Merge pull request #6110 from gunnarbeutner/feature/for-loop-var

Implement support for optionally specifying the 'var' keyword in 'for' loops

doc/17-language-reference.md

@@ -830,7 +830,7 @@ Example:
 
     var list = [ "a", "b", "c" ]
 
-    for (item in list) {
+    for (var item in list) {
       log("Item: " + item)
     }
 
@@ -841,7 +841,7 @@ Iterating over dictionaries can be accomplished in a similar manner:
 
     var dict = { a = 3, b = 7 }
 
-    for (key => value in dict) {
+    for (var key => var value in dict) {
       log("Key: " + key + ", Value: " + value)
     }
 
@@ -849,6 +849,9 @@ The `continue` and `break` keywords can be used to control how the loop is execu
 skips over the remaining expressions for the loop body and begins the next loop evaluation. The `break` keyword
 breaks out of the loop.
 
+The `var` keyword is optional when declaring variables in the loop's header. Variables declared without the `var`
+keyword are nonetheless local to the function.
+
 ## Constructors <a id="constructor"></a>
 
 In order to create a new value of a specific type constructor calls may be used.

lib/config/config_parser.yy

@@ -469,6 +469,10 @@ combined_set_op: T_SET
 	| T_SET_BINARY_OR
 	;
 
+optional_var: /* empty */
+	| T_VAR
+	;
+
 lterm: T_LIBRARY rterm
 	{
 		$$ = new LibraryExpression(std::unique_ptr<Expression>($2), @$);
@@ -603,7 +607,7 @@ lterm: T_LIBRARY rterm
 	}
 	| apply
 	| object
-	| T_FOR '(' identifier T_FOLLOWS identifier T_IN rterm ')'
+	| T_FOR '(' optional_var identifier T_FOLLOWS optional_var identifier T_IN rterm ')'
 	{
 		BeginFlowControlBlock(context, FlowControlContinue | FlowControlBreak, true);
 	}
@@ -611,11 +615,11 @@ lterm: T_LIBRARY rterm
 	{
 		EndFlowControlBlock(context);
 
-		$$ = new ForExpression(*$3, *$5, std::unique_ptr<Expression>($7), std::unique_ptr<Expression>($10), @$);
+		$$ = new ForExpression(*$4, *$7, std::unique_ptr<Expression>($9), std::unique_ptr<Expression>($12), @$);
-		delete $3;
+		delete $4;
-		delete $5;
+		delete $7;
 	}
-	| T_FOR '(' identifier T_IN rterm ')'
+	| T_FOR '(' optional_var identifier T_IN rterm ')'
 	{
 		BeginFlowControlBlock(context, FlowControlContinue | FlowControlBreak, true);
 	}
@@ -623,8 +627,8 @@ lterm: T_LIBRARY rterm
 	{
 		EndFlowControlBlock(context);
 
-		$$ = new ForExpression(*$3, "", std::unique_ptr<Expression>($5), std::unique_ptr<Expression>($8), @$);
+		$$ = new ForExpression(*$4, "", std::unique_ptr<Expression>($6), std::unique_ptr<Expression>($9), @$);
-		delete $3;
+		delete $4;
 	}
 	| T_FUNCTION identifier '(' identifier_items ')' use_specifier
 	{
@@ -1103,24 +1107,24 @@ use_specifier_item: identifier
 	;
 
 apply_for_specifier: /* empty */
-	| T_FOR '(' identifier T_FOLLOWS identifier T_IN rterm ')'
+	| T_FOR '(' optional_var identifier T_FOLLOWS optional_var identifier T_IN rterm ')'
 	{
-		context->m_FKVar.top() = *$3;
+		context->m_FKVar.top() = *$4;
-		delete $3;
+		delete $4;
 
-		context->m_FVVar.top() = *$5;
+		context->m_FVVar.top() = *$7;
-		delete $5;
+		delete $7;
 
-		context->m_FTerm.top() = $7;
+		context->m_FTerm.top() = $9;
 	}
-	| T_FOR '(' identifier T_IN rterm ')'
+	| T_FOR '(' optional_var identifier T_IN rterm ')'
 	{
-		context->m_FKVar.top() = *$3;
+		context->m_FKVar.top() = *$4;
-		delete $3;
+		delete $4;
 
 		context->m_FVVar.top() = "";
 
-		context->m_FTerm.top() = $5;
+		context->m_FTerm.top() = $6;
 	}
 	;