19.1.1

Problem #1: Names Too Specific

LALR(1) GRAMMAR

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

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