{
         +String owner
         +BigDecimal balance
-        +deposit(amount)
+        +deposit(amount) : bool
         +withdrawl(amount)
 }
 ```

src/diagrams/class/classRenderer.js

@@ -288,23 +288,14 @@ const drawClass = function(elem, classDef) {
   }
 
   const addTspan = function(textEl, txt, isFirst) {
+    let isMethod = txt.indexOf(')') > 1;
     let displayText = txt;
     let cssStyle = '';
-    let methodEnd = txt.indexOf(')') + 1;
 
-    if (methodEnd > 1 && methodEnd <= txt.length) {
-      let classifier = txt.substring(methodEnd);
-
-      switch (classifier) {
-        case '*':
-          cssStyle = 'font-style:italic;';
-          break;
-        case '$':
-          cssStyle = 'text-decoration:underline;';
-          break;
-      }
-
-      displayText = txt.substring(0, methodEnd);
+    if (isMethod) {
+      let method = buildDisplayTextForMethod(txt);
+      displayText = method.displayText;
+      cssStyle = method.cssStyle;
     }
 
     const tSpan = textEl
@@ -322,6 +313,40 @@ const drawClass = function(elem, classDef) {
   };
 
   const id = classDef.id;
+  const buildDisplayTextForMethod = function(txt) {
+    let cssStyle = '';
+    let methodEnd = txt.indexOf(')') + 1;
+    let methodName = txt.substring(0, methodEnd);
+
+    let classifier = txt.substring(methodEnd, methodEnd + 1);
+
+    switch (classifier) {
+      case '*':
+        cssStyle = 'font-style:italic;';
+        break;
+      case '$':
+        cssStyle = 'text-decoration:underline;';
+        break;
+    }
+
+    let method = {
+      methodname: methodName,
+      displayText: methodName,
+      cssStyle: cssStyle
+    };
+
+    let returnTypeStart = txt.indexOf('[') + 1;
+    let returnTypeEnd = txt.indexOf(']');
+
+    if (returnTypeStart > 1 && returnTypeEnd > returnTypeStart) {
+      let returnType = txt.substring(returnTypeStart, returnTypeEnd);
+
+      method.displayText = methodName + ' : ' + returnType;
+    }
+    
+    return method;
+  }
+
   const classInfo = {
     id: id,
     label: classDef.id,