Added variables

pkg/yqlib/operator_variables.go

@@ -0,0 +1,29 @@
+package yqlib
+
+import (
+	"container/list"
+	"fmt"
+)
+
+func getVariableOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	variableName := expressionNode.Operation.StringValue
+	log.Debug("getVariableOperator %v", variableName)
+	result := context.GetVariable(variableName)
+	if result == nil {
+		result = list.New()
+	}
+	return context.ChildContext(result), nil
+}
+
+func assignVariableOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	lhs, err := d.GetMatchingNodes(context, expressionNode.Lhs)
+	if err != nil {
+		return Context{}, nil
+	}
+	if expressionNode.Rhs.Operation.OperationType.Type != "GET_VARIABLE" {
+		return Context{}, fmt.Errorf("RHS of 'as' operator must be a variable name e.g. $foo")
+	}
+	variableName := expressionNode.Rhs.Operation.StringValue
+	context.SetVariable(variableName, lhs.MatchingNodes)
+	return context, nil
+}