[glsl-new] Add jump statements (#179)

* [glsl-new] Add jump statements

- continue
- break
- return
- discard

* [glsl-new] Fix clippy error for return statement

src/front/glsl_new/lex.rs

@@ -139,6 +139,11 @@ pub fn consume_token(mut input: &str) -> (Option<Token>, &str) {
                 // values
                 "true" => (Some(Token::BoolConstant((meta, true))), rest),
                 "false" => (Some(Token::BoolConstant((meta, false))), rest),
+                // jump statements
+                "continue" => (Some(Token::Continue(meta)), rest),
+                "break" => (Some(Token::Break(meta)), rest),
+                "return" => (Some(Token::Return(meta)), rest),
+                "discard" => (Some(Token::Discard(meta)), rest),
                 // types
                 "void" => (Some(Token::Void(meta)), rest),
                 word => {

src/front/glsl_new/parser.rs

@@ -53,6 +53,7 @@ pomelo! {
     %type simple_statement Statement;
     %type expression_statement Statement;
     %type declaration_statement Statement;
+    %type jump_statement Statement;
 
     // expressions
     %type unary_expression ExpressionRule;
@@ -600,7 +601,7 @@ pomelo! {
     //simple_statement ::= switch_statement;
     //simple_statement ::= case_label;
     //simple_statement ::= iteration_statement;
-    //simple_statement ::= jump_statement;
+    simple_statement ::= jump_statement;
 
     compound_statement ::= LeftBrace RightBrace {vec![]}
     compound_statement ::= left_brace_scope statement_list(sl) RightBrace {
@@ -671,6 +672,21 @@ pomelo! {
     type_specifier_nonarray ::= Void { None }
     type_specifier_nonarray ::= TypeName(t) {Some(t.1)};
 
+    jump_statement ::= Continue Semicolon { Statement::Continue }
+    jump_statement ::= Break Semicolon { Statement::Break }
+    jump_statement ::= Return Semicolon { Statement::Return{ value: None } }
+    jump_statement ::= Return expression(mut e) Semicolon {
+        let ret = Statement::Return{ value: Some(e.expression) };
+        if !e.statements.is_empty() {
+            e.statements.push(ret);
+            Statement::Block(e.statements)
+        } else {
+            ret
+        }
+    }
+    jump_statement ::= Discard Semicolon  { Statement::Kill } // Fragment shader only
+    // Grammar Note: No 'goto'. Gotos are not supported.
+
     // misc
     translation_unit ::= external_declaration;
     translation_unit ::= translation_unit external_declaration;