Add conditional value emitting

Signed-off-by: Marcel Müller <neikos@neikos.email>

src/compiler/mod.rs

@@ -57,6 +57,7 @@ pub enum Instruction {
     LoadFromContextToSlot {
         name: NomoInput,
         slot: VariableSlot,
+        fail_on_not_found: bool,
     },
     EmitFromSlot {
         slot: VariableSlot,
@@ -440,6 +441,14 @@ fn emit_expr_load(
             eval.push(Instruction::LoadFromContextToSlot {
                 name: template_token.source().clone(),
                 slot: emit_slot,
+                fail_on_not_found: true,
+            });
+        }
+        TemplateAstExpr::ConditionalAccess(template_token) => {
+            eval.push(Instruction::LoadFromContextToSlot {
+                name: template_token.source().clone(),
+                slot: emit_slot,
+                fail_on_not_found: false,
             });
         }
         TemplateAstExpr::Literal { source, value } => {
@@ -476,7 +485,6 @@ fn emit_expr_load(
                 slot: emit_slot,
             });
         }
-        TemplateAstExpr::ConditionalAccess { .. } => todo!(),
         TemplateAstExpr::Invalid { .. } => eval.push(Instruction::Abort),
         TemplateAstExpr::StaticContent { .. } | TemplateAstExpr::Interpolation { .. } => {
             unreachable!("Invalid AST here")
@@ -523,6 +531,7 @@ mod tests {
                     slot: VariableSlot {
                         index: 0,
                     },
+                    fail_on_not_found: true,
                 },
                 EmitFromSlot {
                     slot: VariableSlot {

src/compiler/snapshots/nomo__compiler__tests__check_if_else_if.snap

@@ -20,6 +20,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 1,
             },
+            fail_on_not_found: true,
         },
         JumpIfNotTrue {
             emit_slot: VariableSlot {
@@ -51,6 +52,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 3,
             },
+            fail_on_not_found: true,
         },
         JumpIfNotTrue {
             emit_slot: VariableSlot {

src/eval/mod.rs

@@ -93,15 +93,34 @@ pub fn execute(
         match instr {
             Instruction::NoOp => (),
             Instruction::AppendContent { content } => output.push_str(content),
-            Instruction::LoadFromContextToSlot { name, slot } => {
+            Instruction::LoadFromContextToSlot {
-                let value = scopes
+                name,
-                    .get_scoped(name)
+                slot,
-                    .ok_or(EvaluationError::UnknownVariable(name.clone()))?;
+                fail_on_not_found,
+            } => {
+                let value = scopes.get_scoped(name);
+
+                let value = if let Some(val) = value {
+                    val
+                } else {
+                    if *fail_on_not_found {
+                        return Err(EvaluationError::UnknownVariable(name.clone()));
+                    } else {
+                        &NomoValue::Undefined
+                    }
+                };
 
                 scopes.insert_into_slot(*slot, value.clone());
             }
             Instruction::EmitFromSlot { slot } => {
-                let value = scopes.get(slot).try_to_string().unwrap();
+                let value = scopes.get(slot);
+                let value = if let Some(value) = value.try_to_string() {
+                    value
+                } else if matches!(value, NomoValue::Undefined) {
+                    String::new()
+                } else {
+                    panic!("Unknown variable");
+                };
 
                 output.push_str(&value);
             }
@@ -286,4 +305,26 @@ mod tests {
         )
         "#);
     }
+
+    #[test]
+    fn check_conditional_access() {
+        let input = "Hello {{= unknown? }}";
+
+        let parsed = crate::lexer::parse(input.into()).unwrap();
+
+        let ast = crate::parser::parse(parsed.tokens()).unwrap();
+
+        let emit = crate::compiler::emit_machine(ast);
+
+        let context = Context::new();
+        let function_map = FunctionMap::default();
+
+        let output = execute(&function_map, &emit, &context);
+
+        insta::assert_debug_snapshot!(output, @r#"
+        Ok(
+            "Hello ",
+        )
+        "#);
+    }
 }

tests/cases/condition.3-instructions.snap

@@ -22,6 +22,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 1,
             },
+            fail_on_not_found: true,
         },
         JumpIfNotTrue {
             emit_slot: VariableSlot {
@@ -56,6 +57,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 3,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {

tests/cases/identifiers.3-instructions.snap

@@ -4,12 +4,12 @@ expression: emit
 info:
   input: "{{= _name }}\n{{= a_name }}\n{{= name }}\n{{= _name1 }}\n{{= _namE }}\n{{= name1 }}"
   context:
-    name1: Foo
-    _name: Foo
-    _namE: Foo
     a_name: Foo
-    name: Foo
+    _name: Foo
     _name1: Foo
+    _namE: Foo
+    name1: Foo
+    name: Foo
 ---
 VMInstructions {
     labels: {},
@@ -19,6 +19,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 0,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -33,6 +34,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 1,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -47,6 +49,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 2,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -61,6 +64,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 3,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -75,6 +79,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 4,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -89,6 +94,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 5,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {

tests/cases/if_else_if.3-instructions.snap

@@ -26,6 +26,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 1,
             },
+            fail_on_not_found: true,
         },
         JumpIfNotTrue {
             emit_slot: VariableSlot {
@@ -57,6 +58,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 3,
             },
+            fail_on_not_found: true,
         },
         JumpIfNotTrue {
             emit_slot: VariableSlot {

tests/cases/interpolation.3-instructions.snap

@@ -20,6 +20,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 0,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {

tests/cases/multiple.3-instructions.snap

@@ -21,6 +21,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 0,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -35,6 +36,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 1,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {

tests/cases/simple_for.3-instructions.snap

@@ -39,6 +39,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 4,
             },
+            fail_on_not_found: true,
         },
         CreateIteratorFromSlotToSlot {
             iterator_slot: VariableSlot {
@@ -78,6 +79,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 6,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {
@@ -104,6 +106,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 11,
             },
+            fail_on_not_found: true,
         },
         CreateIteratorFromSlotToSlot {
             iterator_slot: VariableSlot {
@@ -143,6 +146,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 13,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {

tests/cases/trim_whitespace.3-instructions.snap

@@ -4,8 +4,8 @@ expression: emit
 info:
   input: "{{ if test -}}\n    Hello {{= stuff -}}\n{{- end }}"
   context:
-    stuff: Hemera
     test: true
+    stuff: Hemera
 ---
 VMInstructions {
     labels: {
@@ -22,6 +22,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 1,
             },
+            fail_on_not_found: true,
         },
         JumpIfNotTrue {
             emit_slot: VariableSlot {
@@ -42,6 +43,7 @@ VMInstructions {
             slot: VariableSlot {
                 index: 3,
             },
+            fail_on_not_found: true,
         },
         EmitFromSlot {
             slot: VariableSlot {