The LanguageThe language is based on the fragments in Chapter 6: expressions, arrays,boolean expressions, statements, declarations, blocks:P  ->  { DD SS }DD ->  e | DD D | DD  ->  T id ;T  ->  T [ num ] | int | float | char | boolSS ->  e | SS S | SS  ->  L = E ; | if ( B ) S | if ( B ) S else S | while ( B ) S   |   do S while ( B ) ; | break ; | { DD SS }B  ->  B or B | B and B | ! B | ( B ) | E rel E | true | falseE  ->  E + E | E - E | E * E | E / E | L | ( B ) | numL  ->  L [ B ] | idPackage lexerclass Tag. Tags distinguish tokens.class Token with subclasses Num, Real, and Wordclass Lexer, with procedure scanPackage symbolsclass Type.  Put types here.class Id.  Could have put Id's with expressions; in fact Id extends Exprclas Env.  Linked symbol tables.Package inter for intermediate codeFor simplicity, the front end builds syntax trees.  Three-address code isemitted during a subsequent pass.  We generate short-circuit code forboolean expressions.An optimizing compiler would presumably create intermediate-code objectsrather than emitting strings.  Further, Chapter 9 has examples with codethat might be produced by backpatching -- that's a variant to be exploredseparately.Package parserAt one point, I had the parser and lexer in one package, called syntax.The parser is kept separate for readability.  We can present the lexerearly -- the parser "touches" the other packages, so it's best presentedlater.Directories tests and tmpThe makefile automatically runs a compiled front end on tests, presumedto be in files ending in ".t"; for example, prog0.t is the quicksortfragment from the running example in Chapter 9.  The expected output isin a file ending in ".i"; for example, prog0.i.To distinguish between multiple declarations of the same name, uncommentthe line//	public String toString() {return "" + op.toString() + offset;}in class Id in package inter.  The intermediate code will then print theoffset as a suffix to an identifier.