19.1.1 Problem #1: Names Too Specific

Consider the two groups of productions:

PackageName:

	Identifier

	PackageName . Identifier

TypeName:

	Identifier

	PackageName . Identifier

and:

MethodName:

	Identifier

	AmbiguousName . Identifier

AmbiguousName:

	Identifier

	AmbiguousName . Identifier

Now consider the partial input:

class Problem1 { int m() { hayden.

When the parser is considering the token hayden, with one-token lookahead to symbol ".", it cannot yet tell whether hayden should be a PackageName that qualifies a type name, as in:

hayden.Dinosaur rex = new Hayden.Dinosaur(2);

or an AmbiguousName that qualifies a method name, as in:

hayden.print("Dinosaur Rex!");

Therefore, the productions shown above result in a grammar that is not LALR(1). There are also other problems with drawing distinctions among different kinds of names in the grammar.

The solution is to eliminate the nonterminals PackageName, TypeName, ExpressionName, MethodName, and AmbiguousName, replacing them all with a single nonterminal Name:

Name:

	SimpleName

	QualifiedName

SimpleName:

	Identifier

QualifiedName:

	Name . Identifier

A later stage of compiler analysis then sorts out the precise role of each name or name qualifier.

For related reasons, these productions in §4.3:

ClassOrInterfaceType:

	ClassType

	InterfaceType

ClassType:

	TypeName

InterfaceType:

	TypeName

were changed to:

ClassOrInterfaceType:

	Name

ClassType:

	ClassOrInterfaceType

InterfaceType:

	ClassOrInterfaceType