你好,我正在尝试实现一个解析器,用于处理一个语法结构简单的语言。
program ::= "program" declarations "begin" statements "end"
declaration ::= "var" ident "as" type
type ::= "string" | "int"
我已经完成前两项,我该如何编写类型语法?
program( prog( DECLS, STATS ) ) -->
[ 'program' ], declarations( DECLS ),
[ 'begin' ], statements( STATS ), [ 'end' ].
declaration( decl( IDENT, TYPE ) ) -->
[ 'var' ], ident( IDENT ), [ 'as' ], type( TYPE ).