next | previous | forward | backward | up | top | index | toc | Macaulay2 website
HyperplaneArrangements :: Classic (missing documentation)

Classic -- a parser for classic Macaulay syntax

Description

This package provides a parser for polynomials in the classic Macaulay format. Some users prefer it, for ease and speed of typing polynomials, ideals, and matrices.

Only ring variables that are single letters, or single letters indexed by a sequence of numbers can be handled with this parser.

The rules for creating polynomials using the classic parser include:

The source code for this parser is relatively short, since it is based on the package Parsing. Here it is.

export "poly"
symbolP = (x -> (
          if not isGlobalSymbol x then error("symbol ",x," undefined");
          getGlobalSymbol x)) % letterParser
seqP = (comma, parser) -> prepend % parser @ * (last % comma @ parser)
variableP = value % symbolP
intP = NNParser | variableP
subscriptP = ((lb,x,rb) -> x) % andP( "[", unsequence % seqP_"," intP, "]" )
ringVariableP = ((x,n) -> value if n === nil then x else x_n) % 
                symbolP @ optP subscriptP
numberP = ZZParser | QQParser
powerP = ((x,n) -> if n === nil then x else x^n) % 
         (futureParser parenExprP | ringVariableP) @ optP NNParser
monomialP = times @@ deepSplice % 
            optionalSignParser @ (numberP @ *powerP | +powerP )
polyP = plus @@ deepSplice % +monomialP | terminalParser 0
parenExprP = ((l,x,r) -> x) % andP("(", futureParser parenExprP | polyP, ")")
listPolyP = toList % seqP_"," polyP
arrayPolyP = toList % seqP_";" listPolyP
poly = method()
polyParser = polyP : nonspaceAnalyzer
poly String :=  RingElement => x -> polyParser x
idealParser = ideal % listPolyP : nonspaceAnalyzer
ideal String := Ideal => x -> idealParser x
monomialIdealParser = monomialIdeal % listPolyP : nonspaceAnalyzer
monomialIdeal String := MonomialIdeal => x -> monomialIdealParser x
matrix String := Matrix => 
                 opts -> matrix_opts % arrayPolyP : nonspaceAnalyzer

For the programmer

The object Classic (missing documentation) is a symbol.

Menu