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parser.js
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parser.js
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// Polyhédronisme
//===================================================================================================
//
// A toy for constructing and manipulating polyhedra and other meshes
//
// Copyright 2019, Anselm Levskaya
// Released under the MIT License
// Parser Routines
//===================================================================================================
// fairly straightforward Parser Expression Grammar spec for simple
// operator-chain-on-base-polyhedra recipes
const PEG_parser_spec = `\
/* series of opspecs */
start = opspec+
/* opspec one of:
A - single letter
A3 - single letter and float
B(5,4.3,3) - function call format w. float args
*/
opspec =
let:opcode args:opargs {return {"op":let,"args":args};}
/ let:opcode float:float {return {"op":let,"args":[float]};}
/ let:opcode {return {"op":let,"args":[]};}
/*
parentheses surrounding comma-delimited list of floats i.e.
( 1 , 3.2, 4 ) or (1) or (2,3)
*/
opargs = "("
num:( float:float ","? {return float} )+
")" {return num;}
/* just a letter */
opcode = op:[a-zA-Z] {return op;}
/* standard numerical types */
int = digits:[0-9-]+ { return parseInt(digits.join(""), 10); }
float = digits:[0-9.-]+ { return parseFloat(digits.join(""), 10); }\
`;
const op_parser = PEG.buildParser(PEG_parser_spec);
//applies func fn to array args i.e. f, [1,2,3] -> f(1,2,3)
const dispatch = function(fn, args) { return fn.apply(this, args || []); };
const basemap = {
"T": tetrahedron,
"O": octahedron,
"C": cube,
"I": icosahedron,
"D": dodecahedron,
"P": prism, //takes integer arg
"A": antiprism, //takes integer arg
"Y": pyramid, //takes integer arg
"J": johnson, //takes integer arg
"U": cupola, //takes integer arg
"V": anticupola, //takes integer arg
};
const opmap = {
"d": dual,
"a": ambo,
"k": kisN,
"g": gyro,
"p": propellor,
"r": reflect,
"c": chamfer,
"w": whirl,
"n": insetN, //-->needle
"x": extrudeN,
"l": loft,
"P": perspectiva1,
"q": quinto,
"u": trisub,
//z --> zip
"H": hollow,
"Z": triangulate,
"C": canonicalize,
"A": adjustXYZ,
};
//unclaimed: yihfzv
// list of basic equivalences, easier to replace before parsing
const specreplacements = [
[/e/g, "aa"], // e --> aa (abbr. for explode)
[/b/g, "ta"], // b --> ta (abbr. for bevel)
[/o/g, "jj"], // o --> jj (abbr. for ortho)
[/m/g, "kj"], // m --> kj (abbr. for meta)
[/t(\d*)/g, "dk$1d"], // t(n) --> dk(n)d (dual operations)
[/j/g, "dad"], // j --> dad (dual operations) # Why not j --> da ?
[/s/g, "dgd"], // s --> dgd (dual operations) # Why not s --> dg ?
[/dd/g, ""], // dd --> null (order 2)
[/ad/g, "a"], // ad --> a (a_ = ad_)
[/gd/g, "g"], // gd --> g (g_ = gd_)
[/aO/g, "aC"], // aO --> aC (for uniqueness)
[/aI/g, "aD"], // aI --> aD (for uniqueness)
[/gO/g, "gC"], // gO --> gC (for uniqueness)
[/gI/g, "gD"]]; // gI --> gD (for uniqueness)
const getOps = function(notation) {
let expanded = notation;
for (let [orig,equiv] of specreplacements) {
expanded = expanded.replace(orig,equiv);
}
console.log(`${notation} executed as ${expanded}`);
return expanded;
};
// create polyhedron from notation
const newgeneratePoly = function(notation) {
//poly = new polyhedron()
const ops_spec = getOps(notation);
const oplist = op_parser.parse(ops_spec).reverse();
let op = oplist.shift();
const basefunc = basemap[op["op"]];
const baseargs = op["args"];
let poly = dispatch(basefunc, baseargs);
for (op of oplist) {
const opfunc = opmap[op["op"]];
const opargs = [poly].concat(op["args"]);
poly = dispatch(opfunc, opargs);
}
// Recenter polyhedra at origin (rarely needed)
poly.vertices = recenter(poly.vertices, poly.edges());
poly.vertices = rescale(poly.vertices);
// Color the faces of the polyhedra for display
poly = paintPolyhedron(poly);
// return the poly object
return poly;
};