Add the ability to ignore errors in ExprTags

README.md

@@ -26,6 +26,7 @@ Salix's syntax is similar to Leaf and (in my opinion at least), it's much more f
   - [Global Functions](#global-functions)
   - [Adding Custom Functions](#adding-custom-functions)
 - [Expressions](#expressions)
+  - [Ignoring errors](#ignoring-errors)
   - [Ternary Expressions](#ternary-expressions)
   - [Coalescing operator](#coalescing-operator)
   - [The `in` operator](#the-in-operator)
@@ -189,6 +190,19 @@ You can include custom functions as variables using the WithVarMap method on tem
 
 Salix's expressions mostly work like Go's, but there are some extra features worth mentioning.
 
+### Ignoring errors
+
+If you'd like to ignore errors in an expression tag, you can do that by adding a question mark at the end.
+
+
+```html
+<!-- This would return an error if example wasn't defined or if it didn't have an Example() method -->
+#(example.Example())
+
+<!-- This would ignore any error and keep executing the rest of the template -->
+#(example.Example())?
+```
+
 ### Ternary Expressions
 
 Salix supports ternary expressions, which allow you to choose a value based on whether a condition is true. For example:

ast/ast.go

@@ -32,8 +32,9 @@ func (t Tag) Pos() Position {
 }
 
 type ExprTag struct {
-	Value    Node
+	Value       Node
-	Position Position
+	IgnoreError bool
+	Position    Position
 }
 
 func (et ExprTag) Pos() Position {

examples/readme/readme.salix.html

@@ -13,4 +13,4 @@
         </div>
         #!for
     </body>
-</html>
+</html>

parser/salix.peg

@@ -59,12 +59,12 @@ Root = items:(Tag / ExprTag / EndTag / Text)* {
     return out, nil
 }
 
-Tag = '#' name:Ident params:ParamList? body:':'? {
+Tag = '#' name:Ident params:ParamList? ignoreErr:'?'? body:':'? {
     return ast.Tag{
-        Name:     name.(ast.Ident),
+        Name:        name.(ast.Ident),
-        Params:   toNodeSlice(params),
+        Params:      toNodeSlice(params),
-        HasBody:  body != nil,
+        HasBody:     body != nil,
-        Position: getPos(c),
+        Position:    getPos(c),
     }, nil
 }
 
@@ -75,10 +75,11 @@ EndTag = "#!" name:Ident {
     }, nil
 }
 
-ExprTag = "#(" item:Expr ')' {
+ExprTag = "#(" item:Expr ')' ignoreErr:'?'? {
     return ast.ExprTag{
-        Value:    item.(ast.Node),
+        Value:       item.(ast.Node),
-        Position: getPos(c),
+        IgnoreError: ignoreErr != nil,
+        Position:    getPos(c),
     }, nil
 }
 
@@ -248,4 +249,4 @@ ArithmeticOp = ('+' / '-' / '/' / '*' / '%') {
 
 Text = . [^#]* { return ast.Text{Data: c.text, Position: getPos(c)}, nil }
 
-_ "whitespace" ← [ \t\r\n]*
+_ "whitespace" ← [ \t\r\n]*

salix.go

@@ -112,7 +112,11 @@ func (t *Template) execute(w io.Writer, nodes []ast.Node, local map[string]any)
 		case ast.ExprTag:
 			v, err := t.getValue(node.Value, local)
 			if err != nil {
-				return err
+				if node.IgnoreError {
+					continue
+				} else {
+					return err
+				}
 			}
 			if _, ok := v.(ast.Assignment); ok {
 				continue