Add check on valid parse.
Add check on valid parse.

antlr/antlr4,parrt/antlr4,parrt/antlr4,parrt/antlr4,antlr/antlr4,ericvergnaud/antlr4,antlr/antlr4,parrt/antlr4,parrt/antlr4,ericvergnaud/antlr4,ericvergnaud/antlr4,antlr/antlr4,parrt/antlr4,ericvergnaud/antlr4,antlr/antlr4,antlr/antlr4,antlr/antlr4,antlr/antlr4,antlr/antlr4,ericvergnaud/antlr4,parrt/antlr4,antlr/antlr4,ericvergnaud/antlr4,parrt/antlr4,parrt/antlr4,ericvergnaud/antlr4,parrt/antlr4,ericvergnaud/antlr4,ericvergnaud/antlr4,ericvergnaud/antlr4